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Epilepsy Surgery

BIDMC Comprehensive Epilepsy Center

Beth Israel Deaconess Medical Center (BIDMC) is a preeminent clinical center in the United States for the diagnosis and treatment of patients with seizures. It is a Level 4 Comprehensive Epilepsy Center accredited by the National Association of Epilepsy Centers, which is the highest level of care available in the field.

Epilepsy services offered at BIDMC include: 

  • The ability to record video of the patients as well as their brain waves or electroencephalogram (EEG) during seizures (long-term video/EEG monitoring), including high-density EEG (HD-EEG)
  • High-resolution MRI imaging and functional MRI for brain mapping
  • Positron Emission Tomography (PET) scanning and Single Photon Emitted Computer Tomography (SPECT) for localization of seizure onset
  • Specialized neuropsychological testing
  • Phase 2 intracranial EEG monitoring
  • Minimally invasive stereotactic depth electrodes (stereoEEG or sEEG)
  • Subdural grid electrodes
  • Surgical resection of the seizure onset location including temporal lobectomy
  • Laser ablation, a minimally invasive treatment targeting the seizure onset location
  • Neurostimulation
  • Vagus nerve stimulation (VNS)
  • Deep brain stimulation (DBS)
  • Responsive neurostimulation (RNS)
  • Clinical trials including surgical trials (See Clinical Trials under the Menu Bar)
The epilepsy center is staffed by a team of board-certified neurologists who have had formal training in epilepsy and a board-certified neurosurgeon, Dr. Aronson, who completed dedicated subspecialty fellowship training in epilepsy surgery.

Each patient who enters the center receives individualized care during diagnosis and treatment. Patients are often referred to the BIDMC Comprehensive Epilepsy Center by another medical care provider such as a local neurologist. The epilepsy team works with the referring physician to coordinate care. Many patients can be managed with medications or alternative approaches such as specialized diets (ketogenic, low glycemic index therapy) in the outpatient setting. However, others with seizures not well controlled by medications will need admission to the hospital for further evaluation and testing.

Overall, medications work for about 70% of patients with epilepsy. When they do not work, epilepsy surgery is a standard option for some types of epilepsy. Of the 30% of patients whose seizures cannot be controlled by medications approximately half may be candidates for epilepsy surgery. The BIDMC neurosurgery team will review details of your specific epilepsy symptoms and help determine what surgery options would be recommended. The possible benefits and risks will be explained in detail and you must consent before any surgery is performed.

When Should a Patient Consider Epilepsy Surgery?

Surgery for epilepsy is usually considered when:

  • Anti-seizure medications do not control seizures
  • You cannot tolerate the side effects of anti-seizure medications
  • Seizures are frequent, severe, and debilitating
  • Surgery may also be considered if the seizures are caused by non-epileptic conditions such as a brain tumor or vascular lesion, such as an arteriovenous malformation (AVM) or cavernous malformation.

What is Epilepsy Surgery?

Epilepsy surgery is surgery on the nervous system to stop or reduce the number of seizures you are having and/or their severity.

Surgical approaches to manage seizures include:

  • Precisely implanting electrodes (wires) to record seizures from your brain
  • Removing part of your brain where seizures start
  • Using a laser to ablate (destroy) the precise location in the brain where seizures start
  • Disconnecting the two halves of the brain to stop the spread of seizures
  • Implanting a pacemaker-like device that sends electrical signals to block or disrupt seizure activity

What Tests are Done for Patients Considering Surgery?

Outpatient Management - Neurology

Patients will be seen in the outpatient setting by a neurologist who specializes in epilepsy. The initial visit includes a complete history and physical exam. Other tests such as electroencephalogram (EEG) and a brain imaging study such as a magnetic resonance image (MRI) may be requested prior to the visit. It is important for the provider to know what treatments have been tried in the past, and to bring previous medical records or have them sent ahead of time. Following the initial visit, additional testing may be recommended and scheduled, and medications may be adjusted.

Adult Inpatient video/EEG Monitoring (Phase I)

The inpatient video/EEG monitoring unit is part of the BIDMC Epilepsy Monitoring Unit located in the Rosenberg Building on the BIDMC West Campus.

