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Examination of Cerebrospinal Fluid
EXAMINATION OF (;EREBROSPINAL FLUID FREDERIC C. MOLL, M.D.
Since diseases of the central nervous system may develop without localizing signs and symptoms, frequently the physician must examine the cerebrospinal fluid to establish a diagnosis. Further, because early specific therapy can prevent tragic sequelae in purulent meningitis, it behooves the physician to make a careful, accurate and complete observation of the cerebrospinal fluid. This requires proper methods of collecting and handling of the fluid to assure that the maximum information be obtained. Since much depends upon the immediate examination of the fluid, the physician himself should be able to perform the studies and interpret the results. MECHANISM OF FORMATION AND CIRCULATION
The elaboration of cerebrospinal fluid has long been thought to be a function of the choroid plexus of the cerebral ventricles, and it was also thought that the fluid flowed from the ventricles into the subarachnoid space to be reabsorbed largely by the arachnoid villi. Through isotope tracer studies in man, Sweet and LockeleyB have suggested that the cerebrospinal fluid is formed as extracellular fluid in that water and electrolytes enter both in the ventricles and throughout the subarachnoid space. Thus the formation of the fluid would not be dependent wholly upon the choroid plexus. These studies further indicate that each constituent of cerebrospimil fluid is exchanged with blood at its own characteristic rate and will therefore reflect systemic changes in the individual. Protein, however, is largely reabsorbed by the archnoidal villi, which serve much as lymphatics do in the general circulation. From the Department of Pediatrics, University of Washington School of Medicine, and the King County Hospital; Seattle. '].27
228
EXAMINATION OF CEREBROSPINAL FLUID
Gardner2 and others suggest that increase in the cerebrospinal fluid protein molecules associated with brain tumors and other diseases accumulates against the semipermeable membrane of the arachnoid villi and that this prevents reabsorption of fluid and protein. Such obstruction produces an increase in the cerebrospinal fluid pressure. Regardless of the mechanism for the elaboration and reabsorption of cerebrospinal fluid, the effect of local and systemic disease on the fluid is characteristic enough to be diagnostic. The response to purulent infection of the meninges is a profuse leukocytic exudation in the presence of bacteria. A viral invasion is manifested by a limited lymphocytic response, and bleeding is reflected by the presence of blood in the fluid. Abnormal cells from infection or tumor produce elevation of the protein content of the cerebrospinal fluid, and many metabolic diseases are reflected in the cerebrospinal fluid by changes comparable to that seen in the blood, such as hypocalcemia in tetany. In general, the cerebrospinal fluid behaves as other extracellular compartments, and the specific characteristics of some diseases can be delineated there as elsewhere. The amount of cerebrospinal fluid in the infant varies inversely with the body size. The brain develops in a fluid-filled space, but at birth the brain nearly fills the skull. Some 10 to 15 cc. of cerebrospinal fluid can be obtained at autopsy of infants weighing 1500 to 2000 gm. if they have been delivered from below. If they are delivered by cesarean section, Potter6 states that 30 to 60 cc. of fluid can be collected at autopsy. She suggests that delivery through the vagina has forced some of the fluid out of the meninges. The rate of formation of cerebrospinal fluid is unknown, but for practical purposes 1 to 2 cc. may be removed from a premature and 10 cc. from a 10-kilogram infant with no deleterious effects. The cerebrospinal fluid tension is an effective counterpressure, for it protects the brain from large changes in intravascular pressure. The cerebrospinal fluid pressure varies directly with the venous pressure. This relationship can be demonstrated by determining the cerebrospinal fluid pressure above and below the level of the heart, and the dynamics can be further explored by the Queckenstedt test. This study consists in increasing the venous pressure by gentle compression of the jugular veins. Unless some obstruction is present, the cerebrospinal fluid pressure promptly rises and then falls as the venous compression is released. Such a study should not be done in the presence of increased intracranial pressure. Exact meaSllrement of pressure in the infant and child may be difficult because of the lack of cooperation of the child and the amount of fluid needed to fill the manometer. However, the clinician can estimate roughly the presence of increased pressure by the bulging fontanel and the pressure with which fluid is forced through the needle.
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METHODS OF OBTAINING CEREBROSPINAL FLUID Lumbar Puncture
The simplest method of obtaining fluid is by lumbar puncture if there is no evidence of prolonged increase of intracranial pressure or evidence of choked disks. This is most easily done with the infant flexed and lying on his side. With sterile precautions the needle is introduced between the second and third lumbar vertebrae. It is useful to permit about eight drops of fluid to drop directly on a chocolate agar slant for culture. Two other sterile tubes are used to collect 5 additional cc. This is sufficient to use one for cell counts and chemistry and the other for bacteriologic studies. Manometric studies can be performed if indicated on the older children.
