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19-09-2011 | General practice | Article

DBS has meaningful and lasting effects in epilepsy


Free abstract

MedWire News: Deep brain stimulation (DBS) has proved to significantly reduce the frequency of disabling partial seizures in patients with drug-refractory epilepsy in a randomized, blinded trial published in Neurology.

All 191 patients in the trial were implanted with a programmable neurostimulator connected to one or two leads that were placed according to the seizure focus. One month after implantation, the patients were randomly assigned to have active treatment, so that the neurostimulator was programmed to detect abnormal electrocorticographic activity and then give stimulation, or to have control treatment, involving sham programming of the neurostimulator.

During the next 12 weeks, the number of seizures among patients in the active treatment group was 37.9% lower than during the 12-week period leading up to implantation. The control group experienced a 17.3% reduction; the difference between the two groups was statistically significant.

The number of seizure-free days increased between the first and the third months of study in the active treatment group, but fell in the control group.

After the blinded evaluation period, all patients entered an open-label phase, in which all had their neurostimulators programmed. By 1 year after implantation, 43% of all patients had at least a 50% reduction in seizure frequency, as had 46% of those who had 2 years of follow-up. At the time of most recent analysis, 7.1% of patients had been seizure free over the most recent 3-month period.

"Given the long duration and severity of their epilepsy, and many treatment failures, this sustained seizure reduction with responsive stimulation is clinically meaningful," writes Martha Morrell (NeuroPace Inc., Mountain View, California, USA), on behalf of the RNS System in Epilepsy Study Group.

The patients, who were aged 34.9 years on average, had epilepsy lasting an average of 20.5 years, with an average of 1.2 seizures per day. They had tried an average of 2.8 anti-epileptic drugs and a third had undergone surgery for epilepsy.

The serious adverse event rate during the first 28 days after implantation was 12%, including events not related to the device. This was not worse than the prespecified comparator rate of 15% derived from the literature for implantation of intracranial electrodes. The event rate over the first 84 days was 18%.

Adverse events included intracranial hemorrhage, infection, implant site pain, and headache. Six patients died, four of whom had sudden unexpected death in epilepsy. One died from lymphoma and one, who had a history of depression, committed suicide.

Editorialist Robert Fisher (Stanford University School of Medicine, California, USA) said that "the present study is a landmark advance and adds to the recent thalamic stimulation trial in a mutually supportive way."

He said that DBS is no longer just "a possible treatment for epilepsy," but is now "a treatment for epilepsy."

Fisher concluded: "Patients with medication-resistant partial and secondarily generalized seizures, families, and clinicians eagerly await the opportunity to utilize this new therapy."

By Eleanor McDermid

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