Human body– this is a perfect, clearly working, well-coordinated biological mechanism. Each cellular structure, tissue, organ system, and metabolite is required for specific purposes and in specific quantities.
The compounds produced by our body include biological substances that perform a lot of important functions: protective and regulatory. The volume, composition, color and other characteristics released can indicate whether a person is healthy or should consider visiting a doctor. The most significant essences are breast milk, colostrum, blood, sperm, saliva, urine, vaginal secretions, as well as cerebrospinal fluid, which will be discussed today.
Cerebrospinal fluid (CSF, or CSF) is a liquid medium that fills the space in the ventricles of the brain, flows along the liquor pathway, and circulates in the subarachnoid segment. Alternative name –liquor.
The synthesis and release of the substance is due to the process of filtration of plasma (the liquid part of the blood) through the capillary wall and the subsequent secretion of substances into exudate from ependymal and secretory cellular structures.
If there is any pathological condition with a violation of the integrity and structure of the bone and soft fabric cranium, then it arisesliquorrhea– discharge of cerebrospinal fluid from the ears, nose or defective, damaged areas of the skull and spine. Probable reasons:
traumatic brain injury;
hernial tumors or tumors;
carelessness of medical manipulations;
postoperative suture weakness.
Any deviation from the norm in the functioning of the organ system affects the density, transparency and quantity of the secreted substance, therefore some pathologies can be determined by its condition.
Like every substance in the human body, CSF performs many vital functions:
Mechanical protection. Providing a shock-absorbing effect during sudden movements or head impacts - equalizing intracranial pressure,cerebrospinal fluidprotects the brain from damage, ensuring its integrity and normal functioning even in traumatic situations.
Excretion of metabolites. Some substances can accumulate in the brain space, which will negatively affect its functioning - the cerebrospinal fluid is responsible for their release (excretion) and outflow.
Transport of necessary connections. Hormones, biologically active substances and metabolites that are responsible for central performance are transported to the gray matter using the cerebrospinal substance.
Breathing (performing respiratory function). Neuronal clusters that are responsible for respiratory function of the body, are located at the very bottom of the fourth ventricle of the brain and are washed by cerebrospinal fluid. If you slightly change the component ratio (for example, increase the concentration of potassium or sodium ions), a change in the amplitude and frequency of inhalations/exhalations will follow.
Acting as a regulator, stabilizing structure for the central nervous system. It is the CSF that maintains a certain acidity, salt and cation-anion composition, and constant osmotic pressure in the tissues.
Maintaining a stable brain environment. This barrier must be practically insensitive to changes in the chemical composition of the blood, so that the brain continues to work even when a person is sick or struggling with pathology.
The work of natural immunoregulators. Assess condition nervous system and it will be possible to trace the course of diseases only with the help of detailed analysis punctate, the study of which will help clarify the diagnosis or predict the patient’s health status.
Cerebrospinal substance is produced, on average, at a rate of about 0.40-0.45 ml per minute (in an adult). The volume, rate of production, and most importantly, the component composition of CSF directly depends on the metabolic activity and age of the body. Typically, tests show that the older a person is, the more reduced production is.
This substance is synthesized from the plasma part of the blood, however, both the substrate and the producer differ significantly in ionic and cellular content. Main components:
Protein.
Glucose.
Cations: sodium, potassium, calcium and magnesium ions.
Anions: chloride ions.
Cytosis (presence of cells in the cerebrospinal fluid).
An increased content of protein and cell aggregates indicates a deviation from the norm, which means it is a condition that requires further tests and mandatory consultation with the attending physician.
The study of cerebral spinal puncture is a method that is used to identify and diagnose various disorders of the brain structures and membranes, the central nervous system. Such pathologies include:
meningitis, tuberculous meningitis;
inflammatory processes in the membrane;
tumor formations;
encephalitis;
syphilis.
Carrying out the procedure for analyzing and studying SM fluid requires taking a sample as a punctate from the lumbar region spinal cord. The collection is made through a small puncture in the desired area of the spine.
A complete analysis of CSF includes macroscopic and microscopic examination, as well as cytology, biochemistry, bacterioscopy and bacterial culture on a nutrient medium.
The spinal tap will be examined according to several parameters:
Transparency.
The cerebrospinal fluid of a healthy person is absolutely transparent, like clean water, therefore, during macroscopic analysis it is compared with a standard - distilled highly purified water in good lighting. If the sample taken is not clear enough or there is a strong, obvious cloudiness, then there is a reason to look for the disease. After detecting a discrepancy with the standard, the test tube is sent to a centrifuge - the procedure will determine the nature of the turbidity:
If the sample is still cloudy after centrifugation, this indicates bacterial contamination.
If the sediment sank to the bottom of the flask, then the turbidity was caused by blood cells or other cells.
Color.
Liquor produced by a healthy body should be absolutely colorless. The change indicates the presence of any compounds in it that normally should not be there - many pathological conditions of the body are provoked by xanthochromia of the CSF, that is, its coloring in shades of red and orange. Xanthochromia is caused by the presence of hemoglobin and its species in the sample, for example:
yellowishness - the presence of bilirubin fraction, released during the breakdown of hemoglobin;
light pink, red-pink shading indicates oxyhemoglobin (hemoglobin saturated with oxygen) in the cerebrospinal fluid;
orange shades – the sample contains bilirubin compounds that appear as a result of the breakdown of oxyhemoglobin;
brown colors - reflect the presence of methemoglobin (an oxidized form of hemoglobin) - this condition is observed in tumor phenomena, strokes;
cloudy green, olive - the presence of pus during purulent meningitis or after opening an abscess.
redness reflects the presence of blood.
If a little ichor gets into the sample during punctate collection, then such a mixture is considered a “travel” and does not affect the result of macroscopic analysis. Such an admixture is not observed throughout the entire volume of the punctate, but only on top. Impurities can be pale pink, cloudy pink or grayish pink.
The xtanochromic intensity of the sample is assessed according to the “pluses” set by the laboratory assistant during visual assessment:
first degree (weak).
second degree (moderate).
third degree (strong).
fourth degree (excessive).
Blood fractions or strong saturation of the punctate suggest one of the diagnoses: rupture of aneurysm vessels and subsequent intracranial hemorrhage, hemorrhagic encephalitis or stroke, moderate and severe TBI, hemorrhage in the brain tissue.
Cytology.
The state of the cerebrospinal fluid of a healthy person allows for a slight content of cells, but within the established values.
Leukocytes in one cubic mm:
up to 6 units (in adults);
up to 8-10 units (in children);
up to 20 units (in infants and toddlers up to 10 months).
There should be no plasma cells. The presence indicates infectious diseases central nervous system: multiple sclerosis, encephalitis, meningitis or recovery after surgery with a wound that has not healed for a long time.
Monocytes are observed in numbers up to 2 per cubic mm. If the number increases, then this is a reason to suspect a chronic pathology of the central nervous system: ischemia, neurosyphilis, tuberculosis.
The neutrophil component is present only during inflammatory processes, altered forms are present during recovery from inflammation.
Granular macrophage cells can only be present in the CSF when the body's brain tissue is disintegrating, as in the case of a tumor. Epithelial cells enter the punctate only if a tumor of the central nervous system develops.
In addition to the constituent components, transparency and color characteristics,normal cerebrospinal fluidmust correspond to other indicators: reaction of the environment, number of cells, chlorides, glucose, protein, maximum cytosis, absence of antibodies, etc.
Deviation from the given indicators can serve asidentifierdiseases - for example, immunoglobulins andantibodiesoligoclonal type in a specimen may indicate the presence or risk of developing multiple sclerosis.
Protein in liquor: lumbar – 0.21-0.33 g/liter, ventricular – 0.1-0.2 g/liter.
Pressure in the range of 100-200 mm water column. (sometimes they indicate values of 70-250 mm - in countries outside the post-Soviet space).
Glucose: 2.70-3.90 mmol per liter (some sources indicate: two thirds of total plasma glucose).
CSF chloride: 116 to 132 mmol per liter.
Optimal indicators of the reaction of the environment are considered to be values in the range of 7.310 – 7.330 pH. Changes in acidity have an extremely negative impact on performance biological functions, the quality of the CSF and the speed of its flow through the cerebrospinal fluid tract.
Cytosis in the cerebrospinal fluid: lumbar – up to three units. per µl, ventricular - up to one per µl.
What should NOT be in the puncture of a healthy person?
Antibodies and immunoglobulins.
Tumor, epithelial, plasma cells.
Fibrinogens, fibrinogen film.
The density of the sample is also determined. Norm:
The total density should not exceed 1.008 grams per liter.
Lumbar fragment – 1.006-1.009 g/l.
Ventricular fragment – 1.002-1.004 g/l.
Suboccipital fragment – 1.002-1.007 g/l.
The value may decrease with uremia, diabetes mellitus or meningitis, and increase with hydrocephalic syndrome (an increase in the size of the head due to the accumulation of fluid and its difficult removal).
The main disease states associated with CSF include liquorrhea, liquorodynamic imbalance, cerebral hydrocele, and increased intracranial pressure. Their development mechanism differs, as does the symptom complex.
It is the most pathogenetically simple disease, because its mechanism is clear: the integrity of the bones of the base of the skull or meninges is disrupted, which provokes the release of the spinal substance.