J
'
i
Cisternal Tap
"
Occasionally because of obstruction, increased intracranial pressure or inability to obtain cerebrospinal fluid for other reasons, a cisternal tap is
A B Fig. 27. A, Subdural taps. The spinal needles are introduced at a right angle to the skin in a suture line iust outside the angle of the fontanel. Note that the head is shaved. B, Cisternal tap. The needle is passed in the midline below the occiput and in a line extending through the external auditory canal and the glabella.
necessary. The occiput and neck are first shaved, and the usual sterile precautions are taken. Then, with the head sharply flexed and the child in a sitting or lying position, the needle is introduced through the skin in the midline at the base of the occiput. The needle is then directed in a line from the base of the occiput through the external auditory meatus to the glabella. The cisterna lies at a depth of 1 to 2 cm. in infantsl and
,
23 0
EXAMINATION OF CEREBROSPINAL FLUID
4 to 4.5 cm.'!' in the adult. Care must be taken not to exceed these depths. The needle is introduced cautiously, removing the stilet from time to time, until the cisterna is entered. The fluid is collected as outlined for cerebrospinal fluid. Subdural Tap
This method is discussed in another clinic in this volume (p. 239) and is mentioned here only for completeness. ROUTINE EXAMINATION OF CEREBROSPINAL FLUID
The following routine examination should be performed on all cerebrospinal fluid: Appearance. Upon examination in daylight the fluid should be clear and colorless. Turbidity and xanthochromia are abnormal. Pressure. Normal pressure is 40 to 110 mm. of water in infants, and up to 200 mlU. in adults. This rises and falls promptly with gentle jugular compression. Cell Count. The cell count may be obtained by placing the cerebrospinal fluid in a hemacytometer counting chamber. All nine squares are counted, and the total number of cells is multiplied by 10/9. To lyse the red cells and stain the white cells the fluid can be diluted 1: 10 in a white cell pipet with a staining fluid of glacial acetic acid and crystal violet. The normal cell count is 0 to 10, and these cells are mononuclear. If blood is present, owing to a bloody tap or cerebrovascular hemorrhage, the total cell count should be first obtained without dilution with the acetic acid. Then the fluid can be diluted and recounted. If more than 10 cells are present, a differential count of the centrifuged sediment can be done by using Wright's stain. Protein. The protein content can be roughly estimated by the Pandy test or by a number of other tests. The Pandy test consists in precipitation of protein in a saturated solution of phenol. It is wise to warm the Pandy solution first if it is cloudy. A drop of cerebrospinal fluid is then introduced into a test tube containing about 2 cc. of Pandy solution. Normally, a faint trace of precipitate may be seen after the descent of the crop. If the protein value is high, the Pandy solution will be grossly cloudy. If blood is present, the Pandy test will be positive. The quantitative determination varies with the individual laboratory, and the normal values range between 15 and 45 mg. per 100 cc. If high protein content exists, a pedicle will form in the cerebrospinal fluid upon standing. Sugar. The sugar determination may be roughly estimated by using five test tubes containing I cc. of Benedict's solution and introducing
FREDERIC C. MOLL
231
one, two, three, four and five drops of cerebrospinal fluid into individual tubes. These are then placed in a bath of boiling water for five minutes. Reduction is evident in the fourth and fifth tubes only if the sugar content is normal. If the sugar is low as in meningitis, nO reduction is seen. On the contrary, diabetes may be suspected because of 4+ reduction in all the tubes. The quantitative sugar values vary between 40 and 80 mg. per 100 cc., depending upon the blood sugar, which is usually about 50 per cent higher. Chloride. The normal values are 116 to 125 mg. per liter (675 to 730 mg. of sodium chloride per 100 ml.). Bacteriology. All cerebrospinal fluid should be examined for organisms if meningitis is suspected even though the fluid appears clear. The centrifuged sediment is smeared, stained and examined. In addition, culture of the cerebrospinal fluid should be a routine procedure. It has . been my experience that if about eight drops of fluid are dropped directly on a chocolate agar slant and then incubated, the number of positive cultures is significantly higher than when culture materials are subsequently inoculated with cerebrospinal fluid in the laboratory. Other. Other special studies such as Wassermann, colloidal gold and cell blocks are done as indicated. CEREBROSPINAL FLUID IN THE NEWBORN
The fluid in the new'born is frequently xanthochromic, is under less pressure and is less in amount than in the older infant. Because of the size of the infant, and the low volume and pressure, the lumbar puncture is technically more difficult than in the older infant. I have followed the suggestion of Glaser,s who suggests using a small needle (no. 24 or 26) and placing the infant in a sitting position~ Presumably this position distends the lumbar sac and permits easier entry. By attaching a syringe to the needle 1.5 to 2 cc. may be withdrawn. This fluid is frequently xanthochromic and contains both red and white blood cells. Since the traumatic tap is not uncommon in the newborn and premature, the significance of the blood is not always clear. If the cerebrospinal fluid tends to become clearer as it is obtained, if the cells are not crenated, and if after centrifugation the supernatant fluid is only slightly xanthochromic, this suggests that the blood is traumatic in origin. This is not absolute, and the evaluation of the findings rests upon the clinical judgment of the operator. The protein in the cerebrospinal fluid is higher (60 to 90 mg. per 100 cc.) than in older infants, but with cerebral hemorrhage it is frequently 300 to 500 mg. or more. The cerebrospinal fluid sugar and chloride are normal. Because of the technical difficulties the value of a lumbar puncture in the newborn is questioned. Certainly if neurologic symptoms are
232
EXAMINATION OF CEREBROSPINAL FLUID
