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 favourable 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.[77] 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. 

Aetiology is one of the most important prognostic indicators and improved aetiological diagnostics should allow for more accurate prognostic counselling. 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 favourable outcome. However, individuals with primarily genetic causes such as SCN2A are more likely to have poor developmental outcomes.[78] If the aetiology 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.[79][80][81]​​ Patients with symptomatic aetiology may still have a favourable seizure outcome if the aetiology is neonatal hypoglycaemia, Down syndrome, stroke or infarct, periventricular leukomalacia, or neurofibromatosis.[82]​ The outcome is almost always poor in children with severe brain malformations, post-infectious aetiology, and tuberous sclerosis. 

Several studies have found a relationship between short time (lead-time) to treatment and improved mental outcome.[39][79][80]​​​​​​​[83]​​[84][85]​​​​​[86]

Adverse prognostic indicators include:[77]​ 

  • Underlying aetiology (previously called ‘symptomatic’ infantile spasms): in particular, brain malformations, post-infectious aetiology, and tuberous sclerosis

  • Presence of developmental abnormalities at spasm onset

  • Longer duration of hypsarrhythmia (>3 weeks).[86]

Predictors of favorable outcome include:[77]

  • Unknown aetiology (previously called ‘idiopathic' or ‘cryptogenic' infantile spasms)

  • Normal development at spasm onset

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

  • Short lead-time to treatment.

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