Subtemporal amygdalohippocampectomy for treating medically intractable temporal lobe epilepsy

A SUBTEMPORAL AMYGDALOHIPPOCAMPECTOMY technique has been developed for mesial temporal lobe epilepsy. The conventional subtemporal approach has been modified to diminish temporal lobe retraction and the risk of damage to the temporal lobe. In the new technique, the surgeons' position has moved from above to below and the approach has been changed from anterolateral to posterolateral, thereby avoiding the voluminous and steeply inclined anterior temporal lobe. By this modified approach, it was unnecessary to remove the roof of the external auditory meatus and it was estimated that both the retraction pressure and the extent of temporal lobe retraction were reduced. To date, surgeons using this approach have operated on four patients with temporal lobe epilepsy whose epileptic foci were in the mesial temporal structure; the inferior temporal gyrus, the temporal tip, the vein of Labbé, and the ventral bridging veins were preserved. After surgery, two patients became completely free of seizures and the other two showed over 90% reduction in seizure frequency without neurological sequelae. Postoperative visual field examination revealed full visual fields without quadrantanopsia. This approach can preserve the temporal stem and lateral temporal lobe, it can be used to remove as much of the posterior hippocampus as necessary, and it can be extended to conventional lobectomy if it is indicated.