Implantable Devices Could Be More Effective Than Antiepileptic Drugs in the Long Term

New Devices May Become Available in the Future
Two newer devices that have not received regulatory approval may one day broaden neurologists' options for brain stimulation in epilepsy. One is a responsive neurostimulator system that is implanted into the skull and connected to electrodes that can be implanted bilaterally in the brain. The device administers high-frequency stimulation if it detects abnormal brain activity.

The system continuously records intracranial EEG or electrocorticography and, when it detects a seizure or abnormal activity, applies a single pulse of stimulation as many as five times. The patient is required to interrogate the device daily, download the data, and send it to his or her neurologist.

In a pivotal double-blind, controlled study, the system had an overall mean rate of seizure reduction of 37%, compared with placebo. The rate increased to more than 40% during the last month of treatment. As with VNS and DBS, efficacy may increase slightly over time.

The percentage of seizure-free patients at two years was about 17%. The system had a low explantation rate and low rates of infection, pain, and hemorrhages. The number and location of epilepsy foci did not affect the system's efficacy, nor did previous epilepsy surgery. The system is expected to be approved and commercially available in the near future.

Another new machine, a seizure risk-alerting device implanted in the chest, records, analyzes, and archives real-time ambulatory intracranial EEG data from 16 contacts. The device gives the patient a daily reading based on his or her EEG data, and the individual can alter his or her behavior or apply acute treatment as necessary. A red light indicates that seizures are likely and suggests that the patient should remain in a safe place. A white light suggests that the patient is at moderate risk for seizures, and a blue light indicates that the patient can take part in his or her normal activities. A study of 15 patients in Australia suggested that the device was safe and useful.

Future Device Trials Could Improve Epilepsy Management
Future studies that investigate combinations of medication, implantable devices, and callosotomy would help improve the management of epilepsy. "You may even think about combining devices," said Dr. Jobst. "There's no real reason why you couldn't have a VNS and a brain stimulator."

With more funding, investigators could develop more effective devices that offer greater improvements in seizure control. Further examination of current devices could improve treatment, as well. Researchers should determine which epilepsy syndromes respond best to which devices, said Dr. Jobst. "Hopefully, this will make more patients seizure-free."