Narcolepsy and traumatic brain injury: cause or consequence?

摘要

Dear Sir, Narcolepsy with cataplexy is caused by a loss of hypothalamic hypocretin (orexin) neurons, but the etiology of this loss is unclear [1]. After traumatic brain injury (TBI), hypocretin neurons are partially reduced [2], and excessive daytime sleepiness (EDS) belongs to the most common posttraurnatic sleep-wake disturbances [3], In contrast, there are few, mostly ambiguous, reports on posttrau-matic narcolepsy [4]. We retrospectively assessed the frequency of TBI in 37 consecutive patients with well-diagnosed narcolepsy with cataplexy and characterized the TBI subgroup. We only included patients with positive HLA DQBl*0602 and low or undetectable cerebrospinal fluid hypocretin levels. TBI prior to the occurrence of narcolepsy symptoms was present in 7 out of 37 patients (19%) (Table 1). This number is considerably higher than most of the reported prevalences of TBI in the general population, which are about 1% [5]. Three of these patients were diagnosed with severe TBI. The others had mild injuries. Four patients had multiple TBIs throughout their lives. The interval between the last TBI and narcolepsy was up to 2 years in six patients, and 10 years in one patient. Clinical symptoms and sleep laboratory tests did not differ between narcolepsy patients with preceding TBI and those without brain trauma.