Depending on the symptoms and visual manifestations, liquorrhea is called:
Hidden - cerebrospinal fluid flows through the nasal passages, which is not visually noticeable due to aspiration or accidental ingestion.
Explicit - a clear liquid or mixed with ichor is intensely released from the ears, fracture sites, which is noticeable by the leakage of the bandage headband.
Also distinguished:
The primary nature of the disease - the discharge manifests itself immediately after injury, after surgery.
Secondary, or cerebrospinal fluid fistulas - leakage is observed in the later stages of severe complications of infectious diseases.
If the primary pathology is not treated for a long period of time, and then inflammation (meningitis or encephalitis) develops, then this is fraught with the development of a fistula.
Common causes of CSF leakage:
severe bruises with traumatic brain injury;
injuries and serious injuries to the spine;
complicated hydrocephalus;
hernial neoplasms and tumors in dangerous proximity or directly in the brain tissue;
inaccuracy of medical procedures - washing or draining the ENT profile;
weakness of the sutures of the dura mater after neurosurgical operations;
Spontaneous liquorrhea is very rare.
CSF dynamics are disrupted if there is difficulty or improper circulation of cerebrospinal fluid. The course of the disease can be hypertensive (associated with high blood pressure) or hypotensive (on the contrary, with low blood pressure).
Hypertensivethe form occurs when:
excessive secretion - due to the strong excitability of the choroid plexuses, which are responsible for the production of CSF;
insufficient absorption and excretion.
Liquor is produced in large quantities or is simply not absorbed, which provokes the following symptoms:
severe headaches, especially intense in the morning;
nausea, frequent gagging, periodic vomiting;
dizzy;
slow heartbeat – bradycardia;
sometimes nystagmus – frequent involuntary movements eye, “trembling” of the pupils;
symptoms characteristic of meningitis.
Hypotensivethe form occurs less frequently, with hypofunction or weak activity of the choroid plexuses, the consequence is reduced production of the liquor substance. Symptoms:
severe headache in the occipital and parietal regions;
discomfort, increased pain during sudden movements, excessive physical activity;
hypotension.
When a malfunction occurs in the body, the outflow of cerebrospinal substance and its resorption may be disruptedfrom the brain– due to this, deviations develop that manifest themselves differently in adults and children.
An adult will respond to a deviation by increasing intracranial pressure due to a strong, “overgrown” cranium. The bones of the child’s skull are immature and have not yet fused together, so excessive accumulation of spinal substance provokes hydrocephalus (dropsy) and other unpleasant manifestations.
The cranium contains not only brain tissue and a great many neurons - a significant part of the volume is occupied by CSF. Its larger share is located in the ventricles, and the smaller one washes the GM and moves between its arachnoid and soft membranes.
Intracranial pressure directly depends on the volume of the skull and the amount of fluid circulating in it. Whether the production of a substance increases or its resorption decreases, the body immediately responds to this by increasing ICP.
This indicator reflects how much the pressure inside the skull exceeds atmospheric pressure - the norm is a value from 3 to 15 mm Hg. Minor fluctuations lead to a deterioration in well-being, but an increase in ICP to 30 mm Hg. Art. already threatens to be fatal.
Manifestations of increased ICP:
constantly sleepy, low performance;
severe headaches;
deterioration of visual acuity;
forgetfulness, absent-mindedness, low concentration;
“jumps” in pressure are noticeable - hypertension is regularly replaced by hypotension;
poor appetite, nausea, vomiting;
emotional instability: mood swings, depression, apathy, severe irritability;
spinal pain;
chills;
increased sweating;
failures of respiratory activity, shortness of breath;
skin is more sensitive;
muscle paresis.
The presence of 2-3 symptoms is not a reason to suspect increased ICP, but an almost complete complex is a good reason to consult a specialist.
The clearest sign of the disease is a girdling headache that is not expressed in any particular area. Coughing, sneezing and sudden movements only provoke increased pain, which are not relieved even by analgesics.
Second important sign increased ICP - vision problems. The patient suffers from double vision (diplopia), notices deterioration of vision in the dark and in bright light, sees as if in a fog and suffers from attacks of blindness.
Blood pressure may also increase healthy body, however, it immediately returns to normal - for example, during physical and emotional stress, stress, coughing or sneezing.
Young children cannot report how they are feeling, so parents must be able to identify a violation of the cerebrospinal fluid outflow by the external signs and behavior of the baby. These include:
noticeable vascular network on the skin of the forehead, neck;
restlessness at night, poor sleep;
frequent crying;
vomit;
protrusion of the fontanel, its pulsation;
convulsions;
increase in head size;
uneven muscle tone - some are tense and some are relaxed.
The most serious sign increased ICPin a childis hydrocephalus, which occurs with a frequency of up to one case in a couple of thousand newborns. Male babies suffer from dropsy of the brain more often, and the defect itself is usually diagnosed by doctors during the first 3 months of life.
“Cerebral hydrocephalus”, as an independent disease, should not be confused with the diagnosis of “hypertensive-hydrocephalic syndrome”. It reflects that the newborn has a slightly increased ICP, but this does not require therapy or surgery, since it resolves itself.
The childhood form of the disease can be congenital or acquired, depending on the cause of development, of which, according to medical experts, there can be up to 170. The congenital disease is provoked by:
injury to the child during childbirth;
hypoxia during childbirth (insufficient oxygen supply);
genetic failures;
infectious diseases transmitted by the fetus while in the womb (cytomegalopathy, acute respiratory viral infections, mycoplasma and toxoplasma infections, syphilis, rubella, mumps and herpesvirus).
Genetic abnormalities causing the congenital form:
underdeveloped cerebrospinal fluid ducts;
Chiari syndrome - the child’s skull is larger in volume than his brain;
narrowed liquor duct;
other chromosomal pathologies.
The acquired form occurs as a result of toxic poisoning, the development of tumors, cerebral hemorrhages, infectious diseases outside the mother's womb - these include otitis media, meningitis and encephalitis.
Speaking about hydrocephalus in newborns, it is worth considering that normally the head circumference of babies increases quite quickly (one and a half centimeters per month), however, if the growth exceeds the indicators, then this is a good reason to examine the child.
The baby’s skull is soft, not yet ossified, and excess cerebrospinal fluid slows down the overgrowth of the fontanel, “spreads apart” the bones and prevents normal development cranium - because of this, the head grows disproportionately. Piling upin the subarachnoid space, which separates the meninges, the cerebrospinal fluid compresses some parts of the brain. Despite the pliability of children's cranial bones, this manifestation of the disease is dangerous and requires immediate treatment. An increase in head size is not the only sign of obstructed liquor outflow in children. Characteristic is:
the specific sound of a “broken pot”, heard when lightly tapping the skull;
difficulty raising and holding the head in one position;
trembling of the chin, hands.
It is important to pay attention to the baby’s eyes, because some signs are indicative:
involuntary, chaotic eye movements;
occasional eye rolling;
eyes “squint”;
“setting sun” syndrome - when blinking, a thin white stripe is noticeable between the pupil and the upper eyelid.
Hydrocephalus up to 2 years of age is manifested by this symptom complex, and later it is combined with vomiting, nausea, problems with coordination, irritability, diplopia or even blindness.
Sometimes hydrocephalic syndrome develops in adults as a consequence of previous infections, but this is a rare occurrence.
The pathology of liquor outflow in a baby is usually learned from a neurologist, whose examination takes place in the first month after birth. Primary examination and identifying the signs requires medical correction, since this disease will interfere with the normal development of the child.
If the condition little patient complex, then specialists use surgical intervention to create “bypass paths” for the CSF and eliminatepoor churnartificially. If the situation does not threaten the baby’s life, treatment can also take place at home with drug therapy. In order to prescribe the optimal medications for a child, it is necessary to understandwhat can interfere with the outflow of cerebrospinal fluid with hydrocephalus. The cause, origin and complications - all factors will play a role in the selection of treatment.
Pharmacological correctionoutflow disordersin children includes:
drugs that improve and stimulate blood flow (Actovegin, Pantogam, Cinnarizine);
medications that help remove excess fluid (Triampur or Diakarb);
neuroprotective drugs (Ceraxon).
Children's diseases of cerebrospinal fluid dynamics are most often corrected by pharmacotherapy, but adults need to be prescribed physiological procedures:
A course of electrophoresis with aminophylline (ten visits) - drug “recharge” will activate the delivery of oxygen to brain tissue suffering from hypoxia with increased ICP. The condition of the vessels returns to normal, which will ensure normal resorption.
15 sessions of massage of the collar area - the procedure is simple, so over time the patient can carry out a similar manipulation himself. With its help, muscle hypertonicity is reduced, spasm is relieved and outflow is improved.
Magnetic influence on collar area– reduction of swelling and vascular spasm, improvement of innervation.
Therapeutic swimming or supportive exercise. charger.
A developing area in medicine is craniosacral osteopathy. The condition and composition of the cerebrospinal fluid can determine many ailments in the body. Mediators that regulate:
respiratory activity;
sleep and wakefulness patterns;
stability of endocrine systems;
work of the cardiovascular complex.
For normal human functioning, cerebrospinal fluid must continuously circulate along its “path” and maintain component constancy. The slightest violation of the integrity of the cranial sutures leads to pinching of a section of brain tissue, then the effect spreads to the underlying structures.
