Revolutionize Vestibular Testing: New Ways to Assess Patients with Central Disorders

By Maggie Boorazanes and Brianna Young

This article is a part of the May/June 2017, Volume 29, Number 3, Audiology Today issue.

The patient journey for vestibular assessment can be a lengthy process. A 2011 survey by the Vestibular Disorders Association (VEDA) states that, on average, patients consult four to five doctors before receiving a diagnosis. Furthermore, it takes an average of three to five years for a person with a vestibular disorder to receive a diagnosis (VEDA, 2011). By applying new testing techniques, clinicians can scale down their workflow and obtain an accurate diagnosis in less time. The article, “A Streamlined Approach to Assessing Patients with Peripheral Disorders,” featured in the September/October 2015 issue of Audiology Today, presented a comprehensive review of the assessment process for peripheral vestibular disorders. The authors proposed management modification through changes to the current, widely accepted, protocols for testing that center around videonystagmography and electronystagmography (VNG and ENG, respectively).

The effectiveness of vestibular assessment has been improved by technological developments such as the video head impulse test (vHIT) that can provide unique insights to differential diagnosis. The vHIT itself has been a major development in the area of vestibular development as it has allowed the evaluation of all six semicircular canals independently. The diagnostic utility of the vHIT has been further increased by technological advances allowing unique insight in the central vestibular function. Originally released in 2013 with only vHIT capability, the ICS Impulse^® has since been enhanced with additional technological advances and made available to audiologists in the United States following Food and Drug Administration clearance of the ICS Impulse Oculomotor and Positional modules.

As recently as September 2016, the ICS Impulse was again updated to include the Suppression Head Impulse Paradigm (SHIMP), which was introduced at the Barany Society meeting in June, 2016. The SHIMP tracks the presence of anti-compensatory saccades after a head turn. These results can support residual vestibular function (MacDougall, et al, 2016). Initial reports of SHIMP results focuses on findings for those with normal vestibular function, unilateral vestibular loss, and bilateral vestibular loss (MacDougall, et al, 2016) where, “in all participants, SHIMP [and vHIT] resulted in a reversed saccadic pattern.” This means that healthy controls with normal vestibular function showed few catch-up saccades with vHIT, whereas testing with SHIMP demonstrated large negative saccades. Conversely, patients with bilateral vestibular loss showed frequent overt saccades during vHIT but few saccades during SHIMP. In comparison, patients with unilateral vestibular loss demonstrated covert saccades when vHIT was performed to the affected side, with large downward saccades to the healthy side during SHIMP. While more work needs to be done to better understand the clinical utility of SHIMP and its relation to the vHIT test, the initial results are indeed promising.