Abstract, originally published in Epilepsia Open
Objective: There is no consensus on the type or duration of the post-treatment EEG needed for assessing treatment response for infantile spasms (IS). We assessed if outpatient electroencephalograms (EEGs) are sufficient to confirm infantile spasms (IS) treatment response.
Methods: Three-year retrospective review identified new onset IS patients. Only presumed responder to IS treatment at 2-weeks with a prolonged (> 90 min) outpatient EEG to assess treatment response, and at least 3 mo follow-up were included. Hypsarrhythmia, electroclinical spasms, and sleep were evaluated for the first hour and for the duration of the EEG.
Results: We included 37 consecutive patients with new onset IS and presumed clinical response at 2-weeks post treatment. Follow-up outpatient prolonged EEGs (median:150 min, range:90-240 min) were obtained 14 days (IQR:13-17) after treatment initiation. EEGs detected ongoing IS in 11 of 37 (30%) of presumed early responders. Prolonged outpatient EEG had a sensitivity of 85% (confidence interval [CI] 55-98%) for detecting treatment failure. When hypsarrhythmia and/or electroclinical spasms were not seen, EEG had a negative predictive value 92% (CI:75-99%) for confirming continued IS resolution. Outpatient EEG combined with clinical assessment, however identified all treatment failures at two-weeks. Compared to the entire prolonged EEG, the first hour recording missed IS in 45% (5/11). While sleep was captured in 95% (35/37) of the full EEG recording, the first hour of recording captured sleep in only 54% (20/37).
Significance: IS treatment response can be confirmed with a clinical history of spasm freedom and an outpatient prolonged EEG without evidence for ongoing spasms (hypsarrhythmia/electroclinical spams on EEG). Outpatient prolonged EEG, but not routine EEGs, represent an alternative to inpatient long-term monitoring for IS post-treatment EEG follow-up.