Authors :
Presenting Author: Surya Suresh, MBBS – The University of Texas Health Science Center at Houston
Ramya Talanki Manjunatha, MBBS – Research Associate, Neurology, The University of Texas Health Science Center at Houston; Yash Vakilna, M.S. – Research Associate, Neurology, The University of Texas Health Science Center at Houston; Ganne Chaitanya, M.D – Resident, Neurology, The University of Texas Health Science Center at Houston; Yosefa Modiano, PhD – Assistant Professor, Clinical Neuropsychology, The University of Texas Health Science Center at Houston; Sandipan Pati, MD – Associate Professor in Neurology, Neurology, The University of Texas Health Science Center at Houston
Rationale:
Responsive Neurostimulation (RNS) has emerged as a preferred therapeutic option for drug-resistant multifocal inoperable epilepsy (DRE), showcasing notable success with conventional high-frequency stimulation ( >100 Hz) employing five short bursts of 100 milliseconds (ms) each in response to seizure detection. Nevertheless, in cases where the outcomes fall short of optimal, there is a pressing need to explore novel stimulation parameters that can provide superior seizure control. In response to this clinical imperative, we present a study aimed at investigating the seizure and cognitive outcomes associated with cortical long-bursting responsive neurostimulation ( >1000 ms) in individuals with DRE. By evaluating these alternative stimulation parameters, we aim to determine its potential for enhancing seizure management in this patient population.
Methods:
This single-center retrospective study included patients with DRE who underwent RNS therapy and had suboptimal seizure outcomes (< 30% reduction in seizures) and required a modification of the stimulation parameters, specifically by increasing the burst duration to over 1000 ms. Patient selection was limited to those with a follow-up duration exceeding four months post-stimulation trial with long bursts, ensuring an adequate assessment period. Importantly, no changes were made to the seizure detection parameters following the switch to longer burst duration. We investigated the impact of stimulation duration in terms of seizure and cognitive outcome within each patient. The evaluation comprised the following metrics: median percent change in a) patient-reported seizure frequency and b) daily histogram of long events. The responder rate (the percentage of patients with a ≥ 50% reduction in seizure frequency) was also estimated. Finally, cognitive changes were assessed by neuropsychological test batteries.Results:
A total of 16 subjects comprising eight (50%) males and eight (50%) females (mean [SD] age, 37 [16] years) with suboptimal response to RNS received an adjustment of burst duration from 100ms to >1000 ms (N= 5000[12], 3600[1], 2000[1] and 1000[2] ms). Background anti-seizure medication use for the patients ranges from two to six, with a mean of 4.1[SD:1.6]. During an average follow-up of four months [SD: 2], 5 of 16 (31.25%) patients who received long-bursting RNS achieved a 50-90% reduction in seizure frequency, whereas four of 16 (25%) patients showed a 30-45% reduction in seizure frequency. Most significantly, there were no discernible adverse events or cognitive changes.Conclusions:
The study demonstrates that implementing cortical long bursting responsive neurostimulation, with durations lasting up to 5000 ms, can significantly reduce seizure frequency among individuals with DRE. Importantly, this stimulation parameter adjustment was well-tolerated, with no observed side effects or worsening of cognition. However, given our limited sample size, the conclusions should be considered preliminary, serving as a basis for future research.
Funding: N/A