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.

Several medications are approved to treat coronavirus disease 2019 (COVID-19) in Korea including nirmatrelvir/ritonavir, remdesivir, and regdanvimab. There is potential drug-drug interaction between antiepileptic drugs (AEDs) and the medications used to treat COVID-19. Several AEDs such as phenytoin, carbamazepine, phenobarbital, and primidone are strong cytochrome P450 inducers and can inhibit the drugs used for COVID-19. Particularly, these drugs are contraindicated with nirmatrelvir/ritonavir (Paxlovid®). There is a weaker drug-drug interaction between the AEDs and remdesivir. No significant interaction has been reported between the AEDs and molnupiravir. Pharmacokinetic interactions of the AEDs are important in effective management of COVID-19 in patients with epilepsy.

Obstructive sleep apnea (OSA) and dizziness are common conditions observed in the general population, and several epidemiological studies have reported an association between OSA and dizziness. Vestibular dysfunction, autonomic instability, and cerebellar degeneration secondary to recurrent hypoxia are implicated as mechanisms underlying dizziness in patients with OSA. Moreover, OSA is a risk factor for many diseases associated with dizziness, including Meniere disease, stroke, and psychiatric conditions. A dizziness questionnaire, vestibular function tests, and tests for autonomic function are useful for evaluation of OSA and concomitant dizziness. A growing body of evidence has shown that effective treatment of OSA including continuous positive airway pressure therapy reduces dizziness in these patients. Greater attention to dizziness is warranted in patients with OSA.

Objectives: In South Korea, a significant number of patients with obstructive sleep apnea have benefited from the insured continuous positive pressure for sleep apnea as of 2018. However, there is limited information on public awareness of sleep apnea syndrome in the country. A nationwide survey was conducted to evaluate the current status of public awareness on the diagnosis and treatment of sleep apnea. Methods: We conducted an online survey using structured questionnaires on symptoms and knowledge of diagnosis and treatment modalities for sleep apnea. A total of 4,000 participants aged 21 to 69 were proportionally allocated according to the residential area, gender, and age group. Results: The STOP questionnaire, a screening tool for sleep apnea, revealed that 1,044 (21.6%) scored ≥2 points, 327 (8.1%) scored ≥3 points, and 64 (1.6%) scored 4 points. However, only 19 of the 1,044 patients were being treated for sleep apnea, and 13 had been using continuous positive airway pressure. For the diagnosis of sleep apnea, 1,318 participants (33.0%) responded that polysomnography was necessary. For sleep apnea treatment, 1,954 (48.9%) participants responded that lifestyle modification was the treatment of choice, while 1,036 (25.9%) chose continuous positive pressure. Conclusions Although one-fifth were at high risk for sleep apnea, this disorder is still underestimated. Therefore, publicity and support are needed to improve public awareness of sleep apnea.

Melatonin and cortisol are clinically important for diagnosing sleep and mood disorders.We developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/ MS) assay for simultaneous measurement of salivary melatonin and cortisol concentrations according to the Clinical and Laboratory Standards Institute guidelines. Additionally, we compared the LC-MS/MS assay with immunoassays, ELISA (Direct Salivary Melatonin Elisa EK-DSM, Bühlmann Laboratories AG, Schönenbuch, Switzerland) and electrochemiluminescence immunoassay (Cortisol II, Roche, Mannheim, Germany), using 121 saliva samples. The LC-MS/MS assay exhibited good performance in terms of linearity, precision, accuracy, limit of detection, lower limit of quantification, extraction recovery, carry-over, and matrix effect. The LC-MS/MS assay and immunoassays showed strong correlation (Pearson’s r = 0.910 for melatonin, r = 0.955 for cortisol), but demonstrated a significant mean bias of 23.2% (range 54.0–143.7%) for melatonin and 48.9% (range 59.7–184.7%) for cortisol. Our LC-MS/MS assay provided more sensitive and reliable salivary melatonin and cortisol quantification results compared with immunoassays.

Objective: Organic light-emitting diodes (OLEDs) emit less blue light than traditional light-emitting diodes (LEDs), and we previously found that early-night OLED light exposure (LE) delays the melatonin phase by less than LED at a color temperature of 4,000 K. As a follow-up study, we investigated the effects of OLED and LED at a different color temperature (3,000 K) on melatonin profile, sleep, and vigilance. Methods: 24 healthy subjects (27.5±5.1 years) were exposed to three light conditions [OLED, LED, and dim light (DL)] from 17:30 to 24:00, in a random order and with a 1-week interval. Saliva samples for melatonin were taken every hour from 18:00 to 24:00. Polysomnography (PSG) and a psychomotor vigilance test (PVT) were performed. Results: Melatonin onset time was significantly delayed under OLED and LED compared with DL, with no significant difference between OLED and LED. The mean melatonin level at 24:00 under LED was lower than that under DL, but there was no significant difference between OLED LE and DL. The percentage of slow wave sleep (N3) in LED was significantly lower than in OLED. Conclusion Exposure to light in the evening can suppress melatonin secretion late at night and disturb deep sleep, and those effects are slightly worse under LED than OLED.