Craniosacral osteopathy is desirable after serious bruises, road accidents, traumatic brain and birth injuries. Consultation with a specialist will allow you to identify the disease at an early stage, and this is especially important for infants. Plastic disorders of the craniosacral system of a newborn directly affect the subsequent development of cognitive functions, the central nervous system and the musculoskeletal system.
Adults complain of nystagmus, visual and breathing disorders, decreased ability to remember information, concentrate on the subject of thought, disruptions in the menstrual cycle, sudden changes in weight, psycho-emotional instability, intense tearing, salivation and sweating. Typically, such complaints are attributed to other diseases, but an experienced osteopathic doctor will be able to conduct a thorough analysis of the patient’s condition, his skull and spine, after which he will find out and eliminate the original cause.
When the circulation of cerebrospinal fluid is disrupted, many symptoms appear that are very difficult to attribute to one or another pathology of the spine. for example, I recently had an appointment elderly woman, who complained of pain in her legs that appeared at night. The feeling is very unpleasant. My legs are twisting and I feel numbness. Moreover, they appear from the right, then from the left, then from both sides. In order to remove them, you need to get up and walk around for a few minutes. The pain goes away. During the day these pains do not bother me.
MRI shows multiple spinal canal stenosis with signs of impaired cerebrospinal fluid circulation. Red arrows indicate areas of narrowing of the spinal canal; yellow arrows indicate expanded cerebrospinal fluid spaces inside the dural sac.
An MRI examination revealed signs of spondylosis (osteochondrosis) and several levels of spinal canal stenosis in the lumbar region, not very pronounced, but clearly disrupting the cerebrospinal fluid circulation in this area. Dilated veins of the spinal canal are visible. Therefore there is stagnation venous blood. These two problems give rise to the symptoms listed above. When a person lies down, the outflow of blood between the zones and compression of the dural sac with the roots is hampered, venous pressure increases and the absorption of cerebrospinal fluid slows down. This leads to an isolated increase in cerebrospinal fluid pressure, overstretching of the dura mater and ischemia of the spinal cord roots. That's why it appears pain syndrome. As soon as a person gets up, venous blood is discharged, the absorption of cerebrospinal fluid in the venous plexuses increases and the pain disappears.
Other common problem associated with impaired circulation of cerebrospinal fluid appears when the spinal canal narrows at the level cervical spine spine. Obstruction of the outflow of cerebrospinal fluid leads to an increase in cerebrospinal fluid pressure in the cranial cavity, which can be accompanied by headaches that intensify when turning the head, coughing, or sneezing. Often these pains occur in the morning and are accompanied by nausea and vomiting. Patients experience a feeling of pressure on eyeballs, vision decreases, tinnitus appears. And the longer the zone of spinal cord compression, the more pronounced these symptoms are. We will talk about the treatment of these problems further in the following posts. But in addition to increasing intracranial pressure, stenosis at the cervical level creates another problem. Spinal cord nutrition and supply are disrupted nerve cells oxygen. A local pre-stroke state occurs. It is also called myeloptic syndrome. MRI studies make it possible, under certain conditions, to see these damaged areas of the brain. In the next image, the myelopathic focus is visible as a whitish spot in the area of maximum compression of the spinal cord.
MRI of a patient with narrowing of the spinal canal (indicated by arrows) at the level of the cervical spine. Clinically, in addition to the myelopathic process (more details in the following posts), there are signs of impaired cerebrospinal fluid circulation, accompanied by an increase in intracranial pressure.
There are other miracles. In a number of patients, sometimes without apparent reason, pain appears in thoracic region spine. These pains are usually constant, worsening at night. During an MRI study in normal modes There are no signs of compression of the spinal cord or roots. However, with a more in-depth study in special modes, you can see areas of obstructed circulation of cerebrospinal fluid in the subarachnoid spaces (between the membranes of the spinal cord). They are also called centers of turbulence. If such foci exist for a long time, sometimes the arachnoid membrane, under which the cerebrospinal fluid circulates, can encyst due to constant irritation and turn into a cerebrospinal fluid cyst, which can lead to compression of the spinal cord.
On an MRI of the thoracic spine, arrows indicate areas with obstructed cerebrospinal fluid circulation.
A special problem is the appearance of a cerebrospinal fluid cyst in the spinal cord. This is the so-called syringomyelitic cyst. These problems occur quite often. The cause may be a violation of the formation of the spinal cord in children or various compression of the spinal cord by the cerebellar tonsils, tumor, hematoma, inflammatory process, injury. And such cavities are formed inside the spinal cord due to the fact that inside it there is a spinal canal, or central canal, through which cerebrospinal fluid also circulates. The circulation of cerebrospinal fluid within the spinal cord contributes to its normal functioning. Moreover, it connects to the cisterns of the brain and the subarachnoid space of the lumbar spine. It is a reserve pathway for equalizing cerebrospinal fluid pressure in the ventricles of the brain, spinal cord and subarachnoid spaces. Normally, the cerebrospinal fluid moves through it from top to bottom, but when unfavorable factors appear in the subarachnoid space (in the form of compression), it can change its direction.
On MRI, the red arrow indicates the area of compression of the spinal cord with symptoms of myelopathy, and the yellow arrow indicates a formed intracerebral cyst of the spinal cord (syringomyelitic cyst).
HISTORICAL SKETCH OF THE STUDY OF cerebrospinal fluid
The study of cerebrospinal fluid can be divided into two periods:
1) before extracting fluid from a living person and animals and
2) after its removal.
First period is essentially anatomical and descriptive. Physiological prerequisites were then mainly speculative in nature, based on the anatomical relationships of those formations of the nervous system that were in close connection with liquid. These findings were based in part on studies conducted on cadavers.
During this period, a lot of valuable data was already obtained concerning the anatomy of the cerebrospinal fluid spaces and some issues of the physiology of the cerebrospinal fluid. We first find a description of the meninges in Herophilus of Alexandria (Herophile), in the 3rd century BC. e. who gave the name to the dura mater and pia mater and discovered the network of blood vessels on the surface of the brain, the sinuses of the dura mater and their fusion. In the same century, Erasistratus described the ventricles of the brain and the openings connecting the lateral ventricles with the third ventricle. Later these holes were given the name Monroe's.
The greatest merit in the field of studying the cerebrospinal fluid spaces belongs to Galen (131-201), who was the first to describe in detail the meninges and ventricles of the brain. According to Galen, the brain is surrounded by two membranes: soft (membrana tenuis), adjacent to the brain and containing a large number of vessels, and dense (membrana dura), adjacent to some parts of the skull. The soft membrane penetrates the ventricles, but the author does not yet call this part of the membrane the choroid plexus. According to Galen, the spinal cord also has a third membrane that protects the spinal cord during spinal movements. Galen denies the presence of a cavity between the membranes in the spinal cord, but suggests that it exists in the brain due to the fact that the latter pulsates. The anterior ventricles, according to Galen, communicate with the posterior (IV). The ventricles are cleansed of excess and foreign substances through openings in the membranes leading to the mucous membrane of the nose and palate. Describing in some detail the anatomical relationships of the membranes in the brain, Galen, however, did not find fluid in the ventricles. In his opinion, they are filled with a certain animal spirit (spiritus animalis). It produces the moisture observed in the ventricles from this animal spirit.
Further work on the study of cerebrospinal fluid and cerebrospinal fluid spaces dates back to a later time. In the 16th century, Vesalius described the same membranes in the brain as Galen, but he pointed to plexuses in the anterior ventricles. He also did not find any fluid in the ventricles. Varolius was the first to establish that the ventricles are filled with fluid, which he thought was secreted by the choroid plexus.
A number of authors then mention the anatomy of the membranes and cavities of the brain and spinal cord and cerebrospinal fluid: Willis (17th century), Vieussen (17th-18th century), Haller (18th century). The latter assumed that the IV ventricle is connected to the subarachnoid space through the lateral openings; later these holes were called Luschka's holes. The connection of the lateral ventricles with the third ventricle, regardless of the description of Erasistratus, was established by Monroe (Monroe, 18th century), whose name was given to these openings. But the latter denied the presence of holes in the IV ventricle. Pacchioni (18th century) gave a detailed description of granulations in the sinuses of the dura mater, which were later named after him, and suggested their secretory function. The descriptions of these authors dealt mainly with ventricular fluid and the connections of the ventricular containers.
Cotugno (1770) was the first to discover the external cerebrospinal fluid in both the brain and the spinal cord and gave a detailed description of the external cerebrospinal fluid spaces, especially in the spinal cord. In his opinion, one space is a continuation of another; the ventricles are connected to the intrathecal space of the spinal cord. Cotugno emphasized that the fluids of the brain and spinal cord are the same in composition and origin. This fluid is secreted by small arteries, absorbed into the veins of the dura mater and into the sheaths of the II, V and VIII pairs of nerves. Cotugno's discovery was, however, forgotten, and the cerebrospinal fluid of the subarachnoid spaces was described for the second time by Magendie (Magendie, 1825). This author described in some detail the subarachnoid space of the brain and spinal cord, the cerebral cisterns, the connections between the arachnoid membrane and the pia mater, and the perineural arachnoid sheaths. Magendie denied the presence of Bichat's canal, through which the ventricles were supposed to communicate with the subarachnoid space. Through experiment he proved the existence of a hole in lower section The fourth ventricle is under the writing pen, through which the ventricular fluid penetrates into the posterior receptacle of the subarachnoid space. At the same time, Magendie made an attempt to find out the direction of fluid movement in the cavities of the brain and spinal cord. In his experiments (on animals), a colored liquid, introduced under natural pressure into the posterior cistern, spread through the subarachnoid space of the spinal cord to the sacrum and in the brain to the frontal surface and into all ventricles. Magendie rightfully takes the leading place in the detailed description of the anatomy of the subarachnoid space, ventricles, connections between the membranes, as well as in the study of the chemical composition of the cerebrospinal fluid and its pathological changes. However, the physiological role of cerebrospinal fluid remained unclear and mysterious for him. His discovery was not fully recognized at the time. In particular, his opponent was Virchow, who did not recognize free communications between the ventricles and subarachnoid spaces.
