[Sleep and respiratory disorders in myotonic dystrophy of Steinert]

It has been hypothesized that hypersomnia and sleep related respiratory impairment are both central in origin in myotonic dystrophy.

To describe by means of video-polysomnographic recordings the central origin of the sleep respiratory disorders.

We studied 11 patients, 6 men and 5 women (mean age 42.7 years) with myotonic dystrophy. A moderate to severe ventilatory impairment of a primarily restrictive type was seen in all patients, three of them after the first episode of respiratory insufficiency. The patients were evaluated in order to determine their body mass index and presence of sleep-related complaints. Video-polysomnographic recordings (EEG, EOG, EKG, submental and tibialis anterior EMGs, respiration and Sa02) and pulmonary function tests were performed in each patient. Identical recordings were repeated in six cases, which were to undergo non-invasive bi-level ventilation (BiPAP) in order to adjust the inspiratory and expiratory pressures and the machine mode.

We found slight hypopnea and apnea, predominantly of a central type, in stage 1 and REM sleep and alveolar hypoventilation in all patients. Sleep was disrupted and the efficiency index was very low. In three patients HLA typing showed a positive DQ6 haplotype. Six patients were treated with n-BiPAP.

Nasal-BIPAP should be considered as an alternative in ventilatory support during sleep in these patients and video-polysomnography as a valid method of evaluating the ideal time to start treatment.