present, it seems indicated, since clinically one cannot distinguish meningitis from cerebral hemorrhage. Even though cerebral damage and hemorrhage may not be evident upon cerebrospinal fluid examination, an attempt at evaluation should be made. There is little evidence that removal of red cells by repeated cerebrospinal fluid taps is therapeutically valuable. CEREBROSPINAL FLUID IN DISEASE nfeclion of Central Nervous System
Purulent Meningitis. MENINGOCOCCUS, HEMOPHILUS INFLUENZAE AND Examination of the cerebrospinal fluid in purulent in~ningitis is imperative, since the therapy can be tailored to the specific infection. The fluid is under increased pressure as evidenced by the. ~ulging fontanel as well as the actual manometric measurement. The Jlllid is usually turbid, but the appearance can be deceiving and a cell count should be done. The cell count is usually grossly elevated to 5000 to 10,000 cells per cubic milliliter, predominantly polymorphonuclear leukocytes. However, I have seen both a positive smear for pneumococci and a positive culture for meningococci in the presence of a normal cell count. A gram stain of centrifuged sediment may show the organism. However, sterile precaution must be taken, since the fluid becomes contaminated easily. The common organisms found in children are meningococcus, H. influenzae and pneumococcus. The last is easily found, but a search usually must be made for the former two. Because of the frequent use of antibiotics early in the disease before a- diagnosis has been established, the organisms may be difficult to find. For this reason the culture should be carefully examined twelve and twenty-four hours later to confirm or establish the diagnosis. The H. influenzae can be confirmed from the smear or culture by the Quellung reaction with specific antiserum. If the meningococcus is suspected but not found, some laboratories are equipped to do type-specific antiserum titers on the cerebrospinal fluid. This is not yet generally available. Sugar in purulent meningitis is frequently low (0 to 10 mg. per 100 ml.), depending on the severity of the disease, and may be sometimes useful as a guide to prognosis. However, a normal value for the cerebrospinal fluid sugar is not infrequent even in fulminating meningitis. Rather, it is useful if a gradual rise is demonstrable associated with therapy. The protein is nonnal or slightly elevated initially and gradually rises during the .:first forty-eight to seventy-two hours, falling to normal on convalescence. The chloride is normal. ESCHERICHIA COLI AND OTHERS. Occasionally newborn infants have PNEUMOCOCCUS.
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233
meningitis due to Escherichia coli, Staphylococcus albus or other less virulent organisms. The cerebrospinal fluid response is essentially the same,but the disease is less severe. There is increase in pressure, cells and protein, and the sugar is slightly depressed. The organisms are recovered by smear and culture. The disease is less fulminating, however, and the cerebrospinal fluid changes are less dramatic. It is always useful to examine carefully for source of infections such as an intraspinal or intracranial dermoid cyst in the presence of an indolent meningitis, since this may be the source of the infection. TUBERCULOSIS. The meningeal reaction to tuberculosis differs somewhat from other bacterial infection. The cell count is never as high, usually 50 to 400 cells with about 70 per cent lymphocytes. The fluid is, therefore, dear to opalescent. The protein is elevated and the sugar characteristically low. This fluid usually demonstrates low chloride content (85 mg. per liter), and this can be of diagnostic importance. The tubercle bacillus may be found on smear with an acid-fast stain, but more success is obtained by culture in guinea pig on an artificial medium such as that of DuBos. ENCEPHALITIS. Involvement of the central nervous system by a specific virus is not characteristic, and differentiation frequently must be made on other clinical and serologic grounds. However, evidence for a viral encephalitis consists of clear fluid under slightly increased pressure with moderate increase in cells in the neighborhood of 150 to 250 per cubic milliliter. Most of these cells are lymphocytes. There is usually a moderate increase in the protein, but the sugar and chloride determinations are normal. However, in spite of clinical findings of encephalitis the cerebrospinal fluid may be normal. Under these circumstances immunologic studies for mumps, herpes, Eastern and Western equine and St. Louis encephalitis must be done. Lymphocytic choriomeningitis is suggested if the cerebrospinal fluid cell count is around 1000 per cubic milliliter or more and the smear reveals that all cells are lymphocytes. This diagnosis can and should be confirmed by serologic studies. Poliomyelitis produces an unusual response in that, if the studies are done early in the disease, the polymorphonuclear leukocyte predominates. This is reversed within forty-eight to seventy-two hours after onset. Othe~wise the findings are those of any viral infection. Tissue culture of the poliomyelitis virus is still in the experimental stage. A positive stool culture for the Coxsackie virus does not eliminate poliomyelitis, since both infections may exist concurrently. Parasitic Diseases
Infection by Torula histolytica most frequently gives signs of central nervous system involvement. The cerebrospinal fluid appears opalescent,
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TABLE
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13. Cerebrospinal Fluid Values TYPE
Normal
APPEARANCE
Clear
o SUGAR
CHLORIDE
40-110 mm'; 0-8 lymphocytes 15-45 mg. % H 20
60 mg.%
116-125 mg./L.
Normal
Normal
PRESSURE
CELL COUNT
PROTEIN
REMARKS
z
~ o
~
'" ~
Bloody tap
Bloody
Numerous RBCs
15-45 mg.%
Normal
Normal
Normal
RBCs not crenated; supernatant fluid only slightly xanthochromic
Xanthochromic
Low
Few RBCs
50-90 mg.
Cerebrovascular hemorrhage
Bloody
Normal to high
Numerous RBCs
100 mg.%
Normal
Normal
Many crenated RBCs; .supernatant fluid xanthochromic
Purulent meningitis
Cloudy
Elevated
Numerous WBCs, predominantly polymorphonuclears
Elevated 50-100 mg. %
Low
Normal
Gram stain may reveal organisms; early bacteriology may be positive before evidence of cellular response
Opalescent
Slight. dev.
