Abstract TP236: Brain And Infarct Temperature Changes With Active Conductive Head Cooling: A Magnetic Resonance Spectroscopy Imaging Study

Abstract

Background and Purpose: Active conductive head cooling (HC) is a simple and non-invasive intervention that may potentially slow infarct growth in patients with stroke. Using magnetic resonance spectroscopy imaging (MRSI), we investigated the effect of HC on brain and systemic temperatures. Methods: A cooling cap (WElkins Temperature Regulation System, 2nd Gen) was used to administer HC for 80 minutes to healthy volunteers and patients at least 6 months following a large vessel occlusion stroke. Serial MRSI scans were obtained before and during HC. Brain temperature was estimated using the Metabolite Imaging and Data Analysis System software package, which allows voxel-level temperature calculations using the chemical shift difference between metabolite (N-acetylaspartate, creatine, choline) and water resonances. Rectal temperature, the 11-point Numerical Pain Rating Scale score, heart rate, and blood pressure were measured. The primary outcome was the mean difference in brain temperature before and after HC. Results: Eleven participants (6 healthy volunteers, and 5 post-stroke) had a total of 66 MRSI scans performed over 80±5 minutes of HC. An average absolute temperature of -1.3±0.5°C was delivered via the cooling cap to the scalp of the participants. Following HC, significant reductions in brain temperature (ΔT = -0.9±0.7°C, P =0.002), and to a lesser extent, rectal temperature (ΔT = -0.3±0.1°C, P =0.03) were observed. Linear regression analysis of all 66 MRSI scans showed a brain temperature-by-time gradient of -0.53°C per hour ( P =0.001). In the stroke patients, the temperature-by-time gradient within the infarct was -0.60°C per hour ( P =0.01). HC was well-tolerated, heart rate and blood pressure remained stable, the median (IQR) Numerical Pain Rating Scale score was 2.5 (1-3) at 80 minutes, and none developed shivering. Conclusions: HC was well-tolerated and resulted in potentially clinically meaningful reductions in brain and infarct temperature, with only slight reduction in systemic temperature. Future research should investigate the feasibility of HC as a potential neuroprotective strategy in patients being considered for acute stroke therapies such as mechanical thrombectomy.