The sensitivities and predictive values of visual, somatosensory, and brain 
auditory evoked potentials (EPs), cerebrospinal fluid oligoclonal banding 
(CSF-OB) and magnetic resonance imaging (MRI) were evaluated for the early 
diagnosis of clinically definite multiple sclerosis (CDMS). Paraclinical 
evidence of asymptomatic lesions allows a diagnosis of CDMS. Eighty-two patients 
in whom MS was suspected but diagnosis of CDMS was not possible entered the 
study prospectively. Paraclinical examinations were performed at entry. Patients 
were examined and underwent EPs every 6 months, and MRI yearly. After a mean 
follow-up of 2.9 years, 28 patients (34%) had developed CDMS (McDonald-Halliday 
criteria). The initial MRI was strongly suggestive of MS in 19 of these (68%), 
while 27 (96%) had at least one MS-like abnormality in the initial MRI. CSF-OB 
and EPs had lower sensitivities. CDMS developed during follow-up in 19 of the 36 
patients (53%) who had an initial MRI strongly suggestive of MS but in only 1 of 
the 25 who had normal MRI when first studied. These results support previous 
conclusions that MRI is the most sensitive test for detecting white matter 
asymptomatic lesions, and the most predictive for the diagnosis of CDMS.