Cerebrospinal fluid proteins as indicators of nerve root compression in patients with sciatica caused by disc herniation.

Patients with sciatica caused by lumbar disc herniation were studied to identify biochemical changes in the cerebrospinal fluid related to myelographic findings and clinical observations. One hundred forty-three patients were evaluated by myelography with regard to involvement of the dural sac and the nerve root. A medial group (20 patients) with evidence of dural sac impingement was compared to a lateral group (63 patients) and an extreme lateral group (9 patients) whose condition primarily affected the nerve root. The remaining 51 patients comprised a mixed group with involvement of both the dural sac and the nerve root. The mean cerebrospinal fluid/serum albumin ratio, cerebrospinal fluid/serum immunoglobulin G ratio, and cerebrospinal fluid total proteins showed a significantly increasing trend from the medial through the lateral to the extreme lateral groups. Patients with lateral lumbar disc herniations more often showed neurologic deficits. These results indicate that the elevated cerebrospinal fluid total protein found in the patients with sciatica is due to leaking of plasma proteins primarily from the nerve root into the cerebrospinal fluid. The cerebrospinal fluid proteins may be used as diagnostic parameters of nerve root compression, especially when surgery is a consideration or in patients in whom sciatica is unlikely.