(335) Pupillary Light Responses Differ in Post-Traumatic Headache and Chronic Migraine Compared to Non-Headache Controls

Abstract

Persistent post-traumatic headache (PTH) and chronic migraine (CM) often present with clinically overlapping features including prominent light sensitivity. Dynamic pupillometry is a promising new tool for evaluation of autonomically mediated responses to light in headache disorders, as they may differ between headache phenotypes. While our prior work has evaluated autonomic responses in chronic migraine and mild traumatic brain injury (aka concussion), differences in PTH and chronic migraine have not been explored. The present study sought to identify key sympathetic and parasympathetically mediated variations between pupillary light reflex (PLR) parameters in CM, PTH, and non-headache controls (NH). We hypothesized that while, based on our prior work, CM would exhibit mixed parasympathetic and sympathetic hypo-function resulting in pupillary deficits, PTH would demonstrate a more sympathetically-predominant pattern of dysfunction. We tested PLR's in 23 PTH, 16 CM, and 26 NH age-matched subjects using a digital infrared binocular pupillometer (Neuroptics DP-2000) to quantify direct and consensual pupillary diameter changes in response to a brief light stimulus. Data was exported and analyzed using custom MATLAB code to calculate seven standardized and seven novel parameters of the PLR. We also assessed clinical measures using a REDCAP based questionnaire, including: ICHD-III based headache diagnosis, disease burden and associated symptoms. Groups were compared using the Kruskal-Wallis test, with post-hoc Mann-Whitney test. We found significantly different sympathetically mediated pupillary dilation velocity measures between PTH and NH, and between PTH and CM. In summary, sympathetic pupillometry parameters were significantly different between PTH and CM, as well as between both headache groups and NH, suggesting distinctive pupillary autonomic regulation in PTH and CM and different profiles of dysfunction. Our findings support the hypothesis that PTH and CM are physiologically distinguishable entities, and suggest further investigation into pupillary responses to light as a physiological and clinical biomarker of PTH and CM.