Respiratory patterns during sleep in mitochondrial myopathies with ophthalmoplegia

Nocturnal polygraphic recordings (electroencephalography, electro-oculography, submental and intercostal muscle electromyography, electrocardiography, respiration by thoracic strain gauges and oronasal thermistors) with continuous monitoring of arterial oxyhemoglobin saturation by pulse oximeter were performed in 8 patients with ophthalmoplegia plus. All patients except 1 had normal blood gas values and normal lung volumes associated with a diminished ventilatory response to inhaled CO₂ during wakefulness. Four patients showed pathological sleep-related breathing patterns consisting of sleep apneic polygraphic tracings mainly of the central type or of REM-related hypoventilation episodes. It is suggested that these disorders in patients with ophthalmoplegia plus may have a central origin and be related to the underlying metabolic disturbance.