What Is Cerebrospinal Fluid?

Cerebrospinal fluid: Cerebrospinal fluid is a colorless and transparent liquid that exists in the ventricles and subarachnoid space. The specific gravity is 1.005, and the total amount is 130 to 150 ml. The average daily production is 524ml. Cerebrospinal fluid surrounds and supports the entire brain and spinal cord, effectively reducing the weight of the brain to 1/6, and playing a protective role in trauma. In removing metabolites and inflammatory exudates, it plays the role of lymph fluid in other parts of the body.

Cerebrospinal fluid: Cerebrospinal fluid is a colorless and transparent liquid that exists in the ventricles and subarachnoid space. The specific gravity is 1.005, and the total amount is 130 to 150 ml. The average daily production is 524ml. Cerebrospinal fluid surrounds and supports the entire brain and spinal cord, effectively reducing the weight of the brain to 1/6, and playing a protective role in trauma. In removing metabolites and inflammatory exudates, it plays the role of lymph fluid in other parts of the body.

Chinese name

Cerebrospinal fluid

Foreign name

Cerebro-Spinal Fluid, CSF

Applied discipline

medicine

Scope of application

diagnosis

Scope of application

Mind and brain

Cerebrospinal fluid overview

The site of cerebrospinal fluid is the choroid plexus in the lateral ventricle, most of which is a kind of ultrafiltration of plasma, but there are also active components secreted by the choroid plexus. Between the blood and the cerebrospinal fluid, there are mechanical and permeable barriers between the cerebrospinal fluid and the brain, called the blood-cerebrospinal fluid barrier and the cerebrospinal fluid-brain barrier, respectively.

Produced by special blood vessels inside the brain and reabsorbed by special venous branches. Provides shock absorption and support to the central nervous system. Normal adults have 130 ml of clear cerebrospinal fluid; in order to diagnose neurological diseases, cerebrospinal fluid is often taken for testing.

Is one of the inherent contents of the cranial cavity. It is mainly produced from the choroid plexus in the lateral ventricle, the third ventricle, and the fourth ventricle. The secretion pressure of CSF mainly depends on the difference between mean arterial pressure and ICP. The absorption of CSF mainly passes through the arachnoid granules, and CSF unidirectionally enters the sinus at a certain flow rate. The rate of absorption depends on the pressure difference between the ICP and the venous pressure. Secretion and absorption are in a relatively balanced state. It can be seen that ICP is the key to regulating balance.

Cerebrospinal fluid production

Cerebrospinal fluid

Cerebrospinal fluid production : In the central nervous system, the rate of cerebrospinal fluid production is 0.3 ml / min, and the daily secretion volume is 432 ml. The choroid plexus in the lateral ventricle is the main structure that produces cerebrospinal fluid. The choroid plexus is mainly distributed at the bottom of the lateral ventricle and the top of the third and fourth ventricles. Its structure is a cluster of capillary networks covered with a layer of ependymal epithelium, which looks like microvilli. This microvilli is like a one-way open membrane, secreting cerebrospinal fluid only to the ventricular cavity and subarachnoid space. It is also believed that the ventricular membrane and the brain parenchyma also have the effect of generating cerebrospinal fluid.

If the cerebrospinal fluid is produced too much, or the circulation pathway is blocked, both can increase the intracranial pressure.

Cerebrospinal fluid circulation

Cerebrospinal fluid rhinorrhea

The flow of cerebrospinal fluid has a certain direction. The choroid plexus of the two lateral ventricles is the most abundant and produces the most cerebrospinal fluid. These cerebrospinal fluids flow into the third ventricle through the interventricular foramen and then into the fourth ventricle through the midbrain aqueduct. The cerebrospinal fluid produced by each ventricle choroid plexus reaches the fourth ventricle and flows into the subarachnoid space of the brain and spinal cord through the median and lateral holes of the fourth ventricle. Finally, the arachnoid granules next to the sagittal sinus osmotically infiltrate the cerebrospinal fluid to the superior sagittal sinus and return the cerebrospinal fluid to the venous system. Cerebrospinal fluid reflux (or absorption) is mainly determined by the intracranial venous pressure and the pressure difference between the cerebrospinal fluid and the effective colloid osmotic pressure between the blood-brain barrier. Brain and spinal blood vessels, peri-nerve space and ependyma are also involved in the absorption of cerebrospinal fluid.

