Polysomnography in chronic neuromuscular disease

Sleep is a risk factor for respiratory failure in patients with chronic neuromuscular diseases (NMD).

To explore the diagnostic value of monitoring sleep parameters in addition to nocturnal respiratory parameters.

Thirty-one patients with chronic NMD underwent whole-night polysomnograms including EMG from accessory respiratory muscles.

Sleep macrostructure was normal on average. The number of respiratory arousals per hour of sleep was above the upper limit observed in a control group (>2.1) in 71% of the patients, but was moderate in most cases. Nadir oxygen saturation <85% was the most common finding indicating respiratory dysfunction and was present in 80% of the patients. Noninvasive blood gas monitoring identified all but 2 patients with respiratory-induced sleep abnormalities. The respiratory arousal rate was correlated with the oxygen desaturation index, but otherwise there were no significant correlations between sleep and nocturnal respiratory parameters. Vital capacity was significantly positively correlated with obstructive apnea index and daytime base excess to nadir oxygen saturation. Inspiratory activity in accessory respiratory muscles was present during REM sleep and/or slow wave sleep in 70% of the patients.

The severity of nocturnal respiratory dysfunction is not reflected in the extent of sleep impairment in patients with chronic neuromuscular diseases.