Motor system excitability in patients with restless legs syndrome.

In 18 patients with idiopathic restless legs syndrome (RLS), intracortical inhibition by paired transcranial magnetic stimulation (TMS) was significantly reduced for both foot and hand muscles, suggesting that the entire motor cortex is disinhibited in RLS. Decreased intracortical facilitation in the foot muscle but not in the hand muscle may be due to subliminal activation of the symptomatic lower limbs. Motor excitability measurements of single TMS were not altered. These results support a subcortical origin of RLS.