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The purpose of this article is to review relevant literature on the effect of mild traumatic brain injury (mTBI) and blast injury on the vestibular system. Dizziness and imbalance are common sequelae associated with mTBI, and in some individuals, these symptoms may last for six months or longer. In war-related injuries, mTBI is often associated with blast exposure. The causes of dizziness or imbalance following mTBI and blast injuries have been linked to white matter abnormalities, diffuse axonal injury in the brain, and central and peripheral vestibular system damage. There is some evidence that the otolith organs may be more vulnerable to damage from blast exposure or mTBI than the horizontal semicircular canals. In addition, benign paroxysmal positional vertigo (BPPV) is a common vestibular disorder following head injury that is treated effectively with canalith repositioning therapy. Treatment for (non-BPPV) mTBI-related vestibular dysfunction has focused on the use of vestibular rehabilitation (VR) augmented with additional rehabilitation methods and medication. New treatment approaches may be necessary for effective otolith organ pathway recovery in addition to traditional VR for horizontal semicircular canal (vestibulo-ocular reflex) recovery.

Purpose The purpose of this study was to evaluate the effectiveness of triaging patients with motion-provoked dizziness into a benign paroxysmal positional vertigo (BPPV) clinic. Method A retrospective chart review was performed of veterans who were tested and treated for BPPV in a triaged BPPV clinic and veterans who were tested and treated for BPPV in a traditional vestibular clinic. Results The BPPV triage clinic had a hit rate of 39%. On average, the triaged BPPV clinic reduced patient wait times by 23 days relative to the wait times for the traditional vestibular clinic while also reducing patient costs. Conclusion Triaging patients with BPPV is one method to improve access to evaluation and treatment and a mechanism for the effective use of clinic time and resources.

The otolith organs (the saccule and utricle) are located in the inner ear and sense linear acceleration, head tilt, and gravity. Recently, the vestibular evoked myogenic potential (VEMP) and the subjective visual vertical (SVV) have been described as clinical tests for otolith function. VEMPs are short latency electromyograms (EMG) evoked by high-level acoustic and vibratory stimuli recorded from surface electrodes over the tonically contracted SCM muscles (cervical VEMP) or extra-ocular muscles (ocular VEMP). The SVV is a psychophysical measure of the angle between perceptual vertical and true (gravitational) vertical and can be measured during unilateral centrifugation (off-axis eccentric rotation). The purpose of this paper is to discuss the clinical use and recent developments of the cervical VEMP, ocular VEMP, and SVV as tests of saccular and utricular function.

Vestibular-evoked myogenic potentials (VEMPs) are proposed as a reliable test to supplement the current vestibular test battery by providing diagnostic information about saccular and/or inferior vestibular nerve function. VEMPs are short-latency electromyograms (EMGs) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid muscle. VEMP amplitude is influenced by the EMG level, which must be controlled. This study examined the ability of subjects to achieve the EMG target levels over a range of target levels typically used during VEMP recordings. In addition, the influence of target EMG level on the latency and amplitude of the click- and tone-evoked VEMP was examined. The VEMP amplitude increased as a function of EMG target level, and the latency remained constant. EMG target levels ranging from 30 microV to 50 microV are suggested for clinical application of the VEMP.

The Motion Sensitivity Test (MST) is a clinical protocol designed to measure motion-provoked dizziness during a series of 16 quick changes to head or body positions. The MST has been used as a guide for developing an exercise program for patients with motion-provoked dizziness and as a treatment outcome measure to monitor the effectiveness of vestibular rehabilitation therapy. This study determined validity, test-retest reliability, and interrater reliability of the MST. Fifteen individuals with motion-provoked dizziness and ten control individuals were tested during sessions occurring 90 min and/or 24 hr after baseline testing. The MST was found to be reliable across raters (intraclass correlation coefficient [ICC] = 0.99) and test sessions (ICC = 0.98 and 0.96). Test validity was good. The results indicated that the MST can be used reliably in clinical practice to develop exercise programs for patients with motion-provoked dizziness and to provide evidence of intervention efficacy.