Cerebrospinal fluid effect

The role of cerebrospinal fluid: Cerebrospinal fluid is continuously produced and absorbed and returned to the vein. It plays the role of lymph fluid in the central nervous system. It supplies certain nutrients to brain cells, transports metabolites from brain tissues, and regulates the acid and alkali in the central nervous system. balance. It also buffers the pressure on the brain and spinal cord and has a protective and supportive effect on the brain and spinal cord.

Cerebrospinal fluid traits

Cerebrospinal fluid appearance

Normal cerebrospinal fluid is colorless and transparent. Cerebrospinal fluid can be yellow when newborn cerebrospinal fluid (because it contains bilirubin), old bleeding or high protein content. New hemorrhage is red or bloody. It must be distinguished from hemorrhage caused by puncture accidental injury. The former cerebrospinal fluid blood staining concentration is uniform before and after. The supernatant is yellow or light yellow after centrifugation. The occult blood test is positive. The edge of red blood cell morphology shrinks or ruptures. The opposite is true for traumatic bleeding. In bacterial meningitis, the cerebrospinal fluid can be milky white or green turbid, and a film-like deposit can appear after standing still. For example, tuberculous meningitis has a funnel-like spider web film suspended from the liquid surface to the bottom of the test tube. The positive rate of bacteria found in the material is generally high. Specific gravity measurement: 1.005-1.009.

Cerebrospinal fluid examination

Adult normal white blood cell count is below 0.01 × 109 cells / L (premature infants and newborns are within 0.03 × 109 cells / L), but multinucleated white blood cells 9 should not exceed 5, mainly small and medium lymphocytes. When the meninges are irritating or inflammatory, the white blood cell count of cerebrospinal fluid can increase. Therefore, when infectious lesions of the central nervous system, multinucleated or monocytes are increased to varying degrees; various brain tumors, especially those near the meninges, ventricles or malignant cells, also have increased white blood cells.

Using a special cerebrospinal fluid cell centrifugal precipitator, the cells concentrated on the glass can be stained with various stains, and the morphological changes of the cells can be observed in detail, which greatly improves the diagnostic effect. For example, the increase of eosinophils indicates central nervous system parasitism. Worm disease; phagocytic cells containing hemosiderin suggest old bleeding in the cerebrospinal fluid. In addition, tumor cells and parasite eggs can be directly observed, and the immune function of cells can be studied.

Cerebrospinal fluid biochemistry

Cerebrospinal fluid protein

The normal cerebrospinal fluid protein content is 150-400mg / L in the subarachnoid space, 1g / L in newborns, and up to 2g / L in preterm infants. Increased protein and cell proliferation occur at the same time, seen in various central nervous system infections. It is also possible that only the protein is increased and the white blood cell count is normal or slightly more. It is called "protein-cell separation". It is more common in intracranial and spinal tumors, spinal canal obstruction, acute infectious polyneuritis, hyperthyroidism, diabetes and lead, mercury. And other metal poisoning.

Cerebrospinal fluid sugar

The normal content is 450-750mg / L, which is about 1 / 2-2 / 3 of the blood sugar level. Decreased sugar is seen in bacterial or cryptococcal meningitis, malignant brain tumors, etc., because of the acceleration of sugar fermentation. Increased glucose levels are seen in increased blood glucose levels (so blood glucose levels should be checked at the same time), as well as central system virus infections, traumatic brain injuries, posterior cranial foci, and tumors and high fever in the bottom of the ventricle III, all of which are related to increased blood-brain barrier permeability.

chloride

The normal content is 7.2-7.5g / L, which is higher than the blood chloride content of 5.7-6.2g / L. When bacterial (especially tuberculosis) and mycotic meningitis and blood chloride levels are reduced (such as vomiting, adrenal hypofunction), blood chloride levels (such as uremia, dehydration, etc.) are increased.

