Composition of cerebrospinal fluid in various nosologies. How is a cerebrospinal fluid analysis done, and what diseases can it detect? The nature of cerebrospinal fluid in meningococcal infection

The review presents changes in laboratory parameters of cerebrospinal fluid in major severe diseases of the central nervous system.

MENINGITIS

Cerebrospinal fluid testing is the only method that can quickly diagnose meningitis. The absence of inflammatory changes in the cerebrospinal fluid always allows one to exclude the diagnosis of meningitis. The etiological diagnosis of meningitis is established using bacterioscopic and bacteriological methods, virological and serological studies.

Pleocytosis is the most characteristic feature of CSF changes. Based on the number of cells, serous and purulent meningitis are distinguished. With serous meningitis, cytosis is 500-600 in 1 μl, with purulent meningitis - more than 600 in 1 μl. The study must be carried out no later than 1 hour after receiving it.

According to the etiological structure, 80-90% of bacteriologically confirmed cases are Neisseria meningitides, Streptococcus pneumoniae and Haemophilus. Bacterioscopy of CSF, due to the characteristic morphology of meningococci and pneumococci, gives a positive result at the first lumbar puncture 1.5 times more often than culture growth.

CSF with purulent meningitis ranges from slightly cloudy, as if whitened with milk, to densely green, purulent, sometimes xanthochromic. In the initial stage of development of meningococcal meningitis, there is an increase in intracranial pressure, then mild neutrophilic cytosis is noted in the cerebrospinal fluid, and in 24.7% of patients the CSF is normal in the first hours of the disease. Then, in many patients, already on the first day of the disease, cytosis reaches 12,000-30,000 in 1 μl, neutrophils predominate. A favorable course of the disease is accompanied by a decrease in the relative number of neutrophils and an increase in lymphocytes. Occurring cases of purulent meningitis with a typical clinical picture and relatively little cytosis can probably be explained by a partial blockade of the subarachnoid space. There may not be a clear correlation between the severity of pleocytosis and the severity of the disease.

The protein content in the CSF during purulent meningitis is usually increased to 0.6-10 g/l and decreases as the cerebrospinal fluid is sanitized. The amount of protein and cytosis are usually parallel, but in some cases with high cytosis the protein level remains normal. A high protein content in the CSF is more common in severe forms with ependymitis syndrome, and its presence in high concentrations during the recovery period indicates an intracranial complication (block of the cerebrospinal fluid tract, dural effusion, brain abscess). The combination of low pleocytosis with high protein content is a particularly unfavorable prognostic sign.

In most patients with purulent meningitis, from the first days of illness there is a decrease in glucose levels (below 3 mmol/l); in case of death, the glucose level was in the form of traces. In 60% of patients, the glucose level is below 2.2 mmol/l, and the ratio of glucose level to that in the blood in 70% is less than 0.31. An increase in glucose level is almost always a prognostically favorable sign.

In tuberculous meningitis, bacterioscopic examination of the CSF often gives a negative result. Mycobacteria are more often found in fresh cases of the disease (in 80% of patients with tuberculous meningitis). The absence of mycobacteria in lumbar punctate is often noted when they are detected in the cisternal CSF. In case of negative or questionable bacterioscopic examination, tuberculosis is diagnosed by culture or biological test. In tuberculous meningitis, the CSF is clear, colorless, or slightly opalescent. Pleocytosis ranges from 50 to 3000 in 1 μl, depending on the stage of the disease, amounting to 100-300 in 1 μl by the 5-7th day of illness. In the absence of etiotropic treatment, the number of cells increases from the beginning to the end of the disease. There may be a sudden drop in cytosis with a repeat lumbar puncture performed 24 hours after the first. The cells are predominantly lymphocytes, but often at the onset of the disease mixed lymphocytic-neutrophilic pleocytosis occurs, which is considered typical for milliary tuberculosis with seeding of the meninges. Characteristic of tuberculous meningitis is the diversity of the cellular composition, when, along with the predominance of lymphocytes, there are neutrophils, monocytes, macrophages and giant lymphocytes. Later, pleocytosis acquires a lymphoplasmacytic or phagocytic character. A large number of monocytes and macrophages indicates an unfavorable course of the disease.

Total protein in tuberculous meningitis is always increased to 2-3 g/l, and earlier researchers noted that protein increases before the onset of pleocytosis and disappears after its significant decrease, i.e., in the first days of the disease, protein-cell dissociation takes place. Modern atypical forms of tuberculous meningitis are characterized by the absence of typical protein-cell dissociation.

With tuberculous meningitis, an early decrease in glucose concentration is observed to 0.83-1.67 mmol/l and below. In some patients, a decrease in chloride levels is detected. In viral meningitis, about 2/3 of cases are caused by the mumps virus and a group of enteroviruses.

In serous meningitis of viral etiology, the CSF is transparent or slightly opalescent. Pleocytosis is small (rarely up to 1000) with a predominance of lymphocytes. In some patients, neutrophils may predominate at the onset of the disease, which is typical for a more severe course and a less favorable prognosis. Total protein is within 0.6-1.6 g/l or normal. In some patients, a decrease in protein concentration is detected due to overproduction of cerebrospinal fluid.

CLOSED CRANIO BRAIN INJURY

The permeability of cerebral vessels in the acute period of traumatic brain injury is several times higher than the permeability of peripheral vessels and is directly dependent on the severity of the injury. To determine the severity of the lesion in the acute period, a number of liquorological and hematological tests can be used. These include: the severity and duration of the presence of hyperproteinorachia as a test characterizing the depth of dysgemic disorders in the brain and the permeability of the blood-cerebrospinal fluid barrier; the presence and severity of erythroarchia as a test that reliably characterizes ongoing intracerebral bleeding; the presence of pronounced neutrophilic pleocytosis within 9-12 days after injury, which serves as an indication of the unresponsiveness of the tissues limiting the cerebrospinal fluid spaces and the inhibition of the sanitizing properties of the arachnoid cells or the addition of an infection.

