eMedicine Specialties > Neurology > Pediatric Neurology

Spinal Muscular Atrophy: Follow-up

Author: Bryan Tsao, MD, Associate Professor, Department of Neurology, Loma Linda University; Chair and Service Chief, Department of Neurology, Loma Linda University Medical Center
Coauthor(s): Carmel Armon, MD, MSc, MHS, Professor of Neurology, Tufts University School of Medicine; Chief, Division of Neurology, Baystate Medical Center
Contributor Information and Disclosures

Updated: Jan 14, 2009

Follow-up

Deterrence/Prevention

  • Genetic counseling should be offered to all families of patients with spinal muscular atrophy. Obtaining a complete family history facilitates genetic counseling.
  • 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), 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).38
    • 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.
      • 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.
  • The life expectancy of patients with SMA type III is close to that of the healthy population. Antibiotic treatment has not prolonged survival in SMA type I. Birnkrant  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.37

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.

Miscellaneous

Medicolegal Pitfalls

  • As weakness and disability progress, patients with spinal muscular atrophy may reach a point when it is unsafe for them to operate a motor vehicle or other machinery that requires dexterity.
  • The risk of falling may increase.
  • In addition to advising patients about the matters listed above, the physician should instruct them to comply with state regulations and to apply common sense.
  • A decision should be made about how patients wish to be treated when they develop ventilatory failure, preferably well before it occurs.
    • Advance directives are in order for adults.
    • Early discussions regarding end-of-life issues with parents of affected children and adolescents are highly recommended.

Special Concerns

  • Other diseases and disease processes can mimic spinal muscular atrophy.
  • In Walton's 1957 series of 107 floppy infants, spinal muscular atrophies accounted for 62% of cases, followed by the congenital myopathies (17%), which represented numerous unrelated disease processes that were histochemically distinct. Atonic cerebral palsy accounted for 14% (most with intellectual impairment), followed by congenital muscular dystrophy (3%). Polymyositis, myasthenia gravis, and scurvy represented the remaining cases.
  • The terms benign maturation delay and dissociated motor development describe the floppy infant with delayed motor milestones but preserved fine motor development and speech without evidence of a muscular disorder. A spectrum of disorders characterized by abnormal muscle maturation has been termed syndrome of congenital fiber type disproportion. Afflicted infants are usually developmentally delayed.
  • Other differential diagnoses in the infantile- and childhood-onset forms include the following:
    • Adrenoleukodystrophy
    • Congenital hypomyelination neuropathy
    • Congenital polyneuritis
    • Down syndrome
    • Infantile botulism
    • Marfan or Prader-Willi syndrome
    • Metabolic disorders (including the organic acidurias and mitochondrial diseases)
    • Neonatal and congenital myasthenia gravis
    • Peripheral neuritis
    • Poliomyelitis
    • Spinal-cord transection
  • Degeneration of the motor neurons as a part of generalized storage diseases is rare, but it has been observed in the following conditions:
    • Acid maltase deficiency (type II glycogenosis)
    • GM1 gangliosidosis
    • Hurler syndrome
    • Infantile Gaucher disease
    • Type II (Pompe) glycogen storage disease
  • A poliomyelitislike illness associated with acute asthma in childhood (asthmatic amyotrophy, Hopkins syndrome) has been described.39
  • Juvenile ALS with an autosomal recessive inheritance pattern can occur with a rapidly progressive flaccid paralysis of all 4 limbs, but patients later develop pyramidal signs.
  • Bulbar palsy in familial ALS and hereditary progressive bulbar palsy may mimic adult-onset spinal muscular atrophies. In both cases, bulbar dysfunction may be the initial manifestation, though patients with ALS invariably develop limb and respiratory weakness in a short time.
  • Alexander disease may cause bulbar paresis. The diagnosis is made by means of electromyelography (EMG), head imaging studies, and appropriate biochemical testing.
  • The adult spinal muscular atrophy forms (especially early in the disease course) can be difficult to distinguish from familial motor neuron disease (FMND). However, FMND, by definition, eventually affect both the upper and lower motor neuron systems, leading to pyramidal-tract signs and rapid progression.
 


More on Spinal Muscular Atrophy

Overview: Spinal Muscular Atrophy
Differential Diagnoses & Workup: Spinal Muscular Atrophy
Treatment & Medication: Spinal Muscular Atrophy
Follow-up: Spinal Muscular Atrophy
References
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References

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Further Reading

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Keywords

bulbospinal muscular atrophy, Davidenkow syndrome, Fazio-Londe disease, hereditary motor neuronopathy, Kennedy syndrome, progressive muscular atrophy, Vialetto-van Laere syndrome, spinal muscular atrophy, SMA, progressive muscular weakness, acute infantile SMA, SMA type I, Werdnig-Hoffman disease, chronic infantile SMA, SMA type II, chronic juvenile SMA, SMA type III, Kugelberg-Welander disease, adult-onset SMA, SMA type IV

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Contributor Information and Disclosures

Author

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.

Coauthor(s)

Carmel Armon, MD, MSc, MHS, Professor of Neurology, Tufts University School of Medicine; Chief, Division of Neurology, Baystate Medical Center
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, Movement Disorders Society, and Sigma Xi
Disclosure: Nothing to disclose.

Medical Editor

Robert Baumann, MD, Program Director, Professor, Departments of Neurology and Pediatrics, University of Kentucky
Robert Baumann, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, American College of Epidemiology, American Epilepsy Society, and Child Neurology Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Kenneth J Mack, MD, PhD, Senior Associate Consultant, Department of Child and Adolescent Neurology, Mayo Clinic
Kenneth J Mack, MD, PhD is a member of the following medical societies: American Academy of Neurology, Child Neurology Society, Phi Beta Kappa, and Society for Neuroscience
Disclosure: Nothing to disclose.

CME Editor

Selim R Benbadis, MD, Professor, Director of Comprehensive Epilepsy Program, Departments of Neurology and Neurosurgery, University of South Florida School of Medicine, Tampa General Hospital
Selim R Benbadis, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Sleep Medicine, American Clinical Neurophysiology Society, American Epilepsy Society, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Amy Kao, MD, Assistant Professor, Department of Neurology, Division of Pediatric Neurology, Department of Pediatrics, Oregon Health and Science University; Consulting Staff, Shriners Hospital for Children
Amy Kao, MD is a member of the following medical societies: American Academy of Neurology, American Academy of Pediatrics, American Epilepsy Society, and Child Neurology Society
Disclosure: Nothing to disclose.

 
 
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