Table 1 – Categories and Prognoses of Infantile Spasms1,2,3

Type of IS Description Prognosis


• Identifiable cause can be determined

• Developmental delays present before onset of spasms

• 70–80% of IS cases

• Increased likelihood for cognitive and development delays as well as neurological deficits

• 12.5% of patients considered to have “good” outcome


• No identifiable cause

• Normal development before onset of spasms

• 20–30% of IS cases

• Better overall prognosis compared to symptomatic patients

• Better developmental outcomes seen when patient is treated with hormonal therapy versus vigabatrin

• 54.3% of patients considered to have “normal” or “near-normal” outcomes

Figure 1 Suggested Treatment Algorithm for Infantile Spasms