Cerebrospinal Fluid

CEREBROSPINAL FLUID (liquor cerebrospinalis) is located in the subarachnoid space of the brain and spinal cord and fills the central canal, the ventricles of the brain, and their connections (Fig. 1). It was first discovered by Cotugno (1764). It was secondarily described by Magendie (1825); subsequently, the classic work in this field is that of Key and Retzius (1875), the basic principles of which have not yet been refuted. In 1891, Quincke and Winter independently attempted to obtain fluid from humans by lumbar puncture, and this moment should be considered the beginning of the study of the fluid itself. At present, it is already necessary to make a differentiation depending on from which parts of the subarachnoid space the fluid was obtained. They speak of "lumbar", "spinal" or "fluid of the subarachnoid space of the spinal cord" if the fluid was obtained by lumbar puncture; "cisternal" fluid if a suboccipital puncture was used; "ventricular" fluid if it was obtained by puncture of the brain ventricles, and fluid of the subarachnoid space of the brain if an orbital puncture was used. Physiology. 1. Origin of cerebrospinal fluid. This question until recently has caused great controversy. The following anatomical structures were considered as sources of the fluid, either individually or in combinations: plexus choroidea [see separate table (Vol. XXXIII, pp. 551-552), pnc.6], ependyma of the ventricles, subependymal tissue, glia, nervous parenchyma, soft meninges and their vessels. However, recent studies have shown that the place where cerebrospinal fluid is formed is the choroid plexus. This view is the oldest in the history of the doctrine of C. f.; indirect indications of it can be found even in Galen and later in Willis, Magendie and Luschka. The participation of the meninges in the production of cerebrospinal fluid is apparently insignificant. Levandovsky put forward the hypothesis of the formation of fluid in the brain substance itself. The author believes that not only substances from the fluid enter the nervous system, but also, conversely, metabolic products from the nervous system can enter the fluid through perivascular lymphatic spaces. Regarding lymph formation in the brain and the pathways of lymph spread, there are two points of view. One of them (Sicard) assumes two perivascular systems: each vessel penetrating the brain has two perivascular spaces separated by a membrane. The outer one freely communicates with the subarachnoid space, ending blindly in its central segment, in the place where the brain vessels turn into capillaries; this space contains cerebrospinal fluid. The inner segment of the perivascular space accompanies the vessels throughout their course and not only in the nervous parenchyma but also in the subarachnoid space, not communicating with it. Lymph circulates in this inner segment of the perivascular space. Another point of view (Mestrezat) assumes a single system of perivascular spaces continuing to the capillaries, with lymph located in the capillary part, partially communicating with the fluid of the perivascular spaces. None of the presented points of view has yet received full recognition; thus the question of the systems of perivascular spaces should be considered controversial. The point of view of Mestrezat about the presence of one system of perivascular spaces connected with the subarachnoid space is more correct. 2. Mechanism of fluid formation and its composition. There is still no single view on this issue. According to some authors, the fluid is a simple transudate, according to others it is a dialysate or the result of ultrafiltration; finally it can be a product of the secretory activity of the choroid plexus. The theory of dialysis of the components of the fluid through a semipermeable membrane is quite common (Walter) and finds its explanation in the poverty of the fluid in colloids and in the predominance of crystalloids in it. Semipermeable membranes do not allow colloids to pass, while the tendency to equalize osmotic equilibrium between blood and fluid determines the high content in the fluid of ions with a charge univalent to the blood colloid and the equalization of other ions. However, the presence of protein, enzymes, antitryptic action of the fluid and some other features not inherent in dialysates speaks against the dialysis theory. Is cerebrospinal fluid a secretion? There are a number of facts in favor of this point of view. Some moments stimulate the production of fluid (e.g. extirpation of the epiphysis in young animals), others, on the contrary, delay it (administration of morphine). The formation of fluid does not depend on blood pressure, the fluid contains substances which are not contained in the blood or are contained in a different amount. Thus, many facts speak against the normal fluid being a simple transudate or dialysate and one must think that it is closest in nature to secretions (Kafka). Under pathological conditions, when any part of the subarachnoid space can become a source of fluid formation, transudate and exudate can also be mixed into it. However, a strict distinction should be made between the production of normal fluid and permeability (blood-brain barrier). Normal C. f. is transparent and colorless. Sp. gr. 1.003-1.008 (Mestrezat, Kafka). Viscosity is somewhat higher than water - 1.02-1.027 at 38° (Polanyi), 1.0424-1.0489 (Levinson). Freezing point depression D= from 0.52 to 0.56°. Surface tension (by stalagmometer) 101-105 drops. The temperature of cerebrospinal fluid has only recently been studied (1925). According to some studies (Giuffre, Mannino, Schiff) t° of the fluid on average is 36.8°. The temperature of the fluid is on average 0.5° higher than the axillary t°. These data do not yet have practical significance and are of interest only from a physiological point of view. The composition of the fluid is clear from the table provided. Fluid taken from different parts of the subarachnoid space is not the same in composition. Comparative data by Sestan, Riser and Laborde for lumbar fluid and ventricular fluid: total protein content - 0.03 : 0.01%; sugar - Components of cerebrospinal fluid (in ‰)

Figure 1. Container of Cerebrospinal Fluid in the brain: 1- cavum subdurale; 2-pia mater; 3-ventriculus IV; 4-foramen Magendie; 5-cisterna magna; 6-cisterna pontis; 7 - ventriculus III; 8-dura mater.