100-500 cells 70% lymphocytes
Elevated
Low
Low
Smear and culture are positive; fluid may form pedicle on standing
Newborn
Tuberculous meningitis
Few crenated RBCs; supernatant fluids xanthochromic
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Z
~
"1
G
s
Viral encephalitis
Clear to opalescent
Normal to slight. elev.
0-500 cells 90% lymphocytes
Slightly elevated
Normal
Normal
Frequently completely normal; serologic differentiation'
Poliomyelitis
Clear to opalescent
Elevated
50-500 cells 70% lymphocytes
Slightly elevated
Normal
Normal
Early the cell count is predominantly polymorphonuclear cells
Slight. elev.
1000 cells Lymphocytes
Elevated
Normal
Normal
Serologic studies positive
Lymphocytic Opalescent choriomeningitis GuillainBarre syndrome
Clear
Elevated
Normal
Elevated
Normal
Normal
Meningismus
Clear
Slight. elev.
Normal
Normal
Normal
Normal
Lead encephalitis
Clear
Elevated
8-50 cells
Elevated
Normal
Normal
Tumor and abscess
Clear
Elevated
8-300 cells
Elevated
Normal
Normal
Clinical evidence of meningeal irritation only
May be normal
~
t!l ~
Subdural hematoma in infants
Clear to xanthochromic
Maybe elevated
May have RBCs
Normal to elevated
Normal
Normal
CSF may be normal, but xanthochromic fluid in subdural taps with high protein content
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236
EXAMINATION OF CEREBROSPINAL FLUID
the cell count and protein are increased, and the diagnosis may be established by demonstrating budding yeast cells on smear or in culture. Space-Occupying Lesions
The examination of the cerebrospinal fluid in the presence of a tumor, abscess or hematoma can be dangerous, yet helpful in diagnosis. In the presence of increased intracranial pressure the danger lies in removal of fluid from below the lesion, permitting the cerebellar tonsils to herniate through the foramen magnum. This accident may occur with the rapid removal of fluid even in purulent meningitis when a partial block is present due to exudate at the base of the brain. It is, therefore, wise to obtain fluid from the cisterna or ventricle if such a condition is suspected. Under these circumstances the fluid is under increased pressure, and a moderate increase in mononuclear cells m a y be present, but the protein is usually significantly increased. The remaining constituents are normal. This does not differentiate the lesion, but does suggest the presence of one. Systemic Diseases
Infections localized outside the central nervous system may produce signs of meningeal irritation without producing significant change in the cerebrospinal fluid examination other than a slight increase in pressure. This is designated meningismus and frequently accompanies upper and lower respiratory infections, but may occur with infections at any site. Acute plumbism produces signs of meningeal irritation and convulsions. The cerebrospinal fluid examination shows an increase in pressure, and elevated prot~in, but is otherwise normal. Examination in polyradiculitis (Guillain-Barre syndrome) produces protein level of 100 to 200 mg. per 100 cc. in the presence of normal cell count and evidence of increased cerebrospinal pressure. Diagnosis of diabetes is not infrequently established in an infant with central nervous system lesions because of a high cerebrospinal fluid sugar. Hallman and Tiihka 4 have demonstrated that diarrheal diseases are frequently accompanied by an increase in lymphocytes (50 to 100 per cubic milliliter) and elevated protein in the cerebrospinal fluid. If salicylism is suspected, the fluid may be tested for salicylate with ferric chloride. This test consists in adding 2 or 3 drops of 10 per cent chloride to the cerebrospinal fluid. A dark purple color indicates the presence of salicylates. This is positive only if the blood levels have reached toxic concentration. Although distinctly a less common problem, congenital and juvenile syphilis are reflected in the cerebrospinal fluid by positive Wassermann tests. During the acute
FREDERIC C. MOLL
237
syphilitic meningitis the cells and protein are elevated, and in juvenile syphilis the' paretic gold curve may be obtained. SUMMARY
The examination of the cerebrospinal fluid is an important diagnostic procedure if the fluid is carefully studied and interpreted. The characteristic responses are outlined in Table 13. In general, inflammatory and metabolic diseases are reflected in the cerebrospinal fluid examination as they are in other extracellular fluid spaces in the body. With careful examination of the fluid, and cautious interpretation in the clinical situation, there is good reason to make an exact diagnosis so that specific therapy can be used. REFERENCES
1. Ford, F. R.: Diseases of the Nervous System in Infancy, Childhood and Adolescence. 3rd ed. Springfield, Ill., Charles C Thomas, 1952. 2. Gardner, J. W., Spitler, D. K., and Whitten, C.: Increased Intracranial Pressure Caused by Increased Protein Content in the Cerebrospinal Fluid. New England J. Med., 250:932, 1954. 3. Glaser, J.: The Cerebrospinal Fluid of Premature Infants. Am. J. Dis. Child., 36: 195, 1928. 4. Hallman, N., and Tahka, H.: Observations on the Cerebrospinal Fluid in Infantile Diarrhea. Acta paediat., 41:437, 1952. 5. Potter, E. L.: Pathology of the Fetus and the Newborn. Chicago, Year Book Publishers, Inc., 1952. 6. Santamarina, V.: La punction sub-occipital 0 cinsernal en la clinica infantiI. Arch. de la Soc. de Estud. Clin. de la Habana: 32:57,1938. Cited in Ford, F. R.1 7. Sweet, W. H., and Locksley, H. B.: Formation, Flow and Reabsorption of Cerebrospinal Fluid in Man. Proc. Soc. Exper. BioI. & Med., 84:397, 1953, University of Washington School of Medicine Seattle 5, Wash.
