Coexisting narcolepsy (with and without cataplexy) and multiple sclerosis : Six new cases and a literature review.

ABSTRACT

BACKGROUND: There are increasing data suggesting the involvement of the immune system in narcolepsy. The co-occurrence of narcolepsy with other autoimmune disorders (including multiple sclerosis, MS) is rare. PATIENTS AND METHODS: International multicenter sleep center survey and literature review on narcolepsy with (NC) and without (NwC) cataplexy. RESULTS: A total of 26 patients (pts), 6 in the survey and 20 in the literature were found. Two different types of association were identified (1) Symptomatic type (5 pts) MS preceding the onset of narcolepsy, which was always without cataplexy (NwC); sleep onset REM episodes (SOREM) and hypocretin deficiency were observed in some, and lesions in the hypothalamus in all patients. (2) Coexisting type (18 pts) MS preceding or following the appearance of NC with SOREM, hypocretin deficiency but no lesions in the hypothalamus. A positive effect of steroids, immunoglobulins or natalizumab on narcolepsy symptoms was observed in four patients. DISCUSSION: Narcolepsy and MS are rarely associated. In addition to NwC secondary to hypothalamic demyelination, some patients present a coexistence of MS with NC without detectable hypothalamic lesions. The rarity of reports on this association probably reflects underrecognition. The elucidation of underlying genetic and immune mechanisms needs further studies.