independently of each other made attempts to obtain fluid on humans by lumbar puncture, and this moment should be considered the beginning of the study of the fluid itself. At present, it is already necessary to make a differentiation depending on from which parts of the subarachnoid space the fluid was obtained. They speak of "lumbar", "spinal" or "fluid of the subarachnoid space of the spinal cord" if the fluid was obtained by lumbar puncture; "cisternal" fluid if a suboccipital puncture was used; "ventricular" fluid if it was obtained by puncture of the brain ventricles, and fluid of the subarachnoid space of the brain if an orbital puncture was used. Physiology. 1. Origin of cerebrospinal fluid. This question until recently has caused great controversy. The following anatomical structures were considered as sources of the fluid, either individually or in combinations: plexus choroidea [see separate table (Vol. XXXIII, pp. 551-552), pnc.6], ependyma of the ventricles, subependymal tissue, glia, nervous parenchyma, soft meninges and their vessels. However, recent studies have shown that the place where cerebrospinal fluid is formed is the choroid plexus. This view is the oldest in the history of the doctrine of C. f.; indirect indications of it can be found even in Galen and later in Willis, Magendie and Luschka. The participation of the meninges in the production of cerebrospinal fluid is apparently insignificant. Levandovsky put forward the hypothesis of the formation of fluid in the brain substance itself. The author believes that not only substances from the fluid enter the nervous system, but also, conversely, metabolic products from the nervous system can enter the fluid through perivascular lymphatic spaces. Regarding lymph formation in the brain and the pathways of lymph spread, there are two points of view. One of them (Sicard) assumes two perivascular systems: each vessel penetrating the brain has two perivascular spaces separated by a membrane. The outer one freely communicates with the subarachnoid space, ending blindly in its central segment, in the place where the brain vessels turn into capillaries; this space contains cerebrospinal fluid. The inner segment of the perivascular space accompanies the vessels throughout their course and not only in the nervous parenchyma but also in the subarachnoid space, not communicating with it. Lymph circulates in this inner segment of the perivascular space. Another point of view (Mestrezat) assumes a single system of perivascular spaces continuing to the capillaries, with lymph located in the capillary part, partially communicating with the fluid of the perivascular spaces. None of the presented points of view has yet received full recognition; thus the question of the systems of perivascular spaces should be considered controversial. The point of view of Mestrezat about the presence of one system of perivascular spaces connected with the subarachnoid space is more correct. 2. Mechanism of fluid formation and its composition. There is still no single view on this issue. According to some authors, the fluid is a simple transudate, according to others it is a dialysate or the result of ultrafiltration; finally it can be a product of the secretory activity of the choroid plexus. The theory of dialysis of the components of the fluid through a semipermeable membrane is quite common (Walter) and finds its explanation in the poverty of the fluid in colloids and in the predominance of crystalloids in it. Semipermeable membranes do not allow colloids to pass, while the tendency to equalize osmotic equilibrium between blood and fluid determines the high content in the fluid of ions with a charge univalent to the blood colloid and the equalization of other ions. However, the presence of protein, enzymes, antitryptic action of the fluid and some other features not inherent in dialysates speaks against the dialysis theory. Is cerebrospinal fluid a secretion? There are a number of facts in favor of this point of view. Some moments stimulate the production of fluid (e.g. extirpation of the epiphysis in young animals), others, on the contrary, delay it (administration of morphine). The formation of fluid does not depend on blood pressure, the fluid contains substances which are not contained in the blood or are contained in a different amount. Thus, many facts speak against the normal fluid being a simple transudate or dialysate and one must think that it is closest in nature to secretions (Kafka). Under pathological conditions, when any part of the subarachnoid space can become a source of fluid formation, transudate and exudate can also be mixed into