Background: and Purpose Epidemiological data on narcolepsy are rare in South Korea.We aimed to provide an overview of the burden of narcolepsy and its temporal trend in South Korea. Methods: Patients with narcolepsy were identified by their registration in the Rare and Intractable Disease (RID) register and the Health Insurance Review and Assessment database.Individuals registered in the RID program with the code V234 were considered as having ‘definite narcolepsy’, while those who claimed health insurance with G47.4 as the primary diagnostic code were considered as having ‘probable narcolepsy’. We estimated the annual prevalence, incidence, and medical costs of narcolepsy between 2010 and 2019. Results: The prevalence of definite narcolepsy was 8.4/100,000 in 2019, peaking at 32.0/100,000 in those aged 15–19 years. The prevalence was higher in males, with a relative risk of 1.72. The prevalence has increased over the past 6 years, with an average annual growth rate (AAGR) of 12.2%. The prevalence of probable narcolepsy was 10.7/100,000 in 2019. The incidence of definite narcolepsy increased up to 1.3/100,000 in 2019 with an AAGR of 7.1%. Annual medical expenditure for definite narcolepsy gradually increased up to 4.1 billion KRW in 2019, with a compound annual growth rate of 11.9%. Conclusions This study has provided the first nationwide estimates for narcolepsy in South Korea. The prevalence of diagnosed narcolepsy in South Korea was at the low end of the range of narcolepsy prevalence rates reported for other countries. However, the prevalence and incidence have been steadily increasing over the past decade.

Technological advances over the years have led to the widespread use and popularity of consumer wearable devices. Although polysomnography and actigraphy are standard tools for objective evaluation of sleep, common wearable devices that can be used daily can aid with diagnosis and management of sleep disorders. Accelerometer and photoplethysmography sensors are included both in actigraphy and wearable devices; therefore, the wearable device functions as an actigraphy tool to analyze sleep architecture. Easy accessibility, cost-effectiveness, and ease of long-term monitoring serve as advantages of this device; however, scientific validation is warranted to promote the use of the commercial apparatus as a medical device.

Objectives: Various sensory symptoms have been recognized after COVID-19 vaccination. Here, we aimed to explore the association between the suggestive symptom of restless legs syndrome (RLSss) and COVID-19 vaccination using an online survey. Methods: We prospectively studied participants who were working in our hospital after at least the first dose of the ChAdOx1 or BNT162b2 mRNA vaccine. The participants were invited via smartphone messages and voluntarily filled out an online questionnaire that included adverse events after vaccination. We considered the participants as having RLSss if they reported that they had three or more symptoms in the restless legs syndrome (RLS) diagnostic criteria. Results: A total of 628 participants (506 female; mean age, 37.7±12.4 years) responded fully to our online survey. 588 participants (93.6%) received the first dose of the ChAdOx1 vaccine (BNT162b2 mRNA vaccine for 40 participants). A total of 44 out of the 628 participants (7.0%) reported that they had RLSss. Myalgia was more common in participants with RLSss than in those without RLSss (97.7% vs. 67.3%, p<0.001). Multivariate testing showed that age (odds ratio, 1.037 per 1 year increase; 95% CI, 1.004–1.071) and the presence of myalgia (odds ratio, 20.479; 95% CI, 4.266–368.206) were associated with the presence of RLSss. Conclusions This pilot study explored RLSss after COVID-19 vaccination and the results suggested that RLS might be one of the causes of adverse symptoms after COVID-19 vaccination. Further studies are required to confirm the relationship between RLS and COVID-19 vaccination.

