DMD
DMD is a life-limiting condition. The survival of patients with DMD has improved over time, with an increase from a median of 26 years for those born between 1955 and 1969 to 41 years for those born between 1970 and 1994. This is due primarily to increased use of corticosteroid therapy, non-invasive ventilation, and cardioprotective medicines.[9]Ryder S, Leadley RM, Armstrong N, et al. The burden, epidemiology, costs and treatment for Duchenne muscular dystrophy: an evidence review. Orphanet J Rare Dis. 2017 Apr 26;12(1):79.
https://ojrd.biomedcentral.com/articles/10.1186/s13023-017-0631-3
http://www.ncbi.nlm.nih.gov/pubmed/28446219?tool=bestpractice.com
Patients with DMD typically lose the ability to walk by around age 12 years, have established cardiomyopathy by age 18 years, and require ventilatory support by age 20 years.[9]Ryder S, Leadley RM, Armstrong N, et al. The burden, epidemiology, costs and treatment for Duchenne muscular dystrophy: an evidence review. Orphanet J Rare Dis. 2017 Apr 26;12(1):79.
https://ojrd.biomedcentral.com/articles/10.1186/s13023-017-0631-3
http://www.ncbi.nlm.nih.gov/pubmed/28446219?tool=bestpractice.com
[31]Quinlivan R, Messer B, Murphy P, et al; ANSN. Adult North Star Network (ANSN): consensus guideline for the standard of care of adults with Duchenne muscular dystrophy. J Neuromuscul Dis. 2021;8(6):899-926.
https://content.iospress.com/articles/journal-of-neuromuscular-diseases/jnd200609
http://www.ncbi.nlm.nih.gov/pubmed/34511509?tool=bestpractice.com
Other muscular dystrophies
Disease severity, time of onset, and prognosis vary greatly among and within other muscular dystrophies.[12]Ashizawa T, Gagnon C, Groh WJ, et al. Consensus-based care recommendations for adults with myotonic dystrophy type 1. Neurol Clin Pract. 2018 Dec;8(6):507-20.
https://cp.neurology.org/content/8/6/507
http://www.ncbi.nlm.nih.gov/pubmed/30588381?tool=bestpractice.com
[13]Tawil R, Kissel JT, Heatwole C, et al. Evidence-based guideline summary: evaluation, diagnosis, and management of facioscapulohumeral muscular dystrophy: report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology and the Practice Issues Review Panel of the American Association of Neuromuscular & Electrodiagnostic Medicine. Neurology. 2015 Jul 28;85(4):357-64.
https://n.neurology.org/content/85/4/357
http://www.ncbi.nlm.nih.gov/pubmed/26215877?tool=bestpractice.com
[14]Narayanaswami P, Weiss M, Selcen D, et al. Evidence-based guideline summary: diagnosis and treatment of limb-girdle and distal dystrophies: report of the guideline development subcommittee of the American Academy of Neurology and the practice issues review panel of the American Association of Neuromuscular & Electrodiagnostic Medicine. Neurology. 2014 Oct 14;83(16):1453-63.
https://n.neurology.org/content/83/16/1453
http://www.ncbi.nlm.nih.gov/pubmed/25313375?tool=bestpractice.com
[15]Kang PB, Morrison L, Iannaccone ST, et al. Evidence-based guideline summary: evaluation, diagnosis, and management of congenital muscular dystrophy: report of the Guideline Development Subcommittee of the American Academy of Neurology and the Practice Issues Review Panel of the American Association of Neuromuscular & Electrodiagnostic Medicine. Neurology. 2015 Mar 31;84(13):1369-78.
https://n.neurology.org/content/84/13/1369
http://www.ncbi.nlm.nih.gov/pubmed/25825463?tool=bestpractice.com
For example, the severity of myotonic dystrophy type 1 varies widely among affected individuals, and even among members of the same family.[12]Ashizawa T, Gagnon C, Groh WJ, et al. Consensus-based care recommendations for adults with myotonic dystrophy type 1. Neurol Clin Pract. 2018 Dec;8(6):507-20.
https://cp.neurology.org/content/8/6/507
http://www.ncbi.nlm.nih.gov/pubmed/30588381?tool=bestpractice.com
Spinal muscular atrophy (SMA)
For patients with SMA, earlier age of onset of symptoms is generally associated with shorter survival. The number of copies of the SMN2 gene also predicts survival and disease severity.[4]Finkel RS, Sejersen T, Mercuri E, et al; ENMC SMA Workshop Study Group. 218th ENMC International Workshop: revisiting the consensus on standards of care in SMA Naarden, The Netherlands, 19-21 February 2016. Neuromuscul Disord. 2017 Jun;27(6):596-605.
https://www.nmd-journal.com/article/S0960-8966(17)30138-4/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/28392274?tool=bestpractice.com
[28]Finkel RS, Mercuri E, Meyer OH, et al; SMA Care Group. Diagnosis and management of spinal muscular atrophy: part 2: pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018 Mar;28(3):197-207.
https://www.nmd-journal.com/article/S0960-8966(17)31290-7/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/29305137?tool=bestpractice.com
For children with type 1 SMA, typical survival is less than 1 year if supportive care is not provided, but enteral feeding and non-invasive ventilation can improve survival by months to years. Patients with type 2 SMA can live for several decades. Patients with type 3 SMA have a normal lifespan.[4]Finkel RS, Sejersen T, Mercuri E, et al; ENMC SMA Workshop Study Group. 218th ENMC International Workshop: revisiting the consensus on standards of care in SMA Naarden, The Netherlands, 19-21 February 2016. Neuromuscul Disord. 2017 Jun;27(6):596-605.
https://www.nmd-journal.com/article/S0960-8966(17)30138-4/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/28392274?tool=bestpractice.com
[28]Finkel RS, Mercuri E, Meyer OH, et al; SMA Care Group. Diagnosis and management of spinal muscular atrophy: part 2: pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018 Mar;28(3):197-207.
https://www.nmd-journal.com/article/S0960-8966(17)31290-7/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/29305137?tool=bestpractice.com