Extra-temporal Epilepsy Surgery

What is an extra-temporal Epilepsy Surgery ?

Extra-temporal seizure surgery constitutes about a quarter of the surgical procedures for epilepsy and includes resection of the frontal lobes, parietal lobes or occipital lobes. These resections are guided by localization from invasive subdural electrodes and, if necessary, detailed cortical functional mapping. Extra-temporal resections are individualized to the seizure onset focus, the type of seizure or syndrome, and the functional mapping which defines a safe resection boundary. Motor and sensory cortex and language cortex localization is performed and greatly minimizes neurological deficits from surgery.

What are the risks involved ?

The risk of a major complication, such as a stroke, is about 1% in these types of surgery. The risk of behavioral changes is higher than with temporal lobectomy although these are often difficult to measure and define. Personality, motivation, ability to plan and to follow up on a multistep process, ability to organize actions over time, social graces, and demeanor are among the behaviors that the frontal lobes help to serve. In parietal and occipital lobectomies, there may be a risk of losing touch sensation or vision.

What is the success rate of temporal lobe resection ?

Results of surgical management for extratemporal epilepsy vary depending upon seizure types, invasive mapping, and epilepsy syndrome. Overall:

  • 50%-60% of patients are free of seizures that impair consciousness or cause abnormal movements.
  • 20%-40% of patients are markedly improved (more than 90% reduction of complex partial and tonic-clonic seizures)
  • 20%-30% of patients have no worthwhile improvement.

Although extratemporal surgical cure rates are not as high as temporal surgery rates, patients with well defined epileptic zones limited to smaller areas of the brain which can be resected do better than in cases of widespread seizure areas. It is in the area of extratemporal seizures that our institution has improving success rates as these more difficult problems are managed with the latest techniques, imaging modalities and our greater understanding.