Cerebrospinal fluid examination method

Cerebrospinal fluid bacteriological examination

It is very necessary for bacterial infection of the nervous system, including bacteria and mold smears and culture. If necessary, animal vaccination is required to identify pathogenic bacteria for reference in clinical medication.

Cerebrospinal fluid immunological examination

Commonly used are complement binding test and immunoglobulin content determination. The former has certain diagnostic value for infections such as cysticercosis, pneumocystis, leptospirosis, and viruses. The latter includes: IgG, IgA, IgM, IgD, IgE, and other immunoglobulins. Among them, IgG concentration is the highest, and IgM is not easy to detect. . Such as increased IgG and the detection of IgM, suggest that the central nervous system infection, demyelinating disease or increased blood-brain barrier permeability.

Cerebrospinal fluid protein electrophoresis

The strips of normal cerebrospinal fluid protein electrophoresis diagrams are similar to serum electrophoresis diagrams, and are mainly divided into prealbumin, albumin, 1, 2, 1, 2, and gamma globulin. The content varies greatly depending on the method used for electrophoresis. Related to cerebrospinal fluid protein content. When the amount of protein in the cerebrospinal fluid increases, the proportion of prealbumin decreases and may even disappear; albumin comes from serum, has a small molecular weight, and easily crosses the blood-brain barrier. When the cerebrospinal fluid protein increases, the albumin also increases. The increase in 1 and 2 globulin is mainly seen in atrophic and degenerative diseases of the central nervous system. Increased gamma globulin and normal total protein are seen in multiple sclerosis and neurosyphilis. When both are increased, they are seen in chronic inflammation and parenchymal malignancies. They are also related to increased permeability of the blood-brain barrier. The oligoclone zone (oligoclone) It refers to a discontinuous zone that appears in the gamma globulin zone and is generally not seen in peripheral blood. It is a marker of IgG synthesis in the nervous system. It is higher than IgG in 95% of patients with multiple sclerosis. Early, it has important diagnostic value, but positive can also be seen in acute infectious polyneuritis, optic neuritis, and serous meningitis.

Cerebrospinal fluid enzyme test

In normal people, because the blood-brain barrier is intact, the concentration of enzymes in the cerebrospinal fluid is lower than that in the serum. When the brain is injured, intracranial tumors or hypoxia, the blood-brain barrier is destroyed, and the permeability of the cell membrane is also changed. It is increased without being affected by total protein, sugar content and cell number; it is mainly related to the degree of brain cell necrosis and cell membrane damage. Commonly used are aspartate aminotransferase, lactate dehydrogenase, hexose phosphate isomerase, and lysozyme. Among them, lactate dehydrogenase is significantly higher in benign tumors and viral meningitis than in benign tumors and viral meningitis. A certain differential diagnostic value can also reflect the severity of the condition. Changes in lysozyme are closely related to proteins, sugars, and leukocytes, especially neutrophils. They have different contents in purulent, tuberculous, and viral meningitis, and are not affected by drug treatment. Therefore, it is important to identify and judge meningitis. Nature has great value.

Cerebrospinal fluid microscopy

Cell counting and classification: Cerebrospinal fluid is normally free of red blood cells and only a few white blood cells (lymphocytes).

Normal value: Adult: (0--5) × 10 ⁶ / L

Child: (0--15) × 10 ⁶ / L

Clinical significance:

Chemical brain: the number of cells can reach 1000 × 10 ⁶ / L, mainly neutrophils.

Brain knot: The number of cells is less than 500 × 10 ⁶ / L. It is mainly characterized by neutrophils in the early stage, lymphocytes in the later stage, neutrophils, lymphocytes and plasma cells.

Diseased brain: the number of cells is tens of × 10 ⁶ / L, mainly lymphocytes.

Meningeal leukemia: immature cells.

