Spinal Muscular Atrophy Follow-up

Updated: May 31, 2022
  • Author: Jeffrey Rosenfeld, MD, PhD, FAAN; Chief Editor: Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP, FANA  more...
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Genetic counseling should be offered to all families of patients with spinal muscular atrophy. Obtaining a complete family history facilitates genetic counseling. Carrier testing is available for commercial use. A recent study of 68,471 individuals showed that carrier-status testing may be feasible given the high carrier prevalence (1 in 54 overall). [63]

Education on how the disease is inherited may avert conception of affected individuals.

Furthermore, the role of prenatal diagnosis, particularly in pregnant carriers or those with juvenile or adult-onset forms, should also be addressed.



Medical complications associated with the SMAs include pulmonary infections, spinal deformities (eg, scoliosis, hip subluxations/dislocations), joint contractures, and respiratory failure.



See Mortality/Morbidity for more information.

Most patients with SMA type I die before 18 months of age. In contrast, outcomes of juvenile and adult spinal muscular atrophies are difficult to define because the progression of these diseases varies widely.

Survival probabilities for types I and II and probabilities of being ambulatory for type III were derived for 445 patients. These patients were subdivided on the basis of ISMAC criteria (ie, developmental milestones and age of onset). [64]

  • SMA I: Survival probabilities at ages 2, 4, 10, and 20 years were 32%, 18%, 8%, and 0%, respectively.

  • SMA II: Survival probabilities at ages 2, 4, 10, and 20 years were 100%, 100%, 98%, and 77%, respectively.

  • SMA III: Results differed, but life expectancy of patients with SMA type III is close to that of the healthy population. Onset before age 3 years: Probabilities of being ambulatory at ages 2, 4, 10, 20, and 40 years were 98%, 94.5%, 73%, 44%, and 34%, respectively. Onset after age 3 years: Probabilities of being ambulatory at ages 2, 4, 10, 20, and 40 years were 100%, 100%, 97%, 89%, and 67%, respectively.

A recent series of 237 patients showed similar survival probabilities. [65]

Disease onset after age 2-3 months has been correlated to longer survival time in SMA type I. [66, 65] Antibiotic treatment has not prolonged survival in SMA type I. Birnkrant et al examined the role of noninvasive positive-pressure ventilation and gastrostomy in patients with SMA type I. Although these supportive measures can be effective in slowly progressive neuromuscular diseases, they did not alter survival in patients with SMA type I. [61] A later study by Lemoine et al concluded that early noninvasive respiratory intervention prolonged survival time compared with supportive care alone. [67]


Patient Education

Normal schooling in patients with SMA, especially types II and II or more indolent forms, is highly recommended because their intelligence is normal or even superior to that of other individuals.

Support groups are available in some locations for patients and their families.