Concussion: CSF is usually colorless, clear, and contains little or no red blood cells. On days 1-2 after injury, cytosis is normal; on days 3-4, moderately pronounced pleocytosis appears (up to 100 in 1 μl), which decreases to normal numbers on days 5-7. In the liquorogram, lymphocytes with the presence of a small number of neutrophils and monocytes, macrophages, as a rule, are absent. The protein level on days 1-2 after injury is normal, on days 3-4 it rises to 0.36-0.8 g/l and returns to normal by days 5-7.

Brain contusion: the number of red blood cells ranges from 100 to 35,000 and with massive subarachnoid hemorrhage reaches 1-3 million. Depending on this, the color of the CSF can be from grayish to red. Due to irritation of the meninges, reactive pleocytosis develops. For bruises of mild and moderate severity, pleocytosis on days 1-2 is on average 160 in 1 μl, and in severe cases it reaches several thousand. On days 5-10, pleocytosis significantly decreases, but does not reach normal in the next 11-20 days. In the cerebrospinal fluid there are lymphocytes, often macrophages with hemosiderin. If the nature of pleocytosis changes to neutrophilic (70-100% neutrophils), purulent meningitis has developed as a complication. The protein content in mild to moderate cases is on average 1 g/l and does not return to normal by 11-20 days. With severe brain damage, protein levels can reach 3-10 g/l (often fatal).

With traumatic brain injury, the energy metabolism of the brain switches to the path of anaerobic glycolysis, which leads to the accumulation of lactic acid in it, and, ultimately, to brain acidosis.

The study of parameters reflecting the state of brain energy metabolism allows one to judge the severity of the pathological process. A decrease in the arteriovenous difference in pO2 and pCO2, an increase in glucose consumption by the brain, an increase in the venoarterial difference in lactic acid and an increase in it in the cerebrospinal fluid. The observed changes are the result of disruption of the activity of a number of enzyme systems and cannot be compensated by the blood supply. It is necessary to stimulate the nervous activity of patients.

HEMORRHAGIC STROKE

The color of the cerebrospinal fluid depends on the admixture of blood. In 80-95% of patients, during the first 24-36 hours the CSF contains an obvious admixture of blood, and later it is either bloody or xanthochromic. However, in 20-25% of patients with small lesions located in the deep parts of the hemispheres, or in the case of blockage of the cerebrospinal fluid pathways due to rapidly developing cerebral edema, red blood cells are not detected in the CSF. In addition, red blood cells may be absent during lumbar puncture in the very first hours after the onset of hemorrhage, while the blood reaches the spinal level. Such situations are a reason for diagnostic errors - the diagnosis of “ischemic stroke”. The largest amount of blood is found when blood breaks through into the ventricular system. The removal of blood from the cerebrospinal fluid tract begins from the very first day of the disease and continues for 14-20 days in case of traumatic brain injury and stroke, and in case of cerebral aneurysms up to 1-1.5 months and does not depend on the massiveness of the hemorrhage, but on the etiology process.

The second important sign of CSF changes in hemorrhagic stroke is xanthochromia, detected in 70-75% of patients. It appears on the 2nd day and disappears 2 weeks after the stroke. With a very large number of red blood cells, xanthochromia may appear within 2-7 hours.

An increase in protein concentration is observed in 93.9% of patients and its amount ranges from 0.34 to 10 g/l and higher. Hyperproteinorachia and increased bilirubin levels can persist for a long time and, along with liquorodynamic disorders, can cause meningeal symptoms, in particular headaches, even 0.5 - 1 year after subarachnoid hemorrhage.

Pleocytosis is detected in almost 2/3 of patients, it is increasing over 4-6 days, the number of cells ranges from 13 to 3000 in 1 μl. Pleocytosis is associated not only with the breakthrough of blood into the cerebrospinal fluid pathways, but also with the reaction of the meninges to the shed blood. It seems important to determine the true cytosis of the cerebrospinal fluid in such cases. Sometimes, with hemorrhages in the brain, the cytosis remains normal, which is associated with limited hematomas without a breakthrough into the cerebrospinal fluid space, or with the unresponsiveness of the meninges.

With subarachnoid hemorrhages, the admixture of blood can be so large that the cerebrospinal fluid is visually almost indistinguishable from pure blood. On the 1st day, the number of red blood cells, as a rule, does not exceed 200-500 x 109/l, later their number increases to 700-2000 x 109/l. In the very first hours after the development of small-volume subarachnoid hemorrhages, a lumbar puncture can produce clear cerebrospinal fluid, but by the end of the 1st day an admixture of blood appears in it. The reasons for the absence of blood in the CSF may be the same as for a hemorrhagic stroke. Pleocytosis, mainly neutrophilic, over 400-800x109/l, is replaced by lymphocytic by the fifth day. Within a few hours after hemorrhage, macrophages may appear, which can be considered markers of subarachnoid hemorrhage. An increase in total protein usually corresponds to the degree of hemorrhage and can reach 7-11 g/l and higher.

ISCHEMIC STROKE

CSF is colorless and transparent, in 66% the cytosis remains within the normal range, in the rest it increases to 15-50x109/l, in these cases characteristic cerebral infarctions are detected, located close to the cerebrospinal fluid pathways. Pleocytosis, predominantly lymphoid-neutrophilic, is caused by reactive changes around extensive ischemic foci. In half of the patients, the protein content is determined within the range of 0.34-0.82 g/l, less often up to 1 g/l. The increase in protein concentration is due to necrosis of brain tissue and increased permeability of the blood-brain barrier. Protein content can increase by the end of the first week after a stroke and last for over 1.5 months. Quite characteristic of ischemic stroke is protein-cell (increase in protein content with normal cytosis) or cell-protein dissociation.

