Familial orthostatic tremor: An additional report in siblings

Orthostatic tremor (OT) was a term first used to describe tremor that occurred in the legs while patients were standing, and which was relieved while patients were walking, seated, or supine.1 The disorder can be very disabling, and the treatment, which is largely unsuccessful, remains empiric.2,3 Although there is some evidence of a dopaminergic deficit,4 the exact circuit responsible for the high frequency, 13–18 Hz tremor that is pathognomonic for this disorder remains unclear. OT is thought to be sporadic rather than familial, which makes the search for a pathophysiologic mechanism particularly challenging. There are only 2 prior case reports of OT in siblings.5,6 Here we report a third sibling pair, each of whom had clinical and electrophysiologic evidence of OT.