Evidence is accumulating, however, to indicate that VNS may be effective and safe for many patients of all ages and for refractory epilepsy of many types.
Success Rates. Studies have reported that the procedure reduces seizures within 4 months by up to 50% and even more in many patients. Studies report that it has been effective for longer than 7 years.
Complications. Vagus nerve stimulation does not eliminate seizures in most patients and is still somewhat invasive. VNS can cause shortness of breath, hoarseness, sore throat, coughing, ear and throat pain, or nausea and vomiting. These side effects can be reduced or eliminated by reducing the intensity of stimulation. Some studies suggest that the treatment causes adverse changes in breathing during sleep and may cause lung function deterioration in people with existing lung disease. People who have obstructive sleep apnea should be cautious about this procedure. Turning off the VNS (for example before an MRI or surgery) may increase the risk for status epilepticus. (However, VNS may also be helpful for treating status epilepticus in some patients.)
Deep Brain Stimulation. An investigational neurostimulation approach called deep brain stimulation (DBS) targets the thalamus, the part of the brain that produces most epileptic seizures. Early results have shown some benefit. Researchers are also studying other implanted brain and nerve stimulation devices such as the responsive neurostimulator system (RNS), which detects seizures and stops them by sending electrical stimulation to the brain. A third investigational approach, trigeminal nerve stimulation (TNS), stimulates a nerve involved in inhibiting seizures.
Stereotactic Radio Surgery. Focused beams of radiation are able to destroy lesions deep in the brain without the need for open surgery. Sometimes used for brain tumors, stereotactic radio surgery is also under investigation for temporal lobe epilepsy and for seizures due to cavernous malformations. It may be used for patients when an open surgical approach is not possible because the location of the abnormal area is surrounded by delicate brain tissue.
Review Date: 01/28/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.