Normal striatal D-2 receptor binding in idiopathic restless legs syndrome with periodic leg movements in sleep

Abstract

Dopaminergic treatment is very effective in restless legs syndrome (RLS) and periodic leg movements in sleep (PLMS). However, neuroreceptor imaging studies that addressed altered striatal dopaminergic function have given controversial results. In this present study, 14 patients with idiopathic RLS (iRLS) and PLMS with a good response to dopaminergic and non-dopaminergic treatment and ten healthy sex- and age-matched controls were investigated off-medication by using I-123-IBZM and SPELT. RLS symptoms and sleep disturbances were evaluated using three nights of polysomnography, the Pittsburgh Sleep Quality Index, and the International RLS Study Group (IRLSSG) rating scale. The patients presented with sleep disturbances, a high PLMS index (56.2 +/- 33.1 per h), and severe RLS symptoms during SPELT (IRLSSG rating scale 23.1 +/- 8.0), and showed no significant differences in striatal to frontal IBZM binding to D-2 receptors compared to controls (ratio striatum/frontal cortex, right side 1.60 +/- 0.10 vs 1.63 +/- 0.08, P = 0.35, NS; left side 1.61 +/- 0.11 vs 1.63 +/- 0.08, P = 0.51, NS). These findings show normal function of striatal D-2 receptors in successfully treated patients with iRLS and PLMS. Dopaminergic and non-dopaminergic pretreatment does not appear to change striatal D-2 receptor binding as compared to healthy controls. Structures other than striatal D-2 receptors are discussed as possible causes of the treatment effects in RLS. ((C) 2004 Lippincott Williams Wilkins).