Saccades Matter: Reduced Need for Caloric Testing of Cochlear Implant Candidates by Joint Analysis of v-HIT Gain and Corrective Saccades

Functional and imaging anomalies of the vestibular system in motion sickness: a clinical observation study

OBJECTIVE

The aim of this study is to investigate the differences in vestibular organ function tests and the temporal bone computed tomography (CT) findings between healthy individuals and patients with motion sickness (MS), providing a basis for establishing functional and imaging diagnostic criteria for MS.

METHOD

Vestibular organ function tests and temporal bone CT imaging were performed on patients in the MS group (n = 50) and healthy individuals in the control group (n = 50). Functional and imaging anomalies of the vestibular organ were identified and their features and patterns were analyzed. Patients with MS were further stratified based on severity to examine whether temporal bone CT findings varied across severity grade, and indexes of diagnostic significance were identified.

RESULTS

Comparisons of vestibular function tests revealed significantly lower bilateral vestibular evoked myogenic potential (VEMP) amplitudes in the MS group compared to the control group, with statistical significance (P < 0.05). The severity of MS demonstrated a positive correlation with reductions in bilateral cervical VEMP (cVEMP) amplitudes (P < 0.05). Video head impulse test (v-HIT) results indicated statistically significant differences in the gains of the left anterior, right horizontal, and left posterior semicircular canals (P < 0.05). There were significant differences in the bilateral vestibular caloric test (CT) values (P < 0.05). In terms of the temporal bone CT findings in the two groups, the detection rate of high jugular bulb combined with sinusitis, poor mastoid pneumatization, diploetic mastoid, or sclerotic mastoid was higher in patients with MS than in the healthy control group. Additionally, the detection rate of temporal bone anomalies in CT scans was significantly higher in the very severe and severe MS groups compared to the mild and moderate MS groups.

CONCLUSION

In this study, we found that patients with MS exhibited functional and structural anomalies in vestibular function and temporal bone CT findings, which were correlated with the severity of MS. These findings suggest that vestibular function tests and temporal bone CT imaging can be used as objective reference indexes for the diagnosis of MS and assessment of its severity.

Impact of Cochlear Implantation on Canal and Otolith Function

OBJECTIVE

To quantify the impact of cochlear implantation (CI) on all five vestibular end-organs and on subjective ratings of post-CI dizziness.

METHODS

Seventy-two patients undergoing unilateral CI were recruited for the study. All participants completed pre- and post-CI three-dimensional video head-impulse tests (3D vHITs) to assess semicircular-canal (SC) function, air- and bone-conducted (AC and BC) cervical and ocular vestibular-evoked myogenic potentials (cVEMPs and oVEMPs) to assess otolith-function and the dizziness handicap inventory (DHI) to measure self-perceived disability.

RESULTS

Nineteen percent of patients reported new or worsened dizziness postsurgery. Post-CI abnormalities (new lesions and significant deteriorations) were seen in the AC cVEMP (48%), AC oVEMP (34%), BC cVEMP (10%), and BC oVEMP (7%); and lateral (L) (17%), posterior (P) (10%), and anterior (A) (13%) SC vHITs. CI surgery was more likely to affect the AC cVEMP compared with the other tests (χ2 test, p < 0.05). Fifty percent of patients reported no dizziness pre- and postsurgery. In the implanted ear, normal pre-CI vHIT gain was preserved in lateral semicircular canal (LSC) (69%), anterior semicircular canal (ASC) (74%), and posterior semicircular canal (PSC) (67%), and normal reflex amplitudes were found in AC cVEMP (25%), AC oVEMP (20%), BC cVEMP (59%), and BC oVEMP (74%). Statistically significant decreases were observed in LSC vHIT gain, AC cVEMP amplitude, and AC oVEMP amplitude postsurgery (p < 0.05). There was a significant moderate positive correlation between change in DHI scores and the summed vestibular deficit postsurgery (r(51) = 0.38, p < 0.05).

CONCLUSION

CI can impact tests that assess all five vestibular end-organs and subjective ratings of dizziness. These results support pre and post-surgical vestibular testing and assist preoperative counseling and candidate selection.