Symptomatic Narcolepsy and Generalized Seizures Following Surgery for Rathke’s Cleft Cyst

Abstract

Narcolepsy is a chronic sleep disorder characterized by excessive daytime sleepiness and rapid eye movement (REM) sleep-related symptoms such as cataplexy, sleep paralysis, and hypnagogic hallucination. Animal studies show that genetic alterations in either hypocretin ligands or hypocretin receptor-2 can cause narcolepsy in mice and dogs. In humans, mutations in hypocretin-related genes appear to be rare, however, a loss of hypocretin-producing neurons has been demonstrated in human pathology. Consequently, patients with narcolepsy have low or no detectable hypocretin in their cerebrospinal fluid (CSF).1 Narcolepsy is strongly associated with the human leukocyte antigen DQB1*0602, suggesting the involvement of an autoimmune process in idiopathic narcolepsy.2 Symptomatic narcolepsy is a rare disorder secondary to the underlying neurological disorder. In this disorder, the signs and symptoms of narcolepsy are temporally associated with the underlying neurological process. One of the most frequent causes of symptomatic narcolepsy is brain tumors, usually in the region of the third ventricle and the diencephalon, including adenoma, angioma, astrocytoma, cerebral sarcoidosis, choroid plexus carcinoma, colloid cyst, craniopharyngioma, glioma, germinoma, glioblastoma, histiocytosis, lymphoma, medulloblastoma, and subependymoma.3 Abnormalities in sleep and wakefulness that can develop after surgical removal of tumors in the hypothalamic area seem to vary from fragmented nocturnal sleep without daytime sleepiness to typical narcolepsy with cataplexy.4 Tachibana et al.5 reported a series of craniophayringioma patients diagnosed with narcolepsy after surgery. We report a woman with symptomatic narcolepsy that developed after surgical removal of Rathke’s cleft cyst, which has never before been reported as a causative factor for symptomatic narcolepsy. Excessive daytime sleepiness and sleep onset REM sleep episodes were demonstrated using the multiple sleep latency test (MSLT). In addition, the patient also had generalized seizures, including myoclonic and/or tonic-clonic seizures, which are rarely comorbid in patients with symptomatic narcolepsy. Received: November 26, 2014 Revised: December 19, 2014 Accepted: December 29, 2014 Correspondence Sang-Ahm Lee, MD Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul 138-736, Korea Tel +82-2-3010-3445 Fax +82-2-474-4691 E-mail salee@amc.seoul.kr Symptomatic Narcolepsy and Generalized Seizures Following Surgery for Rathke’s Cleft Cyst