Spinal myoclonus induced by an intrathecal catheter.

We report a case of spinal myoclonus induced by the tip of an intrathecal catheter in a 35-year-old patient with severe, adult-onset, generalized dystonia of unknown cause, treated for 2 years using intrathecal baclofen. One month after a falling episode, the patient developed focal myoclonus of the right proximal leg whenever she stood up from a seated position. The electrophysiologic recordings were compatible with spinal segmental myoclonus, originating at a focus corresponding to the L2-S2 segments. At this site, the tip of the intrathecal catheter was demonstrated by myelography to be in close proximity to the nerve roots and conus medullaris. The myoclonus resolved promptly once the catheter tip was withdrawn. We review the literature on spinal myoclonus and discuss the possible mechanisms of spinal myoclonus pertaining to the present case. This report represents an unusual complication of intrathecal catheter systems that, if recognized, can lead to prompt therapeutic intervention.