Prognosis

There are only a limited number of studies that assess long-term outcomes in infantile spasms and they show that, at most, one quarter of patients have a favorable long-term cognitive outcome and one third remain seizure-free. Many comorbidities are associated with infantile spasms (autism, cerebral palsy, sensory defects), and mortality is high throughout life.[78] Several factors influence the prognosis of children with infantile spasms. Most studies investigating short- and long-term outcomes are retrospective and include different populations and treatments. Whether prognosis has changed over time is difficult to assess. 

Etiology is one of the most important prognostic indicators and improved etiologic diagnostics should allow for more accurate prognostic counseling. Where no underlying cause is found (previously called "idiopathic" or "cryptogenic" spasms) after first investigations, a known or presumed genetic predisposition is likely, and these patients generally have a favorable outcome. However, individuals with primarily genetic causes such as SCN2A are more likely to have poor developmental outcomes.[79] If the etiology remains unknown and development was normal before spasm onset, the patient can be free of spasms and have normal or nearly normal psychomotor development in about 80% cases.[80][81][82]​​​​​ Patients with symptomatic etiology may still have a favorable seizure outcome if the etiology is neonatal hypoglycemia, Down syndrome, stroke or infarct, periventricular leukomalacia, or neurofibromatosis.[83]​ The outcome is almost always poor in children with severe brain malformations, postinfectious etiology, and tuberous sclerosis. 

Several studies have found a relationship between short time (lead-time) to treatment and improved mental outcome.[39][80][81]​​​​​​​[84]​​[85][86][87]

Adverse prognostic indicators include:[78]

  • Underlying etiology (previously called "symptomatic" infantile spasms): in particular, brain malformations, postinfectious etiology, and tuberous sclerosis

  • Presence of developmental abnormalities at spasm onset

  • Longer duration of hypsarrhythmia (>3 weeks).[87]

Predictors of favorable outcome include:[78]

  • Unknown etiology (previously called "idiopathic" or "cryptogenic" infantile spasms)

  • Normal development at spasm onset

  • A short duration of hypsarrhythmia (regardless of etiology, but may be especially important in the unknown etiology group)

  • Short lead-time to treatment.

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