DOES PRESURGICAL IQ PREDICT SEIZURE OUTCOME AFTER TEMPORAL LOBECTOMY - EVIDENCE FROM THE BOZEMAN EPILEPSY CONSORTIUM

Purpose: Considerable debate exists concerning whether the presence of low preoperative IQ should be a contraindication for focal resective epilepsy surgery. Methods: We examined the relationship between baseli ne IQ scores and seizure outcome in 1,034 temporal lobectomy cases fro m eight epilepsy surgery centers participating in the Boseman Epilepsy Consortium. Results: Those patients who continued to have seizures fo llowing surgery had statistically lower preoperative IQ scores than th ose who were seizure-free (p < 0.009), but only by 2.3 points. This sm all but statistically significant relationship was fairly robust; it w as observed across seven of the eight centers, and indicates that the findings can be generalized. Among patients with IQ scores of less tha n or equal to 75, 32.8% continued to have seizures following surgery, whereas 23.8% and 16.9% were not seizure-free when IQ scores were betw een 76 and 109 and greater than or equal to 110, respectively. Relativ e risk analyses revealed no significant increase in risk among patient s with low IQ scores who had no structural lesions other than mesial t emporal sclerosis. However, patients with IQ scores of less than or eq ual to 75 had nearly a fourfold (390%) increase in risk for continued seizures as compared with those with higher IQ scores if structural le sions were present. Conclusions: While our results suggest that preope rative IQ scores alone are not good predictors of seizure outcome and should not be used to exclude patients as potential surgical candidate s. IQ scores can be useful for counseling patients and their families concerning the relative risks of surgery.