Cerebrospinal fluid pressure measurement

Cerebrospinal fluid initial pressure

The cerebrospinal fluid pressure measured after puncture is 0.78-1.96kPa (80-200mm water column) for adults in the lateral position, 0.39-0.98kPa (40-100mm water column) for infants and 0.098-0.14kPa (10- 14mm water column).

When observing the initial pressure, you should pay attention to whether the cerebrospinal fluid level has respiratory pulsation (0.098-0.197kPa (water level pulsation with 10-20mm water column) and breath pulsation (0.02-0.039kPa (2-4mm water column with pulsation) Liquid pulsation). When the former disappears, it is suggested that there is obstruction in the spinal canal or foramen magnum hernia, which should be careful.

Cerebrospinal fluid pressure dynamics

(1) The jugular vein compression test (Queckenstedt test): The bilateral jugular veins are compressed by hand to congest the intracranial venous system and increase the intracranial pressure. The increased pressure is transmitted to the pressure glass tube connected to the lumbar puncture needle. Can cause a significant rise in the liquid level, the liquid level drops rapidly after the pressure is relaxed. When the spinal canal is obstructed, the liquid level rises and falls slowly or even after compression. For accurate measurement, use a sphygmomanometer air bag around the neck, inflate to 2.7-5.3-8kPa (20-40-60mm Hg), relax for 30 seconds after 30 seconds of compression, record the pressure every 5 seconds, and draw Into a picture. Patients with increased intracranial pressure or suspected intracranial masses and bleeding are not allowed.

Results: Cerebrospinal fluid pressure should rise to the highest point in about 15 seconds after neck compression when there is no obstruction, and can quickly drop to the initial pressure level in about 15 seconds after decompression; or pressurize to 8kPa (60 mmHg) It can rise above 4.9kPa (500mm water column). In partial obstruction, the pressure rises and falls slowly, or it cannot drop to the initial pressure level after it rises; in complete obstruction, the pressure in the cerebrospinal fluid of the pressure tube does not rise or rises very little after the neck is pressurized.

(2) Abdominal compression test (Stookey test): use a fist to press the patient's upper abdomen or hold their breath to congest the inferior vena cava and epidural vein below the lower thoracic segment, causing a rapid rise in cerebrospinal fluid pressure below the above level Find out if the spinal cord and subarachnoid space in the lower thoracic and lumbosacral regions, as well as lumbar punctures and manometers are obstructed. Normally, the pressure rises about twice the initial pressure. After the compression stops, the pressure rapidly drops to the initial pressure level. If the pressure rises slowly or not, the subarachnoid space obstruction below the lower thoracic segment is indicated. If the lumbar puncture and the pressure measuring tube are not smooth, it can also be positive, and you should pay attention to it.

(3) Double-needle combined puncture test: Simultaneously puncture the upper and lower parts of the spinal canal with obstruction such as lumbar vertebrae 2-3 and lumbar 5 1. The cerebrospinal fluid pressure above and below the obstruction plane is used in the jugular vein compression test. Show the difference. Can be roughly measured for obstruction between 2-5 lumbar spine.

(4) Unilateral jugular vein compression test (Tobey-Ayer test): Compression of the jugular vein on one side causes an increase in cerebrospinal fluid pressure, but there is no change in the pressure when the other jugular vein is compressed. It is said that the unilateral jugular vein compression test is positive. It suggests that the lateral sinus or internal jugular vein is obstructed, such as thrombosis.

Cerebrospinal fluid end pressure

The pressure measured after the cerebrospinal fluid is released is often abnormal when it is less than 1/2 of the original pressure. Normal people's brain pressure reduction after 2-3 ml of fluid is generally not more than 0.098-0.197kPa (10-20mm water column) or remain unchanged. If the pressure drop is greater than 0.5kPa (50mm water column) after 3-5ml of fluid is dissipated, the lower the site of obstruction in the spinal canal or the foramen magnum, the more obvious this phenomenon is; Pressure can sometimes drop to zero. If several months after the release of cerebrospinal fluid, cerebral pressure drops little or returns to the initial pressure level soon, it is suggestive of traffic hydrocephalus or increased intracranial pressure.

