Contribution of CSF/serum immunofixation to the diagnosis of inflammatory diseases of the central nervous system

Introduction

Multiple sclerosis and other inflammatory diseases of the central nervous system produce various and nonspecific symptoms. The diagnosis of these diseases is ultimately a clinical decision, although examination of cerebrospinal fluid (CSF) and other complementary tests such magnetic resonance imaging (MRI) and evoked potentials can be contributive. One important aspect of these diseases is intrathecal synthesis of immunoglobulins.

Patients and methods

In order to determine the contribution of CSF/serum immunofixation to the diagnosis of inflammatory diseases of the central nervous system, we conducted a retrospective study in the biochemistry laboratory of the military instruction hospital Mohammed V. 363 CSF/serum samples were collected over a period of four years.

Results

Immunofixation was less sensitive than MRI for the diagnosis of inflammatory neurological disease (44% vs 87%), but was much more specific than MRI (97% for immunofixation vs 38%). The positive predictive value was higher that for MRI (85% vs 40%). The negative predictive value (80%) was close to that of MRI (86%). The bivariate analysis showed that immunofixation results could be predicted from clinical findings and complementary test results such as the index of Link, syphilis serology in CSF, and MRI.

Conclusions/discussion

Semi-automatic Hydrasys immunofixation of CSF IgG is a technique exhibiting excellent diagnostic and analytical performance for the diagnosis of inflammatory neurological diseases.