Stretching the limbs? Tonic spasms in multiple sclerosis

A 23-year-old man with a clinically isolated syndrome (right optic neuritis) diagnosed 6 months before, presented with recurrent, brief, painful, stereotyped, involuntary posturing movements of the left upper limb. The neurological examination was otherwise unremarkable (except for right optic atrophy). Intravenous methylprednisolone was initiated; the paroxysms persisted and worsened 7 days later, as the left lower limb and hemiface became affected. A video-EEG showed no epileptiform activity despite the movements. Brain MRI revealed new lesions affecting the right pyramidal tract, contralateral to the clinical manifestations. Valproate was prescribed and the paroxysms were completely resolved 5 days later. Tonic spasms are classically, although infrequently, seen in multiple sclerosis, and may clinically resemble primary paroxysmal dyskinesias or even focal motor epileptic seizures.