The risk of progression to multiple sclerosis (MS) after an episode of acute non compressive episode involving the spinal cord remains uncertain. A follow-up study was performed to determine the risk of early progression to MS in 20 patients presenting with clinically isolated lesions of the spinal cord, combined clinical evaluation, spinal and brain magnetic resonance imaging (MRI), visual, brainstem auditory and somatosensory evoked potentials (VEPs, BAEPs, SEPs), and cerebrospinal fluid (CSF) electrophoresis analysis. Spinal cord MRI demonstrated more lesions in cervical region (74 p. 100) than thoracic or lumbar regions (26 p. 100). Six patients (30 p. 100) had an initial brain MRI that was strongly suggestive of MS and 5 patients (25 p. 100) had only one MS-like abnormality. Eight patients (40 p. 100) had abnormal VEPs, 3 (15 p. 100) abnormal BAEPSs and only 44 p. 100 (8/18) abnormal SEPs. In contrast, CSF analysis showed oligoclonal bands (CSFOB) in 15/19 patients (79 p. 100). The diagnosis of MS was performed initially in 13 cases (65 p. 100) (clinically definite MS (CDMS) in 30 p. 100, laboratory-supported definite MS (LSDMS) in 61 p. 100 and clinically probable (CPMS) in one case). During the follow-up period (18 +/- 7 months), 8 patients (40 p. 100) presented one or more exacerbations and time to the first recurrence was 8 +/- 5 months. Seven of these 8 patients were initially treated by infusion of methylprednisolone. Among these patients, all of them had CSF OB and initial brain MRI was strongly suggestive of MS in 3 of them. During this follow-up period, brain MRI showed emergence of lesions in 4 cases with normal initial examination and 3 of them presented exacerbations. At the follow-up term, the diagnosis of MS was performed in 15 cases (75 p. 100) CDMs in 66 p. 100, LSDMS in 26 p. 100 and CPMS in one case). This confirms the predictive value of brain MRI and CSF OB for the diagnosis of MS in patients who present with clinically isolated acute syndrome of the spinal cord.