Abstracts

Rationale: Selective amygdalohippocampectomy (SelAH) is becoming more widely used for patients with mesial temporal lobe epilepsy and hippocampal sclerosis. It is not known if visual field defects are less pronounced with SelAH in comparison with standard temporal lobectomy (StTL). Using quantitative automated static visual field testing, we compared visual field defects in patients who underwent SelAH and those who underwent StTL.Methods: The study was approved by the Vanderbilt IRB. We used automated Humphrey visual field analysis post-operatively in 18 patients who underwent SelAH and 34 patients who had standard temporal lobectomy at Vanderbilt University Medical Center. The SelAH was performed through a transcortical incision in the middle temporal gyrus to locate the temporal horn. The resection included amygdala, 3 cm of hippocampus, and parahippocampal gyrus. The pattern deviation was averaged in the upper quadrant contralateral to surgery, separately for the ipsilateral and contralateral eye. Deviations less than -5 were displayed (Figure). We used two tailed t-test for statistical comparison of visual loss with the two procedures for each tested coordinate. Results: Nine patients had left and eight right SelAH. All but one had identifiable visual field defects in the contralateral superior quadrant. The averaged defect affected mostly the medial sector near the vertical meridian, with minimally less involvement in the contralateral eye. The points closest to the horizontal meridian were relatively spared. Fourteen patients each had a left, and twenty had a right StTL. All had an identifiable visual field defects. The averaged defect involved all points in the affected quadrant, but was also greater in the medial sector. Of 13 tested visual field coordinates, 5 closest to the horizontal meridian were significantly less affected by SelAH in the ipsilateral eye and two in the contralateral eye (Figure). Conclusions: Visual field defects are very common after SelAH, but are significantly less pronounced than with StTL. In particular, the visual field closest to the horizontal meridian is relatively spared.