Objective: Organic light-emitting diodes (OLEDs) emit less blue light than traditional light-emitting diodes (LEDs), and we previously found that early-night OLED light exposure (LE) delays the melatonin phase by less than LED at a color temperature of 4,000 K. As a follow-up study, we investigated the effects of OLED and LED at a different color temperature (3,000 K) on melatonin profile, sleep, and vigilance. Methods: 24 healthy subjects (27.5±5.1 years) were exposed to three light conditions [OLED, LED, and dim light (DL)] from 17:30 to 24:00, in a random order and with a 1-week interval. Saliva samples for melatonin were taken every hour from 18:00 to 24:00. Polysomnography (PSG) and a psychomotor vigilance test (PVT) were performed. Results: Melatonin onset time was significantly delayed under OLED and LED compared with DL, with no significant difference between OLED and LED. The mean melatonin level at 24:00 under LED was lower than that under DL, but there was no significant difference between OLED LE and DL. The percentage of slow wave sleep (N3) in LED was significantly lower than in OLED. Conclusion Exposure to light in the evening can suppress melatonin secretion late at night and disturb deep sleep, and those effects are slightly worse under LED than OLED.

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 PurposeSleep disturbance is common in patients with primary headache disorders. We were interest in whether poor sleep quality affects patients directly or via increases in the frequency and severity of headaches. To that end, we investigated the direct and indirect effects of sleep quality on the headache-related impact among patients with primary headache disorders. Methods: We analyzed migraine and tension-type headache (TTH) in patients included in the headache registry of our headache clinic from October 2015 to May 2018. We collected information on the headache frequency, severity, and psychological status. Sleep quality and headache-related impact were measured using the Pittsburgh Sleep Quality Index and Headache Impact Test-6, respectively. We performed path analyses with headache frequency and severity as covariates to determine the direct effect of sleep quality on the headache-related impact, and the indirect effects mediated by increases in the headache frequency and severity. Results: This study included 915 patients: 784 with migraine and 131 with TTH. Worse sleep quality was independently associated with greater headache-related impact in both patients with migraine and those with TTH. Path analysis revealed a direct effect (β=0.207,p<0.001) of sleep quality and an indirect effect mediated by headache frequency and severity (β=0.067, p=0.004) on the headache-related impact in migraine. In TTH, only direct effects of sleep quality on the headache-related impact were significant (β=0.224, p=0.004). Conclusions We suggest that poor sleep quality can directly increase the headache-related impact in both patients with migraine and TTH as well as indirectly by increasing the headache frequency and severity in patients with migraine.

Background: and Purpose: Organic light-emitting diodes (OLEDs) emit less blue light than traditional light-emitting diodes (LEDs), but the effects of OLED light exposure (LE) on melatonin and sleep have not been evaluated. Methods: Twenty-four healthy subjects (age 26.9±5.7 years; including 18 females) with the intermediate chronotype were exposed to three different light conditions [4,000 K 150 lux OLED LE, 4,000 K 150 lux LED LE, and dim light (DL) at <10 lux] for 6.5 h from 17:30 to 24:00, in a random order and with a 1-week interval. Participants entered the unit for the experiment at 16:00, and their daylight was measured by actigraphy from 8:00 to 16:00 during each session. Saliva samples for melatonin were taken every hour from 18:00 to 24:00. Sleep was monitored by polysomnography, and vigilance was evaluated by psychomotor vigilance test upon awakening. Results: Melatonin onset occurred at 21:11±01:24, 21:20±01:19, and 21:36±01:16 in the DL, OLED, and LED conditions, respectively. Melatonin onset was significantly delayed under LED LE compared to DL (p=0.007) but did not differ under OLED LE (p=0.245). Melatonin suppression, sleep parameters, and vigilance were similar among the three light conditions. The accumulated amount of daytime light in each session was negatively correlated with the melatonin onset time under the DL (rho=-0.634, p=0.002) and OLED (rho=-0.447, p=0.029) conditions, not under the LED condition (p=0.129). Conclusions Melatonin onset under OLED LE was not significantly delayed compared to DL.Exposure to sufficient daylight may advance melatonin onset even when a subject is exposed to OLED LE in the evening.