BRAIN ABSCESS

The initial phase of abscess formation is characterized by neutrophilic pleocytosis and a slight increase in protein. As the capsule develops, pleocytosis decreases and its neutrophilic character is replaced by lymphoid, and the greater the development of the capsule, the less pronounced the pleocytosis. Against this background, the sudden appearance of pronounced neutrophilic pleocytosis indicates a breakthrough of the abscess. If the abscess is located near the ventricular system or the surface of the brain, the cytosis will be from 100 to 400 in 3 μl. Minor pleocytosis or normal cytosis may occur when the abscess was delimited from the surrounding brain tissue by a dense fibrous or hyalinized capsule. The zone of inflammatory infiltration around the abscess in this case is absent or weakly expressed.

CNS TUMORS

Along with protein-cell dissociation, which is considered characteristic of tumors, pleocytosis may occur with normal protein content in the cerebrospinal fluid. With gliomas of the cerebral hemispheres, regardless of their histology and location, an increase in protein in the cerebrospinal fluid is observed in 70.3% of cases, and in immature forms - in 88%. A normal or even hydrocephalic composition of the ventricular and spinal fluid can occur both with deep-seated and with gliomas growing into the ventricles. This is mainly observed in mature diffusely growing tumors (astrocytomas, oligodendrogliomas), without obvious foci of necrosis and cyst formation and without gross displacement of the ventricular system. At the same time, the same tumors, but with gross displacement of the ventricles, are usually accompanied by an increase in the amount of protein in the cerebrospinal fluid. Hyperproteinorachia (from 1 g/l and above) is observed in tumors located at the base of the brain. With pituitary tumors, the protein content ranges from 0.33 to 2.0 g/l. The degree of shift in the proteinogram is directly dependent on the histological nature of the tumor: the more malignant the tumor, the more severe the changes in the protein formula of the cerebrospinal fluid. Beta lipoproteins appear that are not normally detected, and the content of alpha lipoproteins decreases.

In patients with brain tumors, regardless of their histological nature and location, polymorphic pleocytosis quite often occurs. The cellular reaction is determined by the peculiarities of the biological processes occurring in the tumor at certain stages of its development (necrosis, hemorrhage), which determine the reaction. The brain tissue and membranes surrounding the tumor. Tumor cells of the cerebral hemispheres in the fluid from the ventricles can be detected in 34.4%, and in the spinal cerebrospinal fluid - from 5.8 to 15% of all observations. The main factor determining the entry of tumor cells into the cerebrospinal fluid is the nature of the structure of the tumor tissue (poor connective stroma), the absence of a capsule, and the location of the tumor near the cerebrospinal fluid spaces.

CHRONIC INFLAMMATORY DISEASES (arachnoiditis, arachnoencephalitis, periventricular encephalitis)

Tuberculous meningitis occurs more often in children and adolescents than in adults. As a rule, it is secondary, developing as a complication of tuberculosis of another organ (lungs, bronchial or mesenteric lymph nodes) with subsequent hematogenous dissemination and damage to the meninges.

Clinical picture

The onset of the disease is subacute; there is often a prodromal period with increased fatigue, weakness, headache, anorexia, sweating, sleep inversion, character changes, especially in children - in the form of excessive sensitivity, tearfulness, decreased mental activity, and drowsiness.

Body temperature is subfebrile. Vomiting often occurs as a result of headaches. The prodromal period lasts 2-3 weeks. Then, mild shell symptoms gradually appear (stiff neck, Kernig’s sign, etc.). Sometimes patients complain of blurred vision or weakening of vision. Signs of damage to the III and VI pairs of the CN appear early (slight double vision, slight ptosis of the upper eyelids, strabismus). In the later stages, if the disease is not recognized and specific treatment is not started, paresis of the limbs, aphasia and other symptoms of focal brain damage may occur.

The most typical course of the disease is subacute. In this case, the transition from prodromal phenomena to the period of appearance of ophthalmic symptoms occurs gradually, on average within 4-6 weeks. Acute onset is less common (usually in young children and adolescents). A chronic course is possible in patients who were previously treated with specific drugs for tuberculosis of internal organs.

Diagnostics

The diagnosis is established on the basis of an epidemiological history (contact with tuberculosis patients), data on the presence of tuberculosis of internal organs and the development of neurological symptoms. The Mantoux reaction is not very informative.

The study of the cerebrospinal fluid is decisive. The cerebrospinal fluid pressure is increased. The liquid is clear or slightly opalescent. Lymphocytic pleocytosis is detected up to 600-800x106/l, the protein content is increased to 2-5 g/l (Table 31-5).

Table 31-5. Indicators of cerebrospinal fluid are normal and with meningitis of various etiologies

Index	Norm	Tuberculous meningitis	Viral meningitis	Bacterial meningitis
Pressure	100-150 mm water column, 60 drops per minute	Increased	Increased	Increased
Transparency	Transparent	Transparent or slightly opalescent	Transparent	Muddy
Cytosis, cells/µl	1 -3 (up to 10)	Up to 100-600	400-1000 or more	Hundreds, thousands
Cellular composition	Lymphocytes, monocytes	Lymphocytes (60-80%), neutrophils, sanitation in 4-7 months	Lymphocytes (70-98%), sanitation in 16-28 days	Neutrophils (70-95%), recovery in 10-30 days
Glucose content	2.2-3.9 mmol/l	Sharply reduced	Norm	Downgraded
Chloride content	122-135 mmol/l	Downgraded	Norm	Downgraded
Protein content	Up to 0.2-0.5 g/l	Increased by 3-7 times or more	Normal or slightly increased	Increased by 2-3 times
Pandey's reaction	0	+++	0/+	+++
Fibrin film	No	Often	Rarely	Rarely
Mycobacteria	No	"+" in 50% of cases	No	No

Often, at the onset of the disease, mixed neutrophilic and lymphocytic pleocytosis is detected in the cerebrospinal fluid. Characterized by a decrease in glucose content to 0.15-0.3 g/l and chlorides to 5 g/l. When the extracted liquor is stored in a test tube for 12-24 hours, a delicate fibrin web-like mesh (film) is formed in it, which starts from the liquid level and resembles an overturned Christmas tree. Mycobacterium tuberculosis is often found in this film during bacterioscopy. An increase in ESR and leukocytosis are determined in the blood.

