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

## TL;DR

A 49-year-old woman with sleep-related hypoventilation was diagnosed with nemaline myopathy using daytime polysomnography.

## Contribution

Demonstrates the utility of daytime polysomnography in diagnosing sleep-related hypoventilation in neuromuscular disorders.

## Key findings

- Daytime polysomnography revealed decreased chest motion and a pseudo-central event in a patient with hypoventilation.
- Nemaline myopathy was diagnosed through muscle biopsy after suspecting a neuromuscular disorder.
- Daytime PSG can be a safer alternative to overnight PSG in certain neuromuscular diseases.

## Abstract

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.