[Comparative study of magnetic resonance and evoked potentials in patients with clinically defined multiple sclerosis].

In an attempt to establish the efficacy of the most recent diagnostic tests--magnetic resonance (MR) imaging and multimodal evoked potentials (EP), 28 patients with clinically definite multiple sclerosis (MS) (1.a Poser's categories) were studied. The MR was positive in 26 (92%) patients; the EP were altered in 23 (82%)--the visual EP in 18 (64.2%), the auditory EP in 5 (17.8%), and the somatosensory EP in 15 (53.5%). Three patients with abnormal brain stem MR had normal EP. Two patients had normal MR and altered EP. There was not any patient with normal MR and EP. The MR was the most sensitive technique for the diagnosis of MS, but only during the 3 first years of evolution. After this study we consider the convenience to have both MR and EP positive to give a patient the diagnostic of clinically definite with paraclinic support (category 1.b of Poser).