Vestibular Assessment with the vHIT and Skull Vibration-Induced Nystagmus Test in Patients with Nonprogressive Vestibular Schwannoma.

Background: Our primary objective was to monitor nonprogressive unilateral vestibular schwannomas (VSs) to assess the efficiency of rapid bedside examinations, such as the video head impulse test (vHIT) and skull vibration-induced nystagmus test (SVINT), in identifying vestibular damage. Methods: An observational study was conducted from March 2021 to March 2022 on all adult patients (>18 years old) with a confirmed nonprogressive VS (no active treatment). The SVINT (using a 100 Hz vibrator with two (SVINT2) or three (SVINT3) stimulation locations) and vHIT (for the six semicircular canals (SCCs)) were performed on all patients. The asymmetry of function between the vestibules was considered significant when the gain asymmetry was greater than 0.1. Rapid and repeatable assessment of VSs using two- and three-stimulation SVINT plus vHIT was performed to quantify intervestibular asymmetry. Results: SVINT3 and SVINT2 triggered VIN in 40% (24/60) and 65% (39/60) of patients, respectively. There was significant asymmetry in the vestibulo-ocular reflex (VOR), as shown by a VS-side gain < healthy-side gain in 58% (35/60) of the patients. Among the patients with significant gain asymmetry between the two vestibules according to the vHIT (VS-side gain < healthy-side gain), the proportion of patients expressing vestibular symptomatology was significantly greater than that of patients without any symptoms [67% (29/43) vs. 35% (6/17), respectively; p = 0.047]. Conclusions: The SVINT2 can be combined with the vHIT to form an interesting screening tool for revealing vestibular asymmetry. This work revealed the superiority of mastoid stimulation over vertex stimulation for SVINT in patients with unilateral vestibular loss.

Posterior Semicircular Canal Dehiscence with Vestibulo-Ocular Reflex Reduction for the Affected Canal at the Video-Head Impulse Test: Considerations to Pathomechanisms.

Posterior semicircular canal dehiscence (PSCD) has been demonstrated to result in a third mobile window mechanism (TMWM) in the inner ear similar to superior semicircular canal dehiscence (SSCD). Typical clinical and instrumental features of TMWM, including low-frequency conductive hearing loss (CHL), autophony, pulsatile tinnitus, sound/pressure-induced vertigo and enhanced vestibular-evoked myogenic potentials, have been widely described in cases with PSCD. Nevertheless, video-head impulse test (vHIT) results have been poorly investigated. Here, we present six patients with PSCD presenting with a clinical scenario consistent with a TMWM and an impaired vestibulo-ocular reflex (VOR) for the affected canal on vHIT. In two cases, an additional dehiscence between the facial nerve and the horizontal semicircular canal (HSC) was detected, leading to a concurrent VOR impairment for the HSC. While in SSCD, a VOR gain reduction could be ascribed to a spontaneous "auto-plugging" process due to a dural prolapse into the canal, the same pathomechanism is difficult to conceive in PSCD due to a different anatomical position, making a dural herniation less likely. Alternative putative pathomechanisms are discussed, including an endolymphatic flow dissipation during head impulses as already hypothesized in SSCD. The association of symptoms/signs consistent with TMWM and a reduced VOR gain for the posterior canal might address the diagnosis toward PSCD.

Skull Vibration-Induced Nystagmus in Superior Semicircular Canal Dehiscence: A New Insight into Vestibular Exploration-A Review.

