Background: Nitrous oxide (N2O) is used in surgery and dentistry for its anesthetic and analgesic effects. However, neurological and psychiatric manifestations of N2O abuse have been increasingly reported among Korean adults. The aim of this study was to demonstrate laboratory findings of N2O abuse in Korean patients.Methods: Patients diagnosed with N2O-induced neuropathy or myelopathy from August 2018 to December 2019 were enrolled. Their clinical presentations and laboratory and imaging findings were analyzed.Results: Sensory changes and limb weakness were present in nine of the enrolled patients. The laboratory findings revealed that seven patients had high homocysteine levels and five had high methylmalonic acid levels in their blood. Nerve conductions studies indicated that axonal neuropathy was present in four cases and longer F-wave and Hoffman’s-reflex latencies were present in two cases. Signal changes in cervical spine imaging occurred in five patients, while two had normal results.Conclusions: Chronic N2O abuse can cause neurological damage or psychiatric problems. Because N2O is illegal for recreational use in Korea, patients tend to hide their history of use. Even though the spinal imaging results were normal, clinicians should consider the possibility of N2O use, and further electrophysiological tests should be applied for precise evaluations.

Radar is a promising non-contact sensor for overnight polysomnography (PSG), the gold standard for diagnosing obstructive sleep apnea (OSA). This preliminary study aimed to demonstrate the feasibility of the automated detection of apnea-hypopnea events for OSA diagnosis based on 60 GHz frequency-modulated continuous-wave radar using convolutional recurrent neural networks. The dataset comprised 44 participants from an ongoing OSA cohort, recruited from July 2021 to April 2022, who underwent overnight PSG with a radar sensor. All PSG recordings, including sleep and wakefulness, were included in the dataset. Model development and evaluation were based on a five-fold cross-validation. The area under the receiver operating characteristic curve for the classification of 1-minute segments ranged from 0.796 to 0.859. Depending on OSA severity, the sensitivities for apnea-hypopnea events were 49.0–67.6%, and the number of false-positive detections per participant was 23.4–52.8. The estimated apnea-hypopnea index showed strong correlations (Pearson correlation coefficient = 0.805–0.949) and good to excellent agreement (intraclass correlation coefficient = 0.776–0.929) with the ground truth. There was substantial agreement between the estimated and ground truth OSA severity (kappa statistics = 0.648–0.736). The results demonstrate the potential of radar as a standalone screening tool for OSA.

We evaluated the pre- and postoperative sleep quality of patients with newly diagnosed papillary thyroid carcinoma (PTC) who underwent thyroid surgery, and investigated the factors associated with persistent poor sleep quality. The Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale, and Stanford sleepiness scale were used to estimate sleep quality and daytime sleepiness. Face-to-face surveys were conducted preoperatively, and 1, 4, and 10 months after thyroid surgery. The PSQI was administered during a telephone interview about after 5 years after surgery. Forty-six patients (mean age 47.3 ± 10.1 years) with PTC (11 males, 35 females) were included in this study. Twenty-one participants underwent lobectomy and 25 underwent total thyroidectomy. Preoperatively, 35 (76.1%) patients showed poor sleep quality. PSQI scores at postoperative 1, 4, and 10 months were significantly lower than preoperative scores (p < 0.001). Postoperative 5-year PSQI scores decreased significantly compared to the preoperative scores (p < 0.001). Patients newly diagnosed with PTC suffered from sleep disturbance before and after surgery for at least 10 months, recovering to a comparable rate of sleep disturbance with the general population by 5 years after surgery. Higher preoperative PSQI score was at risk for prolonged poor sleep quality in patients with PTC.