Vestibular (Balance/Dizziness) Dysfunction

Persistent vertigo, dizziness, imbalance and visual disturbance are common symptoms of patients with concussion/mTBI and are often associated with objective impairments of the vestibular system.^1,2 Vestibular impairments can occur peripherally in the inner ear, or centrally in nuclei that integrate vestibular signals in order to maintain balance and posture. The vestibular system also affects eye movement through a variety of mechanisms including the vestibulo-occular reflex (VOR).

The most common cause of post-traumatic peripheral vestibular dysfunction is benign paroxysmal positional vertigo (BPPV).^3,4 Patients experience episodes of vertigo, nystagmus and nausea with sudden changes in position, often including rolling over in bed or looking up. These attacks typically last less than 30 seconds but can be quite disabling and can occur multiple times per day. BPPV is caused by dislodged otoconia in the posterior semicircular canal (SCC). The Dizziness Handicap Inventory (Appendix 10.1) can help to assess the functional impact of dizziness. Other causes of dizziness can also be caused by post-concussion migraines, autonomic dysregulation, medications and other peripheral vestibular disorder. Patients with dizziness frequently experience concurrent psychological disorders such as anxiety.⁵ These may exacerbate the feeling of dizziness and should be managed along with primary vestibular treatments (see Section 8).

Assessment of vestibular function following mTBI identifies vestibular deficits that could lead to evidence-based interventions that will benefit the patient. Evaluation should minimally include a focused history⁶, a balance screen, VOR screen and the Dix-Hallpike manoeuvre. Balance testing should reference normal values to document impairment. These can be found in Iverson et al 2008 ⁷ and Vereeck et al 2008.⁸

When the history suggests BPPV, posterior semi-circular canal involvement can be diagnosed by the Dix-Hallpike manoeuvre (see Appendix 10.2 for more information and Appendix F for links to video demonstrations). VOR abnormalities from peripheral vestibular dysfunction usually present with unilateral directed nystagmus in the acute phase of injury. Central compensation usually occurs and as a result spontaneous nystagmus is rarely seen. The presence of bilateral gaze evoked nystagmus or nystagmus in one or more planes is either congenital or representative for central nervous system pathology somewhere in the brain.

When assessment suggests vestibular dysfunction, vestibular interventions can be considered. While historically, medications have been used to suppress vestibular symptoms, including nausea, current evidence does not support this approach.⁹ A Cochrane review by Hillier and Hollohan (2007) identifies vestibular rehabilitation as an effective intervention for unilateral peripheral vestibular dysfunction¹; this has been supported by Gurley et al.⁶ Weaker evidence also suggests vestibular rehabilitation may be helpful for central vestibular dysfunction.¹⁰ Vestibular rehabilitation is typically provided by a specialized a healthcare professional with specialized training and involves various movement-based regimens to bring on vestibular symptoms and desensitize the vestibular system, coordinate eye and head movements, and improve functional balance and mobility. However, for the specific treatment of BPPV, Hillier and Hollohan (2007) conclude that canalith or particle repositioning manoeuvres are more effective than vestibular rehabilitation techniques.¹

Vision Dysfunction

Patients presenting with vision disorders post-concussion/mTBI may have impairment of visual acuity, accommodation, versional eye movements, vergence eye movements, visual field integrity and may experience photosensitivity. Practitioners should take a detailed history of vision symptoms and screen for potentially unrecognized visual deficits with using simple confrontational field testing.^11,12 Mild TBI/concussion patients with complex visual symptoms including diplopia and/or impaired vision should be referred to a neuro-ophthalmologist.^13-15 Patients with impairments of accommodation, version or vergence movements, and/or photosensitivity may benefit from rehabilitative techniques rendered by qualified optometrists.^11-13 Vision rehabilitation can be beneficial for some patients^11,12,16,17 and should be considered for the treatment of persistent vision disorders. Rehabilitative interventions include vision therapy, reading spectacles, prism spectacles and/or tinted spectacles.^11,14,16

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