After Magendie, a significant number of works appeared, mainly relating to the anatomy of the cerebrospinal fluid spaces and partly the physiology of the cerebrospinal fluid. In 1855, Luschka confirmed the presence of an opening between the fourth ventricle and the subarachnoid space and gave it the name foramen Magendie. In addition, he established the presence of a pair of holes in the lateral bays of the fourth ventricle, through which the latter freely communicates with the subarachnoid space. These holes, as we noted, were described much earlier by Haller. Luschka's main merit lies in his detailed study of the choroid plexus, which the author considered to be a secretory organ producing cerebrospinal fluid. In the same works, Lyushka gives a detailed description of the arachnoid membrane.
Virchow (1851) and Robin (1859) study the walls of the vessels of the brain and spinal cord, their membranes and indicate the presence of cracks around the vessels and capillaries of larger caliber, located outward from the own adventitia of the vessels (the so-called Virchow-Robin fissures). Quincke, injecting red lead into dogs into the arachnoid (subdural, epidural) and subarachnoid spaces of the spinal cord and brain and examining the animals some time after the injections, established, firstly, that there is a connection between the subarachnoid space and the cavities of the brain and spinal cord and , secondly, that the movement of liquid in these cavities goes in opposite directions, but more powerful - from bottom to top. Finally, Kay and Retzius (1875) in their work gave a fairly detailed description of the anatomy of the subarachnoid space, the relationships of the membranes with each other, with vessels and peripheral nerves, and laid the foundations for the physiology of the cerebrospinal fluid, mainly in relation to the paths of its movement. Some provisions of this work have not lost their value to this day.
Domestic scientists have made a very significant contribution to the study of the anatomy of the cerebrospinal fluid spaces, cerebrospinal fluid and related issues, and this study was closely related to the physiology of formations associated with the cerebrospinal fluid. Thus, N.G. Kvyatkovsky (1784) mentions in his dissertation about cerebral fluid in connection with its anatomical and physiological relationships with nervous elements. V. Roth described thin fibers extending from the outer walls of brain vessels that penetrate the perivascular spaces. These fibers are found in vessels of all calibers, up to capillaries; the other ends of the fibers disappear into the mesh structure of the spongiosa. Roth views these fibers as the lymphatic reticulum, in which the blood vessels are suspended. Roth discovered a similar fibrous network in the epicerebral cavity, where fibers extend from the inner surface of the intimae piae and are lost in the reticular structure of the brain. At the junction of the vessel and the brain, fibers originating from the pia are replaced by fibers originating from the adventitia of the vessels. These observations by Roth were partially confirmed in the perivascular spaces.
S. Pashkevich (1871) gave a fairly detailed description of the structure of the dura mater. I.P.Merzheevsky (1872) established the presence of holes in the poles of the lower horns of the lateral ventricles, connecting the latter with the subarachnoid space, which was not confirmed by later studies by other authors. D.A. Sokolov (1897), performing a series of experiments, gave a detailed description of the Magendie foramen and the lateral openings of the IV ventricle. In some cases, Sokolov did not find the foramen of Magendie, and in such cases the connection of the ventricles with the subarachnoid space was carried out only by the lateral foramina.
K. Nagel (1889) studied blood circulation in the brain, brain pulsation and the relationship between blood fluctuations in the brain and cerebrospinal fluid pressure. Rubashkin (1902) described in detail the structure of the ependyma and subependymal layer.
To summarize the historical review of cerebrospinal fluid, the following can be noted: the main work concerned the study of the anatomy of the cerebrospinal fluid containers and the detection of cerebrospinal fluid, and this took several centuries. The study of the anatomy of the cerebrospinal fluid containers and the routes of movement of the cerebrospinal fluid made it possible to make a lot of valuable discoveries, to give a number of descriptions that are still unshakable, but partially outdated, requiring revision and a different interpretation in connection with the introduction of new, more subtle methods into research. As for physiological problems, they were touched on incidentally, based on anatomical relationships, and mainly on the place and nature of the formation of cerebrospinal fluid and the paths of its movement. The introduction of the method of histological research has greatly expanded the study of physiological problems and brought a number of data that have not lost their value to this day.
In 1891, Essex Winter and Quincke first extracted cerebrospinal fluid from humans by lumbar puncture. This year should be considered the beginning of a more detailed and more fruitful study of the composition of cerebrospinal fluid under normal and pathological conditions and more complex issues physiology of cerebrospinal fluid. From the same time, the study of one of the significant chapters in the doctrine of cerebrospinal fluid began - the problem of barrier formations, metabolism in the central nervous system and the role of cerebrospinal fluid in metabolic and protective processes.
GENERAL INFORMATION ABOUT CSF
Liquor is a liquid medium circulating in the cavities of the ventricles of the brain, the cerebrospinal fluid ducts, and the subarachnoid space of the brain and spinal cord. The total content of cerebrospinal fluid in the body is 200 - 400 ml. Cerebrospinal fluid is contained mainly in the lateral, III and IV ventricles of the brain, the aqueduct of Sylvius, the cisterns of the brain and in the subarachnoid space of the brain and spinal cord.
The process of liquor circulation in the central nervous system includes 3 main parts:
1) Production (formation) of cerebrospinal fluid.
2) Circulation of cerebrospinal fluid.
3) Outflow of cerebrospinal fluid.
The movement of cerebrospinal fluid is carried out progressively and oscillatory movements, leading to its periodic updating, occurring at different speeds (5 - 10 times a day). What depends on a person’s daily routine, the load on the central nervous system and fluctuations in the intensity of physiological processes in the body.
Distribution of cerebrospinal fluid.
The distribution figures for cerebrospinal fluid are as follows: each lateral ventricle contains 15 ml of cerebrospinal fluid; III, IV ventricles together with the Sylvian aqueduct contain 5 ml; cerebral subarachnoid space - 25 ml; spinal space - 75 ml of cerebrospinal fluid. In infancy and early childhood, the amount of cerebrospinal fluid fluctuates between 40 - 60 ml, in children younger age 60 - 80 ml, in older children 80 - 100 ml.
The rate of formation of cerebrospinal fluid in humans.
Some authors (Mestrezat, Eskuchen) believe that the liquid can be renewed 6-7 times during the day, other authors (Dandy) believe that it can be renewed 4 times. This means that 600 - 900 ml of cerebrospinal fluid are produced per day. According to Weigeldt, its complete exchange takes place within 3 days, otherwise only 50 ml of cerebrospinal fluid is formed per day. Other authors indicate figures from 400 to 500 ml, others from 40 to 90 ml of cerebrospinal fluid per day.
Such different data are explained primarily by different methods for studying the rate of cerebrospinal fluid formation in humans. Some authors obtained results by introducing permanent drainage into the cerebral ventricle, others by collecting cerebrospinal fluid from patients with nasal liquorrhea, and others calculated the rate of resorption of paint injected into the cerebral ventricle or resorption of air introduced into the ventricle during encephalography.
In addition to various methods, attention is drawn to the fact that these observations were carried out under pathological conditions. On the other hand, the amount of cerebrospinal fluid produced in a healthy person undoubtedly fluctuates depending on a number of different reasons: the functional state of higher nerve centers and visceral organs, physical or mental stress. Consequently, the connection with the state of blood and lymph circulation at any given moment depends on the nutritional conditions and fluid intake, hence the connection with the processes of tissue metabolism in the central nervous system in various individuals, the person’s age and others, of course, affect the total amount of cerebrospinal fluid.
One of important issues is the question of the amount of released cerebrospinal fluid necessary for certain purposes of the researcher. Some researchers recommend taking 8 - 10 ml for diagnostic purposes, others - about 10 - 12 ml, and still others - from 5 to 8 ml of cerebrospinal fluid.
Of course, it is impossible to accurately establish more or less the same amount of cerebrospinal fluid for all cases, because it is necessary: a. Take into account the patient’s condition and the level of pressure in the canal; b. Be consistent with the research methods that the puncturing person must conduct in each individual case.
For the most complete study, according to modern laboratory requirements, it is necessary to have an average of 7 - 9 ml of cerebrospinal fluid, based on the following approximate calculation (it must be borne in mind that this calculation does not include special biochemical research methods):
Morphological studies1 ml
Protein determination 1 - 2 ml
Determination of globulins1 - 2 ml
Colloidal reactions1 ml
Serological reactions (Wasserman and others) 2 ml
The minimum amount of cerebrospinal fluid is 6 - 8 ml, the maximum is 10 - 12 ml
Age-related changes in cerebrospinal fluid.
