Restless legs syndrome and periodic limb movements.

The history, clinical aspects, and treatment of restless legs syndrome (RLS), a heterogeneous, distressing sensorimotor disorder, and periodic limb movements (PLMs) that are the typical motor accompaniment of the syndrome, are described. A positive family history, a positive response to dopaminergic treatment, and the presence of PLM while awake or asleep are supportive criteria for the diagnosis of the disorder. RLS and PLM occur more frequently at the beginning of night and exponentially decline across sleep cycles, suggesting circadian influences. Altered circadian rhythmicity in dopamine metabolism and enhanced circadian variations in dopaminergic functions have been reported in the disorder. Dysfunction or atrophy of A11 cells from the diencephalic-spinal dopamine A11 system has been suggested to explain the efficacy of dopaminergic drugs in relieving RLS symptoms and the circadian rhythmicity of RLS. Studies support the hypothesis that the A11 dopaminergic neurons and spinal pathways may be more involved in the pathophysiology of RLS than the nigrostriatal system. Neurophysiological evidence indicates that the involuntary movements in RLS may be of spinal or propriospinal origin. Despite these findings, however, the pathogenic mechanisms underlying the peculiar sensory and motor manifestations of RLS remain unexplained. Among the current treatment options offered for the treatment of RLS, dopaminergic agents have provided the best evidence for efficacy in symptom relief.