Differential diagnosis is facilitated by culture and detailed cytological examination of the cerebrospinal fluid. If tuberculous meningitis is suspected clinically, and laboratory data do not confirm this, anti-tuberculosis therapy exjuvantibus is prescribed for health reasons.

Treatment

Various combinations of anti-tuberculosis drugs are used. During the first 2 months and until sensitivity to antibiotics is detected, 4 drugs are prescribed (the first stage of treatment): isoniazid, rifampicin, pyrazinamide and ethambutol or streptomycin. The regimen is adjusted after determining sensitivity to the drugs. After 2-3 months of treatment (the second stage of treatment), they often switch to 2 drugs (usually isoniazid and rifampicin). The minimum duration of treatment is usually 6-12 months. Several drug combinations are used.

Isoniazid 5-10 mg/kg, streptomycin 0.75-1 g/day in the first 2 months. With constant monitoring of the toxic effect on the VIII pair of the CN - ethambutol 15-30 mg/kg per day. When using this triad, the severity of intoxication is relatively low, but the bactericidal effect is not always sufficient.

To enhance the bactericidal effect of isoniazid, rifampicin 600 mg is added along with streptomycin and ethambutol, 600 mg once a day.

In order to maximize the bactericidal effect, pyrazinamide is used in a daily dose of 20-35 mg/kg in combination with isoniazid and rifampicin. However, when these drugs are combined, the risk of hepatotoxicity increases significantly.

The following combination of drugs is also used: para-aminosalicylic acid up to 12 g/day (0.2 g per 1 kg of body weight in fractional doses 20-30 minutes after meals, washed down with alkaline water), streptomycin and phthivazid in a daily dose of 40-50 mg/kg (0.5 g 3-4 times a day).

The first 60 days of the disease are critical in treatment. In the early stages of the disease (within 1-2 months), it is advisable to use glucocorticoids orally to prevent adhesive pachymeningitis and associated complications.

Treatment in a hospital should be long-term (about 6 months), combined with general strengthening measures, enhanced nutrition and subsequent stay in a specialized sanatorium. Then the patient continues to take isoniazid for several months. The total duration of treatment is 12-18 months.

To prevent neuropathies, pyridoxine (25-50 mg/day), thioctic acid, and multivitamins are used. Monitoring of patients is necessary to prevent drug intoxication in the form of liver damage, peripheral neuropathies, including damage to the optic nerves, as well as to prevent complications in the form of cicatricial adhesions and open hydrocephalus.

Forecast

Before the use of anti-tuberculosis drugs, meningitis ended in death on the 20-25th day of the disease. Currently, with timely and long-term treatment, a favorable outcome occurs in 90-95% of patients. If diagnosis is delayed (after 18-20 days of illness), the prognosis is poor. Sometimes relapses and complications occur in the form of epileptic seizures, hydrocephalus, and neuroendocrine disorders.

Neurosurgeons, neurologists and infectious disease specialists often have to perform a lombal puncture, which is the collection of cerebrospinal fluid (CSF) from a patient. The procedure is a very effective way to diagnose various diseases of the central nervous system (CNS).

In clinics, liquor components are determined, microscopy is performed, and CSF is taken for microorganisms.

There are additional investigative measures, for example, measuring CSF pressure, latex agglutination, checking the color of the supernatant. A thorough understanding of each of the tests allows specialists to use them as the most effective methods for diagnosing diseases.

Why perform a cerebrospinal fluid test?

Liquor (CSF, cerebrospinal fluid) is a natural substance required for the normal functioning of the central nervous system. Its analysis is the most important among all types of laboratory studies.

The analysis is carried out in several stages:

Preparatory– includes preparing the patient, taking and sending the test to the laboratory.
Analytical- this is the procedure for studying liquid.
Post-analytical– is a decryption of the received data.

Only experienced specialists are able to competently perform all of the above actions; the quality of the resulting analysis depends on this.

Cerebrospinal fluid is produced in special plexuses of vessels located in the brain. In adults, it circulates in the subarchnoid space and in the ventricles of the brain, from 120 to 150 ml of fluid, the average value in the lumbar canal is 60 mg.

The process of its formation is endless, the production rate is from 0.3 to 0.8 ml per minute, this indicator directly depends on intracranial pressure. During the day, an average person produces from 400 to 1000 ml of fluid.

Only on the evidence of a lumbar puncture can a diagnosis be made, namely:

excessive protein content in the CSF;
decreased glucose levels;
determination of the total number of white blood cells.

When these indicators are obtained and the level of leukocytes in the blood is elevated, a diagnosis of “serous meningitis” is made; if there is an increase in the number of neutrophilic leukocytes, the diagnosis is changed to “purulent meningitis”. These data are very important, since the treatment of the disease as a whole depends on them.

What is analysis

The liquid is obtained by taking a puncture from the spinal cord, also called lombal, according to a certain technique, namely: inserting a very thin needle into the space where the CSF circulates and taking it.

