NOCTURNAL MYOCLONUS SYNDROME (PERIODIC MOVEMENTS IN SLEEP) RELATED TO CENTRAL DOPAMINE D2-RECEPTOR ALTERATION

The nocturnal myoclonus syndrome (NMS) consists of stereotyped, repetitive jerks of the lower limbs that occur during sleep or wakefulness. NMS is often related with restless-legs syndrome (RLS) and can cause severe sleep disturbances and daytime sleepiness. The efficacy of dopamine agonists in the treatment points to a dopaminergic dysfunction in NMS. We investigated the central dopamine D2-receptor occupancy with [I-123] labeled (S)-2-hydroxy-3-iodo-6-methoxy-([1-ethyl-2-pyrrolidinyl]methyl) benzamide (IBZM) (a highly selective CNS D2 dopamine receptor ligand) ([I-123]IBZM) and single photon emission tomography (SPET) in 20 patients with NMS and in 10 healthy controls. Ln most of the pa with NMS there was a lower [I-123]IBZM binding in the striatal structures compared to controls. The results indicate that NMS is related to a decrease of central D2-receptor occupancy.