Abstracts

Gamma Knife radiosurgery (GKS) is a noninvasive alternative to open surgery for the treatment of mesial temporal lobe epilepsy (MTLE). Prospective trials suggest comparable seizure remission rates. The purpose of this multicenter prospective pilot study was to examine neuropsychological outcome two years after GKS treatment of MTLE., GKS, randomized to 20 Gy or 24 Gy comprising 5.0-7.5mL at the 50% isodose volume, was performed on patients with unilateral MTLE. [ldquo]Dominant[rdquo] surgery indicates that GKS was performed on the language dominant hemisphere based on Wada testing. The Boston Naming Test (BNT), Wechsler Memory Scale-Revised (WMS-R) and California Verbal Learning Test (CVLT) were administered at preoperative baseline and at 24-months postoperatively. Patients were classified as having [ldquo]significant improvement[rdquo], [ldquo]no change[rdquo], or [ldquo]significant impairment[rdquo] based on a Reliable Change Index (RCI) validated in epilepsy populations. They also completed mood (BDI) and quality of life (QOLIE-10) measures., Surgical outcome did not differ by gender, age, or side of surgery. Overall (n=26), the rate of impairment of language and memory functions (BNT and delayed recall from the CVLT and WMS-R) was 19%. For those receiving GKS in the dominant hemisphere, 33% (4/12) had significant impairment on language or memory testing. Only one patient who received non-dominant GKS had a decline. Notably, three patients had improved language (2 dom, 1 nondom) and three demonstrated improved contextual verbal memory (2 dom, 1 nondom). There was no significant change in depression scores. Neither latency to seizure remission nor cumulative number of seizures postoperatively were significantly correlated with depression. Mean QOLIE-10 scores improved significantly from baseline to two year postoperatively (p=.0003). The global QOLIE-10 score and latency to seizure remission were significantly related (p=.0045, R²=0.29), such that patients with the longest seizure free interval reported a better quality of life., This prospective study of GKS treatment of MTLE revealed a lower incidence of verbal memory impairment than that reported following standard surgery. Mood did not change after surgery. Quality of life was correlated with seizure remission and duration of seizure remission. Preliminary findings suggest that GKS should be considered for patients with MTLE who have at-risk cognitive function or who require a non-invasive alternative to open surgery., (Supported by NIH R01 NS039280; Elekta AB (Stockholm, Sweden).)