Persistent imbalance after traumatic brain injury is central in origin
Reviewed by Victor Osei-Lah

Several residual symptoms, including dizziness and imbalance, can follow traumatic brain injury, no matter how mild. This study focused on the mechanisms, peripheral and central, underlying the complaint of persistent imbalance in patients with chronic mild traumatic brain injury (mTBI). To that end, from the general population, 58 adults (18-60 years old) with persistent imbalance of >3months after mTBI were recruited together with 61 age-matched controls. The inclusion and exclusion criteria were very tight. Notably, exposure to blast injury was excluded. All participants completed validated neurobehavioral (NSI) and Dizziness Handicap Inventory (DHI) questionnaires and were subjected to detailed peripheral vestibular, oculomotor and balance assessments. The objective vestibular test battery included vHIT, c- and o-VEMPs, bithermal caloric, VNG and Dix-Hallpike tests. Balance assessment used the NeuroCom Smart Balance Master for the central sensory organisation test (SOT). Data analysis was based on 12 people with mTBI and 28 healthy controls who were able to complete all the tests. There were no significant differences between oculomotor and peripheral vestibular function between the groups, but all paradigms of the central SOT tests were significantly abnormal in the mTBI group (p < 0.001). The worse the vestibular score on NSI and physical score on DHI, the worse the SOT performance. There were a number of limitations but one that is worth highlighting is that participant numbers were different in the various tests due to the symptom-provoking nature of many of the vestibular assessments in the testing battery, for both groups but more so in the mTBI group. Generalisation of the results should be taken with a caution. The authors concluded that only a few mTBI patients with complaints of persistent imbalance had deficits in their peripheral vestibular or oculomotor function, but over half had impaired central sensory integration for balance control when compared to healthy, age-matched controls; worse balance control was related to subjective complaints. Therefore, they argue, that patients with “persistent imbalance post-mTBI should be referred to rehabilitation for balance training and avoid unnecessary initial referrals to otolaryngology or vestibular testing”. This is a good study overall but, in my view, vestibular testing should not be discounted in mTBI.

Exploring persistent complaints of imbalance after mTBI: Oculomotor, peripheral vestibular and central sensory integration function.
Campbell KR, Parrington L, Peterka RJ, et al.
J VESTIB RES
2021;31(6):519-30.