  • Patients are admitted to a specialized monitoring room where a camera, and an EEG machine records brain waves and behaviors continuously for 24 hours a day.
  • The patient stays in the hospital as long as necessary to obtain the needed information, typically a few days.
  • Epilepsy medications will be decreased or stopped to allow a seizure to occur during this time.

Recording typical seizures is important in the diagnosis of epilepsy and for recommending treatment options. Nursing staff are immediately available and automated alarms are used to keep patients safe during seizures. This type of monitoring is done to record abnormal brain waves during typical seizures. Based on the pattern of abnormal activity the epilepsy team may learn about where seizures start in the brain. 

Special Diagnostic Tests

Magnetic Resonance Imaging (MRI)
MRI is useful in the diagnosis of epilepsy. It produces the best images of the brain and does not involve exposure to radiation. Typically, this test is done as an outpatient test, and a standard MRI for epilepsy takes about 40 minutes. The epilepsy team may recommend repeating an MRI even if you had one in the past to evaluate for any changes or to evaluate for findings that were not seen previously. There are constant improvements in MRI sequences used in epilepsy evaluations that make it possible to see abnormalities in the brain that may not be appreciated on prior or standard MRIs. Open MRIs create images with poor image quality, and are not recommended.

Positron Emissions Tomography (PET) scan
A PET scan uses a low-level radioactive tracer, and electroencephalogram (EEG) to show activity in the brain. The tracer is injected through your vein and will attach to glucose in the body. The images may show a decrease in glucose use in the area where seizures are starting.

Single Photon Emitted Computed Tomography (SPECT) scan
A seizure can lead to more blood flow in certain areas of the brain where the seizure begins. The SPECT scan measures blood flow to the brain through the injection of a radioactive tracer at the time of a seizure, followed by a CT scan. SPECT scans are most helpful when done at the beginning of the seizure, the “ictal” part of the seizure, and so this scan is called an “ictal SPECT.” Another injection can be done when a patient is not having a seizure called an “interictal SPECT.” These images are subtracted from each other to contrast the different brain states and can help locate the source of where the seizures are occurring.

Neuropsychological testing
This testing is a standard part of the pre-surgical evaluation which evaluates brain function and measures motor skills, language, and memory. The tests may take four to six hours to complete and are led by a neuropsychologist. This test can be helpful in locating the part of the brain that may be causing seizures, as well as giving information on the risks of surgery on your neurological functioning.

High-density EEG (HD-EEG)
This non-invasive study involves placing a net cap on the scalp with up to 256 electrodes to record brain function which lasts around 30 minutes.

Wada Testing
This test can localize areas of the brain that control language and memory function and is performed during an angiogram. An angiogram is a standard neuroradiology procedure where a catheter is placed in the arm or groin, and dye is injected into the arteries that go to the brain. One side of the brain (hemisphere) at a time is put to sleep with medication for a few minutes. Language and memory are then tested by a neuropsychologist.

How does the Team Decide What Surgery is Recommended?

Epilepsy Surgery Conference and Neurosurgery Appointment

If a patient is a candidate for epilepsy surgery their case will be discussed at a the BIDMC Epilepsy Center Surgical Conference. The members include neurologists, neurosurgeons, nurse coordinators, neuropsychologists, neuroradiologists, and electrodiagnostic technicians. If a patient has a neurologist at a different institution that provider is also able to participate in the conference in person or via teleconference.

At the conference, the team will review the patient’s medical history, seizure history, EEGs including Phase I video/EEG monitoring, imaging, and other testing. The team will then discuss and formulate a plan. The patient will be notified by their neurologist and an appointment will be scheduled with the neurologist and Dr. Aronson, the epilepsy neurosurgeon, to review the recommendation from the epilepsy surgery conference. Expected benefits and risks of the surgery will be presented to the patient who must consent prior to any surgery. If you have any concerns, at any point, please let Dr. Aronson know. Please plan to talk about any additional testing or consultations with Dr. Aronson. It is important to address your concerns at your initial visit so your doctor can order other consults or tests. 