Cerebrospinal fluid clinical

Normal cerebrospinal fluid

1. Color inspection: colorless watery liquid.

2. Transparency check: clear and transparent.

3. Cell count: Adult: (0-8) × 106 / L; Child: (0-15) × 106 / L; Newborn: (0-30) × 106 / L.

4. Qualitative protein test: negative.

5. Semi-quantitative glucose test: 1-5 tubes or 2-5 tubes are positive.

6. Bacteria and parasite inspection: negative.

7, cell classification (DC): red blood cells: none or a small amount; lymph and monocytes: a small amount; mesothelial cells: occasional; other cells: none.

8. Quantitative protein: Lumbar puncture: 0.15-0.45g / L; Ventricular puncture: 0.05-0.15g / 1; Cerebral puncture: 0.10-0.25g / L.

9. Protein electrophoresis: prealbumin: 0.03-0.07; albumin: 0.51-0.63; 1-globulin: 0.06-0.08; 2-globulin: 0.06-0.10; -globulin: 0.14-0.19; -sphere Protein: 0.06-0.10.

10. Glucose quantification: adult: 2.8-4.5mmol / L: child: 3.1-4.4mmol / 1; infant: 3.9-5.0mmol / L.

11. Chloride determination: Adult: 120-132mmol / L; Child: 111-123mmol / L; Infant: 110-122mmol / L.

12. Enzymatic determination of cerebrospinal fluid: transaminase (ALT, AST): about 1/2 of serum enzyme activity; lactate dehydrogenase (LDH); about 1/10 of serum enzyme activity; phosphocreatine kinase (CPK): Below serum enzyme activity.

13. Cerebrospinal fluid immunoglobulin determination: IgG: 10-40mg / L; IgA: 0-6mg / L; IgM: 0-13mg / L; IgE: very small amount

Cerebrospinal fluid color

1, red: common in subarachnoid hemorrhage, cerebral hemorrhage, subdural hematoma and so on. For example, during the lumbar puncture, the outflow of cerebrospinal fluid was observed to be red and then colorless, which is a puncture-induced bleeding.

2. Yellow: seen in old subarachnoid hemorrhage and cerebral hemorrhage, cystic subdural hematoma, purulent meningitis, meningeal adhesion, cerebral embolism; spinal canal obstruction; brain and spinal tumors and severe tuberculous meningitis ; Severe jaundice caused by various reasons; cardiac insufficiency, hemosiderin, caroteneemia, premature babies, etc.

3. Milky white: seen in purulent meningitis.

4, slightly green: seen in P. aeruginosa meningitis, streptococcal meningitis.

5. Brown or black: Melanoma and melanosarcoma found in the central nervous system.

Cerebrospinal fluid transparency

1, slightly mixed: common in Japanese encephalitis, polio, brain abscess (unrupted).

2, turbidity: common in purulent meningitis, tuberculous meningitis and so on.

3, ground glass: common in tuberculous meningitis, viral meningitis and so on.

4, clot: seen in purulent meningitis, encephalitis, polio and so on.

5, thin film: common in tuberculous meningitis.

Cerebrospinal fluid cells

1. The number of cells is significantly increased (> 200 × 106 / L): common in purulent meningitis and epidemic meningitis.

2. Moderate increase (<200 × 106 / L): common in tuberculous meningitis.

3. Normal or mildly increased: common in serous meningitis, epidemic encephalitis (viral encephalitis), and cerebral edema.

Cerebrospinal fluid characterization

1. Cerebrospinal fluid protein is significantly increased (above): common in purulent meningitis, tuberculous meningitis, spinal cavity and other central nervous system malignant tumors and metastatic cancer, cerebral hemorrhage, subarachnoid hemorrhage and obstruction.

2. Mild elevation of cerebrospinal fluid protein (-): Commonly seen in viral meningitis, fungal meningitis, Japanese encephalitis, polio, meningovascular syphilis, paralytic dementia, cerebral thrombosis, etc.