The third window syndrome, often associated with the Tullio phenomenon, is currently most often observed in patients with a superior semicircular-canal dehiscence (SCD) but is not specific to this pathology. Clinical and vestibular tests suggestive of this pathology are not always concomitantly observed and have been recently complemented by the skull-vibration-induced nystagmus test, which constitutes a bone-conducted Tullio phenomenon (BCTP). The aim of this work was to collect from the literature the insights given by this bedside test performed with bone-conducted stimulations in SCD. The PRISMA guidelines were used, and 10 publications were included and analyzed. Skull vibration-induced nystagmus (SVIN), as observed in 55 to 100% of SCD patients, usually signals SCD with greater sensitivity than the air-conducted Tullio phenomenon (ACTP) or the Hennebert sign. The SVIN direction when the test is performed on the vertex location at 100 Hz is most often ipsilaterally beating in 82% of cases for the horizontal and torsional components and down-beating for the vertical component. Vertex stimulations are more efficient than mastoid stimulations at 100 Hz but are equivalent at higher frequencies. SVIN efficiency may depend on stimulus location, order, and duration. In SCD, SVIN frequency sensitivity is extended toward high frequencies, with around 400 Hz being optimal. SVIN direction may depend in 25% on stimulus frequency and in 50% on stimulus location. Mastoid stimulations show frequently diverging results following the side of stimulation. An after-nystagmus observed in 25% of cases can be interpreted in light of recent physiological data showing two modes of activation: (1) cycle-by-cycle phase-locked activation of action potentials in SCC afferents with irregular resting discharge; (2) cupula deflection by fluid streaming caused by the travelling waves of fluid displacement initiated by sound or vibration at the point of the dehiscence. The SVIN direction and intensity may result from these two mechanisms' competition. This instability explains the SVIN variability following stimulus location and frequency observed in some patients but also discrepancies between investigators. SVIN is a recent useful insight among other bedside examination tests for the diagnosis of SCD in clinical practice.

A bone-conducted Tullio phenomenon-A bridge to understand skull vibration induced nystagmus in superior canal dehiscence.

Nystagmus produced in response to air-conducted sound (ACS) stimulation-the Tullio phenomenon-is well known in patients with a semicircular canal (SCC) dehiscence (SCD). Here we consider the evidence that bone-conducted vibration (BCV) is also an effective stimulus for generating the Tullio phenomenon. We relate the clinical evidence based on clinical data extracted from literature to the recent evidence about the physical mechanism by which BCV may cause this nystagmus and the neural evidence confirming the likely mechanism. The hypothetical physical mechanism by which BCV activates SCC afferent neurons in SCD patients is that traveling waves are generated in the endolymph, initiated at the site of the dehiscence. We contend that the nystagmus and symptoms observed after cranial BCV in SCD patients is a variant of Skull Vibration Induced Nystagmus (SVIN) used to identify unilateral vestibular loss (uVL) with the major difference being that in uVL the nystagmus beats away from the affected ear whereas in Tullio to BCV the nystagmus beats usually toward the affected ear with the SCD. We suggest that the cause of this difference is a cycle-by-cycle activation of SCC afferents from the remaining ear, which are not canceled centrally by simultaneous afferent input from the opposite ear, because of its reduced or absent function in uVL. In the Tullio phenomenon, this cycle-by-cycle neural activation is complemented by fluid streaming and thus cupula deflection caused by the repeated compression of each cycle of the stimuli. In this way, the Tullio phenomenon to BCV is a version of skull vibration-induced nystagmus.

Correlation of SVINT and Sensory Organization Test in Children with Hearing Loss.

