Epilepsy Surgery

Penn neurosurgeons provide the full breadth of surgical care for patients with epilepsy, including both open and minimally invasive procedures. Upwards of 1/3 of epilepsy patients have uncontrolled seizures despite treatment with multiple medications. For these patients with drug-resistant epilepsy, surgery can provide substantial relief from seizures and be life-changing.

Pre-surgical Work Up

Epilepsy patients at Penn are initially evaluated by the Penn Epilepsy Center, which includes not only neurosurgeons but also neurologists specializing in the treatment of seizures (epileptologists), radiologists, and psychologists. The goal of this evaluation is to identify the source of seizures in the brain using non-invasive tests. These tests can include the following:

• MRI
• Nuclear medicine studies (PET/SPECT scans)
• Magnetoencephalography (MEG)
• Scalp EEG
• Neuropsychological testing

Once the above data has been collected, patients’ cases are discussed at a multidisciplinary conference to determine the best next steps. Patients are then referred to neurosurgery for discussion of surgical procedures to either (1) gather even more information about where seizures are coming from in the brain or (2) treat the seizures.

Intracranial Electrode Recordings

Identifying the parts of the brain that generate seizures is easier if the electrodes (recording devices) are closer to these locations than the scalp. Intracranial electrodes can be placed in two different ways.

• Grids & Strips: Sheets of electrodes are placed over the surface of the brain through an opening in the skull.
• Stereoencephalography (sEEG): Depth electrodes are paced directly into the brain through tiny holes in the skull just a few millimeters in size. A robotic system assists with the precise placement of these electrodes.

Surgical Treatment of Epilepsy

The surgical treatment of epilepsy falls into two categories: resections/ablations and neuromodulation. Resections/ablations hold the potential for curing a patient of their epilepsy. Neuromodulatory therapies are designed to reduce the frequency of seizures when they arise from multiple areas of the brain. There are surgical therapies to consider for any patient with drug-resistant epilepsy.

Resections/ablations

These treatments include traditional craniotomies for removing lesions or abnormal parts of the brain that are causing seizures and laser interstitial thermal therapy (LITT).

• Open Craniotomies: Penn neurosurgeons utilize the most advanced technology available to maximize the safety and effectiveness of these open procedures. These technologies include neuro-navigation, intraoperative ultrasound, intraoperative MRI, and awake craniotomy techniques. 
• LITT: A laser catheter is inserted into the brain through a small opening in the skull just millimeters in size. Penn neurosurgeons employ intraoperative MRI guidance to ensure the accurate placement of the laser catheter. Intraoperative MRI is also used to monitor the temperature of the brain tissue when the laser is turned on to verify that the target area is ablated, and delicate parts of the brain are preserved.

Neuromodulation

Electrical stimulation can be used to modify the function of the brain. Over time, this stimulation can retrain brain networks to be less likely to generate seizures.

• Deep Brain Stimulation (DBS): Two electrodes (one on each side of the brain) are placed into a deep region of the brain called the thalamus, which is similar to Grand Central Station in that it is connected to many other parts of the brain. The electrodes are connected by wires under the skin to a battery that is placed in the chest, similar in location to a pacemaker for the heart. Unlike DBS for movement disorders like Parkinson's disease, the effect of DBS is not immediate and can take months of years to develop.
• Responsive Neurostimulation (RNS or Neuropace): Electrodes are placed in regions of the brain that cause seizures and connect to a battery device that sits in the skull itself. The device stimulates the brain when it detects a seizure, which may stop the seizure or eventually retrain the brain to become less likely to have seizures.
• Vagus Nerve Stimulator: An electrode is wrapped around the vagus nerve in the neck and connected to a battery in the chest. Stimulation of the vagus nerve has been shown to decrease the frequency of seizures in certain epilepsy patients.