The Comprehensive Epilepsy Surgery Program was established in 1992 and is led by pediatric neurologist Dr. Mary Connolly. There is a large multidisciplinary team, including multiple neurologists, neuropsychologists, psychologists, radiologists, nurses, electrophysiologists and electrophysiology technologists, in addition to neurosurgeons. The neurosurgeons on the epilepsy surgical team comprise Dr. Steinbok and Dr. Singhal. From 1992 onwards, we have operated on over 250 children with intractable epilepsy, with the youngest patient being only 3 months old. The majority of patients have been from British Columbia, but we have also treated children from Alberta, Manitoba, Saskatchewan, Prince Edward Island and Nunavut.
Each individual patient is assessed by a team, which includes neurologists, neurosurgeons, radiologists, nurses, EEG technologists, radiology and nuclear medicine technologists and a neuropsychologist. Potential candidates for epilepsy surgery come to Children’s for video-EEG monitoring over a period of days to capture and record typical seizures. This allows the neurologist to assess where the seizures begin within the brain. MR imaging provides a detailed look at the patient’s brain structure to help identify the epileptic focus. Selected patients undergo SPECT and PET scanning which enable one to look at brain function if the MRI fails to show a structural lesion, and some patients have had magnetoencephalography (MEG).
A neuropsychologist with experience in epilepsy performs a detailed assessment of functions such as language, memory, attention and other tasks. A family-centered care approach helps the parents understand what the procedure looks like and its associated risks.
The procedures have included temporal lobectomies, extratemporal cortical resections, hemispherectomies or hemispherotomies, subpial transections, corpus callosotomies and implantation of vagal nerve stimulators. In approximately 15% of the children with epilepsy surgery we have made use of monitoring directly from the surface of the brain, using subdural grids and strips of electrodes.
Our results are as good as or better than what has been reported from other major centers around the world. The most common epilepsy surgery procedure in approximately 100 children has been extratemporal cortical resections, with 64% of patients being completely seizure free. The subset of patients with frontal lobe epilepsy have done better as a group, with 70% being seizure free. The second most common procedure has been temporal lobectomy, and of these children, 84% are seizure free, 10% are significantly improved and fewer than 10% have not been improved.
We have done over 30 hemispheric operations and almost 90% are seizure free, most off antiepileptic medications. The neurosurgical team has moved away from hemispherectomy and hemidecortication procedures that were being done in the earlier years of the program to the more sophisticated and less invasive peri-insular hemispherotomy procedure. In our hands this procedure has proven to be as successful as a hemispherectomy with fewer complications, shorter hospital stays, and less need for blood transfusion or postoperative cerebrospinal fluid shunting.
Our program has inserted vagal nerve stimulators in over 50 children. Our results are similar to those reported from large centers in the United States and studies in adults, with 58% of the patients having a reduction of seizures of more than 50%. In recent years we have moved away from vagal nerve stimulators to corpus callosotomy, since the latter procedure has provided better seizure control with few complications.
The complications after all types of epilepsy surgery in our hands have been minimal. There have been no deaths. If one excludes the expected loss of function from removing a part of the brain (for example loss of peripheral vision on one side from doing a hemispheric operation) we have had only two patients who lost some neurologic function. Blood transfusions for cortical resections have been unusual. Even for hemispheric operations our transfusion rate is below 30% with the peri-insular hemispherotomy technique. There has been only one significant infection, and that was among the children who have had subdural grids inserted for monitoring.