[Primary progressive forms of multiple sclerosis: application of the new diagnostic criteria in French].

Approximately 15 p.100 of all cases of multiple sclerosis (MS) are primary progressive multiple sclerosis (PPMS). Diagnosis is however frequently delayed due to the lack of relapse. The commonly used Poser criteria established in 1983 are not directly applicable to this subgroup of MS patients. In 2000, Thompson et al proposed new diagnostic criteria for PPMS. The aim of our study was to apply retrospectively these new criteria to a cohort of patients from northern France (G-SEP cohort). The cohort included 184 patients (94 women and 90 men, sex ratio=1.04). Mean age at disease onset was 40.3 years (18-67 years) and mean follow-up was 9.9 (1-39 years). Only one patient was older than 65 years but 13 patients (7.1 p.100) were younger than 25 years. Patients were classed as having definite, probable or possible PPMS on the basis of clinical, MRI, cerebrospinal fluid and visual evoked potential (VEP) data. Most of the patients (61.4 p.100) had one symptom at onset; spastic paraparesis was frequent (79 p.100). Mean delay to diagnosis was 4.4 years. Ten patients (5.4 p.100) were surgically treated for cervic arthrosic myelopathy. Mean EDSS score at the end of follow-up was 5.8 (3-10). MRI was positive in 87.3 p.100 of the patients. Oligoclonal bands were found in 78.2 p.100. VEPs ware abnormal in 79.9 p.100 of the patients. Applying the Thompson criteria, 57.7 p.100 of the patients had definite PPMS, 38.7 p.100 probable PPMS. Our results are very similar to previous studies and confirm the usefulness of the new proposed criteria, which however should be prospectively tested to determine sensitivity and specificity in a new cohort of patients.