Since diseases of the central nervous system may develop without localizing signs and symptoms, frequently the physician must examine the cerebrospinal fluid to establish a diagnosis. Further, because early specific therapy can prevent tragic sequelae in purulent meningitis, it behooves the physician to make a careful, accurate and complete observation of the cerebrospinal fluid. This requires proper methods of collecting and handling of the fluid to assure that the maximum information be obtained. Since much depends upon the immediate examination of the fluid, the physician himself should be able to perform the studies and interpret the results. MECHANISM OF FORMATION AND CIRCULATION
The elaboration of cerebrospinal fluid has long been thought to be a function of the choroid plexus of the cerebral ventricles, and it was also thought that the fluid flowed from the ventricles into the subarachnoid space to be reabsorbed largely by the arachnoid villi. Through isotope tracer studies in man, Sweet and LockeleyB have suggested that the cerebrospinal fluid is formed as extracellular fluid in that water and electrolytes enter both in the ventricles and throughout the subarachnoid space. Thus the formation of the fluid would not be dependent wholly upon the choroid plexus. These studies further indicate that each constituent of cerebrospimil fluid is exchanged with blood at its own characteristic rate and will therefore reflect systemic changes in the individual. Protein, however, is largely reabsorbed by the archnoidal villi, which serve much as lymphatics do in the general circulation. From the Department of Pediatrics, University of Washington School of Medicine, and the King County Hospital; Seattle. '].27
228
EXAMINATION OF CEREBROSPINAL FLUID
Gardner2 and others suggest that increase in the cerebrospinal fluid protein molecules associated with brain tumors and other diseases accumulates against the semipermeable membrane of the arachnoid villi and that this prevents reabsorption of fluid and protein. Such obstruction produces an increase in the cerebrospinal fluid pressure. Regardless of the mechanism for the elaboration and reabsorption of cerebrospinal fluid, the effect of local and systemic disease on the fluid is characteristic enough to be diagnostic. The response to purulent infection of the meninges is a profuse leukocytic exudation in the presence of bacteria. A viral invasion is manifested by a limited lymphocytic response, and bleeding is reflected by the presence of blood in the fluid. Abnormal cells from infection or tumor produce elevation of the protein content of the cerebrospinal fluid, and many metabolic diseases are reflected in the cerebrospinal fluid by changes comparable to that seen in the blood, such as hypocalcemia in tetany. In general, the cerebrospinal fluid behaves as other extracellular compartments, and the specific characteristics of some diseases can be delineated there as elsewhere. The amount of cerebrospinal fluid in the infant varies inversely with the body size. The brain develops in a fluid-filled space, but at birth the brain nearly fills the skull. Some 10 to 15 cc. of cerebrospinal fluid can be obtained at autopsy of infants weighing 1500 to 2000 gm. if they have been delivered from below. If they are delivered by cesarean section, Potter6 states that 30 to 60 cc. of fluid can be collected at autopsy. She suggests that delivery through the vagina has forced some of the fluid out of the meninges. The rate of formation of cerebrospinal fluid is unknown, but for practical purposes 1 to 2 cc. may be removed from a premature and 10 cc. from a 10-kilogram infant with no deleterious effects. The cerebrospinal fluid tension is an effective counterpressure, for it protects the brain from large changes in intravascular pressure. The cerebrospinal fluid pressure varies directly with the venous pressure. This relationship can be demonstrated by determining the cerebrospinal fluid pressure above and below the level of the heart, and the dynamics can be further explored by the Queckenstedt test. This study consists in increasing the venous pressure by gentle compression of the jugular veins. Unless some obstruction is present, the cerebrospinal fluid pressure promptly rises and then falls as the venous compression is released. Such a study should not be done in the presence of increased intracranial pressure. Exact meaSllrement of pressure in the infant and child may be difficult because of the lack of cooperation of the child and the amount of fluid needed to fill the manometer. However, the clinician can estimate roughly the presence of increased pressure by the bulging fontanel and the pressure with which fluid is forced through the needle.
FREDERIC C. MOIL
229
METHODS OF OBTAINING CEREBROSPINAL FLUID Lumbar Puncture
The simplest method of obtaining fluid is by lumbar puncture if there is no evidence of prolonged increase of intracranial pressure or evidence of choked disks. This is most easily done with the infant flexed and lying on his side. With sterile precautions the needle is introduced between the second and third lumbar vertebrae. It is useful to permit about eight drops of fluid to drop directly on a chocolate agar slant for culture. Two other sterile tubes are used to collect 5 additional cc. This is sufficient to use one for cell counts and chemistry and the other for bacteriologic studies. Manometric studies can be performed if indicated on the older children.
