Lobectomy and Cortical Resection
The most common form of epilepsy surgery is a lobectomy or cortical resection. It is estimated that approximately 30% of patients with partial epilepsy have seizures that are not well controlled with medications and could benefit from this surgery. Seizures in the temporal, parietal, frontal or occipital lobes may be treated surgically if the seizure-producing area can be safely removed without damaging vital functions.
When a child has Rasmussen’s encephalitis, a rare, progressive disease affecting one whole hemisphere of the brain, a hemispherectomy may be performed. A hemispherectomy is the removal of all or almost all of one side of the brain. Weakness on the side opposite the operation will continue, but the half that remains takes over many of the functions of the half that was removed. Hemisperectomies may also be performed when children are born with conditions that cause excessive damage to one side of the brain, such as bleeding in the brain prior to birth.
Corpus callosotomy is the sectioning, or separating of the corpus callosum—a nerve bridge which connects the two halves of the brain and integrates its functions. Separating the cerebral hemispheres reduces generalized seizures by confining the spread of an epileptic discharge to one cortex. A corpus callosotomy may be performed when partial seizures secondarily generalize and it’s not possible to identify a single epileptic focus, or when resection of a localized focus would cause a pronounced neurological deficit. Uncontrolled generalized seizures may also be treated with this type of surgery. The operation may be done in two steps. The first operation partially separates the two halves of the brain, but leaves some connections in place. If the generalized seizures stop, no further surgery is done. If they continue, a second operation to complete the separation may be performed.
Multiple Sub-pial Transection
This operation also seeks to control seizures by cutting nerve pathways. It is used when the seizure focus is located in a vital area of the brain that cannot be removed. Instead of taking out the affected tissue, the surgeon severs the parallel connections between cells in the affected area.
Vagal Nerve Stimulator (VNS) Placement
A vagus nerve stimulator (VNS) is similar to a pacemaker. It is a small device implanted under the skin in the collarbone area. A wire (lead) connects the device to the vagus nerve, which is located in the neck. Our neurosurgical experts then create electrical signals that travel along the vagus nerve to the brain at regular intervals for the purpose of preventing the electrical brain activity that causes seizures.
This device is indicated for children in whom no specific seizure area can be found in the brain. In a 2011 NIH study, Over 50% of patients experienced at least 50% reduction in seizure burden with this procedure.
Functional Brain Mapping and Awake Craniotomy
Functional imaging techniques are used to map motor, sensory, language, and memory areas in neurosurgical patients with conditions as diverse as brain tumors, vascular lesions, as well as epilepsy. Functional brain mapping may be useful for both preoperative planning as well as decision making during the surgical procedure. The additional use of functional MRI and other non-invasive technologies adds to the menu of useful tools for pediatric epilepsy patients.
Since about 1999, awake craniotomoies have become more routine, even in young patients. This technique is useful for procedures necessitating brain mapping while avoiding any interference on the recording of important data from the use of anesthesia. Awake functional testing is the best method to direct navigation and test neurological functioning.
There are several non-surgical methods traditionally used for the treatment of epilepsy.
At least half of those newly diagnosed with epilepsy will become seizure-free with their first medication—if they take it regularly and as prescribed. The efficacy of these medications of course depends on the type and severity of the epilepsy. In some cases, medication may diminish but not completely control all seizure activity.
Many various types of anticonvulsant (also called antiepileptic) drugs are available. Some patients respond to one drug and some may need more than one. It may take several months before the best drug and dosage are determined. Patients are monitored throughout the medication process via blood tests.
A ketogenic diet, one which supplies the majority of calories from fat as opposed to glucose, mimics the body’s response to starvation by burning fat for energy. Scientists are not precisely sure why this diet prevents seizures, although it is being studied. Estimates vary from 10-30% of children who try it become seizure free, or almost seizure free. And over half who try it gain a 50% reduction in seizures. The remainder do not respond or are unable to tolerate the diet because of side effects.