Spinal segmental myoclonus during postural maintenance in a patient with cervical spondylosis: a case report.

Spinal segmental myoclonus is defined as a rare involuntary movement characterized by myoclonic jerks of spinal origin. We describe the case of a 62-year-old woman who developed spinal segmental myoclonus 4 months after undergoing cervical laminoplasty for ossification of the posterior longitudinal ligament. Myoclonic jerks were observed in the upper trapezius innervated by C3-4, which corresponded to the level of myelomalacia. These jerks were elicited and aggravated in the sitting and standing positions but were completely suppressed in the supine position. The myoclonus was refractory to medication but improved with the use of a soft neck brace.