ELECTROPHYSIOLOGICAL BRAIN-STEM INVESTIGATIONS IN IDIOPATHIC NARCOLEPSY

Narcolepsy is associated with various rapid eye movement (REM) sleep a bnormalities. Distinct brain stem areas seem to play a prominent role in REM sleep regulation. Recent magnetic resonance imaging (MRI) studi es have led to conflicting findings concerning the presence of structu ral brain stem lesions in patients with idiopathic narcoleptic syndrom e. However, multimodal electrophysiological brain stem investigations may reveal functional brain stem abnormalities even in the absence of MRI abnormality. Therefore we investigated brain stem function in 12 i diopathic narcoleptic patients by systematically studying tegmental br ain stem pathways. All of the patients met the diagnostic criteria of the International Classification of Sleep Disorders, with typical chan ges in polysomnography and the multiple sleep latency test. Electrophy siological investigations comprised masseter reflex, blink reflex, mas seter inhibitory reflex, early auditory evoked potentials and electroo culography with vestibular testing. In no patient were electrophysiolo gical brain stem abnormalities observed. Our findings do not support t he existence of a relevant brain stem lesion in narcoleptic patients w ith normal neurological status.