CHAPTER LII
NEUROLOGICAL CONSIDERATIONS IN TROPICAL DISEASES
There is a great tendency in the tropics to ascribe neurological manifestations to beriberi or malaria. It must be acknowledged, however, that various sensory and motor phenomena, which may show themselves from time to time, in those who have suffered from beriberi, are common and prove sources of confusion in diagnosis. Tropical sunlight with its ultra-violet rays had a vogue which held sway for a brief period as explaining most nervous conditions in Europeans in the tropics. At present we are inclined to believe that excesses in eating and drinking and late hours may be more potent in the production of nervous breakdowns than are factors less cosmopolitan.
While syphilis is rampant in many parts of the tropical world the usual views are that the luetic neurological manifestations, so common in temperate climates, are more or less nonexistent. At the same time it would seem advisable with this point in view to study the cases attributed to other causes along the line of laboratory investigations of the cerebro-spinal fluid.
Clinically there are many points of difference between syphilis as seen in the native races of tropical regions and as observed in Europeans at home, and it would seem advisable to do more work along the line of spinal fluid examinations. The examination of the spinal fluid for syphilis should include a Wassermann test using several concentrations ranging from 0.2 to 1.0 cc., a globulin estimation, cell count and Langes colloidal gold reaction,—the last not being necessary however, unless positive findings are obtained in one or more of the other tests. Of course the most important test is the Wassermann of the spinal fluid and every one should bear in mind the marked complement fixation power of the spinal fluid of paretics. In such a fluid we almost always obtain a positive reaction where quantities of 0.2 cc. or less are employed, while with locomotor ataxia or cerebro-spinal lues amounts of 0.5 to 1 cc. are generally required to give a positive test. It is not necessary to inactivate spinal fluid.
These tests can only be carried out in a well equipped laboratory and the same is true of the colloidal gold one. The tests for cell increase and globulin increase, however, can be made by anyone prepared to do ordinary clinical laboratory work.
The normal spinal fluid is as clear as water, has a specific gravity of about 1.010 and is under a pressure of about 5 to 7 mm. of mercury or 60 to 100 mm. of water. The sugar content is about 0.07% and the proteid content about 0.03 to 0.04%.
Cerebro-spinal Fluid Examinations
To withdraw spinal fluid for bacteriological examination or cytodiagnosis we use a sterile needle about 4 inches long for an adult, preparing the skin as described for blood cultures from a vein (see [page 516]). The patient is placed on the left side with knees drawn up and head and shoulders carried forward to give the greatest possible space between the spinous processes by arching the spine. A line at the level of the iliac crests passes between the third and fourth lumbar vertebrae. Select a point midway between the spinous processes of these lumbar vertebrae and enter the needle two-fifths of an inch to the right of this point, pushing the needle inward and upward. Collect the material in two or three sterile test tubes, to avoid contamination of the entire sample by a drop of blood which may come out in the first portion. The presence of blood in very slight amount interferes with cytodiagnosis and globulin tests and, if present in more than a trace, it makes the colloidal gold test practically worthless. Make cultures on blood serum at the earliest possible moment. Centrifugalize a portion of the fluid at high speed and examine the sediment for bacterial content. After the puncture the patient should drink a glass or so of water and remain in bed for a day, preferably with the head lower than the feet.
In general terms, excluding syphilis, it may be stated that: