Sleep-disordered breathing (SDB) and respiratory failure (RF) were studied in 27 patients with juvenile and adult acid maltase deficiency (AMD) and compared with polysomnography outcomes at the University of Essen, Germany. Ventilatory restriction was present in 17/27 patients, and inspiratory vital capacity correlated with peak inspiratory muscle pressure and gas exchange by day and night. Diaphragm weakness occurred in 13/27, and was associated with SDB and RF. SDB was characterized by REM-sleep hypopneas and nocturnal hypoventilation. Treatment of RF or hypoventilation with noninvasive ventilation corrected daytime and nocturnal gas exchange. 
COMMENT. Acid maltase deficiency (AMD), Type II glycogenosis or Pompe’s disease, a rare hereditary myopathy, is an autosomal recessive glycogen storage disease that is complicated by heart, CNS and skeletal muscle dysfunction. It presents in childhood or in adults, and is slowly progressive, leading to respiratory failure and obstructive sleep apnea which may be fatal. In infants, acid maltase enzyme is deficient in lysosomes of heart, liver, and skeletal muscle, and glycogen is deposited in every tissue, including the CNS. First symptoms often appear by the second month and include difficulty in feeding, dyspnea, muscle weakness, and cardiac dysfunction, with marked cardiac enlargement. In late childhood and adult onset cases, organomegaly is absent, and muscle weakness is only slowly or nonprogressive, with involvement of lower limb proximal muscles . The above paper stresses the role of diaphragm weakness as the major cause of respiratory failure in juvenile and adult cases of AMD, and the value of noninvasive ventilation in treatment of associated respiratory disorders.