Investigations

If infantile spasm is suspected the following investigations should be carried out:

• EEG
  • should be performed as soon as possible on any infant with concerns for infantile spasms
    • 24-hour video EEG is preferred if available
  • required to confirm the presence of hypsarrhythmia
  • if there are no features of hypsarrhythmia or its variants, repeat the test in 1-2 weeks
  • in up to1/3 of IS, hypsarrythmia may be absent or may show other EEG abnormalities
    • in these cases evaluation and treatment should proceed without delay if the clinical spasms are consistent with infantile spasms
  • is also used to monitor response to treatment
• neuroimaging
  • is not required to make a diagnosis but useful in identifying aetiology and/or to direct further testing in infantile spasms
  • MRI is the initial neuroimaging modality of choice
    • has a higher sensitivity in identifying subtle structural changes compared to CT (1,2)

A basic metabolic screen, including electrolytes, glucose, pyrovate lactate, ammonia, plasma amino acid, and urine organic acid is recommended for cases where examination and neuroimaging fails to identify an aetiology (1).

Neuroimaging or clinical examination may point towards a genetic disorder. In these patients, a targeted genetic test may be carried out (1).

A combination of genetic and metabolic testing may identify the aetiology in an additional 10% of cases (1).

Reference:

• (1) Taghdiri MM, Nemati H. Infantile spasm: a review article. Iran J Child Neurol. 2014;8(3):1-5.
• (2) Nelson GR. Management of infantile spasms. Transl Pediatr. 2015;4(4):260-70.