Objective: The skull vibration-induced-nystagmus test (SVINT) is a noninvasive and effective screening tool for the function of the otolith and canal structures in children. It can instantaneously assess vestibular asymmetry. This study aimed to analyze the SVINT results of healthy children vs. children with hearing loss (HL) and to correlate it with sensory organization test (SOT) results as a functional balance evaluation tool. Design: This case-controlled study compared the results of SVINT to the results of the SOT of the computerized dynamic posturography (CDP) in a control group of 120 healthy normal-hearing children (i.e., NH group) vs. hearing loss (HL) group of 60 children, including 30 children with hearing aids (HAs) and 30 children with a unilateral cochlear implant (CI). The SVINT results were compared to the caloric test (CaT) and video head impulse test (vHIT) and associated with SOT scores. Results: Thirty-one children in the HL group had normal SVINT and normal SOT results. A total of 21 children in the HL group had SVINT-negative and abnormal results in the SOT (possibly due to bilateral vestibular loss (BVL)). Eight children in the HL group had positive SVINT and abnormal SOT results. However, none of the children had only positive SVINT with normal SOT findings. Moreover, 52% of children had a normal result on both the SOT and CaT, whereas 27% had abnormal results on both tests (17% bilateral weakness and 10% unilateral), and 22% had the only result of the SOT suggesting a functional abnormality. Similarly, when associating the result to vHIT, 51% had normal results on both tests, and 25% had abnormal results (13% bilateral and 12% unilateral weakness). Conclusions: SVINT findings can be correlated with SOT findings in the case of the unilateral vestibular lesion (UVL), which adds a diagnostic value in these pediatric cases but may differ in the case of the bilateral vestibular lesion (BVL). However, SVINT findings need to be cautiously interpreted in light of other test findings such as the SOT, CaT, and vHIT.

Benign recurrent vestibulopathy: MRI and vestibular tests results in a series of 128 cases.

PURPOSE: Benign recurrent vestibulopathy is a recent entity, close to probable Meniere's disease and vestibular-migraine. So far, no study has systematically investigated the presence of endolymphatic hydrops of the lateral semicircular canal in benign recurrent vestibulopathy using magnetic resonance imaging. The aim of this study was to determine magnetic resonance imaging data and vestibular test results in patients with benign recurrent vestibulopathy. METHODS: 128 patients with benign recurrent vestibulopathy included since 2010 were retrospectively analyzed. Patients had magnetic resonance imaging with a delayed acquisition, audiogram, head shaking test, caloric-test, skull-vibration-induced-nystagmus-test, video-head- impulse-test, and vestibular evoked myogenic potential. Endolymphatic hydrops presence was classified into four categories: cochlear, saccular, lateral semicircular canal and association with saccule. RESULTS: In benign reccurent vestibulopathy, 23% of cases showed an endolymphatic hydrops on magnetic resonance imaging, more frequently located in the lateral semicircular canal (59%) and related to the disease duration. The most often impaired tests were caloric-test (49%) with fluctuations of hypofunction in 67% and skull-vibration-induced-nystagmus-test (61%). No correlation between the caloric-test and the presence and location of the endolymphatic hydrops was observed. CONCLUSION: In our series of benign reccurent vestibulopathy, a rare endolymphatic hydrops was most often observed for the lateral semicircular canal and correlated with the seniority of the pathology. Hydrops identified at the magnetic resonance imaging was not correlated with the caloric-test results. Skull-vibration-induced-nystagmus-test and caloric-test were the most often modified vestibular tests.

Skull Vibration Induced Nystagmus Test: Correlations with Semicircular Canal and Otolith Asymmetries.

BACKGROUND: To establish in patients with peripheral vestibular disorders relations between skull vibration-induced nystagmus (SVIN) different components (horizontal, vertical, torsional) and the results of different structurally related vestibular tests. METHODS: SVIN test, canal vestibular test (CVT: caloric test + video head impulse test: VHIT), otolithic vestibular test (OVT: ocular vestibular evoked myogenic potential oVEMP + cervical vestibular evoked myogenic potential cVEMP) performed on the same day in 52 patients with peripheral vestibular diseases (age < 65 years), and 11 control patients were analyzed. Mixed effects logistic regression analysis was performed to assert whether the presence of nystagmus in SVIN (3D analysis) have an association with the presence of peripheral vestibular dysfunction measured by vestibular explorations (CVT or OVT). RESULTS: We obtained different groups: Group-Co (control group), Group-VNT (dizzy patients with no vestibular tests alterations), Group-O (OVT alterations only), Group-C (CVT alterations only), Group-M (mixed alterations). SVIN-SPV horizontal component was significantly higher in Group-M than in the other groups (p = 0.005) and correlated with alterations of lateral-VHIT (p < 0.001), caloric test (p = 0.002) and oVEMP (p = 0.006). SVIN-SPV vertical component was correlated with the anterior-VHIT and oVEMP alterations (p = 0.007; p = 0.017, respectively). SVIN-SPV torsional component was correlated with the anterior-VHIT positivity (p = 0.017). SVIN was the only positive test for 10% of patients (83% of Group-VNT). CONCLUSION: SVIN-SPV analysis in dizzy patients shows significant correlation to both CVT and OVT. SVIN horizontal component is mainly relevant to both vestibular tests exploring lateral canal and utricle responses. SVIN-SPV is significantly higher in patients with combined canal and otolith lesions. In some patients with dizziness, SVIN may be the only positive test.

