Vestibular assessment in sudden sensorineural hearing loss: Role in the prediction of hearing outcome and in the early detection of vascular and hydropic pathomechanisms

Abstract

Introduction: Predicting hearing outcome in sudden sensorineural hearing loss (SSNHL) is challenging, as well as detecting the underlying pathomechanisms. SSNHL could be associated with vestibular damage since cochleo-vestibular structures share the same vascularization, along with being in close anatomical proximity. Whereas viral inflammations and autoimmune/vascular disorders most likely represent the involved aetiologies, early-stage Menière's disease (MD) can also present with SSNHL. Since an early treatment could beneficially influence hearing outcome, understanding the possible etiology plays a pivotal role in orienting the most appropriate treatment. We aimed to evaluate the extent of vestibular damage in patients presenting with SSNHL with or without vertigo, investigate the prognostic role of vestibular dysfunctions on hearing recovery and detect specific lesion patterns related to the underlying pathomechanisms.

Methods: We prospectively evaluated 86 patients with SSNHL. Audio-vestibular investigation included pure-tone/speech/impedance audiometry, cervical/ocular-VEMPs, vHIT and video-Frenzel examination. White matter lesions (WML) were evaluated on brain-MRI. Patients were followed-up and divided into "SSNHL-no-vertigo," "SSNHL+vertigo" and "MD" subgroups.

Results: Hearing was more impaired in "SSNHL+vertigo" patients who exhibited either down-sloping or flat-type audiograms, and was less impaired in "MD" where low frequencies were mostly impaired (p < 0.001). Otolith receptors were more frequently involved than semicircular canals (SCs). Although the "SSNHL-no-vertigo" subgroup exhibited the lowest vestibular impairment (p < 0.001), 52% of patients developed otolith dysfunctions and 72% developed nystagmus. Only "MD" subjects showed anterior SC impairment and upbeating spontaneous/positional nystagmus. They more frequently exhibited cervical-VEMPs frequency tuning (p = 0.036) and ipsilesional spontaneous nystagmus (p < 0.001). "SSNHL+vertigo" subjects presented with more frequently impaired cervical-VEMPs and posterior SC and with higher number of impaired receptors (p < 0.001). They mainly exhibited contralesional spontaneous and vibration-induced nystagmus (p < 0.05) and only they showed the highest WML score and "vascular" lesion patterns (p < 0.001). Concerning the outcomes, hearing was better in "MD" and worse in "SSNHL+vertigo" (p < 0.001). Hearing recovery was mostly affected by cervical-VEMPs impairment and the number of involved receptors (p < 0.05). Patients with "vascular" lesion patterns presented with the highest HL degree and WML score (p ≤ 0.001), while none of them exhibited a complete hearing recovery (p = 0.026).

Conclusions: Our data suggest that vestibular evaluation in SSNHL can provide useful information on hearing recovery and underlying aetiologies.

Keywords: Menière's disease; labyrinthine ischemia; spontaneous nystagmus; sudden sensorineunal hearing loss; vestibular evoked myogenic potentials (VEMPs); vestibulo-ocular reflex (VOR); video head impulse (vHIT).

Figure 1

Bar plots showing the number of cases among overall cohort of 86 cases exhibiting different instrumental findings. (A) Normal or impaired function of otolith receptors. (B) Normal or impaired function of semicircular canals. Relative percentages are reported in each column and p-values of categorical comparisons are reported. ASC, anterior semicircular canal; HSC, horizontal semicircular canal; PSC, posterior semicircular canal.

Figure 2

Presenting audiometric features of the affected ear of the overall cohort, divided in subgroups based on clinical course. (A) Audiogram. (B) Box plot correlating median values of PTA among subgroups. Statistically significant differences at the ANOVA test are shown. (C, D) Bar plots showing the number of cases presenting with different HL configurations (C) and different HL degree (D) among subgroups. Relative percentages are reported in each column and p-values of categorical comparisons are reported. HL, hearing loss; MD, Menière's disease; PTA pre, presenting pure tone average; SSNHL, sudden sensorineural hearing loss.

