Surgery for epilepsy may be an option when medications do not control seizures, a condition known as medically refractory epilepsy or drug-resistant epilepsy. The goal of epilepsy surgery is to eliminate seizures or limit their severity with or without the use of medications. There are two surgical categories: diagnostic and therapeutic.
Diagnostic Epilepsy Surgery
Diagnostic surgical procedures involve advanced monitoring technology when regular diagnostic methods do not identify the area of the brain where a patient’s seizures originate. Diagnostic procedures include stereoelectroencephalography (SEEG) and grid implantation.
SEEG: SEEG is a 3-dimentional method of diagnosing and localizing seizures by guiding electrodes on tiny wires into the brain through small holes in the skull. The electrodes can precisely detect the electrical activity deep within the brain and identify areas of the brain where seizures are originating.
These electrodes are visually guided with the ROSA robot. Using brain imaging and ROSA, surgeons can pinpoint the exact targets for safe and precise placement of the electrodes.
Patients who undergo the 3-4 hour minimally invasive SEEG procedure typically recover quickly but remain in the hospital for 1-2 weeks while they are monitored.
Grid Implantation: Sometimes patients need to have electrodes placed on the surface of the brain to help identify where seizures are originating. This involves placement of a thin silicone sheet with electrodes that can detect brain activity using electrocorticography (ECoG). The procedure is useful in planning a future epilepsy surgery. The electrodes remain in place for 1-2 weeks to record seizures and provide brain mapping. They are removed at a second surgery that also involves removal of the epileptic focus.
Therapeutic Epilepsy Surgery
Surgical procedures aimed at treating or curing seizures are known as therapeutic surgeries. They range from minimal access laser procedures, to operations involving implantation of seizure-stopping devices, to removal of seizure-causing tissue or disconnection of the seizure-causing region from the rest of the brain. These therapeutic surgeries are divided into three categories: resection, modulation and disconnection.
Resection
For patients whose seizures are coming from a specific area of the brain, an option may be to surgically remove or inactivate that area, a procedure known as focal resection.
Temporal lobe resection (also known as a temporal lobectomy) is a commonly performed procedure in which a portion of the temporal lobe of the brain where seizures originate is removed. Temporal lobe resection often results in a cure or significant improvement in the number and severity of seizures. Research shows 60-70 percent of patients are free of seizures following this surgery, which is typically well tolerated and requires a brief hospital stay. Surgery is approximately 4 hours and is followed by a 3-day hospital stay and a 4-6 week recovery period at home.
Another type of resection — laser interstitial thermal therapy (LITT) — uses a laser to inactivate epileptic tissue. This minimally invasive surgical treatment is for certain patients whose seizures originate in a small region of the brain.
During LITT, a tiny hole is drilled in the skull. An MRI-guided laser wire is then routed to the area of the brain where the seizures originate. The laser is turned on and directed toward the epileptic region to inactivate the seizures.
LITT is less invasive than other surgical treatments, offering patients a quicker, less painful recovery. The 6-8 hour procedure is performed under general anesthesia and the patient typically can leave the hospital the next morning.
Not all patients are candidates for LITT. It is important that a patient be evaluated at a center that offers both LITT and resection surgeries.
Modulation
Modulation involves the use of an electrical device to inactivate an area of the brain causing the seizure by sending small currents without removing or damaging the area. These procedures include vagus nerve stimulation (VNS), responsive nerve stimulation (RNS) and deep brain stimulation (DBS).
Vagus Nerve Stimulation (VNS): Vagus nerve stimulation (VNS) involves attaching an electrode to the vagus nerve in the neck. The electrode is connected by a lead to a small stimulator placed under the skin in the chest. The automatic stimulator provides a mild electrical signal on and off throughout the day. This stimulation reduces the ability of the seizure to spread and typically results in a substantial reduction in seizure frequency and severity.
VNS is used for the treatment of a wide variety of epilepsies and has low risks and minimal side effects. The procedure reduces the number and severity of seizures, but is not a cure for epilepsy. The best candidates are typically patients who are not candidates for epilepsy surgeries focused on stopping seizures altogether.
VNS surgery is performed under general anesthetic on an outpatient basis and typically takes 1-2 hours. Patients are able to return to daily activities within 1-2 weeks.
Responsive Nerve Stimulation (RNS): Responsive nerve stimulation (RNS) is a breakthrough treatment option for adult patients with partial onset epilepsy who have not benefitted from a minimum of two seizure medications and who are not candidates for resection.
The procedure features a battery-operated device, similar to a pacemaker, that monitors brain waves and responds to seizure-like brain activity 24 hours a day. The device is implanted within the skull and is connected to electrodes placed in the brain. When the electrodes detect the start of a seizure, small pulses of electrical current are delivered to that region of the brain to stop the seizure from developing or spreading. Patients must undergo detailed testing to determine where the seizures originate in the brain.
RNS surgery is performed under general anesthesia and typically takes 2-4 hours. Patients remain in the hospital for 1-3 days and are able to return to daily activities soon after discharge.
Deep Brain Stimulation (DBS): Deep brain stimulation (DBS) is a new treatment intended to reduce seizures. DBS involves implanting electrodes into a deep area of the brain known as the thalamus, which is responsible for sensory perception and regulation of motor functions. These electrodes are connected to a stimulating device typically placed under the skin in the chest. The pacemaker-like device sends electrical impulses to the thalamus to block the spread of seizures.
DBS surgery is performed under general anesthesia and typically takes 3 hours. Patients remain in the hospital for a brief stay and are able to return to daily activities after 4-6 weeks.
Disconnection
Disconnection surgery is intended to disconnect the epileptic region of the brain to stop the spread of seizures. The procedure reduces the severity of seizures but does not stop them altogether. Disconnection procedures include:
- Corpus callosotomy: Typically performed on patients with severe generalized epilepsy (seizures that involve both sides of the brain). The procedure involves splitting the main connection pathway between the two cerebral hemispheres (sides of the brain) to prevent seizures on one side from moving to the other side.
- Multiple subpial transection (MST): A procedure intended to stop seizures from spreading through the brain while preserving vital brain functions. MST involves a series of small surgical cuts in the brain tissue to disconnect seizure impulses.
Epilepsy Surgery at Michigan Medicine
The Michigan Medicine Epilepsy Surgery Program, part of a collaborative partnership between the Department of Neurosurgery and the Department of Neurology, has a national reputation for excellence in patient care, treatment and research.
For surgery, a multidisciplinary review of each patient — involving neurology, neurosurgery, neuropsychology, neuropathology, social work, speech and language and radiology — is conducted to determine which surgery, if any, would be most beneficial. Each patient under consideration for surgery participates in a thorough evaluation, which includes sophisticated testing and analysis, to determine if surgery is the best treatment option.
In some cases, surgery is not possible. Seizures may come from multiple brain areas, or the risk on brain function may be too high. In these situations, other options are available. New treatments for epilepsy are continually being developed and it may be possible to participate in an experimental trial of a new drug or other therapy.
Make an Appointment
To make an appointment to discuss treatment for epilepsy, contact our General Neurology Clinic at 734-936-9020.