According to Tassovatz, G.D. Aronovich and others, in normal, full-term children at birth, the cerebrospinal fluid is transparent, but colored yellow (xanthochromia). The yellow color of the cerebrospinal fluid corresponds to the degree of general jaundice of the infant (icteruc neonatorum). The quantity and quality of the formed elements also does not correspond to the normal cerebrospinal fluid of an adult. In addition to erythrocytes (from 30 to 60 in 1 mm3), several dozen leukocytes are found, of which 10 to 20% are lymphocytes and 60 to 80% are macrophages. Total quantity protein is also increased: from 40 to 60 ml%. When the cerebrospinal fluid stands, a delicate film is formed, similar to that found in meningitis; in addition to an increase in the amount of protein, disturbances in carbohydrate metabolism should be noted. For the first time 4 - 5 days of a newborn's life, hypoglycemia and hypoglycorrachia are often detected, which is probably due to underdevelopment nervous mechanism regulation of carbohydrate metabolism. Intracranial bleeding and especially bleeding in the adrenal glands enhance the natural tendency for hypoglycemia.
In premature babies and during difficult births accompanied by fetal injuries, even more dramatic changes in the cerebrospinal fluid are detected. For example, with cerebral hemorrhages in newborns, on the 1st day there is an admixture of blood in the cerebrospinal fluid. On the 2nd - 3rd day, an aseptic reaction from the meninges is detected: severe hyperalbuminosis in the cerebrospinal fluid and pleocytosis with the presence of erythrocytes and polynuclear cells. On the 4th - 7th day, the inflammatory reaction from the meninges and blood vessels subsides.
The total amount in children, as well as in old people, is sharply increased compared to a middle-aged adult. However, judging by the chemistry of the cerebrospinal fluid, the intensity of redox processes in the brain in children is much higher than in old people.
Composition and properties of liquor.
Cerebrospinal fluid obtained during spinal puncture, the so-called lumbar cerebrospinal fluid, is normally transparent, colorless, and has a constant specific gravity of 1.006 - 1.007; the specific gravity of cerebrospinal fluid from the ventricles of the brain (ventricular cerebrospinal fluid) is 1.002 - 1.004. The viscosity of cerebrospinal fluid normally ranges from 1.01 to 1.06. Liquor has a slightly alkaline pH of 7.4 - 7.6. Long-term storage of cerebrospinal fluid outside the body at room temperature leads to a gradual increase in its pH. The temperature of the cerebrospinal fluid in the subarachnoid space of the spinal cord is 37 - 37.5o C; surface tension 70 - 71 dynes/cm; freezing point 0.52 - 0.6 C; electrical conductivity 1.31 10-2 - 1.3810-2 ohm/1cm-1; refractometric index 1.33502 - 1.33510; gas composition (in vol%) O2 -1.021.66; CO2 - 4564; alkaline reserve 4954 vol%.
The chemical composition of cerebrospinal fluid is similar to the composition of blood serum: 89 - 90% is water; dry residue 10 - 11% contains organic and inorganic substances involved in brain metabolism. Organic substances contained in cerebrospinal fluid are represented by proteins, amino acids, carbohydrates, urea, glycoproteins and lipoproteins. Inorganic substances - electrolytes, inorganic phosphorus and trace elements.
The protein of normal cerebrospinal fluid is represented by albumin and various fractions of globulins. The content of more than 30 different protein fractions in the cerebrospinal fluid has been established. The protein composition of cerebrospinal fluid differs from the protein composition of blood serum by the presence of two additional fractions: prealbumin (X-fraction) and T-fraction, located between the fractions and -globulins. The prealbumin fraction in the ventricular cerebrospinal fluid is 13-20%, in the cerebrospinal fluid contained in the cistern magna 7-13%, in the lumbar cerebrospinal fluid 4-7% of total protein. Sometimes the prealbumin fraction in the cerebrospinal fluid cannot be detected; since it can be masked by albumin or, with a very large amount of protein in the cerebrospinal fluid, be completely absent. The Kafka protein coefficient (the ratio of the number of globulins to the number of albumins), which normally ranges from 0.2 to 0.3, has diagnostic significance.
Compared with blood plasma, cerebrospinal fluid contains a higher content of chlorides and magnesium, but a lower content of glucose, potassium, calcium, phosphorus and urea. Maximum quantity sugar is contained in the ventricular cerebrospinal fluid, the smallest in the cerebrospinal fluid of the subarachnoid space of the spinal cord. 90% of sugar is glucose, 10% dextrose. The concentration of sugar in the cerebrospinal fluid depends on its concentration in the blood.
The number of cells (cytosis) in the cerebrospinal fluid normally does not exceed 3-4 in 1 μl; these are lymphocytes, arachnoid endothelial cells, ependymal ventricles of the brain, polyblasts (free macrophages).
The pressure of the cerebrospinal fluid in the spinal canal with the patient lying on his side is 100-180 mm of water. Art., in a sitting position it rises to 250 - 300 mm of water. Art., In the cerebellocerebral (in the large) cistern of the brain, its pressure decreases slightly, and in the ventricles of the brain it is only 190 - 200 mm of water. st... In children, cerebrospinal fluid pressure is lower than in adults.
BASIC BIOCHEMICAL INDICATORS OF cerebrospinal fluid are normal
FIRST MECHANISM OF CSF FORMATION
The first mechanism for the formation of cerebrospinal fluid (80%) is production carried out by the choroid plexuses of the ventricles of the brain through active secretion by glandular cells.
COMPOSITION OF LIQUOR, traditional system of units, (SI system)
Organic matter:
Total protein of the cistern cerebrospinal fluid - 0.1 -0.22 (0.1 -0.22 g/l)
Total protein of ventricular cerebrospinal fluid - 0.12 - 0.2 (0.12 - 0.2 g/l)
Total protein of lumbar cerebrospinal fluid - 0.22 - 0.33 (0.22 - 0.33 g/l)
Globulins - 0.024 - 0.048 (0.024 - 0.048 g/l)
Albumin - 0.168 - 0.24 (0.168 - 0.24 g/l)
Glucose - 40 - 60 mg% (2.22 - 3.33 mmol/l)
Lactic acid - 9 - 27 mg% (1 - 2.9 mmol/l)
Urea - 6 - 15 mg% (1 - 2.5 mmol/l)
Creatinine - 0.5 - 2.2 mg% (44.2 - 194 µmol/l)
Creatine - 0.46 - 1.87 mg% (35.1 - 142.6 µmol/l)
Total nitrogen - 16 - 22 mg% (11.4 - 15.7 mmol/l)
Residual nitrogen - 10 - 18 mg% (7.1 - 12.9 mmol/l)
Esters and cholesterols - 0.056 - 0.46 mg% (0.56 - 4.6 mg/l)
Free cholesterol - 0.048 - 0.368 mg% (0.48 - 3.68 mg/l)
Inorganic substances:
Inorganic phosphorus - 1.2 - 2.1 mg% (0.39 - 0.68 mmol/l)
Chlorides - 700 - 750 mg% (197 - 212 mmol/l)
Sodium - 276 - 336 mg% (120 - 145 mmol/l)
Potassium - (3.07 - 4.35 mmol/l)
Calcium - 12 - 17 mg% (1.12 - 1.75 mmol/l)
Magnesium - 3 - 3.5 mg% (1.23 - 1.4 mmol/l)
Copper - 6 - 20 µg% (0.9 - 3.1 µmol/l)
The choroid plexuses of the brain, located in the ventricles of the brain, are vascular-epithelial formations, are derivatives of the pia mater, penetrate into the ventricles of the brain and participate in the formation of the choroid plexus.
Vascular Basics
The vascular base of the IV ventricle is a fold of the pia mater, which protrudes together with the ependyma into the IV ventricle, and has the appearance of a triangular plate adjacent to the inferior medullary velum. In the vascular base, blood vessels branch, forming the vascular base of the IV ventricle. In this plexus there are: a middle, oblique-longitudinal part (lying in the IV ventricle) and a longitudinal part (located in its lateral recess). The vascular basis of the IV ventricle forms the anterior and posterior villous branches of the IV ventricle.
The anterior villous branch of the fourth ventricle arises from the anterior inferior cerebellar artery near the flocculus and branches into the vascular base, forming the vascular base of the lateral recess of the fourth ventricle. The posterior villous part of the fourth ventricle arises from the posterior inferior cerebellar artery and branches in the middle part of the vascular base. The outflow of blood from the choroid plexus of the fourth ventricle is carried out through several veins flowing into the basal or great cerebral vein. From the choroid plexus located in the area of the lateral recess, blood flows through the veins of the lateral recess of the fourth ventricle into the middle cerebral veins.
The vascular base of the third ventricle is a thin plate located under the fornix of the brain, between the right and left thalamus, which can be seen after removal of the corpus callosum and fornix of the brain. Its shape depends on the shape and size of the third ventricle.
In the vascular basis of the third ventricle, 3 sections are distinguished: the middle (located between the medullary stripes of the thalamus) and two lateral (covering the upper surfaces of the thalamus); in addition, the right and left edges, the upper and lower leaves are distinguished.
