Figure 1: Visualase MRI-guided laser ablation of a target lesion at the amygdala and hippocampus. The left image shows live temperature in the target area; the right image is
a post-treatment T1-MRI + C of the ablated lesion. Image: Timothy Lucas II, MD, PhD.
Epileptologists from the departments of Neurosurgery and Neurology at Penn Medicine have recently introduced a collection of innovative technologies to better treat patients with drug-resistant epilepsy (defined as having seizures refractory to two or more seizure medications).
Medications can control seizures in about two-thirds of persons with epilepsy. The approximate one-third of patients with drug-resistant epilepsy experience a significant impact on quality of life, elevated risk of injury and increased risk of sudden unexpected death.
For patients with drug-resistant epilepsy, the options available at Penn Medicine include resective surgery and vagus nerve stimulation (VNS), as well as newer approaches. Surgery has the potential to cure or decrease seizure frequency when an epileptogenic focus can be identified. Intracranial EEG evaluations are often performed to identify seizure foci prior to resection. Vagus nerve stimulation is an option for patients who are not resective surgical candidates. VNS reduces the frequency and intensity of seizures, but is not curative.
The new technologies available to treat patients with refractory epilepsy at Penn Medicine include Visualase® MRI-Guided Laser Ablation and the NeuroPace RNS® System. Penn neurosurgeons and neurologists have collaborated to introduce these advanced modalities, which can better identify the source of seizures and treat or prevent seizures in patients with drug-resistant epilepsy.
Figure 2: Post-implant lateral and PA skull X-ray showing placement of three NeuroPace Cortical Strip Leads across the central sulcus. The inferior leads are connected to
the neurostimulator; the superior lead is not connected. The neurostimulator battery, integrated circuits and connector assembly are seen in both images.
Visualase MRI-Guided Laser Ablation Technology
Visualase laser ablation is a technology that combines a saline-cooled 15 watt, 980-diode laser probe (less than 2 mm diameter) with real-time MRI-guidance to induce interstitial thermal ablation of targeted lesions in the brain (Fig. 1). Pre-treatment images are acquired for target planning and an intraoperative temperature map is used to minimize damage to healthy tissue. Open surgery is not required. Patients may be awake during therapy and are usually discharged the next day.
NeuroPace RNS System
The NeuroPace RNS System (Fig. 2) is a programmable responsive neurostimulation system designed to detect and treat abnormal electrical activity in the brain. The System employs brief bursts of electrostimulation from an RNS neurostimulator implanted in the cranium to abort pre-seizure EEG patterns programmed by physicians. Structural MRI, fdg-PET and ictal scalp EEG recordings cannot identify the epileptic network in many refractory epilepsy patients having pre-surgical evaluation.
Figure 3: Intracranial EEG data from subject with non-lesional right temporal lobe epilepsy. Hippocampal and
amygdala subfield localization of the right amygdala depth electrode are seen in upper left insert, which illustrates subdural electrodes on the right hemisphere. The electrode where seizure originates is identified to be in CA1 (shown in A-D).
Intracranial EEG (iEEG)
For these patients, intracranial EEG (iEEG) hybrid depth and subdural grid and strip electrodes (Fig. 3) are required for long-term, high-resolution monitoring and mapping of the cortical surface. iEEG allows Penn clinicians to map the epileptic network and cortical function, making safe resective surgery with a goal of cure possible for many drug-resistant epilepsy patients.
Epilepsy Monitoring Unit
The Epilepsy Monitoring Unit features a modern eight-bed unit with video EEG for the evaluation of individuals who are candidates for surgery and for differential diagnosis of "spells." Epilepsy patients are admitted for long-term monitoring (anywhere from 3 to 7 days) and are typically weaned from medications to determine the cause and origin of seizures. Some patients undergoing this treatment require intracranial electrode monitoring. A number of other diagnostic tools may also be used to locate the origin of the seizures, including MRI, MEG, EEG, SPECT and PET.
Visualase®; 2015 Medtronic, Inc. Minneapolis, Minnesota.
NeuroPace RNS® System; 2015 NeuroPace, Inc. Mountain View, CA.
Access
Penn Neuroscience Center
Perelman Center for Advanced Medicine
South Pavilion, 2nd Floor
3400 Civic Center Boulevard
Philadelphia, PA 19104
Pennsylvania Hospital
330 South 9th Street
Philadelphia, PA 19107
Penn Medicine Bucks County
777 Township Line Road
Yardley, PA 19067
Published on: March 15, 2019
References
1. Azarion AA, Wu J, Pearce A, Krish VT, Wagenaar J, Chen W, Zheng Y, Wang H, Lucas TH, Litt B, Gee JC, Davis KA. An open-source automated platform for three-dimensional visualization of subdural electrodes using CT-MRI coregistration. Epilepsia 2014;55:2028-2037.
About the Penn Epilepsy Center
The Penn Epilepsy Center (PEC) is comprised of an interdisciplinary team of clinicians dedicated to advancing the fields of invasive neurophysiology, neuroimaging and neurosurgery for patients with
epilepsy in all of its forms. The PEC offers state-of-the-art diagnostic techniques, medical treatments, surgery and support to patients with epilepsy.
Penn Faculty Team
Perelman Professor of Neurology
Professor of Neurology in Neurosurgery
Division Chief, Epilepsy
Associate Director, Center for Neuroengineering and Therapeutics
Director, Penn Epilepsy Center
Associate Professor of Neurology at the Hospital of the University of Pennsylvania
Associate Professor of Clinical Neurology