The Epidemiology of Neuromuscular Disorders: A Comprehensive Overview of the Literature.

BACKGROUND In 1991, the first world survey of neuromuscular disorders (NMDs) was published in the peer reviewed literature. Since then, diagnostics have been greatly improved through genetic confirmation and consensus on criteria. This prompted us to search the scientific literature since 1990 for the epidemiology of NMDs. OBJECTIVES To study occurrence rates, gender and age distribution. METHODS Pubmed was searched for 'epidemiology', 'incidence' and 'prevalence' regarding thirty NMDs for peer reviewed literature from 1990-2014. RESULTS We found incidence rates for ten disorders, ranging from 0.05 to 9 per 100,000/yr. Most NMDs showed prevalence rates between 1 and 10 per 100,000 population, except for multifocal motor neuropathy, Lambert-Eaton myasthenic syndrome, Emery-Dreifuss dystrophy, oculopharyngeal muscular dystrophy, and congenital muscular dystrophies, which were <1/100,000. Post-polio syndrome and Charcot-Marie-Tooth disease revealed prevalences >10/100,000. Information regarding incidence, prevalence, age distribution and gender was complete for eight disorders. No data were found for chronic inflammatory demyelinating polyneuropathy, neuralgic amyotrophy, progressive spinal muscular atrophy, McArdle's and Pompe's disease. For the 17 remaining disorders, information was partially available. CONCLUSIONS Compared to 1991, prevalence rates of Becker muscular dystrophy, facioscapulohumeral dystrophy, myotonic dystrophy and Charcot-Marie-Tooth disease showed increase, yet with highly overlapping ranges with the exception of myotonic dystrophy. The sum of the available prevalence rates comprises only the tip of the iceberg, but is already in range with the prevalence of Parkinson's disease. Although individual NMDs are rare, as a group they are not.