Reduced vestibular perception thresholds in persistent postural-perceptual dizziness- a cross-sectional study

Abstract

Background: Persistent postural-perceptual dizziness (PPPD) is the most common functional vestibular disorder. A multisensory mismatch altered by psychological influences is considered to be an important pathophysiological mechanism. Increased cortical and subcortical excitability may play a role in the pathophysiology of PPPD. We hypothesized that decreased motion perception thresholds reflect one mechanism of the abnormal vestibular responsiveness in this disorder. We investigated the vestibular perception thresholds and the vestibular ocular reflex with a rotatory chair experiment to gain insights in the processing and adaption to vestibular provocation.

Methods: In this cross-sectional study 26 female PPPD patients and 33 healthy female age matched controls (HC) were investigated sitting in a motorized rotary chair shielded regarding visual and acoustic stimuli. The chair was rotated for 20 minutes with slowly increasing velocity to a maximum of 72°/s. We functionally tested motion perception thresholds and vegetative responses to rotation as well as vestibular-ocular reflex thresholds. We additionally investigated several psychological comorbidities (i.e. depression, anxiety, somatosensory amplification) using validated scores. Conventional dizziness scores were obtained to quantify the experienced dizziness and impact on daily life.

Results: PPPD patients showed a significant reduced vestibulo-perceptual threshold (PPPD: 10.9°/s vs. HC: 29.5°/s; p<0.001) with increased motion sensitivity and concomitant vegetative response during and after the chair rotation compared to healthy controls. The extent of increased vestibular sensitivity was in correlation with the duration of the disease (p=0.043). No significant difference was measured regarding nystagmus parameters between both groups.

Conclusion: PPPD patients showed increased vegetative response as well as decreased vestibulo-perceptual thresholds which are related to disease duration. This is of interest as PPPD might be sustained by increased vestibular excitability leading to motion intolerance and induction of dizziness when exposed to movement.

Keywords: Persistent postural-perceptual dizziness; functional vestibular disorder; motion sensitivity; vestibular perceptual threshold.

Fig. 1

a Rotary motion perception threshold. Thresholds for initial rotary motion perception are shown for persistent postural-perceptual dizziness (PPPD) patients and healthy controls (HC). PPPD patients had a significantly lower threshold (PPPD: 10.85 +/-14.12 °/s; HC: 29.48 +/-23.49 °/s; p<0.001, Mann-Whitney test). Bars indicate standard error of mean. b Individual motion perceptual thresholds in PPPD patients and HC. Subjects’ data points for the individual motion perceptual thresholds are shown. In addition, the respective data of direction-specific perception of PPPD patients and HC are presented

Fig. 2

Duration of phases with vegetative symptoms during rotation. Mean duration of sickness rating phases (SR 1-3) are shown during rotation. PPPD patients develop vegetative symptoms earlier as they pass through the different phases with vegetative symptoms faster (SR 1; PPPD: 283.19 s +/-145.06; HC: 1043.61 s +/-275.14; p<0.001, Mann-Whitney test; SR 2; PPPD: 220.27 s +/-139.49; HC: 417 s +/-277.89; p=0.008, Mann-Whitney test). Duration of SR 3 did not differ significantly (PPPD: 308.81 s +/-187.76; HC: 265 +/-199.4; p=0.809, Mann-Whitney test). SR 4 is not illustrated as the entry in this phase leads to the interruption of the rotation. Bars indicate standard error of mean

Fig. 3

Recovery from vegetative symptoms after completion of rotation. After completion of rotation PPPD patients recovered significantly slower than healthy controls (HC) from vegetative symptoms (sickness rating score = SR) (mean SR: minute 1; PPPD: 2.65 +/-0.8, HC: 1.18 +/-0.39; p<0.001 and minute 5; PPPD: 1.65 +/-0.8, HC: 1 +/-0; p<0.001, Mann-Whitney test). Since all HC were symptom-free from minute 5 after completion (SR 1), no bars and error bars appear for HC from minute 5 to 15. After 20 minutes all participants were again asymptomatic, therefore this is not illustrated