Application of envelope trend to analyze early EEG changes in the frontal regions during intracarotid amobarbital procedure in children

- We examined the role of early EEG changes to predict the failure of intracarotid amobarbital procedure (IAP) in children.
- The presence of focal slowing in the ipsilateral and contralateral frontal regions is associated with failure to complete IAP.
- Younger children may fail to complete IAP because of the behavioral changes during the procedure.
- Total dosage used for IAP and other clinical variables do not correlate with the outcome of IAP.

BackgroundIntracarotid amobarbital procedure (IAP) is acknowledged as the gold standard test for language lateralization. EEG is performed routinely during IAP to monitor the anesthetization of a brain hemisphere. Here, we studied the correlation between the early EEG changes using envelope trend and the clinical outcome of IAP.MethodFifty consecutive patients underwent IAP at Texas Children's Hospital (2004-2009). Intracarotid amobarbital procedure was considered “complete” or “incomplete” based on the outcome if the procedure was completed or aborted due to behavior changes. Envelope trend was used to calculate the median EEG amplitude changes within the first 60 s of IAP. Statistical analysis was performed to determine the role of EEG changes and clinical features on the procedure outcome.ResultsOnly 30 IAP-EEG files were available for review. Amobarbital was administered at the dose of 60-150 mg (mean: 110 ± 20). The intracarotid amobarbital procedure was recorded as complete in 23 patients and incomplete in 7 patients. EEG changes occurred within the first few seconds following amobarbital injection. Following amobarbital injection, focal slowing was present in the ipsilateral frontal region or both ipsilateral and contralateral frontal regions. Elapsed time to the first EEG change or duration and change in median EEG amplitude in the ipsilateral frontal regions were indifferent between the complete and incomplete groups (p > 0.05). However, the median amplitude changes between the ipsilateral and contralateral frontal regions within each group were found significant only in the complete group (p < 0.05), suggesting ipsilateral without contralateral frontal slowing. Other than age at the time of IAP (p = 0.03), none of the other clinical features correlated with the clinical outcome of IAP (p > 0.05).ConclusionEarly EEG changes during IAP using envelope trend may predict successful completion of the IAP test. Younger children are at risk of behavioral changes during IAP.