The first drops of fluid are removed (considered "travel" blood), but after that at least 2 tubes are collected. The regular (chemical) one is collected for general and chemical examination, the second is sterile - for examination for the presence of bacteria.

When referring a patient for a CSF analysis, the physician must indicate not only the patient’s name, but also his clinical diagnosis and the purpose of the examination.

Analyzes supplied to the laboratory must be completely protected from overheating or cooling, and some samples are heated in special water baths for 2 to 4 minutes.

Research stages

This liquid is examined immediately after its collection. Laboratory research is divided into 4 important stages.

Macroscopic examination

The process has several important indicators that are necessary to determine an accurate diagnosis.

Color

In its normal state, this liquid is absolutely colorless and cannot be distinguished from water. With pathologies of the central nervous system, some changes in the color of the cerebrospinal fluid are possible. To accurately determine the color, the substance is compared in detail with purified water.

A slightly red tint may mean that impurities of unchanged blood - erythrocytes - have entered the liquid. Or is it an accidental ingestion of a couple of drops of blood during a test.

Transparency

In a healthy person, CSF is transparent and does not differ in appearance from water. A cloudy substance may mean that pathological processes are occurring in the body.

If, after the centrifugation process, the liquid in the test tube becomes transparent, this means that the cloudy consistency is due to some elements included in the composition. If it remains cloudy - microorganisms.

A slight opalescence of the liquid may occur with an increased content of some dispersed proteins, such as fibrinogen.

Fibrinous film

In a healthy state, it contains almost no fibrinogen. When its concentration is high, a thin mesh, bag or clot similar to jelly is formed in the test tube.

The outer layer of protein folds, resulting in a bag of liquid. Liquor, which contains a lot of protein, immediately after release begins to coagulate into a jelly-like clot.

If the cerebrospinal fluid contains red blood cells, the film described above does not form.

Microscopic examination

Finding the total number of cerebrospinal fluid cells must be carried out immediately after taking the analysis, since its cells are characterized by rapid destruction.

Under normal conditions, the cerebrospinal fluid is not rich in cellular elements. In 1 ml you can find 0-3-6 lymphocytes, because of this they are counted in special large-capacity chambers - Fuchs-Rosenthal.

Under magnification in a counting chamber, the number of white blood cells in the fluid is calculated after all red blood cells have been destroyed. Samson's reagent is used in the process.

How to determine:

First of all they place CSF in vitro.
The reagent is filled into the melanger up to the 1 mark. Samson.
Next, add liquor and solution to the 11 mark vinegar acid, indicating an admixture of red blood cells, fuchsin is added, which gives the leukocytes, or rather their nuclei, a red-violet color. Afterwards, carbolic acid is added for preservation.
Reagent and the liquor is mixed, for this the melangeur must be rolled between the palms and left for half an hour for coloring.
The first drop is immediately sent to filtering paper, mix the Fuchs-Rosenthal square, consisting of 16 large squares, each of which is divided into 16 more, thereby forming 256 squares.
The last step is to count the total number leukocytes in all squares, the resulting number is divided by 3.2 - the volume of the chamber. The result obtained is equal to the number of leukocytes in 1 μl of CSF.

Normal indicators:

lumbar - from 7 to 10 in the chamber;
cisternal – from 0 to 2;
ventricular – from 1 to 3.

Increased cytosis - pleocytosis, is an indicator of active inflammatory processes that affect the membranes of the brain, that is, meningitis, organic lesions of gray matter (tumors, abscesses), arachnoiditis, trauma and even hemorrhage.

In children, the normal level of cytosis is higher than in adults.

Detailed steps for reading a cytogram:

Liquid centrifuge for 10 minutes, the sediment is drained.
Sediment clean up onto the glass slide, shaking it slightly so that it is evenly distributed on the surface.
After the smear dried warm throughout the day.
For 5 minutes immerse in methyl alcohol or 15 in ethyl alcohol.
They take Azur-eosin solution, previously diluted 5 times, and paint the smear.
Apply immersion oil for microscopy.

In a healthy person, the CSF contains only lymphocytes.

If there are some pathologies, you can find all types of leukocytes, macrophages, polyblasts, and cells of newly formed tumors. Macrophages are formed after blood loss in the central nervous system or after tumor decomposition.

Biochemical analysis

This analysis helps clarify the primary cause of brain tissue pathology, helps assess the damage caused, adjust the sequence of treatment and determine the prognosis of the disease. The main disadvantage of the analysis is that it is carried out only by invasive intervention, that is, a puncture is made to collect CSF.

In the normal state, the liquid contains the protein albumin, and its ratio in the liquid and the percentage of its content in the plasma are very important.

This ratio is called the albumin index (normally its value should not exceed 9 units). Its increase indicates that the blood-brain barrier (the barrier between brain tissue and blood) is damaged.

Bacterioscopic and bacteriological

This study of liquid involves obtaining it by piercing the spinal canal. The resulting substance or sediment, which is obtained after centrifugation, is examined under magnification.

From the final material, laboratory assistants receive smears, which they study after repainting them. It doesn’t matter whether microorganisms were found in the CSF or not, the study will definitely be carried out.

If there is a suspicion of an infectious form of meningitis, the analysis is carried out by a doctor who is necessary in various situations in order to establish the type of irritant. The disease can also be caused by unusual flora, possibly streptococci; meningococcus is a standard causative agent, as is the tuberculosis bacillus.

A few weeks before the onset of meningitis, patients often notice the appearance of a cough, temporary fever and runny nose. The development of the disease can be indicated by a constant migraine of a bursting nature, which does not respond to painkillers. In this case, body temperature can rise to high levels.

With meningococcus, a rash forms on the surface of the body, most often on the legs. Patients also often complain of a negative perception of bright light. The muscles in the neck become harder, as a result the person is unable to touch the chin to the chest.

