Visual disorders may be an important driver of symptom profiles following concussion in adolescents, and they have the potential to provide prognostic post-injury information, according to findings published in Vision Research.
The study reviewed the clinical characteristics of patients who have experienced a traumatic brain injury (TBI) who had a receded near point of convergence (NPC) vs those without a receded NPC. Researchers assessed 123 total participants, comparing those with a receded NPC (>6cm) break point distance to those with a normal NPC distance on symptom, behavioral, and clinical assessments. NPC break points between those who did and did not recover within 28 days of injury were also compared.
The study found that 63% (n=77) of participants demonstrated a receded NPC when tested within 14 days of injury, and they were significantly younger than those with a normal NPC break point (n=46). There was a significantly greater proportion of patients reporting headaches in the receded NPC break point group (86% vs 61%), and a significantly greater cognitive (mean=13.4 vs mean=8.8), somatic (mean=10.0 vs mean=6.9), and overall (mean=23.7 vs mean=15.8) symptom severity than in the normal NPC break point group. More severe somatic symptoms were significantly associated with a greater NPC break point (β=0.26; 95% CI=0.01, 0.52), which was indicated in the multivariable model. There was a significantly greater NPC break point at initial evaluation in the group who went on to experience persistent symptoms, compared to those without persistent symptoms (mean = 9.7 vs mean = 7.0). Conversely, participants with a receded NPC break point at initial evaluation showed an increased symptom burden compared with those without a receded NPC break point, with somatic symptoms being most notable.
The study notes that, in future research, meaningful clinical insights and identification of patients who would benefit from closer monitoring or additional intervention to facilitate faster recovery may result from clinical concussion evaluations that assess vergence in some capacity.
The researchers consider the lack of inter-rater reliability assessments a study limitation. Additionally, the sample may not be representative of those seen in populations other than sports medicine clinics, where the present study’s sample originated. Finally, possible confounding factors contributing to variations in NPC break point and concussion recovery are a limiting factor.
Walker GA, Wilson JC, Seehusen CN, Provance AJ, Howell DR. Is near point convergence associated with symptom profiles or recovery in adolescents after concussion? Vision Res. 2021;184(7):52-57. doi:10.1016/j.visres.2021.03.007