Near Point of Convergence and Gait Deficits in Adolescents After Sport-Related Concussion

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Abstract

Objective:

To prospectively examine gait characteristics of participants acutely after concussion with and without receded near point of convergence (NPC), compared with healthy controls.

Design:

Cross-sectional study.

Setting:

Sports-medicine clinic.

Participants:

Patients examined after concussion (n = 33; mean ± SD = 7.2 ± 3.1 days) and a group of uninjured athletes (n = 31) completed a Postconcussion Symptom Scale, underwent NPC testing, and single/dual-task gait assessments.

Independent Variables:

Near point of convergence was defined as the patient-reported diplopia distance when a fixation target moved toward the nose. Receded NPC was defined as a distance >5 cm from the tip of the nose.

Main Outcome Measures:

Spatiotemporal gait characteristics in single-task and dual-task conditions were evaluated with analysis of variance; correlations were calculated between NPC and gait measures.

Results:

Eighteen of 33 (55%) patients with concussion presented with receded NPC. Those with receded NPC exhibited slower gait speed (single-task = 1.06 ± 0.14 m/s vs 1.19 ± 0.15 m/s; dual-task = 0.80 ± 0.13 m/s vs 0.94 ± 0.13 m/s; P = 0.003) and shorter stride lengths (single-task = 1.11 ± 0.10 m vs 1.24 ± 0.11 m; dual-task = 0.97 ± 0.11 m vs 1.09 ± 0.11 m; P = 0.001) than healthy controls. Near point of convergence was moderately correlated with dual-task average walking speed for the normal NPC group (ρ = −0.56; P = 0.05). Postconcussion Symptom Scale scores did not significantly differ between groups (27 ± 18 vs 28 ± 16).

Conclusions:

After concussion, adolescents with receded NPC exhibited significant gait-related deficits compared with healthy controls, whereas those with normal NPC did not. Vergence and gross motor system dysfunction may be associated after concussion. Gait and vergence measures may contribute useful information to postconcussion evaluations.

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