Meningitis requires urgent hospitalization, followed by examination and urgent treatment in a hospital setting.

Decoding of cerebrospinal fluid indicators

Changed color of different intensities may be due to the mixing of red blood cells, which appear with recent brain injury or blood loss. The presence of red blood cells can be visually noticed when their number is more than 600 per µl.

With various disorders and inflammatory processes occurring in the body, the CSF may become xanthochromic, that is, have a yellow or brownish color due to the breakdown products of hemoglobin. We should not forget about false xanthochromia - the cerebrospinal fluid is colored due to medication.

In medical practice, a green tint is also found, but only in rare cases of purulent meningitis or brain abscess. In the literature, brown color is described as a rupture of a craniopharyngoma cyst into the cerebrospinal fluid pathway.

Cloudiness of the liquid may indicate the presence of microorganisms or blood cells in it. In the first case, the turbidity can be removed by centrifugation.

Studying the composition of CSF is a particularly important task, which includes a large number of different manipulations, tests and calculations, while it is necessary to pay attention to many other indicators.

After the procedure, the patient is prescribed bed rest for a day. Over the next few days, he may begin to complain of a migraine. This is due to overstraining of the meninges due to the collection of fluid during the procedure.

Introduction…………………………………………………………………………………..3

Laboratory methods for studying cerebrospinal fluid………………………………….3

Physiology of cerebrospinal fluid………………………………………………………..3
Composition and functions of cerebrospinal fluid……………………………………………………3
Preanalytical stage……………………………………………………….7
Methods for laboratory testing of cerebrospinal fluid……………………………..9
1. Macroscopy of cerebrospinal fluid………………………………………………………...9
  Microscopic examination of cerebrospinal fluid………………………………….10
  General clinical examination of cerebrospinal fluid…………………...15
  Biochemical study of cerebrospinal fluid………………………………………22

Conclusion…………………………………………………………………………………..31

INTRODUCTION

CSF studies are an integral part of diagnosing diseases affecting the central nervous system. Cerebrospinal fluid is a direct continuation of the extracellular and pericapillary space of the nervous tissue, so it immediately responds to any changes that occur in the brain. Based on the physicochemical parameters and cellular composition of the cerebrospinal fluid, one can judge the nature of the pathology, its stage and monitor the progress of treatment. In case of viral infections of the central nervous system, antigens of the pathogen are detected in the cerebrospinal fluid; in case of bacterial infections, microbial bodies are detected by microscopic method; by bacteriological method, the type of bacteria and their sensitivity to antibiotics are determined.

Modern laboratory diagnostic capabilities have significantly expanded the amount of information that can be obtained as a result of lumbar puncture. Creation of highly sensitive methods

LABORATORY METHODS FOR STUDYING CSF

Physiology of cerebrospinal fluid

Liquor (cerebrospinal fluid) is a biological fluid that washes the structures of the central nervous system. Its synthesis occurs in the venous vascular plexuses of the lateral ventricles of the brain, from where the fluid enters the third cerebral ventricle through the foramen interventriculare. The latter, through the Sylvian aqueduct, communicates with the IV ventricle, from which the cerebrospinal fluid passes through the median and lateral apertures into the subarachnoid space of the spinal cord and brain. A small part of the fluid also penetrates into the subdural space.

Figure 1 – Scheme of the main pathways for the formation of cerebrospinal fluid.

The formation of cerebrospinal fluid in the lateral ventricles occurs quite intensively, due to which sufficient pressure is created in their cavity to give the fluid flow a caudal direction. However, cerebrospinal fluid cannot be equated to the filtrate of blood plasma, since it is mixed with extracellular fluid of the nervous tissue entering through the ventricular ependyma. To some extent, the reverse process also occurs - the flow of cerebrospinal fluid through the ependyma to neurocytes and glial cells.

Modern radioisotope research methods have made it possible to establish that cerebrospinal fluid leaves the ventricular cavity within a few minutes and enters the subarachnoid space from the cisterns at the base of the brain within 4-8 hours. An adult secretes about 500 ml of cerebrospinal fluid per day, the amount of it in the cerebrospinal fluid ducts is 125-150 ml (10-14% of the mass of the brain). In the lateral ventricles there is 10-15 ml of fluid, in the III and IV a total of about 5 ml, in the subarachnoid cranial space - 30 ml, in the spinal space - 70-80 ml. During the day, the cerebrospinal fluid changes up to 3-4 times in adults and up to 8 times in children.

The circulation of cerebrospinal fluid in the subarachnoid space occurs through a system of cerebrospinal fluid channels and subarachnoid cells. The fluid flow accelerates when the position of the body in space changes and under the influence of muscle contractions. Today it is believed that the cerebrospinal fluid located in the lumbar region moves cranially within one hour; it is possible that circulation occurs in both directions simultaneously.

The outflow of cerebrospinal fluid by 30-40% occurs through the Pachionian granulations of the arachnoid membrane into the superior sagittal sinus, which is part of the venous system of the dura mater. They appear in humans at the age of 1.5 years, growing on the outer surface of the arachnoid membrane along the large sinuses and veins. The granulations face the dura mater and do not come into contact with the brain matter. Liquor accumulates in the superior sagittal sinus, creating a pressure of 15-50 mm Hg. higher than the venous one, due to which the transition of fluid from the liquor ducts to the circulatory system occurs.

Figure 2 – Scheme of the relationship between the membranes of the brain and granulations of the arachnoid membrane (Pachyon granulations).

1 – dura mater; 2 – subdural space; 3 – arachnoid membrane; 4 – subarachnoid space; 5 – granulation of the arachnoid membrane; 6 – superior sagittal sinus; 7 – lateral lacuna; 8 – choroid.

