Vagus nerve stimulation for epilepsy: a review

Area of Science:

• Neurology
• Neurosurgery
• Epileptology

Background:

• Vagus nerve stimulation (VNS) is an established epilepsy treatment involving implanted electrodes stimulating the left vagus nerve.
• The precise mechanism of action for VNS in epilepsy remains unknown despite observed changes in brain electrophysiology, metabolism, and neurochemistry.

Discussion:

• Clinical trials for VNS face challenges in blinding due to surgical requirements and sensory feedback.
• Parallel design, controlled trials have successfully demonstrated the efficacy and safety of VNS in adults with medically intractable partial seizures.
• Efficacy, though modest, shows progressive improvement over time, with approximately 50% of patients achieving a 50% seizure reduction after 18 months.

Key Insights:

• VNS demonstrates modest but progressive seizure reduction, with about 50% of patients experiencing significant improvement after 18 months.
• Common side-effects like voice hoarseness and coughing are intensity-dependent and typically habituate.
• Controlled trials focus on refractory partial seizures in adults, but post-marketing data suggests efficacy across various epilepsy types and age groups.

Outlook:

• Further research may elucidate the unknown mechanisms of action for vagus nerve stimulation.
• Optimizing stimulation parameters could enhance VNS efficacy and patient tolerance.
• Expanded clinical investigation into VNS for diverse epilepsy populations and age groups is warranted.