Background: and Purpose Obesity is known of one of the risk factors for obstructive sleep apnea (OSA). Although body mass index (BMI) can be an indicator for obesity, it does not represent the actual body composition of fat or muscle. We hypothesized that bioelectrical impedance analysis (BIA) can help analyze the fat and muscle distributions in males and females with OSA. Methods: This study screened subjects who visited the Department of Neurology, Samsung Medical Center, Seoul, Korea due to sleep disturbances with symptoms suggestive of OSA from December 2017 to December 2019. All subjects underwent overnight type I polysomnography (PSG) and BIA. Results: PSG and BIA were completed in 2,064 OSA patients who had an apnea-hypopnea index (AHI) of ≥5/hour (77.1% males and 22.9% females). The females had remarkably higher fat indicators and lower muscle indicators. The AHI was significant correlated with all BIA parameters in all OSA patients: body fat mass (ρ=0.286, p<0.001), percentage body fat (ρ= 0.130, p<0.001), visceral fat area (VFA) (ρ=0.257, p<0.001), muscle mass (ρ=0.275, p<0.001), and skeletal muscle mass (SMM) (ρ=0.270, p<0.001). The correlations in males were similar to those in all patients, where those in females were not. In females with OSA, all of the BIA fat indicators were correlated with AHI, whereas the muscle indicators were not. Adjusting age and BMI when analyzing the SMM/VFA ratio showed a strong correlation in males with OSA (p= 0.015) but not in females with OSA (p=0.354). Conclusions This study has revealed that the body composition of fat and muscle has different patterns in OSA patients. The SMM/VFA as measured using BIA is the factor most significantly associated with AHI in males but not in females after adjusting for age and BMI.

Background: and Purpose Obesity is known of one of the risk factors for obstructive sleep apnea (OSA). Although body mass index (BMI) can be an indicator for obesity, it does not represent the actual body composition of fat or muscle. We hypothesized that bioelectrical impedance analysis (BIA) can help analyze the fat and muscle distributions in males and females with OSA. Methods: This study screened subjects who visited the Department of Neurology, Samsung Medical Center, Seoul, Korea due to sleep disturbances with symptoms suggestive of OSA from December 2017 to December 2019. All subjects underwent overnight type I polysomnography (PSG) and BIA. Results: PSG and BIA were completed in 2,064 OSA patients who had an apnea-hypopnea index (AHI) of ≥5/hour (77.1% males and 22.9% females). The females had remarkably higher fat indicators and lower muscle indicators. The AHI was significant correlated with all BIA parameters in all OSA patients: body fat mass (ρ=0.286, p<0.001), percentage body fat (ρ= 0.130, p<0.001), visceral fat area (VFA) (ρ=0.257, p<0.001), muscle mass (ρ=0.275, p<0.001), and skeletal muscle mass (SMM) (ρ=0.270, p<0.001). The correlations in males were similar to those in all patients, where those in females were not. In females with OSA, all of the BIA fat indicators were correlated with AHI, whereas the muscle indicators were not. Adjusting age and BMI when analyzing the SMM/VFA ratio showed a strong correlation in males with OSA (p= 0.015) but not in females with OSA (p=0.354). Conclusions This study has revealed that the body composition of fat and muscle has different patterns in OSA patients. The SMM/VFA as measured using BIA is the factor most significantly associated with AHI in males but not in females after adjusting for age and BMI.

Neuromyelitis optica spectrum disorder (NMOSD) is a rare inflammatory demyelinating disease. Anti-aquaporin-4 antibodies serve as a specific biomarker, while other factors including antecedent infection may also play a role in the development of NMOSD. Abnormal cerebrospinal fluid (CSF) findings such as leukocytosis with concentration >50/mm3 are one of the characteristics of NMOSD, but these were not specific for identifying other infective neurological diseases. Here we describe a rare case of NMOSD with CSF findings suggestive of bacterial meningomyelitis.

BACKGROUND: AND PURPOSE: Shift workers frequently suffer from insomnia and mood disturbances, but little is known about the relationships of these conditions with the chronotypes and different working schedules of shift workers. We hypothesized that different shift-work schedules are associated with different severities of sleep and mood disturbances, and that the individual chronotype plays a role in sleep disturbances in shift workers. METHODS: This study enrolled 276 participants, comprising 77 nurses working in a three-shift schedule (3S, 27.9%), 60 firefighters working in a 24-h-every-other-day shift schedule (EOD, 21.7%), and 139 day workers (DW, 50.4%). All of the participants completed the following questionnaires to assess their sleep disturbances, mood, and chronotype: Insomnia Severity Index (ISI), Epworth Sleepiness Scale, Hospital Anxiety and Depression Scale, and Morningness-Eveningness Questionnaire. RESULTS: ISI questionnaires were worse in both shift workers compare to DW, 35.1% of 3S, 23% of EOD had clinically significant insomnia (ISI score >14). Depressive mood and anxiety symptom were significantly worse in 3S compare to EOD. The sleep disturbance by ISI score had significant correlations with depressive mood and anxiety symptoms for both EOD and 3S (EOD: rho=0.57, rho=0.57, 3S: rho=0.37, rho=0.33 respectively). Chronotype type in shift workers had no significant correlation with sleep disturbance, depressive mood, nor anxiety symptom. However, after adjustment, the eveningness chronotype have relationship to the depressive mood in shift workers. CONCLUSIONS Sleep disturbances are more frequent in shift workers than DW. Depressive mood and anxiety symptoms were frequently reported in 3S, then EOD. Different shift schedules cab be a determinant of depressive mood and anxiety symptom.

