Abstracts

Rationale: Minimally invasive Gamma Knife stereotactic radiosurgery (SRS) is a minimally invasive alternative to open surgery for mesial temporal lobe epilepsy (MTLE).  Our pilot study of SRS for MTLE demonstrated that the degree of a postoperative visual field defects (VFD) consisting of homonymous superior quandrantanopsias (HSQ) correlated with seizure remission. In the ROSE Trial, we evaluated the hypothesis that minimally invasive SRS would cause less severe VFD than standard anterior temporal lobectomy (ATL). Methods: This multicenter prospective trial of RS randomized patients with unilateral hippocampal sclerosis and concordant video-EEG findings to standardized protocols of SRS (24Gy delivered to the amygdala, hippocampal head, and parahippocampal gyrus, exposure to optic nerve was limited to standard protocols of SRS (24Gy delivered to the amygdala, hippocampal head, and parahippocampal gyrus, exposure to optic nerve was limited to Results: Postoperative VF results were available for 30 of 31 SRS and 26 of 27 ATL patients. No patients complained of VFD or poor acuity, and confrontation examinations were normal. Interpretations of perimetry showed that 13 patients had no VFD, 35 had VFD consisting of HSQ VFD deficits above or at the horizontal meridian, and 8 had some deficits extending below the meridian. No patient had complete homonymous hemianopsia. Regression models showed that no significant differences in severity of VFD ratios were present by arm, language dominant surgery, or age at surgery. Younger age at diagnosis correlated with worse VFD ratios (P=0.005, beta = 0.405 (95%CI 0.001-0.006)).  Conclusions: The severity of VFD did not differ by treatment arm or seizure remission. Age at diagnosis of epilepsy correlated with worse visual field defects, and this risk did not differ by surgical treatment. Minimally invasive epilepsy surgery did not spare optic tract involvement. Funding: NIH-NINDS, Elekta AB