Brainstem Associated Somatosensory Evoked Potentials and Response to Vagus Nerve Stimulation: An Investigation of the Vagus Afferent Network
Suresh H, Mithani K, Brar K, Yan H, Strantzas S, Vandenberk M, Sharma R, Yau I, Go C, Pang E, Kerr E, Ochi A, Otsubo H, Jain P, Donner E, Snead OC, Ibrahim GM.
Front. Neurol., 18 February 2022
https://doi.org/10.3389/fneur.2021.768539
A new #retrospective study by Suresh et al. 2022 examines how different characteristics of sub-cortical ulnar nerve somatosensory evoked potentials (#SSEP) may correlate with vagus nerve stimulation (#VNS) efficacy.
The study analyzed intraoperative (during VNS implantation) registrations of ulnar nerve SSEPs (used a measurement of brainstem circuity) from 7 children, 9.1-18 years old, with #focal drug-resistant epilepsy (#DRE). All patients had previously underwent epilepsy surgery with no effect (median duration between epilepsy surgery and VNS implantation: 3 years) and had a mean follow-up duration of 1.4 years.
The study found a negative association between the SSEP amplitude and seizure frequency. Hence, lower SSEP amplitudes might constitute potential biomarkers for VNS response. On the contrary, SSEP latency could not be related to seizure outcome.
To conclude, understanding the association of afferent brain stem connectivity and VNS efficacy are vital for unraveling the mechanism of action behind VNS Therapy, and patient selection for VNS.
Figure legend: The association (based on a Robust Multivariate linear fixed effects model) of ulnar nerve SSEP amplitude (left) and latency (right) with seizure frequency. The left graph shows a negative association between the SSEP amplitude and seizure frequency. The dashed line separates VNS responders from non-responders and * indicates p<0.01.
