Analysis of causes of visual dysfunction induced by temporal lobectomy and its prevention in the patients with temporal lobe epilepsy

Objective To analyze the causes of visual dysfunction after the temporal lobectomy in order to improve the strategy and techniques of the temporal lobectomy and decrease the rate of postoperative visual dysfunction occurrence in the patients with temporal epilepsy.Methods Forty-two patients with temporal epilepsy were treated by the improved temporal lobectomy on the basis of further understanding the temporal anatomy related to visual pathway and the operative experience in treating the temporal epilepsy.The subpial rescetion of the medial structures of the temporal lobe should be restrictly performed,and heat radiation from the bipolar cautery should be avoided during the procedures in order to decrease occurrent rate of the postoperative diplopia caused by the injury to the oculomotor nerve and trochlear nerve.The anterior temporal lobe removed by the operation should be within 3.5 cm from the pole of temoral lobe in order to decrease the visual field defect caused by the injury to Meyer's loop of visual radiation.Results The diplopia occurred in 2 patients and there was no visual field defect in all the patients after the operation.The following up of 39 patients from 7 to 26 months showed that the seizures were controlled(Engel grades I~II) in 31 patients(79.5%),and improved(Engel grades Ⅲ~Ⅳ) in 8 patients.Conclusions The primary causes of the postoperative diplopia and visual field defect are the injury to the trochlear nerve,oculomotor nerve and visual radiation during the operation in the patients undergoing the temporal lobectomy for the temporal epilepsy.It is possible to prevent the postoperative complications by improving the surgical procedures and techniques of the temporal lobectomy in the patients with temporal epilepsy.