Sleep-related periodic leg involvements associated with spinal cord lesions

We describe three patients who developed progressive paraparesis and sleep-related periodic leg movements (SRPLM) associated with thoracic spinal cord lesions; one patient had a schwannoma and two had intramedullary lesions. The patients showed periodic repetitive involuntary movements involving one or both lower limbs. The involuntary movements consisted of a single rapid dorsiflexion of the great toe or ankle, two to four repetitive dorsiflexions of the toes and ankle, and a mixture of repetitive jerks and prolonged spasms causing flexion of the hip and knee and dorsiflexion of the ankle and toes. In the patient with a schwannoma, paraparesis and SRPLM improved completely after surgical removal of the mass lesion. In one patient the SRPLM associated with an intramedullary lesion improved markedly after levodopa treatment. We suspect that thoracic spinal lesions partially disinhibit the lumbosacral generator. Such disinhibition seems to be enhanced by the activation of the neuronal systems related to periodic somatic and vegetative phenomena during sleep.