POSTTRAUMATIC STIMULUS SUPPRESSIBLE MYOCLONUS OF PERIPHERAL ORIGIN

A patient is described who presented with myoclonus of the first dorsa l interosseus muscle of the right foot. This myoclonus occurred 18 mon ths after trauma of the cutaneous branch of the deep peroneal nerve on the dorsal aspect of the foot. Tactile stimulation in the dermatome o f this nerve, or an anaesthetic block of the deep peroneal nerve stopp ed the myoclonus. The different innervation between the efferent motor activity responsible for the movements and the sensory afference supp ressing it points firmly towards involvement of central connections; H owever, abolition of the movement by anaesthesia suggests the presence of a peripheral ectopic generator. This finding confirms that focal m yoclonus can have its origin in the peripheral nervous system and may be modulated by sensory inputs.