Objective To characterise specific measures of neurologic dysfunction and recovery associated with concussion in student-athletes using the clinical examination and Cleveland Clinic Concussion application (C3 app).

Design Retrospective observational study

Setting Tertiary sports concussion clinic

Participants 181 student-athletes aged 14-20 diagnosed with concussion by a Cleveland Clinic physician were included.

Interventions C3 data were collected pre-season, and at least once post-injury, along with a physician clinical examination. Individuals were stratified into two groups based on recovery time: typical <21 days (n=97) or protracted 21+ days (n=84).

Outcome measures Near point convergence (NPC) and the following modules of the C3 app were administered: 1) Graded symptom checklist (GSC); 2) Standardised Assessment of Concussion (SAC); 3) Trail Making Test (TMT); 4) Simple and Choice Reaction Time; 5) Processing Speed Test (PST); 6) Biomechanical quantification of balance during the BESS.

Main results At baseline, both groups performed similarly on all C3 modules. Significant differences in NPC were seen among the typical versus protracted group (mean 7.62 cm versus 13.57 cm, p=0.0002). Also, significantly worse performance among the protracted group was seen in GSC (p=0.0001), and measures affected by vestibulo-ocular dysfunction including biomechanical quantification of BESS (p<0.05), simple and choice reaction time (p<0.001), and TMT-B (p=0.01). No difference between groups was noted in BESS errors, SAC, or PST.

Conclusions Abnormal NPC or convergence insufficiency is associated with protracted recovery and should be included in the assessment of student-athletes at baseline and post-injury. Identification of vestibulo-ocular dysfunction helps guide post-concussion assessment, treatment, and return-to-play decision-making.

Competing interests Bob Gray, Rick Figler, Jason Cruickshank, Maureen Lally, Tanujit Day: None. Susan Linder and Jay Alberts have authored intellectual property associated with the mobile application presented in this study.