Authors :
Presenting Author: Anna Zolyan, MD – University of California, Irvine
Sumeet Vadera, MD – Neurosurgery – University of California, Irvine; Jack Lin, MD – University of California, Irvine; Lilit Mnatsakanyan, MD – University of California, Irvine
Rationale:
We aim to retrospectively review and characterize clinical outcomes and combination treatment rationale in patients treated concurrently with surgical resection and responsive neurostimulation (RNS). RNS System (Neuropace, Mountain View, CA) is an adjunct treatment option to improve seizure control when surgical resection is not an option. RNS system continuously monitors epileptiform activity and attempts to stop or shorten seizure duration by delivery of electrical current by reducing seizure frequency in patients with up to two areas of seizure onset zone (SOZ). Patients with independent and multiple ictal onset zones remain a great challenge to treat. The aim of this study was to review the potential advantages, indications and benefits of combined resection + RNS system therapy.
Methods:
Retrospective review of 64 patients who underwent RNS system implantation at University of California, Irvine (UCI) from 2014-2022. Inclusion criteria is as follows:
- Patients for whom the intended treatment plan involved combination of resection and RNS System implantation.
- Treatments occurred either concurrently in a single procedure or in staged procedures separated by no more than 90 days.
- Patients implanted with the RNS System for a minimum of 1 year and followed at the center that performed the initial implant (9 months – greater than 2 years).
The following formula Seizure Reduction Formula = 1- (# seizures per month at time of last follow-up divided by # seizures per month at baseline) x 100 was used to calculate seizure reduction.
Results:
A total of 19 patients met inclusion criteria. Six of nineteen patients had bilateral temporal SOZ. The average age ~36.16 years old. The decision for combined therapy was based on extensive pre-surgical evaluation and intracranial monitoring, supporting 2 SOZ or overlap of SOZ with eloquent cortex. All risks related to surgical resection were carefully addressed.
There was a 76.84% reduction in seizures based on calculations with seizure reduction formula, and seven of nineteen (36.84%) patients became seizure free.
Conclusions:
Patients with drug-resistant epilepsy (DRE) represent a challenging group. Resection may offer a cure, however, up to 40% of patients with DRE will not qualify for curative surgery. Neurostimulation devices have offered additional benefits as an adjunct therapy but efficacy dependents on many factors, not limited to number of seizure onset foci, ability to localize the focus, precise implantation and most importantly, the time needed to achieve seizure control. Combination therapy in patients with two or more SOZ can help achieve more sustained and faster results without risking postoperative complications (i.e., resection of eloquent cortex) therefore, properly selected patients may benefit from combined resection + RNS therapy. This retrospective study shows potential added benefit from combination treatment of RNS system implantation and surgical resection. Properly selected patients with this treatment approach may serve as a superior alternative to either therapy alone in achieving better seizure control in patients with great than one SOZ. A multi-center study is on the way to further strengthen evidence-based clinical outcomes.
Funding: None