The case of a man 34 year-old presenting upward gaze paralyses and external ophthalmoplegia without involvement of the downward gaze, accompanied by cerebellar disorders, generalized areflexia but no muscular weakness, and moderate sensory impairment of the four extremities is reported. The cerebrospinal fluid showed an albuminocytologic dissociation. Recovery was rapid and almost complete, within 3 weeks, remaining minimal paresis of the upward gaze and lateral movement in both eyes. The improvement had been coinciding with the treatment by cortrosina.