Skull Vibration-Induced Nystagmus Test in a Human Model of Horizontal Canal Plugging.

BACKGROUND/AIM: the aim of this study was to assess the skull vibration-induced nystagmus test (SVINT) results and vestibular residual function after horizontal semicircular canal (HSCC) plugging. METHODS: In this retrospective chart review performed in a tertiary referral center, 11 patients who underwent unilateral horizontal semicircular canal plugging (uHSCCP) for disabling Menière's disease (MD) were included. The skull vibration-induced nystagmus (SVIN) slow-phase velocity (SPV) was compared with the results of the caloric test (CaT), video head impulse test (VHIT), and cervical vestibular-evoked myogenic potentials (cVEMP) performed on the same day. RESULTS: Overall, 10 patients had a strong SVIN beating toward the intact side (Horizontal SVIN-SPV: 8.8°/s ± 5.6°/s), 10 had a significant or severe ipsilateral CaT hypofunction, 10 had an ipsilateral horizontal VHIT gain impairment, and 3 had altered cVEMP on the operated side. Five had sensorineural hearing worsening. SVIN-positive results were correlated with CaT and horizontal VHIT (HVHIT) results (p < 0.05) but not with cVEMP. SVIN-SPV was correlated with CaT hypofunction in % (p < 0.05). Comparison of pre- and postoperative CaT % hypofunction showed a significant worsening (p = 0.028). CONCLUSION: SVINT results in a human model of horizontal canal plugging are well correlated with vestibular tests exploring horizontal canal function, but not with cVEMP. SVINT always showed a strong lesional nystagmus beating away from the lesion side. SVIN acts as a good marker of HSCC function. This surgical technique showed invasiveness regarding horizontal canal vestibular function.

Fifty Years of Development of the Skull Vibration-Induced Nystagmus Test.

This review enumerates most of the studies on the Skull Vibration-Induced Nystagmus Test (SVINT) in the past 50 years from different research groups around the world. It is an attempt to demonstrate the evolution of this test and its increased interest around the globe. It explores clinical studies and animal studies, both permitting a better understanding of the importance of SVINT and its pathophysiology.

Understanding and Managing Trauma-Induced Vestibular Deficits.

OBJECTIVES: Traumatic brain injury occurs frequently worldwide. Half of traumatic brain injuries are related to falls or motor vehicle accidents. The term "concussion" is often used to describe a minor form of traumatic brain injury. These often involve decelerative events to the head (e.g., flexion/extension injury) and can also cause damage to the vestibular system of the inner ear. MATERIALS AND METHODS: The European Society for Clinical Evaluation of Balance Disorders meets yearly and has proposed an investigation and analysis of the vestibular consequences of traumatic brain injury. This review paper outlines these discussions. RESULTS: The Society discussed all aspects of trauma-induced vestibular disorders along with diagnosis and management. They also assessed the diagnostic tests available to investigate these disorders. CONCLUSION: Trauma-induced vestibular disorders are difficult to manage, as our level of understanding of the pathology can be poor and anatomical localization can also be difficult. Accordingly, a definitive diagnosis cannot be pinpointed in many patients, but an extensive history taking is crucial to determine the nature and extent of vestibular involvement. Trauma can not only result in microtrauma to the central nervous system but can also significantly affect peripheral vestibular structures, particularly the otolith organs. The committee hopes that better understanding of trauma to the vestibular system, along with improvements in the field of radiology and vestibular assessments, will aid in more precise techniques of pinpointing pathology in order to develop an adapted treatment plan.

