Deterrence/Prevention

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.

Complications

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

Prognosis

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.

Questions

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Author

Jeffrey Rosenfeld, MD, PhD, FAAN Professor of Neurology, Associate Chairman, Department of Neurology, Director, Neuromuscular ALS/MND Program, Medical Director, The Center for Restorative Neurology, Loma Linda University Health Systems

Jeffrey Rosenfeld, MD, PhD, FAAN is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Neurological Association, Society for Neuroscience

Disclosure: Nothing to disclose.

Coauthor(s)

Carmel Armon, MD, MSc, MHS Chair, Department of Neurology, Assaf Harofeh Medical Center, Tel Aviv University Sackler Faculty of Medicine, Israel

Carmel Armon, MD, MSc, MHS is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Association of Neuromuscular and Electrodiagnostic Medicine, American Clinical Neurophysiology Society, American College of Physicians, American Epilepsy Society, American Medical Association, American Neurological Association, American Stroke Association, Massachusetts Medical Society, Sigma Xi, The Scientific Research Honor Society

Disclosure: Received research grant from: Neuronix Ltd, Yoqnea'm, Israel<br/>Received income in an amount equal to or greater than $250 from: JNS - Associate Editor. UpToDate - Author Royalties.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP, FANA Professor of Pediatrics, Neurology, Neurosurgery, and Psychiatry, Medical Director, Tulane Center for Autism and Related Disorders, Tulane University School of Medicine; Pediatric Neurologist and Epileptologist, Ochsner Hospital for Children; Professor of Neurology, Louisiana State University School of Medicine

Stephen L Nelson, Jr, MD, PhD, FAACPDM, FAAN, FAAP, FANA is a member of the following medical societies: American Academy for Cerebral Palsy and Developmental Medicine, American Academy of Neurology, American Academy of Pediatrics, American Epilepsy Society, American Medical Association, American Neurological Association, Association of Military Surgeons of the US, Child Neurology Society, Southern Pediatric Neurology Society

Disclosure: Nothing to disclose.

Additional Contributors

Bryan Tsao, MD Associate Professor, Department of Neurology, Loma Linda University; Chair and Service Chief, Department of Neurology, Loma Linda University Medical Center

Bryan Tsao, MD is a member of the following medical societies: American Academy of Neurology

Disclosure: Nothing to disclose.

Robert J Baumann, MD Professor of Neurology and Pediatrics, Department of Neurology, University of Kentucky College of Medicine

Robert J Baumann, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society

Disclosure: Nothing to disclose.

Theresa L LaBarte, DO Resident Physician, Department of Neurology, Loma Linda University Medical Center

Theresa L LaBarte, DO is a member of the following medical societies: American Academy of Neurology

Disclosure: Nothing to disclose.