Neuromuscular disorders in childhood: a descriptive epidemiological study from western Sweden

A retrospective epidemiological study of neuromuscular disorders was carried out in children born between 1979 and 1994 in western Sweden. The purpose was to determine overall and specific prevalences, overall cumulative incidence and birth incidences of selected disorders. Cases were ascertained from 12 different sources and medical records, investigations and diagnosis were reviewed. We found a point prevalence in the population < 16 years of age of 63.1 x 10(-5) for all neuromuscular disorders and 53.1 x 10(-5) for inherited neuromuscular disorders. The point prevalence in children of school age was even higher. We found a higher occurrence of hereditary motor and sensory neuropathy, congenital myopathies and mitochondrial encephalo-myopathy, a slightly lower occurrence of Duchenne muscular dystrophy and spinal muscular atrophy and equal occurrence of myotonic dystrophy compared to previous studies in other countries. We conclude that neuromuscular disorders are more common in childhood than has previously been reported.