CEREBROSPINAL FLUID, EXAMINATION OF

Abstract

This chapter describes the examination of cerebrospinal fluid. Measurement of the cerebrospinal fluid pressure with the subject upright shows the following results: it is slightly lower than atmospheric pressure in the lateral ventricles and equal to atmospheric pressure in the cisterna magna, while in the lower lumbar sac, it equals a column of water as high as the distance between the needle and the foramen magnum. The fluid, therefore, spurts out through a lumbar puncture needle in the lumbar sac but has to be withdrawn by syringe-suction from the ventricles and the cisterna magna. For most diagnostic purposes, the fluid is conveniently obtained by lumbar puncture, the patient lying on his side with the spine horizontal and flexed, and the back vertical. In this position, the pressure varies between about 60 and 180 mm of fluid in normal subjects, and it exhibits small oscillations because of the pulse and respiration. Pressures between 60 and 30 mm are suspicious, and those below 30 mm are abnormal.