Surgical Procedures for Epilepsy Management

Intracranial EEG (Phase 2 Monitoring)

In many cases the non-invasive testing does not pinpoint an exact location where seizures are starting or there may be more than one possible location. In these cases, placing electrodes into the brain to record seizures allows the epilepsy team to record from all of these potential locations and determine more precisely where in the brain the seizures are starting. There are two main surgical options for invasive EEG, stereoEEG, a minimally invasive option, and subdural grid/strip electrodes, which allow for detailed coverage of the surface of the brain. Due to safety concerns when electrodes are implanted in the brain patients must stay in bed or in a recliner chair for safety. Pain and nausea medications may be offered for comfort. During this admission a patient may be offered the option of participating in research studies. These are completely voluntary and do not affect your treatment. 

StereoEEG (sEEG)

This minimally invasive procedure involves placing electrodes precisely into brain regions where the team is concerned seizures might be starting. This surgery is done under general anesthesia. What happens during surgery? Given the need for sterility, typically much of the hair is cut using an electric clipper. A robot is used to align each electrode with the planned trajectory in to the brain. A poke is made in the skin and a 2.5mm hole is drilled in the skull. An anchor bolt is fixed to the skull to hold the electrode which is then placed into the brain. Typically, 10-16 electrodes are placed, with each electrode having 4-16 contacts for recording. This means there can be over 200 recording locations in the brain to detect seizures. At the end of the surgery a CT scan is obtained in the operating room to determine the exact placement of the electrodes and ensure there is no unexpected bleeding. 

Following surgery you will be awakened from anesthesia and brought to the post-anesthesia care unit (PACU). After about an hour you will be brought to the Neuroscience Intermediate Monitoring Unit (NIMU) where the electrodes are connected to the EEG equipment. Patients often have some discomfort at the electrode insertion sites, but are awake and interactive within a few hours of surgery. Typically, patients stay in the hospital for 1-2 weeks, but, rarely,  may stay up to 30 days until the necessary seizures are recorded. The team will keep you and your family informed daily of any findings and will discuss discharge timing as seizures are captured on the recordings.

The electrodes and anchors are removed in a brief procedure in the operating room prior to going home the following day. 

This is a minimally invasive procedure, but there are risks that will be discussed with you prior to surgery. These risks include, but are not limited to, bleeding including bleeding in the brain, infection, and failure to localize seizures. Rare risks include stroke, neurological damage, paralysis, and death.

Grid/strip subdural electrode placement 

This procedure requires a large incision and removing a piece of bone from the skull to place a grid electrode or strip electrode on the brain surface. This piece of bone is typically not replaced until after the video/EEG monitoring is complete. This approach, which is more invasive than stereoEEG, is used in select cases where it is important to have detailed coverage over a focused area of brain. For example, if there is a concern that seizures are arising near an area where speech function may be located, a grid electrode can be placed in the area. The team can then precisely map which electrodes are over the seizure onset location and which are over the speech area. This detailed map can then inform further surgical planning. After 1-2 weeks once the necessary seizures are recorded, the patient returns to the operating room for removal of the electrodes and replacement of the bone. What happens during surgery? Hair is clipped in the area of the planned surgery. A large incision is made and a large piece of the skull bone is removed and stored sterilely in the freezer. Grid electrodes are placed over the brain surface. The bone is left off but the skin is closed over the electrodes. A CT scan is performed after surgery to confirm the location of the electrodes and check for any bleeding.

Following surgery you are awakened in the operating room and then brought directly to the Neuroscience Intensive Care Unit (NICU). This intensive care unit is equipped to conduct frequent neurological assessments and monitor for seizures. Patients are often sedated or confused for the first day following surgery. The next day you will be moved to the Neuroscience Intermediate Care Unit (NIMU) and again connected to the EEG equipment.

The risks of subdural grid surgery are greater than stereoEEG. They include risks of bleeding and infection, including the risk of bleeding requiring surgery. Additional risks include failure to localize seizures, stroke, neurological damage, paralysis, and death. 

Functional mapping

The team can map brain function using these electrodes and determine brain regions important for functions such as speech/language, movement, sensation, and vision. The mapping is performed by delivering short durations of electrical current. Patients may be asked to perform a task during stimulation, such as speaking. If stimulation impairs performance of a task, the team then infers that the area of brain that was stimulated is important for that task.

