Spinal Segmental Myoclonus in Primary Progressive Multiple Sclerosis.

Background: A wide variety of associated movement disorders has been described in multiple sclerosis.

Phenomenology shown: A 57-year-old woman with primary progressive multiple sclerosis developed spinal segmental myoclonus associated with focal myelitis.

Educational value: Movement disorders in multiple sclerosis are phenomenologically diverse and have varied pathophysiological mechanisms, making it essential to identify them to initiate appropriate treatment.