Convergence insufficiency in patients with post-concussion syndrome is accompanied by a higher symptom load: a cross-sectional study

Objective: To estimate the prevalence of convergence insufficiency (CI) in adult patients with post-concussion syndrome and determine the impact of CI on symptom load. Methods: Cross-sectional study of 103 patients with neurological symptoms 2–6 months after a concussion. Symptoms were assessed with the Rivermead Post Concussion Symptoms Questionnaire (RPQ), and CI was diagnosed using near point of convergence, vergence facility, and the Convergence Insufficiency Symptom Survey. The RPQ score for patients with and without CI was compared, and sensitivity, specificity, and area under the receiver operating characteristic curve for the two visually related RPQ questions as indicators of CI were calculated. Results: The proportion of patients diagnosed with symptomatic CI was 20.4% (95% confidence interval: 13.1–29.5%). The RPQ score was significantly higher for patients with symptomatic CI both before (p =.01) and after removal of the two visually related questions in the RPQ-questionnaire (p =.03). The two visually related RPQ questions were unable to detect CI. Conclusion: In patients with post-concussion syndrome, the load of nonvisual symptoms is higher in the presence of CI. A prospective interventional study on CI is required to study the relationship between CI and other post-concussion symptoms.