Changes in the Sensory Weighting Strategies in Balance Control Throughout Maturation in Children.

BACKGROUND: The central nervous system integrates information from different sensory inputs (vestibular, visual, and somatosensory) to maintain balance. However, strategies for weighing sensory information change as maturation occurs. PURPOSE: The purpose of this study was to: (1) evaluate postural control development in a large sample of healthy children aged 5 to 17 years old, (2) analyze changes in sensory weighting strategies as maturation occurs, and (3) determine the extent to which anthropometric characteristics (height, weight, body mass index [BMI]) influence postural control. SAMPLE SIZE: This study recruited 120 healthy children, equally distributed in gender and number, into four age groups (5-8 years, 9-11 years, 12-14 years, and 15-17 years) and compared them to a control group of 20 healthy adults (aged 20-25 years). RESEARCH DESIGN: The sensory organization test (SOT) was used to assess overall balance and the use of specific sensory inputs to maintain postural control. All children underwent the six SOT conditions: (1) eyes open, surround and platform stable, (2) eyes closed, surround and platform stable, (3) eyes open, sway-referenced surround, platform stable, (4) eyes open, sway-referenced platform, (5) eyes closed, sway-referenced platform, and (6) eyes open, sway-referenced surround and platform. DATA ANALYSIS: Condition-specific equilibrium scores (ES), composite equilibrium scores (CES), and sensory analysis ratios were analyzed to determine whether the performance was related to age, gender, or specific anthropometric characteristics (height, weight, and BMI). RESULTS: Data showed a significant age-associated improvement in ES for all 6 conditions (p < 0.05) and in CES (p = 0.001). For both genders, (1) somatosensory function was adult-like by age 5 to 8 years, (2) visual function peaked around age 12 years, and (3) vestibular function reached maturity by age 15 to 17 years (p < 0.05). A moderate positive correlation (r(140) = 0.684, p = 0.01; two-tailed) between height and CES was found and a weak positive correlation (r(140) = 0.198, p = 0.01) between height and somatosensory ratio was noted. Lower vestibular ratio scores were observed in children who had a higher BMI (p = 0.001). CONCLUSION: The efficient use of individual sensory system input to maintain balance does not occur at the same age. Age and gender affect the changes in sensory weighting strategies, while height and BMI influence postural control in children. These factors need to be accounted for in child assessment.

The vestibular aqueduct sign: Magnetic resonance imaging can detect abnormalities in both ears of patients with unilateral Meniere's disease.

BACKGROUND AND PURPOSE: In patients with Meniere's disease (MD), saccular hydrops can only be studied by magnetic resonance imaging (MRI) at a late stage when the disease is already responsible for moderate to severe hearing loss. However, these patients may also present vestibular aqueduct (VA) abnormalities. MATERIALS AND METHODS: In this prospective study (38RC14.428 for healthy subjects/38RC15.173 for patients), imaging was carried out on a 3T MRI scanner. Twenty healthy subjects (13 women, median age 53.5 [52.2-66.7]) and twenty MD patients (9 women, median age 54.5 [52-66.7]) had MRI scans with 3D-FLAIR sequences without injection, then 4 hours after a single intra-venous dose of contrast agent. Two radiologists independently ranked the morphology of the VA in the healthy subjects and in MD patients, using a three-level score (completely visible, discontinuous and not visible). Each subject was then graded, based on both the VA's appearance and on saccular hydrops presence. Inter-reader agreement tests were performed. RESULTS: In controls and patients, VA modifications were symmetrical without significant difference between the symptomatic and asymptomatic ears. The presence of at least one ear with discontinuous VA showed a correlation with clinical MD (P < 0.001) with a sensitivity of 90%. Ten patients had saccular hydrops, but only in the symptomatic ears. The evaluation of VA did not differ between MRI, both within MRI series or between the two radiologists (kappa without and with contrast agent = 0.9 and 0.92 respectively). CONCLUSION: Analysis of the vestibular aqueduct by MRI detects abnormalities in both ears of patients with unilateral MD.

