Cerebrospinal fluid as a diagnostic body fluid.

The cerebrospinal fluid is a dynamic, metabolically active substance that has many important functions. It is invaluable as a diagnostic aid in the evaluation of inflammatory conditions, infectious or noninfectious, involving the brain, spinal cord, and meninges. The cerebrospinal fluid may be obtained with relative ease with the use of lumbar puncture, but failing this, alternative techniques are available. With the judicious use of the computerized axial tomographic scan, the removal of cerebrospinal fluid has little attendant risk. Age-related and compartmental variations in chemical and cellular composition are important considerations in the interpretation of results. Alterations in cerebrospinal fluid constituents from different pathologic processes may be similar in certain circumstances and cause interpretation difficulties.