The upper layer extends to the corpus callosum, fornix and further to the cerebral hemispheres, where it is the pia mater of the brain; the lower layer covers the upper surfaces of the thalamus. From the lower layer, on the sides of the midline in the cavity of the third ventricle, villi, lobules, and nodes of the choroid plexus of the third ventricle are introduced. In front, the plexus approaches the interventricular foramina, through which it connects with the choroid plexus of the lateral ventricles.
In the choroid plexus, the medial and lateral posterior villous branches of the posterior cerebral artery and the villous branches of the anterior villous artery branch.
The medial posterior villous branches anastomose through the interventricular foramina with the lateral posterior villous branch. The lateral posterior villous branch, located along the thalamic cushion, extends into the vascular base of the lateral ventricles.
The outflow of blood from the veins of the choroid plexus of the third ventricle is carried out by several thin veins belonging to the posterior group of tributaries of the internal cerebral veins. The vascular base of the lateral ventricles is a continuation of the choroid plexus of the third ventricle, which protrudes into the lateral ventricles from the medial sides, through the gaps between the thalami and the fornix. On the side of the cavity of each ventricle, the choroid plexus is covered with a layer of epithelium, which is attached on one side to the fornix, and on the other to the attached plate of the thalamus.
The veins of the choroid plexus of the lateral ventricles are formed by numerous convoluted ducts. Between the villi of the plexus tissues there are a large number of veins connected to each other by anastomoses. Many veins, especially those facing the ventricular cavity, have sinusoidal expansions, forming loops and semirings.
Choroid plexus of each lateral ventricle is located in its central part and passes into the lower horn. It is formed by the anterior villous artery, partly by branches of the medial posterior villous branch.
Histology of the choroid plexus
The mucous membrane is covered with single-layer cubic epithelium - vascular ependymocytes. In fetuses and newborns, vascular ependymocytes have cilia surrounded by microvilli. In adults, cilia are retained on the apical surface of cells. Vascular ependymocytes are connected by a continuous obturator zone. Near the base of the cell there is a round or oval nucleus. The cytoplasm of the cell is granular in the basal part and contains many large mitochondria, pinocytotic vesicles, lysosomes and other organelles. Folds form on the basal side of vascular ependymocytes. Epithelial cells are located on the connective tissue layer, consisting of collagen and elastic fibers, connective tissue cells.
Under the connective tissue layer is the choroid plexus itself. The arteries of the choroid plexus form capillary-like vessels with a wide lumen and a wall characteristic of capillaries. The outgrowths or villi of the choroid plexus have in the middle central vessel, the wall of which consists of endothelium; the vessel is surrounded by connective tissue fibers; The villus is covered on the outside with connective epithelial cells.
According to Minkrot, the barrier between the blood of the choroid plexus and the cerebrospinal fluid consists of a system of circular tight junctions connecting adjacent epithelial cells, a heterolytic system of pinocytotic vesicles and lysosomes in the cytoplasm of ependymocytes, and a system of cellular enzymes associated with the active transport of substances in both directions between plasma and cerebrospinal fluid.
Functional significance of the choroid plexus
The fundamental similarity of the ultrastructure of the choroid plexus with such epithelial formations as the renal glomerulus gives reason to believe that the function of the choroid plexus is associated with the production and transport of cerebrospinal fluid. Vandy and Joyt call the choroid plexus a periventricular organ. In addition to the secretory function of the choroid plexus, the regulation of the composition of the cerebrospinal fluid, carried out by the suction mechanisms of ependymocytes, is important.
SECOND MECHANISM OF CSF FORMATION
The second mechanism for the formation of cerebrospinal fluid (20%) is blood dialysis through the walls blood vessels and the ependyma of the brain ventricles, which function as dialysis membranes. The exchange of ions between blood plasma and cerebrospinal fluid occurs through active membrane transport.
In addition to the structural elements of the cerebral ventricles, the vascular network of the brain and its membranes, as well as brain tissue cells (neurons and glia), take part in the production of spinal fluid. However, under normal physiological conditions, extraventricular (outside the ventricles of the brain) production of cerebrospinal fluid is very small.
CIRCULATION OF cerebrospinal fluid
The circulation of cerebrospinal fluid occurs constantly, from the lateral ventricles of the brain through the foramen of Monroe it enters the third ventricle, and then flows through the aqueduct of Sylvius into the fourth ventricle. From the IV ventricle, through the foramen of Luschka and Magendie, most of the cerebrospinal fluid passes into the cisterns of the base of the brain (cerebellocerebral, covering the pons cisterns, interpeduncular cistern, optic chiasm cistern, and others). It reaches the Sylvian (lateral) fissure and rises into the subarachnoid space of the convexitol surface of the cerebral hemispheres - this is the so-called lateral pathway of cerebrospinal fluid circulation.
It has now been established that there is another pathway for the circulation of cerebrospinal fluid from the cerebellocerebral cistern into the cisterns of the cerebellar vermis, through the enveloping cistern into the subarachnoid space of the medial sections of the cerebral hemispheres - this is the so-called central pathway of cerebrospinal fluid circulation. A smaller part of the cerebrospinal fluid from the cerebellomedullary cistern descends caudally into the subarachnoid space of the spinal cord and reaches the cistern terminalis.
Opinions about the circulation of cerebrospinal fluid in the subarachnoid space of the spinal cord are contradictory. The point of view about the existence of cerebrospinal fluid flow in the cranial direction is not yet shared by all researchers. The circulation of cerebrospinal fluid is associated with the presence of hydrostatic pressure gradients in the cerebrospinal fluid pathways and receptacles, which are created as a result of pulsation of intracranial arteries, changes in venous pressure and body position, as well as other factors.
The outflow of cerebrospinal fluid mainly (30-40%) occurs through arachnoid granulations (Pachyonian villi) in the superior longitudinal sinus, which are part of the cerebral venous system. Arachnoid granulations are processes of the arachnoid membrane that penetrate the dura mater and are located directly in the venous sinuses. Now let’s look at the structure of arachnoid granulation in more depth.
Arachnoid granulations
The outgrowths of the soft shell of the brain located on its outer surface were first described by Pachion (1665 - 1726) in 1705. He believed that granulations were glands of the dura mater of the brain. Some of the researchers (Hirtle) even believed that granulations were pathologically malignant formations. Key and Retzius (Key u. Retzius, 1875) considered them as “inversions of arachnoideae and subarachnoid tissue”, Smirnov defines them as “duplication of arachnoideae”, a number of other authors Ivanov, Blumenau, Rauber consider the structure of pachyon granulations as growths of arachnoideae, that is “nodules of connective tissue and histiocytes” that do not have any cavities or “naturally formed holes” inside. It is believed that granulations develop after 7 - 10 years.
A number of authors point out the dependence of intracranial pressure on respiration and intrablood pressure and therefore distinguish between respiratory and pulse movements of the brain (Magendie, 1825, Ecker, 1843, Longet, Luschka, 1885, etc. The pulsation of the arteries of the brain in its entirety, and especially the larger arteries of the base of the brain, creates the conditions for pulsatory movements of the entire brain, while the respiratory movements of the brain are associated with the phases of inhalation and exhalation, when, in connection with inhalation, cerebrospinal fluid flows out from the head, and at the moment of exhalation it flows in to the brain and, as a result, intracranial pressure changes.
Le Grosse Clark pointed out that the formation of villi arachnoideae "is a response to changes in pressure from the cerebrospinal fluid." G. Ivanov showed in his works that “the entire, significant in capacity, villous apparatus of the arachnoid membrane is a pressure regulator in the subarachnoid space and in the brain. This pressure, crossing a certain line, measured by the degree of stretching of the villi, is quickly transmitted to the villous apparatus, which Thus, in principle, it plays the role of a high pressure fuse."
The presence of fontanelles in newborns and in the first year of a child’s life creates a condition that alleviates intracranial pressure by protruding the membrane of the fontanelles. The largest in size is the frontal fontanel: it is the natural elastic “valve” that locally regulates the pressure of the cerebrospinal fluid. In the presence of fontanelles, there are apparently no conditions for the development of granulation of arachnoideae, because there are other conditions that regulate intracranial pressure. With the completion of the formation of the bone skull, these conditions disappear, and they are replaced by a new regulator of intracranial pressure - the villi of the arachnoid membrane. Therefore, it is no coincidence that it is in the area of the former frontal fontanel, in the area of the frontal angles of the parietal bone, that in most cases the Pachionian granulations of adults are located.
In terms of topography, Pachionian granulations indicate their predominant location along the sagittal sinus, transverse sinus, at the beginning of the straight sinus, at the base of the brain, in the area of the Sylvian fissure and in other places.
The granulations of the soft shell of the brain are similar to the outgrowths of other internal membranes: villi and arcades of serous membranes, synovial villi of joints and others.
In shape, in particular the subdural, they resemble a cone with an expanded distal part and a stalk attached to the pia mater of the brain. In mature arachnoid granulations, the distal part branches. Being a derivative of the pia mater of the brain, arachnoid granulations are formed by two connecting components: the arachnoid membrane and subarachnoid tissue.
Arachnoid membrane
Arachnoid granulation includes three layers: outer - endothelial, reduced, fibrous and inner - endothelial. The subarachnoid space is formed by many small slits located between the trabeculae. It is filled with cerebrospinal fluid and communicates freely with the cells and tubules of the subarachnoid space of the pia mater of the brain. Arachnoid granulation contains blood vessels, primary fibers and their endings in the form of glomeruli and loops.