it. However, a strict distinction should be made between the production of normal fluid and permeability (blood-brain barrier). Normal C. f. is transparent and colorless. Sp. gr. 1.003-1.008 (Mestrezat, Kafka). Viscosity is somewhat higher than water - 1.02-1.027 at 38° (Polanyi), 1.0424-1.0489 (Levinson). Freezing point depression D= from 0.52 to 0.56°. Surface tension (by stalagmometer) 101-105 drops. The temperature of cerebrospinal fluid has only recently been studied (1925). According to some studies (Giuffre, Mannino, Schiff) t° of the fluid on average is 36.8°. The temperature of the fluid is on average 0.5° higher than the axillary t°. These data do not yet have practical significance and are of interest only from a physiological point of view. The composition of the fluid is clear from the table provided. Fluid taken from different parts of the subarachnoid space is not the same in composition. Comparative data by Sestan, Riser and Laborde for lumbar fluid and ventricular fluid: total protein content - 0.03 : 0.01%; sugar - Components of cerebrospinal fluid (in ‰)

Figure 2. 1-sinus sagittalis sup.; 2 - Pacchionian granulations; 3- falx cerebri; 4-fissura longitudinalis sup.; 5-pia mater; 6-arachnoidea; 7-dura mater.

+ 0.045 : 0.06%, urea - 0.025 : 0.025%; NaCl - 0.73 :0.73%; cells - 3 : 0.1 in 1 l³. Reserve alkalinity of C. f. - 50.7 vol. %; pH - 7.44. 3. Circulation of fluid and its absorption. Normal fluid is formed in the choroid plexus of the ventricles and spreads through the subarachnoid spaces of the brain, penetrating through the brain substance (Monakov) or through its various openings and then into the great cistern and to the subarachnoid spaces of the spinal cord (Kafka). If one accepts this point of view, then the current of fluid, which occurs very slowly, is already indicated. If, on the contrary, one thinks that the plexus is the place of greatest absorption of fluid and that the fluid is formed by the entire nervous tissue, then it is clear that the direction of the current with this concept will already be the opposite. The more accepted view is that the fluid passes from the ventricles into the subarachnoid space of the brain and spinal subarachnoid space in a downward direction. Not all brain fluid from the ventricles goes to the subarachnoid space of the spinal cord, a certain part of it is absorbed in the higher parts. Some upward movement of fluid is noted in the great cistern, however the main current is directed to the spinal parts, where the fluid is mostly absorbed. The movement of fluid in the brain substance is subject mainly to the pulse wave, causing rhythmic fluctuations in the volume of the brain. Movement through perivascular spaces is controversial; most authors think of its direction toward the subarachnoid space. According to most authors, absorption occurs through Pacchionian granulations, through lymphatic and perineural spaces (Fig. 2). The first path is disputed, while the second paths are brought to the forefront. Absorption by other tissues is unlikely. 4. Pressure. Pressure in the subarachnoid space is determined by the elasticity of the subarachnoid sac, the tension of the surrounding tissues and the pressure in the vessels. In the vertical position, hydrostatic pressure of the fluid column is added. Maximum pressure is in the lumbar part of the subarachnoid space; in the upper part the pressure is equal

atmospheric, higher, for example, in the posterior cistern, it is negative. Normal pressure in the lying position ranges from 50-150 mm H₂O (upper limit 200 mm), in the vertical position it can reach 250-300 mm H₂O. Pressure is usually measured with the aid of Claude's manometer. Changes in blood pressure, respiratory fluctuations, position of the head, coughing, straining, taking veins, as well as various emotions (fright, etc.) are reflected in the pressure readings of the fluid. 5. Quantity. The amount of fluid, taken as a whole, varies depending on height, build, and size of the skull and age, ranging from 120-200 cm³. The brain with cisterns contains 30-50 cm³, the ventricles 40-60 cm³; all the remaining fluid falls into the subarachnoid space of the spinal cord. 6. Hemato-encephalic barrier (see Barrier function, hemato-encephalic barrier). It should be thought that we do not have one barrier, but several. The first barrier is between the blood and the fluid. The next component of the barrier are the meninges, and the glial boundary membrane (between the fluid and the brain substance). Anatomical elements of the barrier are also present in the peripheral nervous system. The morphological composition of the barrier, the mesodermal