Responsive Neurostimulator System (RNS)

Responsive Neurostimulator System

RNS (Responsive Neurostimulator System) - Neuropace

The RNS is an implant device that consists of a generator and wires that terminate in depth leads and cortical strip leads which are implanted near the patient's seizure focus. The generator sends electrical impulses to the leads according to programmed parameters.

Efficacy

Neuropace is currently conducting a randomized, double-blind, sham stimulation controlled investigation at approximately 28 sites throughout the United States to assess the safety and effectiveness of the system. The results of a multi-center feasibility investigation determined:

According to Neurosurgery:
During the primary evaluation period, the responder rate (>50% reduction in seizures) in 50 subjects (excluding 1 subject with no disabling seizures at baseline and 14 subjects blinded off) was 32% for CPS (n=44), 63% for GTC (n=16), and 26% (n=50) for total disabling seizures (TDS) (SP motor, CPS and GTC). The median percentage reduction in seizure frequency was: CPS 27%, GTC 59% and TDS 29%; seizure reduction was significant for CPS (p<0.05) and TDS (p<0.001) (Wilcoxon signed-rank test). For the secondary evaluation period, as of 4/28/06, the responder rate for 62 subjects (excluding 1 subject with no disabling seizures at baseline and 2 subjects previously blinded off with fewer than 84-days of therapy on) was 40% for CPS (n=52), 55% for GTC (n=22), and 41% for TDS (n=61). The median percentage reduction was: CPS 34%, GTC 66% and TDS 35%, and seizure reduction was significant for CPS (p<0.05), GTC (p<0.005), and TDS (p<0.001).

It appears from the preliminary study that roughly 40% of patients achieved greater than 50% reduction in seizures (TDS numbers). It scores a 4 for the chart until further studies are released.

Potential Adverse Events

Long term safety and potential adverse events are unknown at this time.

Cost

Costs won't be known until the device is approved by the FDA and available to the public, but I'm reasonably confident that the surgical procedure is cost prohibitive without insurance. It scores an 8 for a general approximation of out of pocket expenses (for what insurance does not cover).

Type

I expect the RNS to work similar to the VNS - on a mostly passive basis once settings have been ramped up to the desired therapeutic level. It may require surgeries to replace batteries every so many years (depending upon model and settings), and patients may be able to manually activate the device, but I scored it as a continuous system with passive participation because that is how it is intended to operate most of the time.

Latency

The initial feasibility investigation reported results over an 84 day period (roughly 3 months). Until longer term studies are completed, the RNS will score a 6 for the chart.

Special Notes

Be sure to read through at least page 2 of this excellent RNS forum discussion.

This page last modified September 9, 2019.

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