131. Muscle sympathetic nerve activity during periodic leg movements in sleep in a narcolepsy with cataplexy patient: A microneurographic study

Abstract

Periodic leg movements in sleep (PLMS) are a sleep-related phenomenon with periodic episodes of repetitive stereotypical movements of the lower extremities but the underlying pathogenesis is poorly understood. The aim of this study was to directly record sympathetic outflow by microneurography during PLMS to shed light on the underlying pathogenesis. We recorded muscle sympathetic nerve activity (MSNA) during sleep with and without PLMS in a woman patient with narcolepsy with cataplexy. The patient underwent nocturnal video-polysomnography with MSNA recording from the peroneal nerve by microneurography. Luckily, MSNA recording site did not change during sleep and it was still preserved also during PLMS. PLMS were evident during early N2 and N3 sleep stages but were absent during subsequently N2 and N3 sleep phases allowing to make a direct comparison of sympathetic activity during the same sleep phase. Sleep phases with PLMS were characterized by a pronounced MSNA increase compared to the same sleep phases without PLMS. Our data demonstrated that sleep phases with PLMS were characterized by a pronounced sympathetic activation. These data suggested that PLMS is not a pure motor phenomenon but it is likely the expression of a generalized increased neuronal excitability during sleep.