J
'
i
Cisternal Tap
"
Occasionally because of obstruction, increased intracranial pressure or inability to obtain cerebrospinal fluid for other reasons, a cisternal tap is
A B Fig. 27. A, Subdural taps. The spinal needles are introduced at a right angle to the skin in a suture line iust outside the angle of the fontanel. Note that the head is shaved. B, Cisternal tap. The needle is passed in the midline below the occiput and in a line extending through the external auditory canal and the glabella.
necessary. The occiput and neck are first shaved, and the usual sterile precautions are taken. Then, with the head sharply flexed and the child in a sitting or lying position, the needle is introduced through the skin in the midline at the base of the occiput. The needle is then directed in a line from the base of the occiput through the external auditory meatus to the glabella. The cisterna lies at a depth of 1 to 2 cm. in infantsl and
,
23 0
EXAMINATION OF CEREBROSPINAL FLUID
4 to 4.5 cm.'!' in the adult. Care must be taken not to exceed these depths. The needle is introduced cautiously, removing the stilet from time to time, until the cisterna is entered. The fluid is collected as outlined for cerebrospinal fluid. Subdural Tap
This method is discussed in another clinic in this volume (p. 239) and is mentioned here only for completeness. ROUTINE EXAMINATION OF CEREBROSPINAL FLUID
The following routine examination should be performed on all cerebrospinal fluid: Appearance. Upon examination in daylight the fluid should be clear and colorless. Turbidity and xanthochromia are abnormal. Pressure. Normal pressure is 40 to 110 mm. of water in infants, and up to 200 mlU. in adults. This rises and falls promptly with gentle jugular compression. Cell Count. The cell count may be obtained by placing the cerebrospinal fluid in a hemacytometer counting chamber. All nine squares are counted, and the total number of cells is multiplied by 10/9. To lyse the red cells and stain the white cells the fluid can be diluted 1: 10 in a white cell pipet with a staining fluid of glacial acetic acid and crystal violet. The normal cell count is 0 to 10, and these cells are mononuclear. If blood is present, owing to a bloody tap or cerebrovascular hemorrhage, the total cell count should be first obtained without dilution with the acetic acid. Then the fluid can be diluted and recounted. If more than 10 cells are present, a differential count of the centrifuged sediment can be done by using Wright's stain. Protein. The protein content can be roughly estimated by the Pandy test or by a number of other tests. The Pandy test consists in precipitation of protein in a saturated solution of phenol. It is wise to warm the Pandy solution first if it is cloudy. A drop of cerebrospinal fluid is then introduced into a test tube containing about 2 cc. of Pandy solution. Normally, a faint trace of precipitate may be seen after the descent of the crop. If the protein value is high, the Pandy solution will be grossly cloudy. If blood is present, the Pandy test will be positive. The quantitative determination varies with the individual laboratory, and the normal values range between 15 and 45 mg. per 100 cc. If high protein content exists, a pedicle will form in the cerebrospinal fluid upon standing. Sugar. The sugar determination may be roughly estimated by using five test tubes containing I cc. of Benedict's solution and introducing
FREDERIC C. MOLL
231
one, two, three, four and five drops of cerebrospinal fluid into individual tubes. These are then placed in a bath of boiling water for five minutes. Reduction is evident in the fourth and fifth tubes only if the sugar content is normal. If the sugar is low as in meningitis, nO reduction is seen. On the contrary, diabetes may be suspected because of 4+ reduction in all the tubes. The quantitative sugar values vary between 40 and 80 mg. per 100 cc., depending upon the blood sugar, which is usually about 50 per cent higher. Chloride. The normal values are 116 to 125 mg. per liter (675 to 730 mg. of sodium chloride per 100 ml.). Bacteriology. All cerebrospinal fluid should be examined for organisms if meningitis is suspected even though the fluid appears clear. The centrifuged sediment is smeared, stained and examined. In addition, culture of the cerebrospinal fluid should be a routine procedure. It has . been my experience that if about eight drops of fluid are dropped directly on a chocolate agar slant and then incubated, the number of positive cultures is significantly higher than when culture materials are subsequently inoculated with cerebrospinal fluid in the laboratory. Other. Other special studies such as Wassermann, colloidal gold and cell blocks are done as indicated. CEREBROSPINAL FLUID IN THE NEWBORN
The fluid in the new'born is frequently xanthochromic, is under less pressure and is less in amount than in the older infant. Because of the size of the infant, and the low volume and pressure, the lumbar puncture is technically more difficult than in the older infant. I have followed the suggestion of Glaser,s who suggests using a small needle (no. 24 or 26) and placing the infant in a sitting position~ Presumably this position distends the lumbar sac and permits easier entry. By attaching a syringe to the needle 1.5 to 2 cc. may be withdrawn. This fluid is frequently xanthochromic and contains both red and white blood cells. Since the traumatic tap is not uncommon in the newborn and premature, the significance of the blood is not always clear. If the cerebrospinal fluid tends to become clearer as it is obtained, if the cells are not crenated, and if after centrifugation the supernatant fluid is only slightly xanthochromic, this suggests that the blood is traumatic in origin. This is not absolute, and the evaluation of the findings rests upon the clinical judgment of the operator. The protein in the cerebrospinal fluid is higher (60 to 90 mg. per 100 cc.) than in older infants, but with cerebral hemorrhage it is frequently 300 to 500 mg. or more. The cerebrospinal fluid sugar and chloride are normal. Because of the technical difficulties the value of a lumbar puncture in the newborn is questioned. Certainly if neurologic symptoms are
232
EXAMINATION OF CEREBROSPINAL FLUID