Normative Values of Saccades and Smooth Pursuit in Children Aged 5 to 17 Years.

BACKGROUND: Pediatric oculomotor function can be evaluated via videonystagmography. Adult normative data for saccades and smooth pursuit tests cannot be used as a benchmark for pediatric patients because children's peripheral and central systems continue to mature throughout adolescence. PURPOSE: The purpose of this study was to establish normative data for saccade and smooth pursuit tests that can be used clinically in the assessment of vestibular and neurological disorders in children, and to investigate the effect of age and eye movement direction (left/right) on tests parameters. RESEARCH DESIGN: The present study is prospective cross-sectional study. STUDY SAMPLE: A total of 120 healthy children were recruited and equally distributed according to age and gender to each of the following groups: 5-8, 9-11, 12-14, and 15-17 years old. Participants had to pass a comprehensive otological and neurological assessment prior to inclusion in the study. Each subject underwent saccade and smooth pursuit testing. DATA COLLECTION AND ANALYSIS: Saccade latency, velocity and accuracy/precision, and smooth pursuit gain were analyzed across groups using a two-way repeated measure multivariate analysis of variance (MANOVA). RESULTS: Saccadic latency was longer in the youngest group aged 5-8 years old (305 ± 48 msec) in comparison to children aged 9-11 years old (276 ± 22 msec) (P = 0.017), 12-14 years old (252 ± 34 msec) (P = 0.001) adolescents 15-17 years (256 ± 33 msec) (P = 0.001). Age did not affect the results of saccadic velocity and accuracy/precision. Saccade parameters (latency, velocity, accuracy/ precision) were not affected by oculomotor direction (left vs. right). Smooth pursuit gain increased from 0.63 in children aged 5-8 years old to 0.85 in children aged 15-17 years (P = 0.0001). The percentage of gain asymmetry was significantly different in the youngest two groups. CONCLUSION: Saccade latency decreased as age increased. Smooth pursuit gains increased with increased age. Saccade velocity and accuracy/precision did not change significantly from ages 5-8 to 15-17 years of age. These data provide normative values for pediatric oculomotor evaluation and suggest that saccade and pursuit pathways may mature at different rates.

Relationship Between Audio-Vestibular Functional Tests and Inner Ear MRI in Meniere's Disease.

OBJECTIVES: Meniere's disease is an inner ear disorder generally attributed to an endolymphatic hydrops. Different electrophysiological tests and imaging techniques have been developed to improve endolymphatic hydrops diagnosis. The goal of our study was to compare the sensitivity and the specificity of delayed inner ear magnetic resonance imaging (MRI) after intravenous injection of gadolinium with extratympanic clicks electrocochleography (EcochG), phase shift of distortion product otoacoustic emissions (shift-DPOAEs), and cervical vestibular-evoked myogenic potentials (cVEMP) for the diagnosis of Meniere's disease. DESIGN: Forty-one patients, with a total of 50 affected ears, were included prospectively from April 2015 to April 2016 in our institution. Patients included had definite or possible Meniere's disease based on the latest American Academy of Otolaryngology-Head and Neck Surgery guidelines revised in 2015. All patients went through delayed inner ear MRI after intravenous injection of gadolinium (three dimension-fluid attenuated inversion recovery sequences), pure-tone audiometry, extratympanic clicks EcochG, shift-DPOAEs, and cVEMP on the same day. Endolymphatic hydrops was graded on MRI using the saccule to utricle ratio inversion defined as when the saccule appeared equal or larger than the utricle. RESULTS: Abnormal EcochG and shift-DPOAEs in patients with definite Meniere's disease (DMD) were found in 68 and 64.5%, respectively. The two methods were significantly associated in DMD group. In DMD group, 25.7% had a positive MRI. The correlation between MRI versus EcochG and MRI versus shift-DPOAEs was not significant. MRI hydrops detection was correlated with hearing loss. Finally, 22.9% of DMD group had positive cVEMP. CONCLUSIONS: EcochG and shift-DPOAEs were both well correlated with clinical criteria of Meniere's disease. Inner ear MRI showed hydrops when hearing loss was higher than 35 dB. The shift-DPOAEs presented the advantage of a rapid and easy measurement if DPOAEs could be recorded (i.e., hearing threshold <60dB). In contrast, EcochG can be performed regardless of hearing loss. In combination with shift-DPOAEs, it enhances the chances to confirm the diagnosis with a better confidence.