Figure 3

Different distribution of saccular (A–D) and utricular dysfunction (E, F), as assessed by c and oVEMPs, respectively, among different subgroups based on clinical course. (A) Bar plot showing the distribution of impaired saccular function of the side affected by SSNHL among different subgroups. Relative percentages are reported in each column and p-value of categorical comparisons is reported. (B) Box plot correlating median values of cVEMPs AR among subgroups. Statistically significant differences at the ANOVA test are shown. Bar plots showing the distribution of positive frequency tuning of cVEMPs of the side affected by SSNHL (C) and of the contralesional side (D) among different subgroups. Relative percentages are reported in each column and p-values of categorical comparisons are reported. (E) Bar plot showing the distribution of impaired utricular function of the side affected by SSNHL among different subgroups. Relative percentages are reported in each column and p-value of categorical comparisons is reported. (F) Box plot correlating median values of oVEMPs AR among subgroups. No statistically significant differences at the ANOVA test are shown. AR, asymmetry ratio; contra, contralesional ear; cVEMPS, cervical vestibular-evoked myogenic potentials; ipsi, affected ear; MD, Menière's disease; oVEMPs, ocular vestibular-evoked myogenic potentials; SSNHL, sudden sensorineural hearing loss.

Figure 4

Different distribution of semicircular canal dysfunction, as assessed by vHIT, among different subgroups based on clinical course. (A, C, E) Bar plots showing the distribution of impaired HSC (A), ASC (C) and PSC function (E) of the side affected by SSNHL among different subgroups. Relative percentages are reported in each column and p-values of categorical comparisons are reported. (B, D, F) Box plots correlating median values of HSC (B), ASC (D), and PSC VOR gain (F) among subgroups. Statistically significant differences at the ANOVA test are shown. ASC, anterior semicircular canal; HSC, horizontal semicircular canal; MD, Menière's disease; PSC, posterior semicircular canal; SSNHL, sudden sensorineural hearing loss; VOR, vestibulo-ocular reflex; vHIT, video-head impulse test.

Figure 5

(A, B) Bar plots showing the different distribution of otolith (A) and semicircular canal (B) lesion patterns among different subgroups based on clinical course. Relative percentages are reported in each column and p-values of categorical comparisons are reported. (C, D) Bar plots showing the different distribution of end-organ lesion patterns (C) and the amount of impaired vestibular receptors (D) among different subgroups. Relative percentages are reported in each column and p-value of categorical comparisons is reported. ASC, anterior semicircular canal; HSC, horizontal semicircular canal; MD, Menière's disease; PSC, posterior semicircular canal; S, sacculus; SSNHL, sudden sensorineural hearing loss; U, utriculus.

Figure 6

Bar plots showing the different distribution of the features of spontaneous (A), positional (B), head shaking (C), vibration-induced (D), and hyperventilation nystagmus (E) among different subgroups based on clinical course. Relative percentages are reported in each column and p-values of categorical comparisons are reported. MD, Menière's disease; SSNHL, sudden sensorineural hearing loss.

Figure 7

Final audiometric features at 6-month follow up of the affected ear of the overall cohort, divided in subgroups based on clinical course. (A) Audiogram. (B) Box plot correlating median values of PTA among subgroups. Statistically significant differences at the ANOVA test are shown. (C) Bar plot showing the different distribution of hearing recovery among different subgroups. Relative percentages are reported in each column and p-value of categorical comparisons is reported. MD, Menière's disease; PTA post, pure tone average at 6-month follow up; SSNHL, sudden sensorineural hearing loss.

Figure 8

Bar plots showing the different distribution of otolith (A, B) and semicircular canal impairment (C–E) ipsilesionally to SSNHL, as measured by cVEMPs, oVEMPs, and vHIT, respectively, once divided the cohort according to hearing recovery. Relative percentages are reported in each column and p-value of categorical comparisons are reported. ASC, anterior semicircular canal; cVEMPs, cervical vestibular-evoked myogenic potentials; HSC, horizontal semicircular canal; oVEMPs, ocular vestibular-evoked myogenic potentials; PSC, posterior semicircular canal; SSNHL, sudden sensorineural hearing loss; vHIT, video-head impulse test.

Figure 9

Correlation between the number of impaired vestibular receptors ipsilesionally to SSNHL and hearing recovery. (A) Bar plots showing the different distribution of hearing recovery among the study cohort divided according to the number of affected sensors. (B) Correlation trend between the number of impaired vestibular receptors and mean percentage of hearing recovery.