origin of its elements gives grounds to include it in the reticulo-endothelial system. The permeability of the barrier, both in physiological (pregnancy, menstrual period) and pathological conditions, is subject to fluctuations. Under normal conditions, substances that easily dissociate with a negative charge (anions) penetrate faster - see the table provided (according to Walter). The mechanism of barrier function at the present time is still insufficiently studied. Some authors identified it with a semi-permeable partition, through which substances pass from a medium rich in colloids (blood) to a medium poor in them (fluid). In reality, the relationships proved to be more complex. When a substance is introduced into the blood, it may not be found in the fluid and is detected in the endothelium of the vessels, cells of the stroma, and epithelium of the plexus. The penetration of a substance into the fluid does not always lead to its presence in the brain (see Permeability).-Clinical determination of barrier permeability is carried out mainly by Walter's bromine method. The ratio of bromine content in the blood and fluid after preliminary administration of bromine orally for 4-5 days characterizes the functional state of the barrier. The normal index P/Q (Permeabilitats-Quotient) = 2.9-3.3 (ratio of blood bromine to fluid bromine). Increased permeability (decreased index) is established in meningitis, progressive paralysis, and meningo-encephalomyelitis (1.8-2.67, according to Walter). In brain tumor, if the membranes are involved in the pathological process, permeability is increased; in epidemic encephalitis and cerebral arteriosclerosis, some increase in permeability is also noted. The greatest increase in permeability is observed in diseases in which the membranes and plexuses are affected. 7. Role of cerebrospinal fluid. Regarding the role and function of cerebrospinal fluid, the opinions of authors differ. For example, Mestres believes that the fluid creates particularly favorable conditions for the function of nerve cells. Halliburton supports this view, asserting that the fluid maintains the osmotic equilibrium of nerve cells. Monakov and L. Stern consider cerebrospinal fluid to be a nutrient medium for the central nervous system. Other authors believe that the role of the fluid is reduced to the process of removing breakdown products (Abbau-stoffe). The common view for most authors is, first, that the fluid protects the central nervous system from external injuries and, second, that it is a regulator of intracranial pressure. The question of the nutritional role of the fluid is currently being reconsidered, and some authors (Walter) tend to deny this role. The basis for this is the fact that removal of a large amount of fluid (100-120 cm³) during encephalography and its replacement with air does not cause disruption of brain activity. This circumstance speaks in favor of the fact that nutrition of the central nervous system occurs directly from the capillaries of the brain. Apparently, one should not speak of the nutritional role of the entire cerebrospinal fluid in toto, but rather of its individual components, for example, sugar, which sharply decreases in the fluid in some infectious diseases. This decrease is apparently associated with increased consumption of sugar by the central nervous system. The ability of the fluid to produce antibodies speaks in favor of its protective role. The production of antibodies in the fluid occurs more slowly than in the blood and does not reach such high figures as in the blood. Local immunity in the subarachnoid space is created under the influence of various vaccines introduced there. Pathology. 1. Changes in appearance and pressure. The normal appearance of the fluid by no means excludes the possibility of its pathological composition (for example, in progressive paralysis). In pathological cases, it can be turbid and colored by the admixture of formed elements. The degree of turbidity from slight opalescence to the appearance of liquid pus (for example, in meningitis) depends on the amount of formed elements contained in the fluid. In some cases, when the fluid stands (in tuberculous meningitis and progressive paralysis), so-called fibrin clots in the form of threads are formed. In cases of injury and damage to the venous plexus vessels, blood can be mixed with the fluid. If the hemorrhage is fresh, whether artificial or caused by disease, the blood usually settles to the bottom of the test tube (erythrochromia). In cases of older hemorrhages, the blood pigment dissolves in the fluid and it acquires a yellow or canary color-xanthochromia (see). Pressure in pathological cases (meningitis, brain tumors) can reach very high figures (up to 800 mm). The increase in pressure is due, on the one hand, to increased production of fluid, and on the other, to impaired outflow due to blockage of the exit openings, for example, by an inflammatory infiltrate. The increase in fluid pressure can be reflected by hypertension and all processes leading to an increase in brain volume. 