0845 Large arachnoid cysts and hypersomnolence: symptomatic or not?

Abstract

Abstract Introduction Arachnoid cysts are the most common type of brain cyst. They are often congenital, and most of them are stable and do not require treatment. On the other hand, some of them present a symptomatic problem such as headache, nausea and seizures. This rare condition was seen in a female patient who also had hypersomnolence. Report of Cases: A 37-year-old female presented to hospital for evaluation of excessive daytime sleepiness (EDS) for the past 20 years, with repeated attacks several times a day without any REM sleep related symptoms. She also showed irregular wake sleep pattern of sleep extending over 24 hours, disturbing nocturnal sleep after each episode. Her sleep log showed sudden onset hypersomnolence with sleep duration of 30-40 hours every week. Epworth sleep scale was 10/24. PSG demonstrated her sleep architecture of 8 hours duration was unusual with sleep onset REM period (SOREMP) and decreased N3 sleep stage. MSLT showed reduced sleep onset latency (average: 5 minutes) and sleep onset REM on 1 of 4 naps. Brain MRI revealed a large arachnoid cyst on her left cerebral hemisphere. She was diagnosed as narcolepsy type2 and referred to the department of neurosurgery, but due to unclear association between hypersomnolence and the cyst, surgical treatment was not carried out. She was started on Modafinil 50mg which progressively increased to 200mg, but little effect was seen in sudden onset hypersomnolence and caused side effects such as headache and nausea. After Modafinil was discontinued, Melatonin agonist was administered in order to control her irregular sleep-wake rhythm, and since then her sleep-wake cycle has changed relatively stable and regular. At present, the frequency of hypersomnolence is gradually getting low and Epworth is 4/24. Conclusion In the present case, there is no evidence that her symptoms concerning sleep were secondary to any other disorder. Also, to our knowledge, there have been only a few cases reporting coexistence of hypersomnolence and arachnoid cysts. We are carefully following up on this patient and will reconsider to refer her to neurosurgery if any other symptoms appear. Support (If Any)