Absence of multiple sleep-onset rapid eye movement periods (SOREMPs) is not a specific feature of patients with pathological sleep prolongation.

Purpose: Multiple sleep-onset rapid eye movement periods (SOREMPs) are involved in the pathophysiology of narcolepsy, but it is not clear whether the lack of multiple SOREMPs is associated with the pathophysiology of idiopathic hypersomnia or not. We examined the significance of multiple SOREMPs in patients with pathological sleep prolongation. Methods: Participants were consecutive patients complaining of unexplained sleepiness and agreed to a 3-day-sleep studies; 24 h polysomnography (PSG) followed by standard PSG and multiple sleep latency test (MSLT). Forty-one (26 females, 21.9 ± 8.1 years old, BMI 20.4 ± 2.3 kg/m2) of 54 eligible patients without other sleep pathologies showed pathological sleep prolongation. We subdivided them into those with and without multiple SOREMPs on MSLT and compared clinical and PSG variables between groups. Results: Six of 41 (14.6%) patients showed multiple SOREMPs on MSLT. There were almost no differences in sleep variables between those with and without multiple SOREMPs. We only found shorter mean sleep latency on MSLT and more REM cycles on 24 h PSG in those with multiple SOREMPs (adjusted p = 0.016 and 0.031). The frequencies of REM-related phenomena and clinical symptoms related to idiopathic hypersomnia were not different between groups. Conclusion: Our results indicated that patients with pathological sleep prolongation had the same clinical profiles regardless of the status of SOREMPs, suggesting the absence of multiple SOREMPs, prerequisite for the diagnosis of idiopathic hypersomnia, is not a specific feature of pathological sleep prolongation. Confirmation of sleep prolongation alone could be a diagnostic tool for idiopathic hypersomnia.

Excessive Daytime Sleepiness Case Confounding with Thyrotoxicosis / 수면정신생리

Narcolepsy is a sleep disorder, which is characterized by excessive daytime sleepiness (EDS) that is typically associated with cataplexy, sleep fragmentation and other REM sleep-related phenomenon such as sleep paralysis and hypnagogic hallucination. Narcoleptic symptoms can be developed from various medical or neurological disorders. A 17-year-old male patient admitted for the evaluation of EDS which started three-month ago. He slept more than 18 hours a day with cataplexy and hypnagogic hallucination. He was obese with body mass index (BMI) of 30.4 kg/m2. After admission he was newly diagnosed to the thyrotoxicosis. T3 391.2 ng/dL (60-181), free T4 4.38 ng/dL (0.89-1.76), TSH <0.01 microIU/mL (0.35-5.5) were measured. His pulse rate ranged 70-90 beats per minute and blood pressure ranged 150/100-120/70 mmHg. Polysomnography revealed many fragmentations in sleep with many positional changes (81 times/h). Sleep onset latency was 33.5 min, sleep efficiency was 47.9%, and REM latency from sleep onset was delayed to 153.6 min. REM sleep percent was increased to 27.1%. Periodic limb movement index was 13.4/h. In the multiple sleep latency test (MSLT), average sleep latency was 0.4 min and there were noted 3 SOREMPs (Sleep Onset REM sleep period) on 5 trials. We couldn't discriminate the obvious sleep-wake pattern in the actigraph and his HLA DQB1 *0602 type was negative. His thyroid function improved following treatment with methimazole and propranolol. Vital sign maintained within normal range. Cataplexy was controlled with venlafaxine 75 mg. Subjective night sleep continuity and PLMS were improved with clonazepam 0.5 mg, but the EDS were partially improved with modafinil 200-400 mg. Thyrotoxicosis might give confounding role when we were evaluating the EDS, though sleep fragmentation was one of the major symptoms of narcolepsy, but enormous amount of it made us think of the influence of thyroid hormone. The loss of sleep-wake cycle, limited improvement of EDS to the stimulant treatment, and the cataplexy not supported by HLA DQB1 *0602 should be answered further. We still should rule out idiopathic hypersomnia and measuring CSF hypocretin level would be helpful.

Changes in Multiple Sleep Latency Test Results according to Different Criteria of Sleep Onset / 수면정신생리

OBJECTIVES: The multiple sleep latency test (MSLT) is commonly used as a valid objective measure of sleepiness. The procedure of MSLT is well standardized but the sleep onset criterion is somewhat variable. One epoch of stage 1 sleep is the most commonly used criterion, and the criterion of three epochs of stage 1 sleep is also used. The purpose of this study was to compare the two criteria used to determine sleep onset. METHODS: We retrospectively analyzed 60 consecutive MSLT that were performed according to a standaridized protocol. We scored each test using the two different criteria for sleep onset and then statistically analyed the results. RESULTS: Using the different criteria, 20 patients among 60 showed changes in mean sleep latency (33.3%). The extent of change ranged from 1.3% to 38.5% (mean 15.9%). Non-narcoleptic patients showed a significantly higher incidence of change than other sleep disorder patients. CONCLUSION: Changes in mean sleep latency occurred according to the different criteria of sleep onset. But the difference arising from different criteria was statistically not significant in patients with moderate to severe sleepiness. Considering that 1 epoch criterion for sleep onset is more sensitive in detecting clinically significant sleepiness, the authors suggest that the 1 epoch criterion is more reliable than the 3 epochs criterion.