Epilepsy Treatment Surgical Options

Resection Surgery

If seizures are arising in a particular lobe or region of the brain, and the risk to brain function is low with removing that area then a lobectomy (removing a lobe) or lesionectomy (removing a focal area of brain where the seizure is starting) may be offered. The most common resection surgery is an anterior temporal lobectomy, removing the amygdala, hippocampus, and outer portion of the temporal lobe. 

The surgery involves an incision in the skin and removing a piece of the skull bone. The portion of the brain is removed with the help of an operating microscope and an image guidance system for precise tracking of the surgery. After the resection is complete, the bone is replaced and held in place with small titanium plates and screws.

After surgery you will be cared for in the Neuroscience Intermediate Care Unit and stay in the hospital for 2-4 days. There may be pain in the region of surgery. Fatigue is common in the weeks after surgery. You may also experience seizures in the post-operative period as your seizures wind down. Risks of surgery: Dr. Aronson will review the risks of your planned surgery in detail, but in general the risks of resection include bleeding, infection, loss of vision in the peripheral visual field opposite the side of surgery (temporal lobectomy), and memory impairment (temporal lobectomy). Rare but major complications of surgery include stroke, paralysis or death.

Laser ablation

If the seizure onset area is deep in the brain, well localized, and the risk to brain function is low, then you may be offered laser ablation, a minimally invasive surgery that can precisely target this region. 

This minimally invasive surgery involves precise placement of laser fibers into the brain to the area where seizures start. This procedure is performed under general anesthesia in an advanced MRI procedure suite. The MRI is used for MR-thermography, a method of measuring temperature in the brain. This enables the neurosurgeon to precisely ablate (burn) the targeted area while avoiding damage to other regions of the brain. The incision and opening in to the brain are less than 3mm in diameter.

Typically, patients stay in the hospital for 1-2 days to recover. Most patients have minimal pain following the procedure, but may have headaches that continue for 2-3 weeks.

Corpus Callosotomy

The corpus callosum connects the two halves of the brain and a corpus callosotomy involves cutting this connection to prevent seizures that start on one side of the brain from spreading to the other side. No brain tissue is removed. This procedure can be done as an open surgery or by using minimally invasive laser ablation. Typically, patients stay in the hospital for a few days after surgery to recover.

Neuromodulation surgery

In certain cases, resection and ablation are not recommended.

For example:

  • The exact location of the seizure onset is uncertain
  • There are multiple areas of independent seizure onset
  • Seizures are starting in an area of the brain that is vital to function

In these cases, a neuromodulation procedure may be recommended. These surgeries involve implanting a device that uses electric current to treat seizures. There are three types of devices:

  • Vagus nerve stimulator (VNS)
  • Deep brain stimulator (DBS)
  • NeuroPace responsive neurostimulator (RNS)

Vagus Nerve Stimulator (VNS)

The vagus nerve originates from the brainstem and serves as a link between the brain and the body. VNS therapy can be used in addition to medications to decrease the number and severity of seizures. VNS therapy is not a drug and does not have the same side effects or interfere with other medications. It delivers periodic stimulations, typically every few minutes, to prevent the irregular electrical activity that causes seizures. The battery lasts 6-10 years and can be replaced through a minor surgical procedure 

The surgery is under general anesthesia. The VNS device has two components, a flexible wire (lead) placed around the vagus nerve in the left neck and a pulse generator (battery) in the left chest that controls the electric current. The VNS implant is completely under the skin. 

Most patients stay one night in the hospital. The device is initially off, and two weeks after surgery, it will be turned on by the neurology or neurosurgery team. Stimulation can cause voice changes or abnormal feeling in the throat while stimulation is being delivered. Complications are rare and include infection and hoarseness. These devices are made by Livanova and are programmable for MRI use. VNS support team member Jared Zanello jared.zanello@livanova.com Nurse case manager at Livanova: 888-867-7846 

Deep Brain Stimulator (DBS)

Deep brain stimulation involves placement of electrodes to a relay area of the brain called the thalamus. DBS can still be used even when the precise brain region where the seizure starts is uncertain. 

