Identifying Trends in Microsaccade Rate on Oculomotor Tracker in Early vs Late Stage Pediatric Cases With Persistent Post-Concussion Symptoms (Ppcs)

Abstract

Background: Oculomotor and visual processing deficits occur commonly after brain injury in young athletes. A subset of these concussed athletes do experience prolonged recoveries or PPCS with ongoing oculomotor deficits and visual symptoms. There have been limited studies conducted to determine the significance of oculomotor tracking (OMT) testing in the pediatric population, and even less investigating the role of microsaccades. Hence, investigations on microsaccades(MS), physiological adjustive micro eye movements critical in visual processing and central/peripheral visual integration, may provide insight on the role of visual dysfunction in PPCS course, prognosis, and management. Purpose: The purpose of this study is to identify possible MS rate trends and differences between early and late stage PPCS pediatric patients. Methods: A retrospective cohort study of 41 pediatric patients with PPCS or symptoms greater than one month from injury. Data was collected from 7/1/2018 to 12/1/2019 and the age group ranged from 8 to 21 years. For each participant, using the OMT device we measured the number of saccades generated, the size and speed of the microsaccades, the area covered and the ratio of vertical-to-horizontal direction component of the fixational eye movements, using a 250 Hz video-eye tracker mounted inside a HTC Vive VR headset. Participants were instructed to fixate on a central dot for 140 seconds, in 20-second intervals. Patients were classified into early or late stages of PPCS (early stage: 1-6 months; late stage: >6 months) to compare MS rate between stages. Exclusion criteria included history of visual disorders, learning disorders, seizure disorder, or intracranial hemorrhage. Results: 27 patients were in the early stage while 14 patients were in the late stage. The early stage group had a mean MS rate of 125 beats/min while the late stage group had a mean MS rate of 116 beats/min. A two sample t-test assuming no difference between early and late stage patients resulted in a p value of 0.51. Conclusion: There is a potential trend in declining MS numbers with progressive PPCS stage. Although the t-test didn’t show statistical significance, this could be due to the small sample size of our study. Future studies are needed to validate this initial finding and to identify the significance of microsaccade patterns in concussion prognosis and management. [Figure: see text]