Visual field deficits in conventional anterior temporal lobectomy versus amygdalohippocampectomy

Objective: To evaluate and identify the incidence of visual field defects ( VFD) after anterior temporal lobectomy (ATL) versus amygdalokippocampectomy (AH). VFD occur frequently after ATL and are usually superotemporal quadra ntanopias. Little is known about the incidence of VFD after AH and this sur gical method offers the possibility of a seizure-free survival without visu al loss. Methods: Patients with similar characteristics were examined. All patients had intractable seizures and mesial temporal sclerosis, small tumo rs localized to only the uncus, amygdala, or hippocampus, or no known patho logy. Postoperative kinetic field testing using the I4e isopter on a Goldma nn perimeter was performed 30 days or more after surgery. Results: Of 29 pa tients examined, 14 underwent AH and 15 had ATL. Four of 14 AH patients (28 %) had a VFD at 10 degrees from center and 11/14 (78%) had VFD at 40 degree s. One of 15 ATL patients (7%) had a VFD at 10 degrees from center and 11/1 5 (73%) had VFD at 40 degrees. There was no significant difference between surgery types. Conclusions: AH in this study was associated with a signific ant number of VFD. No significant difference was found between the frequenc y of VFD produced from AH and ATL. The mechanism of injury is due to direct trauma to the optic radiations while accessing the mesial temporal structu res. Because all patients in the study were asymptomatic for VFD, it remain s to be determined whether these VFD are clinically significant.