The most common surgical procedure performed for epilepsy is the removal of a portion of the temporal lobe, or temporal lobectomy. These brain structures play an important role in the generation or propagation of the majority of temporal lobe seizures. In most cases, a modest portion of the brain measuring approximately 2 inches long is removed. The temporal lobes are important in memory, emotion and language comprehension. However, extensive preoperative assessments (MRI, Wada tests, PET scans) ensure that removal of the area causing seizures will not disrupt any of these critical functions.
Permanent complications associated with temporal lobe resection surgery are very low. Mortality is less than 0.1% and permanent unexpected morbidity less then 1%. In dominant hemisphere resections, temporary language difficulties are seen in 10% of the cases although these usually resolve. An upper quadrantanopsia (partial upper peripheral vision loss) is expected in large temporal resections, but seen in less than 25% of the patients. Memory impairment rarely occurs from temporal lobectomies because of extensive preoperative testing of language and memory functions.
The success rate for seizure control in temporal lobectomy varies:
Therefore, over 85% of patients enjoy a marked improvement in seizure control. Most of them need less medication after surgery. Approximately 25% of those who are seizure-free eventually can discontinue antiepileptic drugs.