Depending on the position of the distal part, they are distinguished: subdural, intradural, intralacunar, intrasinus, intravenous, epidural, intracranial and extracranial arachnoid granulations.
During development, arachnoid granulations undergo fibrosis, hyalinization and calcification with the formation of psammoma bodies. Dying forms are replaced by newly formed ones. Therefore, in humans, all stages of development of arachnoid granulation and their involutional transformations occur simultaneously. As you approach the upper edges cerebral hemispheres in the brain, the number and size of arachnoid granulations increase sharply.
Physiological significance, a number of hypotheses
1) It is a device for the outflow of cerebrospinal fluid into the venous beds of the dura mater.
2) They are a system of mechanisms that regulate pressure in the venous sinuses, dura mater and subarachnoid space.
3) It is a device that suspends the brain in the cranial cavity and protects its thin-walled veins from stretching.
4) It is a device for delaying and processing toxic metabolic products, preventing the penetration of these substances into the cerebrospinal fluid, and the absorption of protein from the cerebrospinal fluid.
5) It is a complex baroreceptor that senses the pressure of cerebrospinal fluid and blood in the venous sinuses.
Outflow of cerebrospinal fluid.
The outflow of cerebrospinal fluid through arachnoid granulations is a particular expression of the general pattern - its outflow through the entire arachnoid membrane. The appearance of blood-washed arachnoid granulations, which are extremely powerfully developed in an adult, creates the shortest path for the outflow of cerebrospinal fluid directly into the venous sinuses of the dura mater, bypassing the bypass route through the subdural space. In small children and small mammals that do not have arachnoid granulations, cerebrospinal fluid is released through the arachnoid membrane into the subdural space.
The subarachnoid fissures of intrasinus arachnoid granulations, representing the thinnest, easily collapsible “tubules,” are a valve mechanism that opens when the pressure of the cerebrospinal fluid increases in the large subarachnoid space and closes when the pressure in the sinuses increases. This valve mechanism ensures the unilateral movement of cerebrospinal fluid in the sinuses and, according to experimental data, opens at a pressure of 20 -50 mm. WHO. column in the large subarachnoid space.
The main mechanism for the outflow of cerebrospinal fluid from the subarachnoid space through the arachnoid membrane and its derivatives (arachnoid granulations) into the venous system is the difference in the hydrostatic pressure of the cerebrospinal fluid and venous blood. Cerebrospinal fluid pressure normally exceeds venous pressure in the superior longitudinal sinus by 15–50 mm. water Art. About 10% of cerebrospinal fluid flows through the choroid plexus of the ventricles of the brain, from 5% to 30% into the lymphatic system through the perineural spaces of the cranial and spinal nerves.
In addition, there are other pathways for the outflow of cerebrospinal fluid, directed from the subarachnoid to the subdural space, and then to the vasculature of the dura mater or from the intercerebellar spaces of the brain to the vascular system of the brain. Some cerebrospinal fluid is resorbed by the ependyma of the ventricles of the brain and the choroid plexuses.
Without deviating much from this topic, it must be said that in the study of neural sheaths, and, accordingly, perineural sheaths, a huge contribution was made by the outstanding professor, head of the department of human anatomy of Smolensk State Medical Institute(now the Academy) P.F. Stepanov. What is curious about his work is the fact that the study was carried out on embryos of the earliest periods, 35 mm of parietal-coccygeal length, until the formed fetus. In his work on the development of neural sheaths, he identified the following stages: cellular, cellular-fibrous, fibrous-cellular and fibrous.
The perineurium anlage is represented by intrastem mesenchymal cells that have a cellular structure. The release of the perineurium only begins at the cellular fibrous stage. In embryos, starting from 35 mm of parietal-coccygeal length, among the intra-stem process cells of the mesenchyme, spinal and cranial nerves, precisely those cells that resemble the contours of the primary bundles begin to gradually predominate in quantitative terms. The boundaries of the primary bundles become more distinct, especially in places of intra-trunk branch separation. As a few primary bundles are isolated, a cellular-fibrous perineurium is formed around them.
Differences in the structure of the perineurium of different bundles were also noticed. In those areas that arose earlier, the perineurium in its structure resembles the epineurium, having a fibrous-cellular structure, and the bundles that arose at a later date are surrounded by perineurium having a cellular-fibrous and even cellular structure.
CHEMICAL ASYMMETRY OF THE BRAIN
Its essence is that some endogenous (internal origin) substances-regulators preferentially interact with the substrates of the left or right hemispheres of the brain. This results in a one-sided physiological response. Researchers have been trying to find such regulators. Study the mechanism of their action, form a hypothesis about biological significance, as well as outline ways to use these substances in medicine.
From a patient with a right-sided stroke and a paralyzed left arm and leg, cerebrospinal fluid was taken and injected into the spinal cord of a rat. Previously, her spinal cord was cut at the top to exclude the influence of the brain on the same processes that can be caused by cerebrospinal fluid. Immediately after the injection, the rat's hind legs, which had been lying symmetrically until then, changed position: one leg bent more than the other. In other words, the rat developed an asymmetry in the posture of the hind limbs. Surprisingly, the side of the animal's bent paw coincided with the side of the patient's paralyzed leg. Such a coincidence was recorded in experiments with the spinal fluid of many patients with left- and right-sided strokes and traumatic brain injuries. So, for the first time, certain chemical factors, carrying information about the side of brain damage and causing asymmetry of posture, that is, they most likely act differently on neurons lying to the left and right of the plane of symmetry of the brain.
Therefore, there is no doubt about the existence of a mechanism that should control, during brain development, the movement of cells, their processes and cell layers from left to right and from right to left relative to the longitudinal axis of the body. Chemical control of processes occurs in the presence of gradients chemicals and their receptors in these directions.
LITERATURE
1. Great Soviet Encyclopedia. Moscow. Volume No. 24/1, page 320.
2. Big medical encyclopedia. 1928 Moscow. Volume No. 3, page 322.
3. Great medical encyclopedia. 1981 Moscow. Volume No. 2, pp. 127 - 128. Volume No. 3, pp. 109 - 111. Volume No. 16, p. 421. Volume No. 23, pp. 538 - 540. Volume No. 27, pp. 177 - 178.
4. Archive of anatomy, histology and embryology. 1939 Volume 20. Second issue. Series A. Anatomy. Book two. State publishing house of honey literature Leningrad branch. Page 202 - 218.
5. Development of neural sheaths and intra-trunk vessels of the human brachial plexus. Yu. P. Sudakov abstract. SSMI. 1968 Smolensk
6. Chemical asymmetry of the brain. 1987 Science in the USSR. No. 1 Page 21 - 30. E. I. Chazov. N. P. Bekhtereva. G. Ya. Bakalkin. G. A. Vartanyan.
7. Fundamentals of liquorology. 1971 A.P. Friedman. Leningrad. "Medicine".
Cerebrospinal fluid (cerebrospinal fluid, cerebrospinal fluid) is a fluid constantly circulating in the ventricles of the brain, cerebrospinal fluid tracts, subarachnoid (subarachnoid) space of the brain and spinal cord. Protects the brain and spinal cord from mechanical influences, ensures the maintenance of constant intracranial pressure and water-electrolyte homeostasis. Supports trophic and metabolic processes between blood and brain. Fluctuation of cerebrospinal fluid affects the autonomic nervous system. The main volume of cerebrospinal fluid is formed by active secretion by glandular cells of the choroid plexuses in the ventricles of the brain. Another mechanism for the formation of cerebrospinal fluid is the sweating of blood plasma through the walls of blood vessels and the ventricular ependyma.
Liquor is a liquid medium circulating in the cavities of the ventricles of the brain, the cerebrospinal fluid ducts, and the subarachnoid space of the brain and spinal cord. The total content of cerebrospinal fluid in the body is 200 - 400 ml. Cerebrospinal fluid is contained mainly in the lateral, III and IV ventricles of the brain, the aqueduct of Sylvius, the cisterns of the brain and in the subarachnoid space of the brain and spinal cord.
The process of liquor circulation in the central nervous system includes 3 main parts:
1). Production (formation) of liquor.
2). Circulation of cerebrospinal fluid.
3). Outflow of cerebrospinal fluid.
The movement of cerebrospinal fluid is carried out by translational and oscillatory movements, leading to its periodic renewal, which occurs at different speeds (5 - 10 times a day). What depends on a person’s daily routine, the load on the central nervous system and fluctuations in the intensity of physiological processes in the body. The circulation of cerebrospinal fluid occurs constantly, from the lateral ventricles of the brain through the foramen of Monroe it enters the third ventricle, and then flows through the aqueduct of Sylvius into the fourth ventricle. From the IV ventricle, through the foramen of Luschka and Magendie, most of the cerebrospinal fluid passes into the cisterns of the base of the brain (cerebellocerebral, covering the pons cisterns, interpeduncular cistern, optic chiasm cistern, and others). It reaches the Sylvian (lateral) fissure and rises into the subarachnoid space of the convexitol surface of the cerebral hemispheres - this is the so-called lateral pathway of cerebrospinal fluid circulation.