OBJECTIVES: It is a paradox that sleep technicians are at risk of shift work sleep disorder to help diagnose other people's sleep disorder. Until now, there have been no guidelines for scheduling shifts for sleep technicians. The purpose of this study was to survey the current shift schedule of sleep technicians. METHODS: We performed a nationwide survey of work schedules for sleep laboratories. We sent email questionnaires to sleep technicians working in university-affiliated hospitals. Information regarding starting time and duration of shift, duty on-duty off pattern for the past month, and rotation and number of sleep technicians in the sleep labs were collected. RESULTS: We received responses from 29 sleep labs. Among the 25 labs which had designated sleep technicians, three labs had night shift schedules mixed with day work on a weekly basis and the remaining 22 labs had night only shift schedule. In cases of night only shift schedules, 11 labs alternated from night shift to day shift works or vice versa every 3 months to 3 years, while the remaining 11 labs had fixed schedules without daytime rotation. Number of night shift was four or less per week, with shift durations of 9–19 hours. CONCLUSIONS: The current policies regarding scheduling shifts varied vastly depending on individual sleep labs. We found that some labs had shift schedules with long work time, quick returns, or permanent night shifts, which are generally not recommended. Further studies are needed to develop consensus guidelines for scheduling shift of sleep technicians.
Appointments and Schedules ; Consensus ; Electronic Mail ; Korea ; Sleep Disorders, Circadian Rhythm ; Sleep Wake Disorders

BACKGROUND: To determine the technical feasibility and success rate of percutaneous radiologic gastrostomy (PRG) after failure of percutaneous endoscopic gastrostomy (PEG). METHODS: Consecutive patients referred for PRG after failure of PEG between May 2011 and June 2016 were included in this study. The reasons for the failure of PEG, as well as the technical success and complications of PRG were noted. RESULTS: Fifteen patients (14 men, 1 woman; age, 27-93 years) were included. The most common reasons for PEG failure were esophageal stricture due to malignancies (n = 8), unfavorable abdominal wall conditions (n = 3), unstable patient condition during endoscopy (n = 2), and other miscellaneous conditions (n = 2). PRG placement was technically successful in all 15 cases. In one case, early slip-out of the gastrostomy tube occurred, which required removal and repositioning. No mortality was noted. CONCLUSION: PRG is technically feasible in patients with failed PEG insertion, and has advantages over PEG and a high overall success rate.
Abdominal Wall ; Endoscopy ; Esophageal Stenosis ; Female ; Gastrostomy* ; Humans ; Male ; Mortality

Neuromyelitis optica spectrum disorder (NMOSD) may present with area postrema syndrome, which is characterized by intractable vomiting and hiccups. Hyponatremia is common in NMOSD and is mostly associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). In contrast to SIADH, cerebral salt wasting syndrome (CSWS) causes hyponatremia, which is associated with severe natriuresis and extracellular volume depletion in patients with cerebral disease. To our knowledge, hyponatremia associated with CSWS has not been reported in a patient with NMOSD. Here, we describe a NMOSD presenting with hyponatremia, which may be caused by CSWS following area postrema syndrome.
Area Postrema ; Hiccup ; Humans ; Hyponatremia ; Inappropriate ADH Syndrome ; Natriuresis ; Neuromyelitis Optica* ; Vomiting ; Wasting Syndrome*