The clinical utility of using involuntary eye movements to assess concussion
Critical decisions are made daily about whether to bench athletes who might have suffered a concussion or mild traumatic brain injury (mTBI). The low-level damage underlying mTBI has been difficult to measure, especially during competition when assessments are made quickly utilizing primarily subjective symptoms. The ideal instrument would be (1) sensitive to low-level diffuse damage, (2) easily and rapidly administered on the sidelines, and (3) unaffected by human bias or sandbagged baselines. Based on a body of research documenting the sensitivity of oculomotor movements (e.g., saccades and smooth pursuits) to mTBI damage, we have constructed 5 Sideline Eye Trackers and are evaluating their clinical use for quick, objective and accurate assessment of mTBI. Current enrollment of athletes is over 1,200, including the entire IU athletic department and several local schools. All enrollees complete a 6-minute, pre-season, baseline oculomotor exam consisting of 2 saccade, 2 pursuit, and 1 ocular following task. Balance is simultaneously measured using a portable balance board. Anyone suspected by the team physician of having a concussion during the season repeats this exam 3 additional times: (1) immediately post-injury (minutes), (2) at the time of being cleared for return-to-play, and (3) as far post-injury as possible (months). To provide 2 separate measures of test-retest variability, 2 control groups are also being studied: (1) within-sport non-concussed matched control group, and (2) non-concussion prone cross-country athletes. Athletes with mTBI show significant deficits in both saccadic and pursuit function compared to their baseline (p = 0.0001). Drift in the center of pressure measure (balance) is also significantly affected in many subjects. Signal detection theory yields a specificity & sensitivity of greater than 85% of 69 concussed athletes. Measuring oculomotor dysfunction in athletes with a 6-minute task may be a promising tool for the diagnosis and management of mTBI.