Visual field deficits in conventional anterior temporal lobectomy versus amygdalohippocampectomy. Egan RA, Shults WT, So N, Burchiel K, Kellogg JX, Salinsky M. Neurology 2000;55:1818–1822.

Abstract

Visual field defects occur frequently after temporal lobe surgery for epilepsy because of the location of the optic radiations in the temporal lobe. The traditional surgery employed is anterior temporal lobectomy (ATL), often resulting in contralateral homonymous superior quadrantanopias. Another surgical procedure, amygdalohippocampectomy (AH), solely removes the epileptogenic mesial temporal lobe structures including the hippocampus, uncus, and amygdala, presumably sparing the lateral temporal lobe anatomy and, hence, the optic radiations. The objective of this study was to evaluate and identify the incidence of visual field defects after ATL versus AH. All patients had intractable seizures and mesial temporal sclerosis, small tumors localized to only the uncus, amygdala, or hippocampus, or no known pathology. Post-operative kinetic field testing using the 14e isopter on a Goldmann perimeter was performed 30 days or more after surgery. Of 29 patients examined, 14 underwent AH and 15 had ATL. Four of 14 AH patients (28%) had a visual field defect at 10 degrees from center and 11 of 14 (78%) had a visual field defect at 40 degrees. One of 15 ATL patients (7%) had a visual field defect at 10 degrees from center and 11 of 15 (73%) had a visual field defect at 40 degrees. There was no significant difference between surgery types. Although it was hoped that AH would cause fewer or no visual field defects when compared with ATL, this was not the case. The mechanism of injury from both procedures is presumably direct trauma to the optic radiations while accessing the mesial temporal lobe structures. Interestingly, all patients in the study were asymptomatic for their visual field defects.—Nancy J. Newman