2. Hyperalbuminosis. Spinal-albuminometry. Determination of protein in the fluid has been particularly developed in recent years. The total amount of protein, albumins, globulins, and globulin reactions are determined. Total amount (by the Roberts-Stolnikov, Brandberg, Zaloziecki, Sikar method): to the fluid under investigation (0.5 cm³) after centrifugation, 4.5 cm³ of physiological NaCl solution (dilution 1:10) is added. From this basic solution, according to the attached scheme, further dilutions are made, which are overlaid with 0.5 cm³ of concentrated nitric acid (see table). After 3 min., the first dilution is noted where a white ring is found at the boundary of the liquids; 0.03 is multiplied by this dilution and the protein content per 1000 in the whole fluid is obtained (according to Zaloziecki, the dilution is multiplied by ¹/₆₀). Basic dilution of cerebrospinal fluid (in cm³) 1:10 Physiological solution (in cm³) Obtained dilution 0.5 0.45 0.4 0.3 0.2 0.09 0.25 0.2 0.3 0.4 1:10 1:12 1:15 1:20 1:30 etc. Determination of globulins in C. f.-see Nonne-Apelt reaction, Pandi reaction. Ross-Jones reaction: cerebrospinal fluid does not mix, but is overlaid with ammonium sulfate as specifically heavier, and the precipitation of flakes at the boundary of the liquids is observed for 3 min. Nogushi reaction (with butyric acid): 2.2 cm³ of fluid is mixed with 1 cm³ of 10% butyric acid, heated to boiling, after which 0.2 cm³ of normal soda solution is added. All this is boiled for several seconds. A positive result is determined after 3 hours. Changes occurring after this time are interpreted as negative. Recently, great attention has been paid to the determination of protein fractions in cerebrospinal fluid (according to Kafka or Stefan). In syphilitic diseases of the nervous system (progressive paralysis, etc.), globulins predominate, in non-syphilitic ones, albumins. The protein coefficient in normal conditions is 1:5 (0.2). In pathological cases, it is subject to various variations.-In the question of the origin of protein in the fluid, there is still not sufficient clarity. With disruption of the integrity of the barrier, part of the proteins passes from the blood, another part arises endogenously (intramurally), directly from nervous tissue.

In spinal block, due to stagnation in the vessels, protein penetrates into the fluid through the vascular wall in large quantities, as a result of which such fluid, after being released, coagulates, turning into a gelatinous mass (massive coagulation). Liquorphanomen. When the cerebrospinal fluid is shaken with half the amount of ether, the ether layer becomes cloudy and gelatinous—phenomena of solidification occur (Erstarrungsphanomen). This phenomenon, which is obtained when ether is shaken with other colloidal fluids, is interesting in that with a negative RWb of the cerebrospinal fluid, the ether layer is more solidified and cloudy than with a positive RW. 3. Toxicity of cerebrospinal fluid. There are data from testing the fluid on animals, indicating the toxicity of the fluid of paralytics. The same applies to the fluid of epileptics, especially its toxicity increases in status epilepticus. There are indications of the presence of neurotoxic substances in the fluid. 4. Cytology. Cytology of the fluid began to be studied by the French (Nageotte, Ravaut, Sicard and Widal), who in 1901 proposed the following method for determining cellular elements. After centrifuging 3-4 cm³ of fluid for ³/₄ hour, the sediment is fixed and stained. When there is an increase in cellular "elements," we speak of "lymphocytosis." Nageotte studied the fluid of tabetics and paralytics and found lymphocytosis in the fluid in 90%. The chamber proposed by Nageotte for counting cells (Nageotte cells) is divided into 40 rectangles, each of which is equal to 2.5 mm². The depth of the chamber is 0.5 mm. The total amount of fluid in one rectangle is 1.25 mm³. For determination, cells are counted in 4 rectangles, which give the amount in 5 mm³ of fluid. The quantitative determination of cellular elements of the fluid in our country is usually performed with the help of the Fuchs-Rosenthal chamber (Fuchs-Rosenthal) (see Counting chambers). The normal content