Cerebrospinal fluid bacteria and parasites

1. There are bacteria in cerebrospinal fluid, which can cause bacterial meningitis. For example, acute suppurative meningitis is often caused by Neisseria meningitidis, Streptococcus pneumoniae, hemolytic streptococcus, staphylococcus, etc .; slower meningitis is often caused by Mycobacterium tuberculosis, new cryptococcus, etc.

2. If schistosomiasis eggs or pulmonary schistosomiasis eggs are found in cerebrospinal fluid, they can be diagnosed as cerebral schistosomiasis or cerebral schistosomiasis.

Cerebrospinal fluid cell classification

1, red blood cells increased: common in cerebral hemorrhage, subarachnoid hemorrhage, cerebral thrombosis, subdural hematoma and so on.

2. Lymphocytic: seen in tuberculous meningitis, fungal meningitis, viral meningitis, paralytic dementia, late stage of encephalitis B, polio, brain tumor, cerebral hemorrhage, polyneuritis.

3, neutrophil increase: see: in purulent meningitis, epidemic meningitis, epidemic encephalitis, cerebral hemorrhage, brain abscess, tuberculous meningitis in the worsening period.

4, eosinophilia: seen in parasitic encephalopathy.

5, mononuclear cells increase: common in serous meningitis.

6, phagocytic cells: common in paralytic dementia, meningitis.

7. Tumor cells: found in brain and spinal tumors.

8. Leukemia cells: found in central nervous system leukemia

Cerebrospinal fluid protein quantification

1. Purulent meningitis, epidemic meningitis protein content is 3-6.5g / L; tuberculous meningitis protein content is 0.3-2.0g / L, symptomatic period is 1.9-7g / L, paralysis period 0.5-6.5g / L; encephalitis protein content is 0.5-3.0g / L.

2. Diseases that cause cerebrospinal fluid circulation obstruction, such as spinal arachnoiditis and spinal tumors, etc., whose protein content can be above 1.0g / L;

3. Cerebrospinal fluid proteins such as tau and a42 can be increased to 0.25-0.8g / L for cerebral softening, tumors, and degenerative diseases.

4. Cerebrospinal fluid proteins such as polyradiculitis, serous meningitis, cerebrospinal syphilis, paralytic dementia, cerebral hemorrhage, cerebral embolism, subarachnoid hemorrhage, epidemic encephalitis, and polio are also increased.

Cerebrospinal fluid protein electrophoresis

1. Increased prealbumin: Commonly seen in chorea, Parkinson's disease, hand and foot asthma; Decrease in prealbumin is common in meningitis.

2, albumin increased: common in cerebrovascular diseases, such as cerebral infarction, cerebral hemorrhage, etc .; albumin reduction seen in the acute phase of brain trauma.

3, 1-globulin increased: common in meningitis, polio and so on.

4, 2-globulin increased: common in brain tumors, metastatic cancers, gliomas and so on.

5, -globulin increased: common in some degenerative changes such as Parkinson's disease, hemiparesis after trauma and so on.

6, -globulin increased: common in gliomas, severe brain trauma, epilepsy, optic neuromyelitis, multiple sclerosis, brain infections, peripheral neuritis and so on.

Cerebrospinal fluid glucose quantification

1. Increased cerebrospinal fluid glucose: common after full meals or intravenous glucose, bloody cerebrospinal fluid, diabetes, acute brain stem injury or poisoning, premature infants or newborns.

2. Cerebrospinal fluid glucose reduction: common in acute purulent meningitis, tuberculous meningitis, fungal meningitis, neurosyphilis, brain tumors, hypoglycemia, etc.

Cerebrospinal fluid measurement

Cerebrospinal fluid chloride determination

1. Increase: seen in chronic renal insufficiency, nephritis, uremia, serous meningitis, and intravenous drip of saline.

2, reduction: seen in meningitis, purulent meningitis and other fine Portuguese meningitis, especially tuberculous meningitis is most obvious. Viral encephalitis, brain abscess, polio, toxic encephalitis, brain tumors, etc. have slightly lower or no significant changes in chloride content.