The outflow of cerebrospinal fluid also occurs through the cerebrospinal fluid channels into the subdural space, from which it enters the blood capillaries of the dura mater and passes into the venous system. In addition, it partially enters the lymphatic system through the perineural spaces of the cranial nerves (5-30%), is absorbed by the ventricular ependyma (10%) and enters the brain parenchyma.

Composition and functions of cerebrospinal fluid

The composition of cerebrospinal fluid is similar to blood plasma and consists of 90% water and 10% dry matter. It contains amino acids (20-25), proteins (about 14 fractions), enzymes involved in the metabolism of the nervous system, sugar, cholesterol, lactic acid and about 15 trace elements. Neurotransmitters are determined in the cerebrospinal fluid: acetylcholine, norepinephrine, dopamine, serotonin; hormones – melatonin, endophins, enkephalins, kinins.

Functions of cerebrospinal fluid:

Mechanical protection of the structures of the central nervous system;

Excretory – metabolic products are removed with the liquid;

Transport - cerebrospinal fluid serves to transport metabolites, biologically active substances, mediators, hormones;

Respiratory – supplies oxygen to the meninges and nervous tissue;

Homeostasis – maintains a stable environment of the brain, neutralizes short-term changes in blood composition, maintains pH at a certain level, osmotic pressure in brain cells, ensures normal excitability of the central nervous system, creates intracranial pressure;

Immune – participates in the creation of a specific immunobiological barrier of the central nervous system.

The functions of the cerebrospinal fluid have not been fully studied to this day, therefore research work on its study continues.

Preanalytical stage

Quincke first obtained cerebrospinal fluid for research in 1891, after which his technique became widespread. A general clinical analysis of cerebrospinal fluid is carried out within 3 hours after collecting the material, so the analysis of everything is carried out urgently. To obtain cerebrospinal fluid, lumbar puncture is used in most cases, suboccipital puncture is rarely used, and ventricular puncture is used intraoperatively.

A lumbar puncture is performed by a neurologist/anesthesiologist-resuscitator in a treatment room, dressing room or operating room. The patient is placed on his side with his knees brought to his chest, after which a needle is inserted into the space between the 4th and 5th lumbar vertebrae in the subarachnoid space. The first five drops of cerebrospinal fluid are removed, since they contain travel blood from blood vessels damaged during the manipulation. The liquid is collected in 2 sterile tubes: one of them is sent for biochemical and cytological studies, the other is used to detect a fibrous film or clot. If there is a need for bacteriological culture, a 3rd tube is filled with cerebrospinal fluid. Without danger to health, you can take 8-10 ml of cerebrospinal fluid from an adult, 5-7 ml from children, 2-3 ml from infants.

You cannot shake the resulting biomaterial or expose it to temperature changes, as this creature changes its parameters. All tubes are labeled before the start of the study, numbered, after filling they are tightly sealed and immediately sent to the laboratory. In the direction you should indicate:

Last name, first name, patronymic of the patient, his age;

Department, ward, medical history number;

Date, time and place of puncture;

Purpose of the study;

Presumptive or clinical diagnosis;

Data of the doctor who sent the material for research.

2.4 Methods for laboratory testing of cerebrospinal fluid

2.4.1. Macroscopic examination

Macroscopic examination is all the information about a biomaterial that a laboratory technician can obtain using the senses.

Color - Normally, cerebrospinal fluid is colorless and does not differ in appearance from water. Its color is determined by comparing a test tube with material with the same test tube filled with water on a white background. It can change in various pathological processes:

red – an admixture of unchanged red blood cells (erythrocytes). It can be determined using test strips (HemoFAN), which have 2 comparison scales: one of them changes color in the presence of intact red blood cells, the other in the presence of free hemoglobin in the cerebrospinal fluid;

xanthochrome (yellow, yellow-brown, pink, brown) color occurs in the presence of oxyhemoglobin, methemoglobin and bilirubin;

the pink color of the cerebrospinal fluid is given by oxyhemoglobin, released from lysed erythrocytes;

The yellow color is due to the high content of bilirubin, which is formed from hemoglobin. To determine bilirubinarchy and its severity, test strips (IctoFAN) are used; their reagent zone changes color from pale pink to deep pink depending on the concentration of bilirubin;

methemoglobin and metalbumin give the brown color to the cerebrospinal fluid; they appear in the presence of encapsulated hematomas and hemorrhages in the central nervous system;

green color occurs with pronounced bilirubinarchy, as bilirubin transforms into biliverdin, an olive-colored pigment. Sometimes it is caused by an admixture of pus.

Transparency – cerebrospinal fluid is normally transparent; this parameter is determined by comparing the resulting material with distilled water. Slight turbidity of the cerebrospinal fluid is observed with leukocytosis over 200x10 6 /l, erythrocyte content more than 400x10 6 /l, total protein - more than 3 g/l. If, after centrifugation, the cerebrospinal fluid becomes transparent, then its turbidity is due to formed elements; if it remains turbid, it is caused by microorganisms. Opalescence of the cerebrospinal fluid occurs at high concentrations of fibrinogen.

Fibrinous film - normally, the cerebrospinal fluid has a low fibrin content and a film does not form during settling. A high fibrin content produces a delicate mesh or film on the walls of the test tube, a sac or a jelly-like clot. Liquor containing a large amount of coarse proteins immediately after release coagulates into a jelly-like clot.

2.4.2. Microscopic examination of cerebrospinal fluid

This is one of the most critical stages of the study of cerebrospinal fluid, based on the data of which diagnoses are often confirmed or refuted.