Figure 10

Vascular patterns. (A, B) Bar plots showing the different distribution of Fazekas grading of WML on MRI (A) and instrumental lesion patterns consistent with a vascular lesion (B) among the study cohort divided according to the clinical course. (C–F) Bar plots showing the different distribution of HL configuration (C), HL degree (D), hearing recovery (E), and Fazekas grading of WML on MRI (F) among the study cohort divided according to the instrumental lesion patterns consistent with a vascular lesion. Relative percentages are reported in each column and p-value of categorical comparisons are reported. HL, hearing loss; MD, Menière's disease; SSNHL, sudden sensorineural hearing loss; WML, white matter lesions.

Figure 11

Presenting scenario of patients #42 with an instrumental lesion pattern consistent with an ischemic damage in the territory mainly supplied by the right VCA (see also the Supplementary Video 1). (A) Pure-tone audiometry exhibiting high-frequency sensorineural HL on the right side. (B) vHIT showing a selective VOR-gain impairment for the right PSC (0.42) with overt saccades. (C) cVEMPs revealing absent potentials on the right side and normal responses on the left side (AR = 100%). (D) oVEMPs with potentials on both sides with an amplitude asymmetry within normality range (L > R, AR = 29%). (E) Schematic representation of the vascular supply of the inner ear, highlighting the assumed ischemic pathomechanism [modified from Schuknecht (63)]. Labyrinthine receptors mainly supplied by the VCA are represented in gray. AC, air-conduction; AICA, anterior-inferior cerebellar artery; ASC, anterior semicircular canal; BC, bone-conduction; cVEMPs, cervical vestibular-evoked myogenic potentials; HSC, horizontal semicircular canal; L, left; LA, left anterior; LL, left lateral; LP, left posterior; oVEMPs, ocular vestibular-evoked myogenic potentials; PSC, posterior semicircular canal; R, right; RA, right anterior; RL, right lateral; RP, right posterior; VCA, vestibulo-cochlear artery; vHIT, video-head impulse test; VOR, vestibulo-ocular reflex.

Figure 12

Presenting scenario of patients #64 with an instrumental lesion pattern consistent with an ischemic damage in the territory mainly supplied by the right CAA (see also the Supplementary Video 2). (A) Pure-tone audiometry exhibiting severe down-sloping sensorineural HL on the right side. (B) vHIT showing a selective VOR-gain impairment for the right PSC (0.6) with both overt and covert saccades. (C) cVEMPs revealing absent potentials on the right side and normal responses on the left side (AR = 100%). (D) oVEMPs with potentials on both sides with an abnormal amplitude asymmetry (L > R, AR = 33%). (E) Labyrinthine receptors mainly supplied by the CCA are represented in gray. AC, air-conduction; AICA, anterior-inferior cerebellar artery; ASC, anterior semicircular canal; BC, bone-conduction; CCA, common-cochlear artery; cVEMPs, cervical vestibular-evoked myogenic potentials; HSC, horizontal semicircular canal; L, left; LA, left anterior; LL, left lateral; LP, left posterior; oVEMPs, ocular vestibular-evoked myogenic potentials; PSC, posterior semicircular canal; R, right; RA, right anterior; RL, right lateral; RP, right posterior; vHIT, video-head impulse test; VOR, vestibulo-ocular reflex.

Figure 13

Presenting scenario of patients #59 with an instrumental lesion pattern consistent with an ischemic damage in the territory mainly supplied by the left IAA (see also the Supplementary Video 3). (A) Pure-tone audiometry exhibiting severe flat sensorineural HL on the left side. (B) vHIT showing VOR-gain impairment for all the left SCs with mainly overt saccades. cVEMPs (C) and oVEMPs (D) revealing absent potentials on the left side and normal responses on the right (AR = 100%). (E) Labyrinthine receptors mainly supplied by the IAA are represented in gray. AC, air-conduction; AICA, anterior-inferior cerebellar artery; ASC, anterior semicircular canal; BC, bone-conduction; CCA, common-cochlear artery; cVEMPs, cervical vestibular-evoked myogenic potentials; HSC, horizontal semicircular canal; L, left; LA, left anterior; LL, left lateral; LP, left posterior; oVEMPs, ocular vestibular-evoked myogenic potentials; PSC, posterior semicircular canal; SC, semicircular canal; R, right; RA, right anterior; RL, right lateral; RP, right posterior; vHIT, video-head impulse test; VOR, vestibulo-ocular reflex.