Abstract 114: Diverse Patients Show Physiologic Benefit From Refined Sphenopalatine Ganglion Electrode Placement and Stimulation Level Selection to Augment Blood Flow and Neurologic Function in Acute Ischemic Stroke (The IMPACT-24M Trial)

Abstract

Background: Two large RCTs have indicated sphenopalatine ganglion (SPG) stimulation reduces 3m disability in acute ischemic stroke patients with confirmed cortical involvement. The current trial evaluated two refinements in SPG stimulation technique: 1) SPG electrode placement with real-time optical tracking guidance; and 2) stimulation intensity comfortable tolerance level (CTL) selection using non-noxious facial physiologic markers. Methods: Single, active arm trial at 4 centers, enrolling patients with anterior circulation ischemic stroke <24h, NIHSS 1-6, not receiving recanalization therapies. Stimulation level was based on ipsilateral facial tingling sensation or lacrimation. SPG stimulation effects were assessed by volumetric blood flow in the ipsilateral common carotid artery (ultrasound) and affected hand grasp and pinch strength before and during stimulation, and by NIHSS change by day 7. Results: Among 50 enrolled patients, age was median 66y (IQR 60-74), 44% female, NIHSS median 5 (IQR 4-5), and median onset-to-screening time 18h (IQR 9-20). Median implantation skin-to-skin time was 4 minutes (IQR 3-7) and all 50 implants were placed correctly. CTL was found based on physiological biomarkers in 96% of patients, including 86% in the optimal, low-medium intensity range. SPG stimulation significantly increased common carotid artery peak systolic and end diastolic blood flow (up 44%, p<0.0001; and up 52%, p<0.0001) and improved pinch strength (up 42%, p<0.0001) and grasp strength (up 26%, p<0.0001). Degree of NIHSS recovery by day 7 was greater than in matched historic controls, median 75% vs 50%, p=0.0003. Forest plot analysis showed benefits were homogenous across the subgroups of: sex, age, time from onset, stroke side, NIHSS, and ASPECTS score. Conclusion: SPG stimulator placement with real-time optical tracking guidance was fast and accurate, and selection of optimal stimulation intensity levels based on non-noxious facial tingling and lacrimation was feasible in nearly all patients. SPG activation led to cranial blood flow augmentation and improved hand motor function during stimulation, and neurologic deficit reduction at 1 week, consistently across broad patient subsets of age, sex, side, severity, and time to treatment.