of cellular elements (lymphocytes) ranges from 3-5 in 1 mm³. Various pathological processes in the central nervous system lead to an increase in cellular elements (pleocytosis), which is most sharply expressed in meningitis (infectious) and progressive paralysis. In other diseases (intoxications, hemorrhages, tumors), pleocytosis is not particularly great. In general, it is considered: 5-10 cellular elements—mild pleocytosis, 10-50—noticeable pleocytosis, from 50 to 250—sharp pleocytosis, over 250—extreme pleocytosis. The character of cellular elements changes depending on the nature of the process. Lymphocytosis is observed in syphilis, toxic lesions of the membranes, encephalitides. In progressive paralysis, plasma cells (of the phagocyte type), fibroblasts are also found. In tuberculous meningitis—plasma cells; in epidemic cerebrospinal meningitis—polynuclears. Destructive and degenerative processes in most cases do not give pleocytosis. 5. Colloidal reactions. Of the colloidal reactions, the most common are Lange's gold reaction (Goldsol) (see Goldsol reaction) and the gum reaction (Emanuel). As a modification of it, the Jacobsthal-Kafka reaction is proposed, the basic solution is prepared according to Emanuel; after shaking, the solution should stand on ice for 24-48 hours. The test solution is prepared from the basic solution by adding 1 cm³ of the basic solution to 9 cm³ of absolute alcohol in a 10-gram pipette, and then all this is poured drop by drop into 40 cm^% of distilled water with simultaneous shaking (mixing time 50 sec.). The solution is left to stand for 30 min. for its maturation. Titration: to 1 cm³ of NaCl solution (from 0% to 105%) is added 1 cm³ of gum solution, after which all tubes are shaken in succession and for the main experiment, that salt concentration is taken at which precipitation of the gum suspension first occurs; the NaCl solution is made from the basic 10% solution (to 10.0 NaCl is added such an amount of Aq. bidestillata until the total weight is equal to 100.0). Main experiment—as in the Lange reaction: to 0.5 cm³ of cerebrospinal fluid is added 1.5 cm³ of the corresponding titrated NaCl solution (in 1 tube), mixed, and descending dilutions of the fluid are made in 12 tubes (1:4-1:4,000), then to each tube is added 1 cm³ of gum emulsion. The tubes are slightly shaken, plugged with cotton plugs (evaporation of alcohol), and the result is determined after 24 hours. Subsequently, the results are plotted as curves on a diagram. The main point in the gum reaction is the preparation of the corresponding gum suspension; since its coagulating capacity undergoes significant fluctuations, the preliminary test for salt sensitivity is in each individual case absolutely necessary. Kirschberg's reaction (Kirschberg, 1917) with a colloidal solution of Berlin blue. Preparation of the solution: 1 g of Berlin blue together with 5 cm³ of 5% oxalic acid is diluted in 100 cm³ of distilled water. The further technique is the same as in the gold reaction. The scheme for recording the results of this reaction is the same as in the Lange reaction (colors: blue, bluish, light blue, white). Application of the reaction: in cases of insufficient fluid (0.02 cm³) and especially for the diagnosis of normal fluid (due to the special sensitivity of this reaction). 6. Chemical shifts in the fluid are expressed by changes in reserve alkalinity and pH (acidosis in meningitis, alcoholism, in epilepsy). The most important are changes in sugar (see Hyperglycorrhachia, hypoglycorrhachia). Chlorides decrease in the fluid in meningitis, and they have the same prognostic value as fluctuations in sugar. Calcium in the fluid = 50-60% of blood calcium; it is distinguished by the particular constancy of its content; in various diseases it fluctuates within almost physiological limits (6-7 mg%). Choline, in normal cerebrospinal fluid (Mott and Halliburton), is not contained. It was found in progressive paralysis and especially in epilepsy (Donath). Cholesterol, normally present in the fluid in traces, was found in progressive paralysis, schizophrenia and epilepsy. In paralysis, the appearance of nucleoprotein was observed (Halliburton and Mott). In many pathological cases, the appearance of lactic acid, an increase in urea content was observed. 7. Reactions for syphilis (see Wassermann reaction, Precipitation, precipitin reactions in serodiagnosis of syphilis). Of syphilitic diseases, progressive paralysis most often gives a positive result (with small doses of fluid—0.2); tabes dorsalis gives a positive result in 70% (doses 0.5-1.0). Syphilitic meningitis and meningo-encephalitides (fresh) very often give a positive result. In vascular syphilis, on the contrary, the result is more often negative. Brain tumors also sometimes give a positive result. 