Epilepsy surgery can be especially beneficial to patients who have seizures associated with structural brain abnormalities, such as:
- benign brain tumors,
- malformations of blood vessels (e.g. arteriovenous malformations, venous angiomas, and cavernous angiomas)
How Does Surgery Treat Epilepsy?
Epilepsy surgery is particularly effective when seizures always originate in the same part of the brains.
Surgery may also help patients who experience frequent seizures that cannot be controlled with anti-epileptic drugs (AED). Epilepsy surgery can greatly reduce the number of seizures.
Epilepsy surgery focuses on the area of the brain where the seizures originate. Dr. Arno Fried explains more in his Q&A article on epilepsy. The operations generally involve either:
- the removal of epileptogenic tissue from the zone where seizures arise,
- an alteration in the brain, by interrupting the nerve pathways along which seizure impulses spread.
Surgery is considered only if the area of the brain, called the seizure focus, can be clearly identified, and its removal does not jeopardize any critical functions, such as movement or language. Extensive testing is conducted prior to any consideration of surgery in order to determine if that surgery is appropriate.
One consideration for epilepsy surgery is that the patient must have unsuccessfully tried at least a combination of two or more AEDs. These medically resistant patients – up 30 percent of epilepsy cases – are candidates for surgical evaluation. Studies show that outcomes improve the earlier surgery is performed, meaning surgery is being considered sooner as a treatment option.
Types of Brain Surgery for Epilepsy
During a treatment program, our experienced team collaborates to customize the surgical approach to each individual patient.
There is a variety of surgical procedures, which are explained in more detail below:
- Lobectomy and cortical resection is the most common surgery, which removes the seizure-producing area.
- Corpus callosotomy, which separates the nerve bridge that connects the two halves of the brain to confine an epileptic discharge to only one cortex and reduce seizures as a result.
- Multiple subpial transactions also aim to reduce seizures by cutting nerve pathways.
- Hemispherectomy, for cases that affect one whole hemisphere of the brain, such as the rare Rasmussen’s encephalitis.
- Vagal Nerve Stimulator (VNS) placement, an implanted device similar to a pacemaker that stops the brain activity that causes seizures.
- Neuropace, an alternative type of implanted device for non-focal seizures.
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.
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.
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.
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 craniotomies 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.
Epilepsy Surgery Recovery Time
Epilepsy surgery is a major neurosurgery. Some risk is associated with it and there is some mild discomfort afterward. The recovery period varies for each individual. The hospital stay also varies, depending on the specific procedure performed.
Most people can resume normal activities 2 to 8 weeks after epilepsy surgery.
Can Surgery Cure Epileptic Seizures?
Epilepsy surgery is measured by the level of improvement in seizures and quality of life. Adult studies of epilepsy surgery have shown that seizures can be greatly reduced or totally controlled in some cases, and many can stop AEDs. Pediatric studies also report that the majority of infants and young children show favorable outcomes in seizure control, and can also stop AEDs after surgery.
Success Rate After Epilepsy Surgery
It is critical for the patient and family to have realistic expectations of the results of the surgery. After surgery, some patients become completely seizure-free and some have no improvement at all.
Many people fall between these extremes, having fewer seizures or seizures that are less intense, or they require less medication. Most people who do become seizure-free after surgery must continue to take seizure medicines to prevent breakthrough seizures.
Although seizures may be greatly reduced or totally controlled following surgery, a number of patients report periods of depression during the adjustment period and it appears that the greatest benefit accrues to those whose seizures are completely controlled.