Counting the number of formed elements is carried out within 30 minutes after extraction of cerebrospinal fluid, followed by cell differentiation. To count leukocytes The preparation is stained with one of the following reagents:

5 ml 10% solution of glacial acetic acid + 0.1 methyl violet + water up to 50 ml – staining time 2 minutes;
Samson's reagent: 2.5 ml of fuchsin alcohol solution 1:10 + 30 ml of acetic acid + 2 g of carbolic acid + distilled water up to 100 ml, staining time 10-15 minutes.

The colored preparation is placed in a 3.2 µl Fuchs-Rosenthal chamber. Leukocytes are counted at low magnification in all 256 squares, with high pleocytosis of 200-1000x10 6 /l, half of the grid is counted and the result is multiplied by 2, with pleocytosis over 1000x10 6 /l, one row of large squares is counted and the result is multiplied by 4. Normal values of cytosis are indicated in table 1, for various types of pathology - in table 2.

Table 1

Cytosis in lumbar cerebrospinal fluid

table 2

Pleocytosis in various diseases

Quantity red blood cells in the liquor are counted in the Goryaev counting chamber. To do this, CSF mixed with blood is diluted 10 times - 9 parts of isotonic sodium chloride solution and 1 part of CSF are mixed in a test tube. The resulting liquid is thoroughly mixed, Goryaev’s counting chamber is filled and, according to the rules for counting the number of red blood cells, the number of red blood cells in five large squares is determined. The number of red blood cells in 1 μl of CSF is determined by the formula:

where A is the number of red blood cells in 5 large (80 small) squares, 1/400 is the volume of a small square, 10 is the dilution of cerebrospinal fluid, 80 is the number of small squares.

When counting in a Fuchs-Rosenthal chamber, nuclear and cytoplasmic structures are visible in fuchsin-stained cellular and formed elements, which allows for their differentiation. They are assessed at a magnification of 7x40. Registration of counting results can have a percentage or numerical expression (liquorogram). Considering that formed and cellular elements can undergo degenerative changes when they remain in the CSF for a long time, it is necessary to evaluate and count the formed and cellular elements in stained preparations.

CSF cells have a completely different affinity for dyes than blood cells, therefore the selection of dyes should be different. The following types of staining of preparations give good results:

Coloring according to Rosina. The CSF is centrifuged for 7–10 minutes. The supernatant liquid is drained, the sediment is placed on a defatted glass, gently rocked, it is distributed on the surface of the glass, and after 1–2 minutes the liquid is drained. The glass is placed in a vertical position and dried in an oven at a temperature of 40–50 ° C, after which it is fixed for 1–2 minutes with methanol and stained according to Romanovsky: the preparations are stained for 6–12 minutes, depending on the thickness of the smear. The preparation is washed with distilled water and dried. If the kernels are pale blue, the smear is repainted for another 2–3 minutes.

Coloring according to Vozna. The sediment obtained during centrifugation is poured onto the glass, shaking it slightly, and evenly distributed on the surface. Dry at room temperature for 24 hours, fix for 5 minutes with methyl alcohol. Then they are stained with a solution of azure eosin (the same as for blood staining, but diluted 5 times) for 1 hour. If the cells are pale colored, finish staining with undiluted paint under the control of a microscope for 2 to 10 minutes. The more formed elements in the cerebrospinal fluid, especially in the presence of blood, the longer the color.

Staining according to Alekseev. Apply 6–10 drops of Romanovsky-Giemsa dye to a dried but not fixed preparation; using the same pipette, carefully distribute it over the entire preparation and leave for 30 seconds. Then add, without draining the paint, 12–20 drops of distilled water, preheated to a temperature of 50–60 °C, in a ratio of 1: 2. By shaking the preparation, mix the paint with water and leave for 3 minutes. Wash off the paint with a stream of distilled water, dry the preparation with filter paper and examine it microscopically. The method is suitable for urgent cytological examination.

Normal values for the content of cellular elements in the cerebrospinal fluid are presented in Table 3.

Table 3

Cytocentrifugation technology (cytospin). Preparation of colored preparations of cerebrospinal fluid from sedimentary liquid after centrifugation does not always make it possible to obtain a thin layer of cells suitable for diagnosis. To solve this problem, cytocentrifugation technology was developed, which involves the hardware production of high-quality drugs. To do this, the resulting cerebrospinal fluid is prepared for examination and placed in a cytochamber, after which it is dosed onto slides placed vertically in the cytocentrifuge rotor. Under the influence of centrifugal force, the cells are evenly distributed over the glass, while the lighter liquid is removed from the surface of the preparation. Drying, fixing and staining of the preparation is also carried out in a cytocentrifuge. The device allows you to create up to 8 diagnostic zones on one slide.

Atypical cells – most often they are tumor cells of the central nervous system or its membranes. They can also occur in chronic inflammatory processes (tuberculous meningitis, meningoencephalitis, multiple sclerosis, encephalomyelitis) - these are ependymal cells of the ventricles of the arachnoid membrane, as well as lymphocytes, monocytes and plasmacytes with changes in the nucleus and cytoplasm.

Altered Cells and Cell Shadows are detected during prolonged stay in the CSF. Most often, neutrophil granulocytes, arachnoid cells, and ventricular ependyma undergo autolysis. Changed cells and cell shadows have no diagnostic value.

Crystals in the liquor are rarely found. On days 4–5 after subarachnoid hemorrhage or traumatic brain injury, hemosiderin crystals are found; in the case of tumor disintegration, crystals of hematoidin, cholesterol, and bilirubin can be found in the contents of the cyst; cholesterol crystals are also formed in areas of fatty degeneration, necrosis of brain tissue, and in brain cysts . To detect crystals in the CSF, the reactions presented in Table 4 are used.

Table 4

Reactions used to detect crystals in liquor

Echinococcus elements – hooks, scolex and fragments of the chitinous membrane of the echinococcal bladder can be detected with multiple echinococcosis of the meninges. They are found extremely rarely.