Journal of Vestibular Research

Persistent Postural Perceptual Dizziness (PPPD) is a recently defined functional syndrome. In other functional disorders there has been concern that the label itself can have negative effects, but research on patient views of PPPD is lacking.

To understand patient views of the PPPD label

Semi-structured interviews were conducted with 13 people with PPPD and thematically analysed.

Four themes were identified. Theme 1 reflects reassurance and validation received through a ‘label’. Theme 2 reflects re-evaluation of illness-beliefs, with the diagnosis giving greater perception of control but also perception of having serious consequences. Theme 3 reflects difficulty understanding terminology. Participants rarely understood “persistent”, “perceptual” and “postural”. They did not tend to use the term “PPPD” to others or themselves. Some interpreted “persistent” as meaning “poor prognosis”. Theme 4 reflects lack of psychological attribution, since participants normalised the experience of distress, but did not view this as part of PPPD.

These data support the relevance of PPPD beyond simply classification. However patients found the components of the term itself confusing and did not tend to adopt it when relating their condition to others or themselves. Simplifying the nomenclature could facilitate shared understanding and management, even potentially influencing outcome.

Embedded within most rapid head rotations are gaze shifts, which is an initial eye rotation to a target of interest, followed by a head rotation towards the same target. Gaze shifts are used to acquire an image that initially is outside of the participant’s current field of vision. Currently, there are no tools available that evaluate the functional relevance of a gaze shift.

The purpose of our study was to measure dynamic visual acuity (DVA) while performing a gaze shift.

Seventy-one healthy participants (42.79±16.89 years) and 34 participants with unilateral vestibular hypofunction (UVH) (54.59±20.14 years) were tested while wearing an inertial measurement unit (IMU) sensor on the head and walking on a treadmill surrounded by three monitors. We measured visual acuity during three subcomponent tests: standing (static visual acuity), while performing an active head rotation gaze shift, and an active head rotation gaze shift while walking (gsDVAw).

While doing gsDVAw, patients with Left UVH (n = 21) had scores worse (p = 0.023) for leftward (0.0446±0.0943 LogMAR) head rotation compared with the healthy controls (–0.0075±0.0410 LogMAR). Similarly, patients with right UVH (N = 13) had worse (p = 0.025) gsDVAw for rightward head motion (0.0307±0.0481 LogMAR) compared with healthy controls (–0.0047±0.0433 LogMAR). As a whole, gsDVAw scores were worse in UVH compared to the healthy controls when we included the ipsilesional head rotation on both sides gsDVAw (0.0061±0.0421 LogMAR healthy vs. 0.03926±0.0822 LogMAR UVH, p = 0.003). Controlling for age had no effect, the gsDVAw scores of the patients were always worse (p < 0.01).

The gaze shift DVA test can distinguish gaze stability in patients with UVH from healthy controls. This test may be a useful measure of compensation for patients undergoing various therapies for their vestibular hypofunction.

The traditional Sensory Organization Test (T-SOT) is a gold standard balance test; however, the psychometric properties of assessing sensory organization with a virtual-reality-based posturography device have not been established.

Our overall aims were to assess the criterion, concurrent, and convergent validity of a next-generation Sensory Organization Test (NG-SOT).

Thirty-four adults (17 vestibular-impaired) participated. We compared the area under the curve (AUC) for receiver operator characteristic (ROC) analysis for the T-SOT and NG-SOT composite scores. Between-group and between-test differences for the composite and sensory analysis scores from each SOT were assessed using Wilcoxon Rank Sum tests. Additionally, we ran Spearman correlations between the NG-SOT composite score and outcomes of interest.

The AUCs for the NG-SOT and T-SOT were 0.950 (0.883, 1) and 0.990 (0.969, 1) respectively (p = 0.168). The median composite, vision, and visual preference scores were lower on the NG-SOT compared to the T-SOT; whereas, the median somatosensory score was higher on the NG-SOT compared to the T-SOT. Associations between the composite score and patient-reported or performance-based outcomes ranged from poor to strong.

The NG-SOT is a valid measure of balance in adults. However, the results of the NG-SOT and T-SOT should not be used interchangeably.

The cervical vestibular evoked myogenic potential (cVEMP) can be affected by the recording parameters used to quantify the response.

We investigated the effects of electrode placement and montage on the variability and symmetry of sternocleidomastoid (SCM) contraction strength and cVEMP amplitude.

We used inter-side asymmetries in electrode placement to mimic small clinical errors in twenty normal subjects. cVEMPs were recorded at three active electrode sites and referred to the distal SCM tendon (referential montages: upper, conventional and lower). Additional bipolar montages were constructed offline to measure SCM contraction strength using closely-spaced electrode pairs (bipolar montages: superior, lower and outer).

The conventional montage generally produced the largest cVEMP amplitudes (P < 0.001). SCM contraction strength was larger for referential montages than bipolar ones (P < 0.001). Inter-side electrode position errors produced large variations in cVEMP and SCM contraction strength asymmetries in some subjects, producing erroneous abnormal test results.

Recording locations affect cVEMP amplitude and SCM contraction strength. In most cases, small changes in electrode position had only minor effects but, in a minority of subjects, the different montages produced large changes in cVEMP and contraction amplitudes and asymmetry, potentially affecting test outcomes.

Cochlear implantation may be complicated by concurrent injury to the vestibular apparatus, potentially resulting in disabling vertigo and balance problems. Information on vestibular function before implantation as measured by the video head impulse test (VHIT) and cervical vestibular evoked myogenic potentials (cVEMPs) is scarce and literature on long-term effects is non-existing.

We aimed to evaluate how vestibular function was affected by cochlear implantation (CI), as measured by VHIT and cVEMPs in the late phase after implantation.

Retrospective repeated measurement study. Patients: Among the 436 patients elected for CI surgery during 2013 to 2018, 45 patients met the inclusion criteria (CI recipients with a vestibular assessment prior to the first CI and a repeated vestibular assessment after the CI operation). Intervention: VHIT and cVEMPs before and after cochlear implantation. Main outcome measures were vestibular function as evaluated by VHIT gain, saccades and cVEMPs.

The mean time between first and second vestibular screening was 19 months. The mean VHIT gain on implanted ears was 0.79 before the operation and showed no change at follow-up (p = 0.65). Likewise, the number of abnormal VHIT gain values was equal before and after the operation (p = 0.31). Preoperatively, saccades were present on 12 ears (14%) compared with 25 ears (29%) postoperatively (p = 0.013) and were associated with significantly lower VHIT gain values. Preoperatively, positive cVEMPs were found in 20 CI ears (49%) and 24 contralateral ears (62%). 10 CI ears lost cVEMP postoperatively compared with 2 ears on the contralateral side (p = 0.0047).

Even though VHIT gain has been reported to be affected in the immediate post-implantation period, the findings in this study show that VHIT gain is normalized in the long-term. However, cochlear implantation is associated with the occurrence of VHIT saccades in the long-term and these are associated with lower VHIT gain values. In addition, cVEMP responses are significantly reduced long-term on implanted ears, which agrees with other studies with shorter follow-up.