Patients with Drug-Resistant Epilepsy May Benefit from Advanced Diagnostic and Surgical Procedures

As many as 70 percent of epilepsy patients can be controlled with anti-seizure medications; however, the remaining 30 percent are thought to have drug-resistant epilepsy with poorly-controlled seizures. The addition or substitution of medications usually does not significantly improve outcomes in this population; in one study, as few as 1 percent of patients receiving a third medication for epilepsy were seizure-free.¹

The Comprehensive Epilepsy Center at Penn State Milton S. Hershey Medical Center, designated as a level IV epilepsy center by the National Association of Epilepsy Centers (NAEC), specializes in the treatment of complicated epilepsy cases, and coordinates multi-disciplinary care for the diagnosis, evaluation, and treatment of both adult and pediatric epilepsy. Medical Director Jayant Acharya, MD, points out that since the facility also participates in both surgical and medical research, eligible patients may have access to pre-approval medications through participation in clinical trials.

If results of both standard and ambulatory EEG prove inconclusive, more extensive monitoring takes place in the inpatient Epilepsy Monitoring Unit (EMU), where patients are monitored by a team of experts while various tests are performed, from noninvasive video-EEG monitoring up to invasive intracranial monitoring with subdural or intracerebral depth electrode placement.

In addition to establishing a correct diagnosis, the EMU conducts a variety of presurgical tests to determine the location of seizure activity, thus allowing neurosurgeons to proceed with temporal lobectomy or more complex surgery as indicated by test results. One such test is stereoelectroencephalography (sEEG), which involves 3D placement of electrodes into deep structures in the brain, and used when seizures are thought to originate from the deep regions of the brain. Subdural electrodes are more suitable when the seizure focus is closer to the surface of the brain. In one study, sEEG monitoring allowed surgeons to localize the epileptic focus in 96 out of 100 patients; of the fifty-three patients who completed a twelve-month follow-up, 62.3 percent were seizure-free.²

Epilepsy surgical options vary, and include vagus nerve stimulation, surgical resection and lobectomy, “awake” surgery (with a neurologist present), and procedures such as NeuroPace® responsive neural stimulation (RNS), indicated for patients with medically refractory epilepsy who experience no fewer than two disabling seizures per month. In RNS, the surgeon implants a neurostimulator, depth leads, and cortical strip leads, and then programs electrical stimulation and tracks brain activity from a computer. This technology is limited to use by level IV epilepsy centers, and has been associated with a 50 percent seizure reduction in more than half the patients who undergo the procedure.³

Once patients are stabilized, most return to the care of their community-based neurologists. Surgical Director Michael Sather, MD, comments, “At the center, our epilepsy neurologists have subspecialty training and a clinical focus in seeing mainly patients with epilepsy, rather than other neurological conditions. This provides evaluation and treatment to patients with complex clinical pictures that may not be fully understood within the traditional boundaries of neurology.”

References

1. Kwan P, Brodie M. Early Identification of Refractory Epilepsy. N Engl J Med. 2000;342:314-619.
2. Gonzalez-Martinez J, Bulacio J, Alexopoulos A, Jehi L, Bingaman W, Najm I Stereoelectroencephalography in the “Difficult to Localize” Refractory Focal Epilepsy: Early Experience From a North American Epilepsy Center. Epilepsy Currents. 2013;13(2):88–89.
3. Neuropace. APL 2013-0002 Rev 1 Rev. Date: 11/2013.