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In Sight: Two Stage Surgery for Epilepsy

In Sight: Two Stage Surgery for Epilepsy 150 150 Abbie Miller

Surgery proves to be a viable option for patients with medically refractory epilepsy.

Childhood onset epilepsy affects 1 percent of children worldwide. About 25 to 30 percent of these patients will have medically refractory epilepsy, continuing to have seizures despite using two or more antiseizure medications. Options for this group of patients include intercranial epilepsy surgery, Vagus nerve stimulator (VNS) insertion, Ketogenic diet and drug trials. It is increasingly recognized that epilepsy surgery may dramatically improve the quality of life for these children in some cases and is the only potentially curative option.

 

Single or Two Stage Epilepsy Surgery

Single stage surgery is performed if imaging and phase 1 data demonstrate concordant findings suggestions lesional epilepsy. It involves resection of the lesion and electrocorticography to ensure all abnormal tissue is removed. Alternatively, diffuse pathology affecting a cerebral hemisphere may warrant hemispherectomy/hemispherotomy. Two stage surgery is performed when phase 1 monitoring contains discordant data or inadequately localizes the epileptigenic zone. This approach allows identification of the epipleptigenic zone, potential adjacent areas of abnormal electrical activity and nearby eloquent functional areas of the brain. Eloquent areas of cortex are localized by cortical stimulation mapping.

Illustration of electroencephalography (EEG) monitoring in a hospital setting. A child lies in a hospital bed while a clinician places electrodes on the scalp. Multiple electrode leads connect the scalp electrodes to an electrode box beside the bed. An enlarged inset shows a close-up of an EEG electrode attached to the skin, with labels explaining that the adhesive backing holds the electrode in place and that signals are sensed through the electrode's active contact area. Labels identify the electrode, electrode leads and electrode box.

Phase 1 Monitoring

Phase 1 is an extensive presurgical workup that helps the neurologist localize the seizures and determine the patient’s candidacy for epilepsy surgery. This involves multiple-day inpatient admission, prolonged video EEG and intended observation of at least three typical seizures. The patient also undergoes imaging sequences including positron emission tomography (PET), single photon emission computed tomography (SPECT) and epilepsy protocol MRI, in addition to outpatient neuropsychology testing. Potential surgical candidates and all of their clinical and radiographic data are discussed thoroughly at the weekly Epilepsy Surgery Conference. Depending on the results from the Epilepsy Surgery Conference, single stage epilepsy surgery, two stage epilepsy surgery, or palliative surgical options (corpus callosotomy or VNS insertion) may be offered.

Stage 1 Surgery

During stage 1 surgery, craniotomy and dural opening allow exposure of the cerebral cortex. Working in collaboration, the neurosurgery and neurology teams identify sites of coverage and access for subdrual grids, strips and/or depth electrodes. Intraoperative electrocorticography confirms adequate placement and signals of intracranial EEG electrodes. The electrodes are safely secured in place as the dura is subsequently

During stage 1 surgery, craniotomy and dural opening allow exposure of the cerebral cortex. Working in collaboration, the neurosurgery and neurology teams identify sites of coverage and access for subdrual grids, strips and/or depth electrodes. Intraoperative electrocorticography confirms adequate placement and signals of intracranial EEG electrodes. The electrodes are safely secured in place as the dura is subsequently closed.

Close-up intraoperative photograph of an exposed section of the brain during neurosurgery. Multiple rectangular electrode strips with blue guide lines are placed across the brain’s surface and secured around the surgical opening. Thin wires extend from the electrodes to collect electrical activity for monitoring and mapping brain function. Surgical drapes and instruments surround the operative field.

Phase 2 Monitoring

During phase 2 monitoring, continuous, long-term intracranial EEG is monitored for approximately one week to identify abnormal electrical signals before and during seizures. Frequently, antiepileptic medications are weaned to help capture typical seizure activity (at least three events). Near the conclusion of phase 2 monitoring, corticostimulation mapping may identify eloquent functional areas that will help surgical planning. Additional discussion during the Epilepsy Surgical Conference solidifies the surgical plan.

Medical illustration of prolonged video EEG monitoring in a hospital room. A child rests in a hospital bed wearing a head wrap with attached electrode leads connected to an EEG monitoring system. A caregiver sits beside the bed using a laptop, while a clinician sits nearby. Labels identify the video camera, EEG monitor, electrode leads, and head wrap. An inset image shows a real-time monitoring station displaying the patient on video alongside EEG brain-wave recordings, illustrating how EEG technologists and epileptologists continuously monitor prolonged video EEG data.

Stage 2 Surgery

Stage 2 surgery typically involves grid-based resection of the epileptigenic zone with careful preservation of adjacent eloquent functional areas. Intraoperative electrocorticography confirms the absence of any residual abnormal electrical activity or identifies additional sites requiring resection. Post operative recovery Following surgery, patients are monitored closely in the pediatric intensive care unit. Once stable, they are transferred to the neurosurgery floor for further recovery. Often patients are discharged to home. However, if needed, transfer to Inpatient Rehabilitation allows for prolonged recovery.

Close-up intraoperative photograph of the exposed brain during epilepsy surgery. A transparent electrode grid containing dozens of numbered contact points is placed directly on the brain’s surface to map and monitor electrical activity. Numerous white wires extend from the grid and cross the surgical field, while additional strip electrodes with blue guide lines are positioned around the edges of the opening. Surgical drapes and monitoring leads surround the operative site, illustrating invasive brain mapping used to identify seizure-producing regions and critical functional areas of the brain.
Intraoperative photograph showing an exposed area of the brain during epilepsy surgery. Several white strip electrodes marked with blue lines are positioned around the surgical opening on the surface of the brain. Thin monitoring wires extend from the electrodes across the surgical field. The brain’s blood vessels and tissue are clearly visible, and sterile surgical drapes surround the operative site. The image illustrates placement of cortical electrodes used to monitor and map brain activity during seizure evaluation.

A Patient Perspective: Stopping Gaige’s Seizures

If he stayed up late, Gaige had a seizure. When he got too excited about an upcoming family event, the arrival of Christmas or his birthday, he had a seizure. If he exerted himself while playing basketball, he had a seizure. Read how the epilepsy surgery team at Nationwide Children’s used two stage epilepsy surgery to help.

 

Graphic: Christina Ullman, Ullman Design

Sources: Jonathan A. Pindrik, MD, pediatric neurosurgeon, Nationwide Children’s Satyanarayana Gedela, MD, pediatric neurologist, Nationwide Children’s

About the author

Abbie (Roth) Miller, MS, MWC, is a passionate communicator of science. As the manager of medical and science content at Nationwide Children’s Hospital, she shares stories about innovative research and discovery with audiences ranging from parents to preeminent researchers and leaders. She is a Medical Writer Certified®, credentialed by the American Medical Writers Association, and received her masters of science in Health Communication from Boston University.

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