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Receded near point of convergence and gait are associated after concussion
  1. David R Howell1,2,3,
  2. Michael J O’Brien1,2,3,4,
  3. Aparna Raghuram3,5,6,
  4. Ankoor S Shah3,5,6,
  5. William P Meehan1,2,3,4,7
  1. 1The Micheli Centre for Sports Injury Prevention., Waltham, MA, USA
  2. 2Division of Sports Medicine, Department of Orthopaedics, Boston Childrens Hospital, Boston, MA, USA
  3. 3Brain Injury Centre, Boston, MA, USA
  4. 4Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA
  5. 5Department of Ophthalmology, Division of Sports Medicine, Boston, MA, USA
  6. 6Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
  7. 7Department of Paediatrics, Harvard Medical School, Boston, MA, USA

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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