Risk factors for unsuccessful testing during the intracarotid amobarbital procedure in preadolescent children

Purpose: Identification of risk factors for unsuccessful testing during int racarotid amobarbital procedure (IAP) in preadolescent children. Methods: A pediatric IAP protocol was attempted in 42 candidates for epilep sy surgery (5-12 years old; mean, 10 years) based on the ability to pass a practice test. Language dominance was defined by marked asymmetry until fir st verbal response and paraphasic errors. Intact hemispheric memory was def ined by recall of greater than or equal to 60% of test items. The odds rati os of baseline variables (age at IAP, Full-Scale IQ, side of disease, age a t seizure onset, amobarbital dose) were calculated for various LAP outcomes . Results: IAPs were accomplished in 40 children. Language dominance was esta blished in 25 (62.5%) of 40 patients: all 21 focal resection candidates wer e left language dominant; four hemispherectomy candidates had intact langua ge after injection of the damaged hemisphere. In 12 (30%) of 40 patients, l anguage testing failed because of agitation or obtundation. Compared with t he 21 children with language dominance established by bilateral ZAP, these 12 children had lower mean Full-Scale IQ (66.4 vs. 87.9; p = 0.014), and mo re frequently, the epileptogenic lesion in the left hemisphere (presumed do minant by right-handedness; 78 vs. 33%; p = 0.04). Excluding hemispherectom y candidates (intentionally only one injection), memory testing could not b e completed in 13 (36%) of 36 children because of obtundation or agitation. These children were significantly younger than the 23 (64%) of 36 with suc cessful bilateral memory testing (mean age, 107.6 vs. 128.7 months; p = 0.0 06). The eight (25%) of 32 children with failing retention scores after ips ilateral injection had lower Full-Scale IQ than did the 24 (75%) patients w ho passed (mean, 59.6 vs. 81.7 months; p = 0.03). Conclusions; The IAP successfully established hemispheric language dominanc e and memory representation for just under two thirds of the preselected pr eadolescent children. Risk factors for unsuccessful tasting included low Fu ll-Scale IQ (especially <80), young age (especially <10 years), and seizure s arising from the left hemisphere presumed dominant by right-handedness.