Cardiac-based vagus nerve stimulation reduced seizure duration in a patient with refractory epilepsy

A novel vagus nerve stimulation (VNS) device was recently approved in Europe which rapidly detects increases in heart rates (HR) and applies an additional stimulus if HR-increases exceed a given threshold. The effects of HR-triggered VNS-pulses on seizures were not reported yet under controlled conditions. Here, we quantified the effects of HR-triggered VNS-pulses on the seizure duration in one patient.

The novel VNS device was implanted in a 29-year old man with refractory epilepsy. After implantation, the patient underwent video-EEG telemetry for 68h with no changes in anticonvulsant drugs. On the first day the patient only received sham-stimulation. During the following 46h HR-related VNS-stimulation was set to 2mA. Seizure duration was determined based on clinical signs.

Twelve stereotypical seizures were recorded (six during sham- and six during the active stimulation). The VNS device recognised a total of 139 events as a seizure and correctly identified 11 seizures. The HR-triggered VNS-stimulation significantly reduced the total seizure duration from 33.2±4.8s to 26.5±5s and the remaining seizure duration after the onset of the extra-stimulation from 27.8±4.3s to 16.2±3.2s. With the given configuration in this patient, sensitivity and specificity of HR-based seizure-detection amounted to 92% and 13.5%, respectively.

This case illustrates that VNS-stimulation in response to seizure-related HR-increases is able to significantly reduce seizure duration. Despite the limitations of our case, its promising results should prompt larger studies to confirm the clinical benefit of this novel device.