It has now been established that there is another pathway for the circulation of cerebrospinal fluid from the cerebellocerebral cistern into the cisterns of the cerebellar vermis, through the enveloping cistern into the subarachnoid space of the medial sections of the cerebral hemispheres - this is the so-called central pathway of cerebrospinal fluid circulation. A smaller part of the cerebrospinal fluid from the cerebellomedullary cistern descends caudally into the subarachnoid space of the spinal cord and reaches the cistern terminalis.
28-29. Spinal cord, shape, topography. Main parts of the spinal cord. Cervical and lumbosacral thickenings of the spinal cord. Segments of the spinal cord. Spinal cord (lat. Medulla spinalis) - the caudal part (caudal) of the central nervous system of vertebrates, located in the spinal canal formed by the neural arches of the vertebrae. It is generally accepted that the border between the spinal cord and the brain passes at the level of the intersection of the pyramidal fibers (although this border is very arbitrary). Inside the spinal cord there is a cavity called the central canal. The spinal cord is protected soft, arachnoid And hard shells. The spaces between the membranes and the canal are filled with cerebrospinal fluid. The space between the outer hard shell and the bone of the vertebrae is called the epidural and is filled with fat and a venous network. Cervical thickening - nerves to the arms, sacral - lumbar - to the legs. Cervical C1-C8 7 vertebrae; Thoracic Th1-Th12 12(11-13); Lumbar L1-L5 5(4-6); Sacral S1-S5 5(6); Coccygeal Co1 3-4.
30. Spinal nerve roots. Spinal nerves. End thread and ponytail. Formation of the spinal ganglia. spinal nerve root (radix nervi spinalis) - a bundle of nerve fibers entering and exiting any segment of the spinal cord and forming the spinal nerve. The spinal or spinal nerves originate in the spinal cord and emerge from it between adjacent vertebrae along almost the entire length of the spine. They contain both sensory neurons and motor neurons, which is why they are called mixed nerves. Mixed nerves are nerves that transmit impulses both from the central nervous system to the periphery and in the opposite direction, for example, trigeminal, facial, glossopharyngeal, vagus and all spinal nerves. Spinal nerves (31 pairs) are formed from two roots extending from the spinal cord - the anterior root (efferent) and the posterior root (afferent), which, connecting with each other in the intervertebral foramen, form the trunk of the spinal nerve. See Fig. 8. The spinal nerves are 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal nerve. Spinal nerves correspond to segments of the spinal cord. Adjacent to the dorsal root is a sensitive spinal ganglion formed by the bodies of large afferent T-shaped neurons. The long process (dendrite) is directed to the periphery, where it ends with the receptor, and the short axon as part of the dorsal root enters the dorsal horn of the spinal cord. The fibers of both roots (anterior and posterior) form mixed spinal nerves containing sensory, motor and autonomic (sympathetic) fibers. The latter are not present in all lateral horns of the spinal cord, but only in the VIII cervical, all thoracic and I - II lumbar nerves. In the thoracic region, the nerves retain a segmental structure (intercostal nerves), and in the rest they are connected to each other by loops, forming plexuses: cervical, brachial, lumbar, sacral and coccygeal, from which peripheral nerves arise that innervate the skin and skeletal muscles (Fig. 228) . On the anterior (ventral) surface of the spinal cord lies a deep anterior median fissure, flanked by shallower anterolateral grooves. The anterior (ventral) roots of the spinal nerves emerge from the anterolateral groove or near it. The anterior roots contain efferent fibers (centrifugal), which are processes of motor neurons that conduct impulses to the muscles, glands and to the periphery of the body. On the posterior (dorsal) surface, the posterior median sulcus is clearly visible. On the sides of it are the posterolateral grooves, into which the posterior (sensitive) roots of the spinal nerves enter. The dorsal roots contain afferent (centripetal) nerve fibers that conduct sensory impulses from all tissues and organs of the body to the central nervous system. The dorsal root forms the spinal ganglion (node), which is a cluster of bodies of pseudounipolar neurons. Moving away from such a neuron, the process divides in a T-shape. One of the processes - a long one - is directed to the periphery as part of the spinal nerve and ends in a sensitive nerve ending. Another process - a short one - follows as part of the dorsal root into the spinal cord. The spinal ganglia (nodes) are surrounded by the dura mater and lie inside the spinal canal in the intervertebral foramina.
31. Internal structure of the spinal cord. Gray matter. Sensory and motor horns of the gray matter of the spinal cord. Nuclei of the gray matter of the spinal cord. The spinal cord consists of gray matter formed by an accumulation of neuron bodies and their dendrites, and covering it white matter consisting of neurites.I. Gray matter,
occupies the central part of the spinal cord and forms two vertical columns in it, one in each half, connected by gray commissures (anterior and posterior). GRAY MATTER OF THE BRAIN, dark-colored nervous tissue that makes up the CEREBRAL CORTEX. Also present in the SPINAL CORD. Differs from so-called white matter in that it contains more nerve fibers (NEURONS) and a large amount of a whitish insulating material called MYELIN.
HORNS OF GRAY MATTER.
Three projections are distinguished in the gray matter of each of the lateral parts of the spinal cord. Throughout the spinal cord, these projections form gray columns. There are anterior, posterior and lateral columns of gray matter. Each of them on a transverse section of the spinal cord is named accordingly
Anterior horn of gray matter of the spinal cord,
Dorsal horn of gray matter of the spinal cord
Lateral horn of the gray matter of the spinal cord The anterior horn of the gray matter of the spinal cord contains large motor neurons. The axons of these neurons, emerging from the spinal cord, constitute the anterior (motor) roots of the spinal nerves. The bodies of motor neurons form the nuclei of efferent somatic nerves that innervate skeletal muscles (autochthonous muscles of the back, muscles of the trunk and limbs). Moreover, the more distally the innervated muscles are located, the more lateral the cells innervating them lie.
The dorsal horns of the spinal cord are formed by relatively small intercalary (switching, conductor) neurons that receive signals from sensory cells lying in spinal ganglia. The cells of the dorsal horns (interneurons) form separate groups, the so-called somatic sensory columns. The lateral horns contain visceral motor and sensory centers. The axons of these cells pass through anterior horn spinal cord and exit the spinal cord as part of the anterior roots. GRAY MATTER NUCLEI.
Internal structure of the medulla oblongata. The medulla oblongata arose in connection with the development of the organs of gravity and hearing, as well as in connection with the gill apparatus related to respiration and blood circulation. Therefore, it contains nuclei of gray matter related to balance, coordination of movements, as well as the regulation of metabolism, respiration and blood circulation.
1. Nucleus olivaris, the nucleus of the olive, has the appearance of a convoluted plate of gray matter, open medially (hilus), and causes the protrusion of the olive from the outside. It is associated with the dentate nucleus of the cerebellum and is an intermediate nucleus of balance, most pronounced in humans, whose vertical position requires a perfect gravitational apparatus. (The nucleus olivaris accessorius medialis is also found.) 2. Formatio reticularis, a reticular formation formed from the interweaving of nerve fibers and the nerve cells lying between them. 3. Nuclei of the four lower pairs cranial nerves(XII-IX), related to the innervation of derivatives of the gill apparatus and viscera. 4. Vital centers of respiration and circulation associated with the nuclei of the vagus nerve. Therefore, if the medulla oblongata is damaged, death can occur.
32. White matter of the spinal cord: structure and functions.
The white matter of the spinal cord is represented by processes of nerve cells that make up the tracts, or pathways of the spinal cord:
1) short bundles of associative fibers connecting segments of the spinal cord located at different levels;
2) ascending (afferent, sensory) bundles heading to the centers of the cerebrum and cerebellum;
3) descending (efferent, motor) bundles going from the brain to the cells of the anterior horns of the spinal cord.
The white matter of the spinal cord is located on the periphery of the gray matter of the spinal cord and is a collection of myelinated and partly poorly myelinated nerve fibers collected in bundles. The white matter of the spinal cord contains descending fibers (coming from the brain) and ascending fibers, which originate from the neurons of the spinal cord and pass into the brain. Descending fibers primarily transmit information from the motor centers of the brain to the motor neurons (motor cells) of the spinal cord. The ascending fibers receive information from both somatic and visceral sensory neurons. The arrangement of ascending and descending fibers is regular. On the dorsal (dorsal) side there are predominantly ascending fibers, and on the ventral (ventral) side - descending fibers.
The spinal cord grooves delimit the white matter of each half into the anterior funiculus of the white matter of the spinal cord, the lateral funiculus of the white matter of the spinal cord and the posterior funiculus of the white matter of the spinal cord
The anterior funiculus is bounded by the anterior median fissure and the anterolateral groove. The lateral funiculus is located between the anterolateral sulcus and the posterolateral sulcus. Posterior cord located between the posterior median sulcus and the posterolateral sulcus of the spinal cord.
The white matter of both halves of the spinal cord is connected by two commissures (commissures): the dorsal one, lying under upward paths, and ventral, located next to the motor columns of the gray matter.
The white matter of the spinal cord consists of 3 groups of fibers (3 systems of pathways):
Short bundles of associative (intersegmental) fibers connecting parts of the spinal cord at different levels;
Long ascending (afferent, sensory) pathways that go from the spinal cord to the brain;
Long descending (efferent, motor) pathways running from the brain to the spinal cord.
