Gamma knife versus open surgery for epilepsy: A longitudinal neuropsychological profiling study

Introduction: Neuropsychological evaluations of preoperative epilepsy surgical candidates have been a routine portion of the multidisciplinary evaluation at most epilepsy centres for decades, hence, it is a laid fact that neuropsychology has played a prominent role throughout the modern era of epilepsy surgery. It has been explored as a means to predict and identify postoperative cognitive deficits after resections (chiefly temporal lobe), and in numerically quantifying those changes that do occur. In addition, neuropsychological results have some predicative power regarding seizure outcome following anterior temporal lobotomy.

Aim: To compare the neuropsychological outcomes in patients with pharmaco-resistant mesial temporal lobe epilepsy undergoing radio surgery and temporal lobe surgery, in particular with respect to verbal memory, visuo-constructive ability, attention and new learning ability function for language-dominant hemisphere treated patients along with psychosocial intervention.

Methods: A sample of 6 randomized consenting subjects were assessed longitudinally on standardized neuropsychological tests namely, verbal memory and learning (AVLT), visuo-constructive memory (CFT), new learning ability (PGIMS, subtest-8), attention (colour trail 1 and 2), depression (BDI) and anxiety (BAI) from baseline to the 36 month assessment (4 follow-ups annually during the 3 year period).

Result: Descriptive statistical analysis shows that there was no statistical significant difference between the groups; i.e the type of epilepsy surgery (radio surgery or temporal lobe surgery) does not affect neuropsychological profile. While there was improved neuropsychological profile more in temporal lobe surgery group than in radio-surgery group over 3 year assessment. Temporal lobe surgery group has improved visuo-constructive ability (8.3 ± 3.8; 15.6 ± 7.4; 28.3 ± 20.8; 30.0 ± 31.2), learning ability (25.8 ± 29.8; 34.1 ± 39.8; 35.8 ± 31.6; 57.5 ± 44.2), delayed memory (15 ± 13.2; 23.3 ± 23.6; 25.0 ± 22.9; 21.6 ± 24.6), attention(43.3 ± 29.1; 77.0 ± 28.2; 58.2 ± 71.0; 84.3 ± 81.0) along with reduced depression and anxiety respectively over 3 year period of time, as compared to radio surgery group where only visuo constructive ability(10.0 ± 4.3; 14.2 ± 7.6; 30.0 ± 2.5; 43.3 ± 10.4) and new learning ability (70 ± 20; 83 ± 11; 90 ± 0; 90 ± 0) was found be improved.

Conclusion: Neuropsychological testing is useful as a means of prediction and risk stratification for postoperative cognitive changes after epilepsy surgery, irrespective of type of surgery. Among the assessments, there are no statistically significant changes in the neuropsychological outcomes, though, there is an evidence of clinically significant results, however, due to small sample size, no conclusive claim can be made.