Cerebrospinal fluid protein concentrations in patients with sciatica caused by lumbar disc herniation: an investigation of biochemical, neurologic, and radiologic predictors of long-term outcome.

We studied 180 adult patients admitted to the Neurological Department, Haukeland Hospital in Bergen, Norway, for a period of 5 years from 1984 to 1988. One hundred fifty-seven patients were followed up 3.9-9.0 years after admittance to the Neurological Department. The purpose of this study was to find out if the total cerebrospinal fluid (CSF) protein concentration could predict the outcome of lumbar disc surgery or conservative treatment in patients with sciatica. Neurologic and radiologic parameters were also included in the investigation. The increase of the CSF total protein concentration in sciatica without spinal block is assumed to be due to leak of plasma proteins into the CSF from the nerve root. A relationship between CSF protein concentrations and certain clinical parameters has been found. At myelography, 10 ml of CSF was collected for analysis. The patients were evaluated for involvement of the nerve root and/or the dural sac, respectively. The neurologic parameters investigated were: straight leg raising tests, paresis, disturbances of sensibility, and altered reflexes. At follow-up, the patients were asked to fill in questionnaires concerning job function, sick leave or disability pension, subjective physical disability and pain perception, and a clinical examination with the same neurologic parameters was performed. Elevated CSF total protein concentration was related to chronic leg pain, leg pain, and subjective physical disability at follow-up. Nonoperated women reported higher subjective physical disability scores and were more often on sick-leave or disability pension than were men at follow-up. Lateral prolapses were associated with good job function outcome and less risk for sick-leave or disability pension. Reduced lower extremity reflexes, laterally located disc herniation and elevated CSF total protein concentration were associated with a favorable long-term outcome in patients with sciatica. CSF proteins as objective measures on nerve root injury are discussed. CSF total protein concentration can be regarded as an indicator of the functional status of the nerve root and a prognostic factor in patients with sciatica.