In vivo imaging of saccular hydrops in humans reflects sensorineural hearing loss rather than Meniere's disease symptoms.

OBJECTIVES: A case-controlled imaging study demonstrated that saccular hydrops was specific to Meniere's disease (MD), but only present in a subset of patients. Here, we compared patients with definite MD, vertigo and sensorineural hearing loss (SNHL) to elucidate the relationship between saccular hydrops and extent of SNHL. METHODS: In this prospective study, we performed 3D-FLAIR sequences between 4.5 and 5.5 h after contrast media injection in patients with MD (n=20), SNHL (n=20), vertigo (n=20) and 30 healthy subjects. Two radiologists independently graded saccular hydrops. ROC analysis was performed to determine the hearing loss threshold to differentiate patients with saccular hydrops. RESULTS: Saccular hydrops was found in 11 of 20 MD patients, 10 of 20 SNHL patients and in none of the vertigo patients and healthy subjects. In SNHL patients, 45 dB was the threshold above which there was a significant association with saccular hydrops, with sensitivity of 100 % and specificity of 90 %. In MD patients, 40 dB was the threshold above which there was a significant association with saccular hydrops, with sensitivity of 100 % and specificity of 44 %. CONCLUSIONS: Our results indicate saccular hydrops as a feature of worse than moderate SNHL rather than MD itself. KEY POINTS: • MRI helps clinicians to assess patients with isolated low-tone sensorineural hearing loss. • Saccular hydrops correlates with sensorineural hearing loss at levels above 40 dB. • Vertigo patients without sensorineural hearing loss do not have saccular hydrops. • Saccular hydrops is described in patients without clinical diagnosis of Meniere's disease.

The Skull Vibration-Induced Nystagmus Test of Vestibular Function-A Review.

A 100-Hz bone-conducted vibration applied to either mastoid induces instantaneously a predominantly horizontal nystagmus, with quick phases beating away from the affected side in patients with a unilateral vestibular loss (UVL). The same stimulus in healthy asymptomatic subjects has little or no effect. This is skull vibration-induced nystagmus (SVIN), and it is a useful, simple, non-invasive, robust indicator of asymmetry of vestibular function and the side of the vestibular loss. The nystagmus is precisely stimulus-locked: it starts with stimulation onset and stops at stimulation offset, with no post-stimulation reversal. It is sustained during long stimulus durations; it is reproducible; it beats in the same direction irrespective of which mastoid is stimulated; it shows little or no habituation; and it is permanent-even well-compensated UVL patients show SVIN. A SVIN is observed under Frenzel goggles or videonystagmoscopy and recorded under videonystagmography in absence of visual-fixation and strong sedative drugs. Stimulus frequency, location, and intensity modify the results, and a large variability in skull morphology between people can modify the stimulus. SVIN to 100 Hz mastoid stimulation is a robust response. We describe the optimum method of stimulation on the basis of the literature data and testing more than 18,500 patients. Recent neural evidence clarifies which vestibular receptors are stimulated, how they cause the nystagmus, and why the same vibration in patients with semicircular canal dehiscence (SCD) causes a nystagmus beating toward the affected ear. This review focuses not only on the optimal parameters of the stimulus and response of UVL and SCD patients but also shows how other vestibular dysfunctions affect SVIN. We conclude that the presence of SVIN is a useful indicator of the asymmetry of vestibular function between the two ears, but in order to identify which is the affected ear, other information and careful clinical judgment are needed.

