ABSTRACT
The vestibular and oculomotor/visual systems are commonly affected in post-concussion syndrome (PCS). Convergence insufficiency (CI) is the most common ocular abnormality after concussion. Electrovestibulography (EVestG) is a relatively new non-invasive method that measures the peripheral vestibular responses; it has shown abnormal vestibular responses in a PCS. Here, we report the results of investigating the correlation between the vestibular and oculomotor systems in PCS population using EVestG and CI measures. Forty-eight PCS patients were tested using EVestG, out of which 20 also completed the Rivermead post-concussion questionnaire (RPQ). An EVestG feature (Field Potential (FP)-area) was extracted from the stationary part of the EVestG signals. A neuro-ophthalmologist (author BM) measured participants’ CI at near vision using cross-cover examination and a prism-bar. Results indicate: (1) vestibular abnormality (i.e. FP-area) and CI values are significantly correlated in PCS (R = 0.68, p < .01), and (2) there are significant correlations between severity of concussion (i.e. RPQ3) and CI (R = 0.70, p < .01) and between RPQ3 and FP-area (R = −0.56, p < .02). To the best of our knowledge, this is the first study that objectively demonstrates a significant positive correlation between the CI and vestibular systems’ abnormality. These findings are scientifically important as they help localise the pathology of PCS, and are clinically valuable as they help physicians in their decision-making about PCS diagnosis and rehabilitation strategies.
Declaration of interest
The author BL is a consultant to the supporting company (Neural Diagnostics Pty. Ltd.).
Glossary
AP: action potential
CI: convergence insufficiency
EVestG: Electrovestibulography
EVS: efferent vestibular system
FEF: frontal eye field
INO: internuclear ophthalmoplegia
LGN: lateral geniculate nucleus
LPCS: long-term PCS
MLF: medial longitudinal fasciculus
mTBI: mild traumatic brain injury
NEER: neural event extraction routine
NRTP: nucleus reticularis tegmenti pontis
PCS: post-concussion syndrome
RPQ: Rivermead post-concussion questionnaire
RPQ3: score of first three symptoms of RPQ
RPQ13: score of last thirteen symptoms of RPQ
SOA: supraoculomotor area
SPCS: short-term PCS
VOMS: vestibular/ocular motor screening
VOR: vestibule-ocular reflex
Supplementary material
Supplementary materials for the article can be accessed on the publisher’s website.