A 38-year-old woman suddenly showed signs of monoballism in the right upper limb. Examination of CSF showed 13 monocytes per mm3 and 28.7% of IgG in oligoclonal bands. MRI examination showed several high signal lesions in T2-weighted images. One of these lesions was located in the left subthalamic region. Visual evoked potentials showed increased latencies for the P100 wave on the left eye. Two years later she experienced vertigo, diplopia, gait unsteadiness and left facial dysesthesia. This clinical syndrome almost completely regressed after 10 days of ACTH therapy (Synacthene). Diagnosis of multiple sclerosis was supported by radiological and neurophysiological investigations.