Brief Autonomic Assessment in Concussion Clinic

Abstract

To examine the feasibility and tolerability of administering a brief autonomic assessment via capnometry and pupillometry in an outpatient concussion clinic. Both acute and chronic phases of concussion have been associated with autonomic nervous system (ANS) dysregulation. Few concussion clinics currently employ autonomic assessments, which could enhance diagnostic accuracy and treatment recommendations. Although less-studied in outpatient concussion clinics, pupillometry and capnometry are two well-validated, peripheral autonomic assessment approaches that together provide information about both sympathetic and parasympathetic responses. In addition to being objective measures, they are fast and non-invasive. In order to investigate the potential utility of these measures as an addition to clinic procedures, the present study sought to examine their feasibility and tolerability as an adjunctive assessment in clinic. This project employed a prospective, observational research design. Eight patients (ages 20-65, 4 females) diagnosed with concussion (>1 month post injury) underwent a 2-minute baseline capnometry that measured end-tidal CO2, respiration rate, pulse rate, and oxygen saturation. Their pupillary response to light was captured using a pupillometer. Tolerability and feasibility were measured via the following metrics: patient tolerability and comfort Likert scales and administration details (e.g., total duration, logistical difficulties, clinic flow variables). Average rating of comfort for the capnometer and pupillometer were between comfortable (4) to very comfortable (5) on a 5-point Likert scale. There were no difficulties due to participant discomfort or time limitations among all patients, and minimal issues with administration logistics were noted. Both measures were completed for all participants in <5 minutes. Capnometry and pupillometry were found to be both tolerable among patients and feasible to administer in a concussion clinic. Given the ease of administration, further studies should investigate the utility of these portable devices in concussion clinics to objectively identify those at risk for persistent post-concussion symptoms and for early treatment stratification.