This procedure is done under general anesthesia. Typically, two electrodes are placed into the brain, one on each side, using intra-operative MRI or CT guidance. These brain electrodes are connected to flexible extension leads just behind the ear, which are tunneled under the skin to a pulse generator (battery) that is placed in the chest. All components of the device are under the skin. Typically, the entire device is implanted in one surgery. 

Patients stay in the hospital for one night. The device is initially off, and you will return to the clinic for programming about 2 weeks after surgery. The device is programmed to stimulate periodically, and most people do not feel any sensation when the electric current is being delivered. The battery lasts 3-5 years and is replaced through a minor surgical procedure. You can get imaging including MRI scans with this device. Speak to your neurosurgeon, or an industry device representative with any questions about precautions needed for other medical procedures or imaging. Medtronic industry support contacts: Sandrine Jabbour sandrine.jabbour@medtronic.com Kendra Simpson kendra.simpson@medtronic.com

NeuroPace Responsive Neurostimulator (RNS)

The NeuroPace RNS system is an advanced device that can detect seizure activity and trigger stimulation. Which can interrupt the abnormal electrical activity, preventing seizures and decreasing seizure severity. The device consists of up to four electrodes placed into the brain in the regions where seizures are starting or traveling to. The second part of the device is the pulse generator that is placed in the skull. 

The electrodes are precisely placed in to the target regions in the brain. Then, a small area of bone is removed and replaced with a titanium tray that holds the battery. The entire device is placed in the head region with no wires along the neck or chest. The surgery is performed under general anesthesia using precise targeting equipment and a CT scan at the end of the surgery which is used to confirm the location of the electrodes. The device is programmed to record brain activity but is not set to stimulate the brain initially. Most patients do not feel any sensation when the device is delivering stimulation.

Patients stay in the hospital for 1-2 days. Patients are given a laptop computer and wand to download brain recordings that are saved on the pulse generator and upload them to a secure cloud-based system. Your neurologist can then review these recordings and train the device to recognize seizure activity. The neurologist can program the device to deliver electrical current to interrupt seizures. Typically, this occurs about a month after surgery. The battery lasts around 10 years and can be changed in a minor surgery. The NeuroPace RNS is programable for MRI use. RNS Support team: 866-726-3876, https://www.neuropace.com

Scheduling Surgery

Our office will reach out to you to schedule your surgery, along with sending you a pre-surgical letter with information about the day of your surgery. A nurse from preadmission testing will call you a few days prior to surgery to confirm your surgery date, time, and provide you with parking instructions along with an arrival time. Please alert the nurse if you are on any diabetic medications, blood thinners, or medications to treat addiction.

Preparing for Surgery

You should stop taking aspirin and NSAIDs (Motrin, Ibuprofen, Advil, or Aleve) one week prior to surgery. If you are taking any blood thinning medications like Plavix, Coumadin (Warfarin), Eliquis (Apixaban), Xarelto, ticagrelor (Brillinta) you will need to contact either your cardiologist or your primary care provider for clearance and instructions on how to stop these medications for surgery. The night before surgery do not eat or drink past midnight. You may have a small sip of water in the morning with any pills you have been instructed to take the morning of surgery. You should continue taking all epilepsy medications as you usually do. 

Day of Surgery

We recommend parking in the Lowry Building Garage, 110 Francis Street, Boston, MA 02215 across from the Klarman Building. At your assigned arrival time go to the Klarman Building 111 Francis Street, Boston, MA 02215 on the 5th floor to check in at the front desk. You will be brought to the pre-operative area where you will change to a hospital gown. You will meet the anesthesia team and an IV will be placed. You will be taken to the operating room on a stretcher.

You will be asked to remove: 

  • All jewelry except your wedding band
  • Dentures or partials
  • Hearing aids
  • Contact lenses and eyeglasses
  • Hair pieces
  • Cosmetics and nail polish (typically remove the night before)

Post-Surgery Recovery

For instructions regarding post-surgery care at home please see Post-Surgery Care Guide under the "For Patients" tab. If you have any questions or concerns contact the neurosurgery team:

Neurosurgeon: Dr. Joshua Aronson, jaronson@bidmc.harvard.edu, Phone: 617-632-7246

Administrative Assistant: Moné Neville, Phone: 617-632-7246

Clinic Nurse: Kelly Goodall, Phone 617-632-0673