present, it seems indicated, since clinically one cannot distinguish meningitis from cerebral hemorrhage. Even though cerebral damage and hemorrhage may not be evident upon cerebrospinal fluid examination, an attempt at evaluation should be made. There is little evidence that removal of red cells by repeated cerebrospinal fluid taps is therapeutically valuable. CEREBROSPINAL FLUID IN DISEASE nfeclion of Central Nervous System
Purulent Meningitis. MENINGOCOCCUS, HEMOPHILUS INFLUENZAE AND Examination of the cerebrospinal fluid in purulent in~ningitis is imperative, since the therapy can be tailored to the specific infection. The fluid is under increased pressure as evidenced by the. ~ulging fontanel as well as the actual manometric measurement. The Jlllid is usually turbid, but the appearance can be deceiving and a cell count should be done. The cell count is usually grossly elevated to 5000 to 10,000 cells per cubic milliliter, predominantly polymorphonuclear leukocytes. However, I have seen both a positive smear for pneumococci and a positive culture for meningococci in the presence of a normal cell count. A gram stain of centrifuged sediment may show the organism. However, sterile precaution must be taken, since the fluid becomes contaminated easily. The common organisms found in children are meningococcus, H. influenzae and pneumococcus. The last is easily found, but a search usually must be made for the former two. Because of the frequent use of antibiotics early in the disease before a- diagnosis has been established, the organisms may be difficult to find. For this reason the culture should be carefully examined twelve and twenty-four hours later to confirm or establish the diagnosis. The H. influenzae can be confirmed from the smear or culture by the Quellung reaction with specific antiserum. If the meningococcus is suspected but not found, some laboratories are equipped to do type-specific antiserum titers on the cerebrospinal fluid. This is not yet generally available. Sugar in purulent meningitis is frequently low (0 to 10 mg. per 100 ml.), depending on the severity of the disease, and may be sometimes useful as a guide to prognosis. However, a normal value for the cerebrospinal fluid sugar is not infrequent even in fulminating meningitis. Rather, it is useful if a gradual rise is demonstrable associated with therapy. The protein is nonnal or slightly elevated initially and gradually rises during the .:first forty-eight to seventy-two hours, falling to normal on convalescence. The chloride is normal. ESCHERICHIA COLI AND OTHERS. Occasionally newborn infants have PNEUMOCOCCUS.
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233
meningitis due to Escherichia coli, Staphylococcus albus or other less virulent organisms. The cerebrospinal fluid response is essentially the same,but the disease is less severe. There is increase in pressure, cells and protein, and the sugar is slightly depressed. The organisms are recovered by smear and culture. The disease is less fulminating, however, and the cerebrospinal fluid changes are less dramatic. It is always useful to examine carefully for source of infections such as an intraspinal or intracranial dermoid cyst in the presence of an indolent meningitis, since this may be the source of the infection. TUBERCULOSIS. The meningeal reaction to tuberculosis differs somewhat from other bacterial infection. The cell count is never as high, usually 50 to 400 cells with about 70 per cent lymphocytes. The fluid is, therefore, dear to opalescent. The protein is elevated and the sugar characteristically low. This fluid usually demonstrates low chloride content (85 mg. per liter), and this can be of diagnostic importance. The tubercle bacillus may be found on smear with an acid-fast stain, but more success is obtained by culture in guinea pig on an artificial medium such as that of DuBos. ENCEPHALITIS. Involvement of the central nervous system by a specific virus is not characteristic, and differentiation frequently must be made on other clinical and serologic grounds. However, evidence for a viral encephalitis consists of clear fluid under slightly increased pressure with moderate increase in cells in the neighborhood of 150 to 250 per cubic milliliter. Most of these cells are lymphocytes. There is usually a moderate increase in the protein, but the sugar and chloride determinations are normal. However, in spite of clinical findings of encephalitis the cerebrospinal fluid may be normal. Under these circumstances immunologic studies for mumps, herpes, Eastern and Western equine and St. Louis encephalitis must be done. Lymphocytic choriomeningitis is suggested if the cerebrospinal fluid cell count is around 1000 per cubic milliliter or more and the smear reveals that all cells are lymphocytes. This diagnosis can and should be confirmed by serologic studies. Poliomyelitis produces an unusual response in that, if the studies are done early in the disease, the polymorphonuclear leukocyte predominates. This is reversed within forty-eight to seventy-two hours after onset. Othe~wise the findings are those of any viral infection. Tissue culture of the poliomyelitis virus is still in the experimental stage. A positive stool culture for the Coxsackie virus does not eliminate poliomyelitis, since both infections may exist concurrently. Parasitic Diseases
Infection by Torula histolytica most frequently gives signs of central nervous system involvement. The cerebrospinal fluid appears opalescent,
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TABLE
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13. Cerebrospinal Fluid Values TYPE
Normal
APPEARANCE
Clear
o SUGAR
CHLORIDE
40-110 mm'; 0-8 lymphocytes 15-45 mg. % H 20
60 mg.%
116-125 mg./L.
Normal
Normal
PRESSURE
CELL COUNT
PROTEIN
REMARKS
z
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Bloody tap
Bloody
Numerous RBCs
15-45 mg.%
Normal
Normal
Normal
RBCs not crenated; supernatant fluid only slightly xanthochromic
Xanthochromic
Low
Few RBCs
50-90 mg.
Cerebrovascular hemorrhage
Bloody
Normal to high
Numerous RBCs
100 mg.%
Normal
Normal
Many crenated RBCs; .supernatant fluid xanthochromic
Purulent meningitis
Cloudy
Elevated
Numerous WBCs, predominantly polymorphonuclears
Elevated 50-100 mg. %
Low
Normal
Gram stain may reveal organisms; early bacteriology may be positive before evidence of cellular response
Opalescent
Slight. dev.
