Abstracts

Rationale: The Neuropace RNS system is a surgically implanted brain stimulation device for the treatment of medically refractory epilepsy.  The surgery for implantation of the Neuropace RNS stimulator involves placement of brain electrodes, usually requiring stereotactic techniques.  Our intraoperative CT scan, the BodyTom, has facilitated the process of surgical implantation of the Neuropace RNS system in two ways.  First, a head CT with head frame and fiducials to be fused to the pre-op MRI can be performed in the operating room, eliminating the need to transport the patient to the radiology department.  Second, another head CT can be performed in the operating room after the electrodes are placed and prior to removal of the head frame and patient extubation to verify placement of the electrodes in appropriate locations.  This study evaluates the efficacy of using the intraoperative BodyTom CT in the surgical placement of Neuropace RNS systems. Methods: We evaluated ten patients who had a total of eleven Neuropace RNS systems surgically implanted over a four year period at Inova Fairfax Hospital.  We evaluated the efficacy of the intraoperative head CT at the beginning of the surgery and at the end of the surgery to determine if they provided increased efficiency or important clinical information for the surgical procedure.  Results: We performed eleven Neuropace RNS implantation surgeries utilizing the intraoperative BodyTom CT in all eleven surgeries.  Intraoperative head CT at the beginning of the surgery was performed in all eleven surgeries whereas intraoperative head CT at the end of the surgery was performed in nine of the eleven surgeries.  The intraoperative head CT allowed for the placement of the stereotactic frame in the operating room under general anesthesia without the need for transportation to the radiology department under anesthesia.  All eleven head CTs successfully transferred to the stereotactic planning software and fused with the pre-operative MRI of the brain.  Zero of the nine intraoperative head CT scans performed at the end of surgery resulted in the repositioning of the electrodes, brining into question the necessity of the second intraoperative head CT.  Because of this, and because of the difficulty repositioning the patient while maintaining a sterile field to obtain the intraoperative head CT at the end of the surgery, the most recent two Neuropace RNS placement surgeries did not include an intraoperative head CT performed at the end of the surgery.  Conclusions: Intraoperative head CT during Neuropace RNS placement surgery has demonstrated efficacy in surgical planning at the beginning of surgery, but did not produce information leading to changes in clinical care when performed at the end of surgery.  This would suggest that intraoperative head CT is efficacious during Neuropace RNS placement surgery, but not necessary as a technique to verify electrode location. Funding: No funding