Visual field defects after selective amygdalohippocampectomy and standard temporal lobectomy.

BACKGROUND

Selective amygdalohippocampectomy (SelAH) is increasingly performed in patients with mesial temporal lobe epilepsy and hippocampal sclerosis. To determine whether visual field defects are less pronounced after SelAH than after standard temporal lobectomy (StTL), we retrospectively analyzed postoperative quantitative visual fields after the 2 procedures.

METHODS

Humphrey visual field analysis was obtained postoperatively in 18 patients who had undergone SelAH and in 33 patients who had undergone StTL. The SelAH was performed via a transcortical approach through the middle temporal gyrus and included the amygdala, 3 cm of the hippocampus, and the parahippocampal gyrus. The visual field pattern deviation was used for analysis. We considered a defect clinically significant if there were 3 contiguous coordinates affected at the 5% level or 2 at the 1% level.

RESULTS

All but 2 of 18 patients who had undergone SelAH had homonymous superior quadrantic visual field defects contralateral to the side of the surgery. One patient had no defects by our criteria, and one had a mild defect that reached significance only in the ipsilateral eye. The averaged defect affected mostly coordinates close to the vertical meridian with relative sparing of points close to the horizontal meridian. All but 3 of the 33 patients who had undergone StTL had homonymous superior quadrantic visual field defects. One patient had no defects; 2 had defects that reached significance in only one eye. The averaged defect involved all points in the affected quadrant, but was also greater near the vertical meridian. Of 13 tested visual field coordinates, 4 were significantly less affected by SelAH in the ipsilateral eye and 3 in the contralateral eye. The coordinates close to the horizontal meridian were significantly spared by SelAH.

CONCLUSIONS

Visual field defects are very common after SelAH but are significantly less pronounced than after StTL. In particular, the visual field close to the horizontal meridian is relatively spared in SelAH.