Cerebrospinal fluid enzyme assay

1. Increased activity of ALT and AST: common in cerebral infarction, brain atrophy, acute craniocerebral injury, toxic encephalopathy, and metastatic cancer of the central nervous system.

2, LDH activity increased: common in bacterial meningitis, cerebrovascular disease, brain tumors and demyelinating diseases such as brain tissue necrosis.

3. Increased CPK activity: common in purulent meningitis, tuberculous meningitis, progressive hydrocephalus, secondary epilepsy, multiple sclerosis, subarachnoid hemorrhage, chronic subdural edema, insufficient cerebral blood supply and Brain tumors, etc.

Cerebrospinal fluid immunoglobulin assay

1, IgG increased: common in neurosyphilis, purulent meningitis, tuberculous meningitis, viral meningitis, small dance disease, nervous system tumors.

2, IgA increased: common in purulent meningitis, tuberculous meningitis, viral meningitis, tumors and so on.

3, IgM increased: common in purulent meningitis, viral meningitis, tumors, multiple sclerosis and so on.

4, IgE increased: common in cerebral parasitic diseases.

Other cerebrospinal fluid measurements

1. Increased pressure is seen in: (1) Various inflammatory lesions in the skull: purulent meningitis, tuberculous meningitis, fungal meningitis, viral meningitis, Japanese encephalitis, and polio. (2) Intracranial non-inflammatory lesions: meningovascular syphilis, paralytic dementia, brain tumor, cerebral abscess (unbroken), cerebral hemorrhage, subarachnoid hemorrhage, subdural hematoma, epidural hematoma, intracranial Sinus thrombosis, hydrocephalus, brain injury, epilepsy, lead poisoning encephalopathy, etc.

(3) Extracranial factors: hypertension, arteriosclerosis, certain eye diseases, local stasis of the head or systemic stasis. (4) Other factors: cough, sneeze, abdominal pressure, crying, deep breathing, etc.

2. The decrease in pressure is seen in: (1) Cerebrospinal fluid circulation is blocked: occipital occlusion, spinal cord compression, spinal cord subarachnoid adhesion, and subdural hematoma. (2) Excessive cerebrospinal fluid loss: Cerebrospinal fluid leakage after craniocerebral injury, multiple cerebrospinal fluid drains in a short period of time, and continuous ventricular drainage. (3) Cerebrospinal fluid secretion is reduced. (4) Unexplained intracranial pressure (low intracranial pressure syndrome). (5) The puncture needle is not completely inside the spinal canal.

3. Determination of pH and gas tension: [normal reference value] pH: 7.28-7.32; HCO3-: 22mmol / L; Po2: 5.3-5.9KPa; PCO2: 5.9-6.7kPa.

[Clinical significance]:

(1) When meningococcal meningitis, diabetic coma, tuberculous meningitis, the pH value of cerebrospinal fluid often decreases.

(2) In acute cerebral infarction, the cerebrospinal fluid pH and PO2 decrease, while lactic acid increases, which is helpful for judging cerebral hypoxia, metabolism and cerebral blood flow.

4. Tryptophan test: [normal reference value] is negative.

[Clinical significance] Purulent meningitis, tuberculous meningitis, and epidemic meningitis can all have positive reactions. Tuberculous meningitis is most common in cerebrospinal fluid that is colorless and transparent in appearance.

5. Quantitative test of lactic acid: [normal reference value] 1.0-2.8mmol / L.

[Clinical significance] Increased lactic acid content in cerebrospinal fluid is common in purulent meningitis, tuberculous meningitis, significantly reduced cerebral blood flow, hypocapnia, hydrocephalus, seizures or persistent state, cerebral abscess, acute cerebral infarction, and brain death Wait.

6. Determination of glutamine: [normal reference value] 0.41-1.61 mmol / L.

[Clinical significance] Increased glutamine in cerebrospinal fluid is common in the late stage of liver cirrhosis, and it can reach as high as 3.4mmol / L when entering the liver coma. Patients with hemorrhagic meningitis show a slight increase.