Temporal lobectomy in children: cognitive outcome

Abstract

The authors sought to determine the impact of early temporal lobectomy (in patients younger than age 17 years) on intellectual functioning. The efficacy of temporal lobectomy for treating seizures is well established and the procedure is becoming more acceptable as a treatment for children whose seizures are intractable. However, cognitive outcomes of temporal lobectomy in children and adolescents are largely unreported. The present study takes advantage of a unique multicenter collaboration to examine retrospectively intellectual functioning in a large sample of children who underwent temporal lobectomy. Intellectual functioning was assessed before and after temporal lobectomy for treatment of medication-resistant seizures in 82 patients at eight centers of epilepsy surgery. All children underwent standard presurgical examinations, including electroencephalography-video monitoring, magnetic resonance (MR) imaging, and neuropsychological testing, at their respective centers. Forty-three children underwent left temporal lobectomy and 39 underwent right temporal lobectomy. For the entire sample, there were no significant declines in intelligence quotient (IQ) following surgery. Children who underwent left temporal lobectomy demonstrated no significant loss in verbal intellectual functioning and improved significantly in nonverbal intellectual functioning. Children who underwent right temporal lobectomy did not demonstrate significant changes in intellectual functioning. Although group scores showed no change in overall IQ values, an analysis of individual changes revealed that approximately 10% of the sample experienced a significant decline and 9% experienced significant improvement in verbal functioning. Significant improvement in nonverbal cognitive function was observed in 16% of the sample and only 2% of the sample showed significant declines. Risk factors for significant decline included older patient age at the time of surgery and the presence of a structural lesion other than mesial temporal sclerosis on MR imaging. The present study provides preliminary data for establishing the risk of cognitive morbidity posed by temporal lobectomy performed during childhood. With respect to global intellectual functioning, a slight improvement was significantly more likely to occur than a decline. However, there were several patients in whom significant declines did occur. It will be necessary to study further the factors associated with such declines. In addition, further study of more specific cognitive functions, particularly memory, is needed.