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AAN Update of VNS Treatment for Epilepsy

Guideline Watch |
December 3, 2013

AAN Update of VNS Treatment for Epilepsy

  1. Robert C. Knowlton, MD, MSPH

New AAN guidelines on vagus nerve stimulation for treatment of epilepsy address important questions of indication, efficacy, and adverse effects.

  1. Robert C. Knowlton, MD, MSPH

Sponsoring Organization: American Academy of Neurology

Background and Objective

In 1997, the U.S. Food and Drug Administration (FDA) approved vagus nerve stimulation (VNS) for treatment of partial epilepsy in patients older than 12. An American Academy of Neurology (AAN) Technology Assessment in 1999 concurred with the evidence supporting the indication but also elaborated that VNS use should be directed at patients who are not surgical candidates (Neurology 1999; 53:666).

Based on a review of published data since 1999, this guideline update was aimed at addressing several issues important in clinical practice regarding use of VNS.

Key Points

Evidence was at best Class III to provide information to answer only some of the questions addressed.

  • Data supported Level C recommendations for VNS to be considered as adjunctive treatment for children with partial or generalized epilepsy, patients with Lennox-Gastaut syndrome, and (with magnet-activated VNS) to abort partial seizures with aura symptoms.

  • Two Class III studies supported a Level C recommendation that VNS may be progressively effective over multiple years (approximately 7% increase in responder rate over 2 years in one study).

  • Weak evidence was available to support a recommendation that VNS is possibly effective for mood improvement in adults with epilepsy.

  • Studies available regarding rapid cycling versus standard stimulation settings all showed no significant difference in efficacy.

  • Data for questions of new safety concerns or differences in adverse events between children and adults were very limited. Comparing three Class IV studies of VNS in children to the clinical trial data in adults acquired for FDA approval, infection risk at the VNS site may be higher in children, (odds ratio, 3.4; 95% confidence interval, 1.0–11.2).

Comment

This update was needed not just because of the time elapsed since the last assessment but, more importantly, because vagus nerve stimulation is widely used today far outside of its indication for adjunctive treatment in adults with partial epilepsy — in particular in children and in those with symptomatic generalized epilepsies. Yet, as the authors note, more investigation is needed regarding efficacy in medically refractory idiopathic generalized epilepsies, a particularly challenging condition.

Important issues not addressed are cost-effectiveness and the known negative impact of VNS on quality of magnetic resonance imaging available to patients with or without the stimulator remaining implanted, especially relative to the impact on presurgical epilepsy evaluation. Even in nonlesional neocortical epilepsy, the chance of seizure freedom — the most important variable by far in quality-of-life outcomes — is much higher after surgery than with VNS treatment. Whenever VNS is discussed for partial epilepsy, clinicians must consider whether a patient is a reasonable candidate for resective epilepsy surgery and must counsel patients and obtain their preference for possible surgery.

  • Disclosures for Robert C. Knowlton, MD, MSPH at time of publication Grant / research support NIH-NINDS Leadership positions in professional societies Southern Epilepsy and EEG Society (Treasurer)

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