Receded near point of convergence and gait are associated after concussion

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Abstract

Objective

To examine post-concussion gait among patients with and without receded near point of convergence (NPC) and uninjured controls.

Design

Prospective observational study.

Setting

Regional sport-concussion clinic.

Participants

Thirty-one patients presented 10.1 [95% CI=8.1, 12.1] days post-concussion (57% female, age=16.5 [15.4, 17.7]); 38 controls were tested (55% female, age=15.5 [13.6, 17.4]). Participants completed symptom, NPC, and single/dual-task gait assessments. Exclusion criteria were a current lower extremity injury or diagnosed learning disability.

Intervention

The effect of group (receded NPC, normal NPC, control) and task (single/dual) were evaluated via ANOVA. NPC and gait correlations were calculated.

Outcome measures

NPC was the patient-reported diplopia point while a fixation target moved toward the nose. Receded NPC was >5 cm from the tip of the nose. Three inertial sensors quantified gait; variables included average gait speed, cadence, and stride length.

Results

Nineteen concussion patients presented with receded NPC, 12 did not. Symptom severity was not significantly different between groups (27.1 [18.6, 35.6] vs. 26.3 [17.1, 35.5]). Those with receded NPC exhibited slower average gait speed (1.02 [0.93, 1.11] m/s vs. 1.19 [1.14, 1.24] m/s, p<0.001) and shorter stride lengths (1.11 [1.05, 1.18] m vs. 1.27 [1.23, 1.31] m, p=0.001) than controls. Near NPC and single-task gait speed were moderately correlated (ρ=−0.54, p= 0.002).

Conclusions

Adolescents with receded NPC post-concussion exhibited significant gait-related alterations compared to healthy controls; those with normal NPC did not. Vergence and gross motor system dysfunction may be interrelated following concussion and may provide useful information to post-concussion evaluations.

Competing interests

Dr. Meehan receives royalties from ABC-Clio publishing for the sale of his book, Kids, Sports, and Concussion: A guide for coaches and parents, and royalties from Wolters Kluwer for working as an author for UpToDate. He is under contract with ABC-Clio publishing for a future book entitled, Concussions, and with Springer International publishing for a future book entitled, Head and Neck Injuries in Young Athletes. His research is funded, in part, by a grant from the National Football League Players Association and by philanthropic support from the National Hockey League Alumni Association through the Corey C. Griffin Pro-Am Tournament. Dr. O’Brien receives royalties from Wolters Kluwer for working as an author for UpToDate. He is under contract with Springer International publishing for a book entitled, Head and Neck Injuries in Young Athletes. Drs. Howell, Shah, and Raghuram have no conflicts of interest to report.

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