SUMMARYPurpose: Epilepsy surgery is a safe surgical procedure, but it may be associated with cognitive changes. Estimates of the risk of decline in specific neuropsychological domains after epilepsy surgery would assist surgical decision making in clinical practice. The goal of this study was to conduct a systematic review to derive pooled estimates of the rate of losses and gains in neuropsychological functions after epilepsy surgery, using empirically based methods for quantifying cognitive change. Methods: An extensive literature search using PubMed, EmBase, and the Cochrane database was conducted, yielding 5,061 articles on epilepsy surgery, with 193 on neuropsychological outcomes (IQ, memory, language, executive functioning, attention, and subjective cognitive changes). Key Findings: Of these, 23 met final eligibility criteria, with 22 studies involving temporal surgery only. Key aspects of inclusion criteria were N ‡ 20 and use of reliable change index or standardized regression-based change estimates. In addition to the proportion of patients experiencing losses and gains in each individual test, a single pooled estimate of gains and losses for each cognitive domain was derived using a random effects model. Weighted estimates indicated a risk to verbal memory with left-sided temporal surgery of 44%, twice as high as the rate for right-sided surgery (20%). Naming was reduced in 34% of left-sided temporal patients, with almost no patients with gains (4%). Pooled data on IQ, executive functioning, and attention indicated few patients show declines post surgery, but a substantial rate of improvement in verbal fluency with left-sided temporal surgery (27%) was found. Self-reported cognitive declines after epilepsy surgery were uncommon, and gains were reported in some domains where losses were found on objective tests (i.e., verbal memory and language). Variations in surgical techniques did not appear to have a large effect on cognitive outcomes, except for naming outcomes, which appeared better with more conservative resections. Sensitivity to postoperative changes differed across visual memory tests, but not verbal memory tests. Few conclusions could be made regarding cognitive risks and benefits of extratemporal epilepsy surgery, or of epilepsy surgery in children. Significance: In sum, epilepsy surgery is associated with specific cognitive changes, but may also improve cognition in some patients. The results provide base rate estimates of expected cognitive gains and losses associated with epilepsy surgery that may prove useful in clinical settings.

Summary Purpose:  The Wechsler Intelligence Scale for Children – Fourth Edition is the most widely used intelligence quotient (IQ) test in use today. However, despite numerous studies on IQ in childhood epilepsy, data exist almost exclusively from prior editions of the test, and no studies to date provide information on the sensitivity of specific WISC‐IV scores (full‐scale IQ [FSIQ], index, and subtest scores) to epilepsy‐related cognitive impairments. The goal of this study was to determine the relative sensitivity of WISC‐IV index and subscale scores in detecting cognitive problems in a group of clinically referred children with epilepsy compared to matched controls, and to define the relationship among WISC‐IV scales, demographic factors, and epilepsy‐related variables. Methods:  WISC‐IV data for children with epilepsy and high seizure burden were obtained from the Alberta Children’s Hospital (ACH) and the New York University Comprehensive Epilepsy Center (NYU), two tertiary care medical centers for pediatric epilepsy. All children were clinically referred and received a standard assessment including WISC‐IV. Matched controls were obtained from the WISC‐IV Canadian and American standardization samples. Key Findings:  WISC‐IV scores from 212 children were included: 106 children with epilepsy (46 girls, 60 boys; mean age 11.0 years, standard deviation [SD] 3.1; parental education 14.5 years, SD 2.8), and 106 controls matched for age, gender, ethnicity, and parental education. Of the children with epilepsy, 44 had a clearly lateralized focus on electroencephalography (EEG) involving either the right or left hemisphere (26 left, 18 right). FSIQ for the epilepsy group was significantly lower than for controls, and 36.8% of children had IQs compatible with intellectual disability (FSIQ < 70), versus <1% of controls. In children with epilepsy, Working Memory and Processing Speed Index scores were lower than those for Verbal Comprehension and Perceptual Reasoning (p < 0.01). At the subtest level, scores for children with epilepsy were highest on visual and verbal subtests measuring reasoning skills such as Matrix Reasoning, and lowest on Coding (mean 5.93, SD 3.6). In terms of percentage of children on each subtest with low scores (i.e., scores below 2 SDs from the expected normative mean of 10), the Coding subtest identified the most children (28.3%) with low scores, and the Similarities subtest identified the fewest (16%). Later age at onset and shorter epilepsy duration were both correlated with higher WISC‐IV FSIQ and index scores (r correlation coefficient values ranging from 0.36 to 0.44, p < 0.0001), and number of current and previous antiepileptic drug trials were both inversely correlated with FSIQ and index scores (r −0.27 to −0.47, all p‐values < 0.01). Neither the FSIQ nor the index scores were significantly related to seizure frequency. A similar pattern was found for subtest scores. No differences in FSIQ, index scores, or subtest scores were found between children with left‐ and right‐hemisphere seizur...