100-500 cells 70% lymphocytes
Elevated
Low
Low
Smear and culture are positive; fluid may form pedicle on standing
Newborn
Tuberculous meningitis
Few crenated RBCs; supernatant fluids xanthochromic
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Viral encephalitis
Clear to opalescent
Normal to slight. elev.
0-500 cells 90% lymphocytes
Slightly elevated
Normal
Normal
Frequently completely normal; serologic differentiation'
Poliomyelitis
Clear to opalescent
Elevated
50-500 cells 70% lymphocytes
Slightly elevated
Normal
Normal
Early the cell count is predominantly polymorphonuclear cells
Slight. elev.
1000 cells Lymphocytes
Elevated
Normal
Normal
Serologic studies positive
Lymphocytic Opalescent choriomeningitis GuillainBarre syndrome
Clear
Elevated
Normal
Elevated
Normal
Normal
Meningismus
Clear
Slight. elev.
Normal
Normal
Normal
Normal
Lead encephalitis
Clear
Elevated
8-50 cells
Elevated
Normal
Normal
Tumor and abscess
Clear
Elevated
8-300 cells
Elevated
Normal
Normal
Clinical evidence of meningeal irritation only
May be normal
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Subdural hematoma in infants
Clear to xanthochromic
Maybe elevated
May have RBCs
Normal to elevated
Normal
Normal
CSF may be normal, but xanthochromic fluid in subdural taps with high protein content
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236
EXAMINATION OF CEREBROSPINAL FLUID
the cell count and protein are increased, and the diagnosis may be established by demonstrating budding yeast cells on smear or in culture. Space-Occupying Lesions
The examination of the cerebrospinal fluid in the presence of a tumor, abscess or hematoma can be dangerous, yet helpful in diagnosis. In the presence of increased intracranial pressure the danger lies in removal of fluid from below the lesion, permitting the cerebellar tonsils to herniate through the foramen magnum. This accident may occur with the rapid removal of fluid even in purulent meningitis when a partial block is present due to exudate at the base of the brain. It is, therefore, wise to obtain fluid from the cisterna or ventricle if such a condition is suspected. Under these circumstances the fluid is under increased pressure, and a moderate increase in mononuclear cells m a y be present, but the protein is usually significantly increased. The remaining constituents are normal. This does not differentiate the lesion, but does suggest the presence of one. Systemic Diseases
Infections localized outside the central nervous system may produce signs of meningeal irritation without producing significant change in the cerebrospinal fluid examination other than a slight increase in pressure. This is designated meningismus and frequently accompanies upper and lower respiratory infections, but may occur with infections at any site. Acute plumbism produces signs of meningeal irritation and convulsions. The cerebrospinal fluid examination shows an increase in pressure, and elevated prot~in, but is otherwise normal. Examination in polyradiculitis (Guillain-Barre syndrome) produces protein level of 100 to 200 mg. per 100 cc. in the presence of normal cell count and evidence of increased cerebrospinal pressure. Diagnosis of diabetes is not infrequently established in an infant with central nervous system lesions because of a high cerebrospinal fluid sugar. Hallman and Tiihka 4 have demonstrated that diarrheal diseases are frequently accompanied by an increase in lymphocytes (50 to 100 per cubic milliliter) and elevated protein in the cerebrospinal fluid. If salicylism is suspected, the fluid may be tested for salicylate with ferric chloride. This test consists in adding 2 or 3 drops of 10 per cent chloride to the cerebrospinal fluid. A dark purple color indicates the presence of salicylates. This is positive only if the blood levels have reached toxic concentration. Although distinctly a less common problem, congenital and juvenile syphilis are reflected in the cerebrospinal fluid by positive Wassermann tests. During the acute
FREDERIC C. MOLL
237
syphilitic meningitis the cells and protein are elevated, and in juvenile syphilis the' paretic gold curve may be obtained. SUMMARY
The examination of the cerebrospinal fluid is an important diagnostic procedure if the fluid is carefully studied and interpreted. The characteristic responses are outlined in Table 13. In general, inflammatory and metabolic diseases are reflected in the cerebrospinal fluid examination as they are in other extracellular fluid spaces in the body. With careful examination of the fluid, and cautious interpretation in the clinical situation, there is good reason to make an exact diagnosis so that specific therapy can be used. REFERENCES
1. Ford, F. R.: Diseases of the Nervous System in Infancy, Childhood and Adolescence. 3rd ed. Springfield, Ill., Charles C Thomas, 1952. 2. Gardner, J. W., Spitler, D. K., and Whitten, C.: Increased Intracranial Pressure Caused by Increased Protein Content in the Cerebrospinal Fluid. New England J. Med., 250:932, 1954. 3. Glaser, J.: The Cerebrospinal Fluid of Premature Infants. Am. J. Dis. Child., 36: 195, 1928. 4. Hallman, N., and Tahka, H.: Observations on the Cerebrospinal Fluid in Infantile Diarrhea. Acta paediat., 41:437, 1952. 5. Potter, E. L.: Pathology of the Fetus and the Newborn. Chicago, Year Book Publishers, Inc., 1952. 6. Santamarina, V.: La punction sub-occipital 0 cinsernal en la clinica infantiI. Arch. de la Soc. de Estud. Clin. de la Habana: 32:57,1938. Cited in Ford, F. R.1 7. Sweet, W. H., and Locksley, H. B.: Formation, Flow and Reabsorption of Cerebrospinal Fluid in Man. Proc. Soc. Exper. BioI. & Med., 84:397, 1953, University of Washington School of Medicine Seattle 5, Wash.