8. Parasitology of the fluid. The following bacteria are found in the cerebrospinal fluid: Diplococcus lanceolatus in pneumococcal meningitis; erysipelas streptococcus; Str. viridans, mucosus in streptococcal meningitis; golden staphylococcus; intracellular meningococcus in epidemic meningitis; tubercle bacilli. "The pale spirochete was found in the fluid in early syphilitic meningitis. In addition, spirochetes of typhus, Trypanosoma gambiense, cysticercus vesicles, and actinomycosis grains were found in the fluid. 9. Individual syndromes in cerebrospinal fluid. The Froin-Nonne syndrome in spinal tumors is characterized by 1) sharply expressed protein-cell dissociation, 2) xanthochromia, 3) a high protein content, which sometimes leads to massive coagulation of the fluid after its release (its transformation into a gelatinous mass), 4) normal content of cellular elements. This syndrome develops as a result of spinal block, giving phenomena of venous stagnation and fluid stagnation (disruption of absorption). It is observed in tumors of the spinal and brain and multiple radiculitis, entirely or partially. The reverse syndrome—cellular-protein dissociation (pleocytosis with normal protein content)—is described in subarachnoid hemorrhages, initial stages of neurosyphilis, epidemic encephalitis (in the acute stage), aseptic meningitis. Dissociation between colloidal reactions and inflammatory (normal content of protein and cellular elements and paralytic type of goldsol reaction curve) is characteristic of disseminated sclerosis and inflammatory-degenerative processes in the brain. 10. Methods of obtaining the fluid—see Lumbar puncture and Puncture. Puncture of the posterior cistern is usually used for the introduction of contrast substances (lipiodol) into the subarachnoid space in spinal tumors. There are advocates of its preferential use (Garkavi, Emdin) instead of lumbar puncture, since suboccipital puncture is usually not accompanied by symptoms of meningism (Fig. 3).

Contraindications for this puncture are: pronounced arteriosclerosis and the presence of a tumor in the surrounding area

Figure 3. Diagram of suboccipital puncture.

of the posterior cistern. Quincke proposed a method for obtaining cerebrospinal fluid from corpses. Lumbar puncture is most advisably performed in a sitting position, since in the recumbent position the fluid flows out under very low pressure. For this purpose an assistant is necessary, who would help overcome the rigidity of the body associated with cadaveric rigor. The site of puncture is determined in the same way as in a living person; the skin is disinfected, and the puncture is performed with a regular trocar. Often during puncture a bloody fluid is obtained. An admixture of blood often depends on injury to the venous plexuses of the meninges. The difference between artificial blood admixture (injury to veins) and blood in the subarachnoid space is the absence in the first case of complete mixing of blood with fluid. With correct introduction of the trocar into the canal, the fluid flows out drop by drop. A larger amount of fluid can be obtained by bending the head of the corpse forward and backward alternately. Under this condition, 10 cm³ of fluid or more can be obtained from a corpse. 11. Comparative evaluation of the fluid of the anterior chamber of the eye, labyrinthine, cerebrospinal fluid of animals and cadaverous. A. The fluid of the anterior chamber of the eye has an alkaline reaction, contains 0.02% protein, its specific gravity is 1.007; sodium chloride content = 700 mg%. With an increase in protein, a parallelism is observed with the cerebrospinal fluid. B. The labyrinthine fluid has the same protein and salt content as the cerebrospinal fluid. Both endolymph and perilymph are products of the labyrinth. C. The cerebrospinal fluid of animals (rabbit, dog) has much in common with human fluid. For example, in the fluid of a dog sugar = 54-75 mg%, sodium chloride = 750-780 mg%. However, there can also be differences, especially in cases of hidden diseases in animals. The permeability of the barrier in animals also does not fully correspond to the human one. D. Cadaverous cerebrospinal fluid. If during agony the fluid has changed little, then after death it sharply changes in its composition: pleocytosis increases, the number of bacteria increases, protein ratios change, and the fluid becomes cloudy and little suitable for research. It must be taken either during agony or immediately after death.