Introduction: Adult-onset acid maltase deficiency myopathy is a rare lysosomal storage disease with an autosomal recessive pattern of inheritance. The disease can be manifested with respiratory insufficiency and fatigue.
Methods: A case of a 45-year-old male patient is presented, and difficulty in diagnosis is discussed.
Results: The patient had been repeatedly examined because of hypersomnia, dyspnea and fatigue for a full year before a neurological consultation was requested. Artificial ventilation resulted in a dramatic improvement of his symptoms. Neurological examination revealed myopathy. Electrophysiological myotonia and glycogen storage in muscle biopsy specimen suggested acid maltase deficiency. The diagnosis was established by genetic testing detecting the previously described homozygous c.-45T > G mutation in the alpha-glucosidase gene.
Discussion: Rare hereditary neurological diseases can be also suspected as cause of chronic unexplained respiratory insufficiency resulted in hypersomnia and fatigue due to hypercapnia and myopathy. A proper diagnosis can contribute to early diagnosis and introduction of enzyme replacement therapy may reduce or stop clinical progression. Genetic diagnosis can also provide a possibility for prenatal testing.