A Case of Nemaline Myopathy With Sleep-Related Hypoventilation Diagnosed Using Polysomnography During Daytime Napping

This is the case of a 49-year-old woman who was admitted to the hospital for a close examination of pulmonary hypertension; however, the next morning, she developed carbon dioxide (CO₂) narcosis and was started on artificial ventilation. As pulmonary arterial hypertension was ruled out, the patient was extubated, and 24-hour transcutaneous partial pressure of carbon dioxide (PCO₂)(transcutaneous carbon dioxide (TcPCO₂)) monitoring was performed to diagnose sleep-related hypoventilation. Polysomnography (PSG) during daytime napping revealed markedly decreased chest motion and a "pseudo-central event," which was neither central nor obstructive hypopnea. Based on the PSG results and physical examination findings, a neuromuscular disorder was suspected, and a muscle biopsy was performed to diagnose nemaline myopathy. Neuromuscular diseases are widely recognized for their association with sleep-disordered breathing; thus, sleep-related hypoventilation should also be considered. Monitoring of TcPCO₂ and PSG are useful tools in identifying the cause of hypoventilation; however, overnight PSG may cause CO₂ narcosis in some diseases. In such cases, PSG may be beneficial during daytime napping.