MRI of endolymphatic hydrops in patients with Meniere's disease: a case-controlled study with a simplified classification based on saccular morphology.

OBJECTIVES: Endolymphatic hydrops (EH) can be studied in patients by MRI. With the semi-quantitative grading system, previous imaging studies showed discrepancies in the occurrence and grading of EH in patients with Meniere's disease (MD). Here, we compared the inversion of the saccule to utricle area ratio (SURI) with the semi-quantitative method of grading conventionally used to diagnose MD. METHODS: Imaging was carried out on a 3-T MRI scanner. We performed 3D-FLAIR sequences 4 h after a single intravenous dose of contrast agent. Two radiologists independently studied the morphology of the inner ear structures in the healthy subjects and MD patients. Each subject was then graded on the basis of the EH semi-quantitative analysis and on saccular morphology using axial and sagittal reference slices in the vestibule plane. RESULTS: Thirty healthy subjects and 30 MD patients had MRI scans. Using the semi-quantitative method, we found no significant difference in the number of subjects with EH between the two groups. SURI was found in 15 out of 30 MD patients and in none of the 30 healthy subjects. In three MD patients the saccule was not visible. CONCLUSION: SURI is currently the most specific criterion for imaging diagnosis of MD. KEY POINTS: • Half of MD patients presented with inversion of the saccule to utricle ratio. • Saccular analysis is crucial when assessing patients with Meniere's disease. • In some patients, the saccule is not visible, suggestive of intra-labyrinthine fistulae.

Topographic analysis of the skull vibration-induced nystagmus test with piezoelectric accelerometers and force sensors.

Vibration-induced nystagmus is elicited by skull or posterior cervical muscle stimulations in patients with vestibular diseases. Skull vibrations delivered by the skull vibration-induced nystagmus test are known to stimulate the inner ear structures directly. This study aimed to measure the vibration transfer at different cranium locations and posterior cervical regions to contribute toward stimulus topographic optimization (experiment 1) and to determine the force applied on the skull with a hand-held vibrator to study the test reproducibility and provide recommendations for good clinical practices (experiment 2). In experiment 1, a 100 Hz hand-held vibrator was applied on the skull (vertex, mastoids) and posterior cervical muscles in 11 healthy participants. Vibration transfer was measured by piezoelectric sensors. In experiment 2, the vibrator was applied 30 times by two experimenters with dominant and nondominant hands on a mannequin equipped to measure the force. Experiment 1 showed that after unilateral mastoid vibratory stimulation, the signal transfer was higher when recorded on the contralateral mastoid than on the vertex or posterior cervical muscles (P<0.001). No difference was observed between the different vibratory locations when vibration transfer was measured on vertex and posterior cervical muscles. Experiment 2 showed that the force applied to the mannequin varied according to the experimenters and the handedness, higher forces being observed with the most experienced experimenter and with the dominant hand (10.3 ± 1.0 and 7.8 ± 2.9 N, respectively). The variation ranged from 9.8 to 29.4% within the same experimenter. Bone transcranial vibration transfer is more efficient from one mastoid to the other mastoid than other anatomical sites. The mastoid is therefore the optimal site for skull vibration-induced nystagmus test in patients with unilateral vestibular lesions and enables a stronger stimulation of the healthy side. In clinical practice, the vibrator should be placed on the mastoid and should be held by the clinician's dominant hand.

Vestibular results after intratympanic gentamicin therapy in disabling Menière's disease.

Intratympanic injection of gentamicin is increasingly used in the treatment of unilateral disabling Menière's disease (MD). Several objective functional and subjective tests have been developed to assess the control of vertigo after gentamicin treatment. The aim of this study was to show that subjective results require a vestibular deafferentation as profound as possible, evidenced with multifrequency vestibular assessment. Sixty four patients with intractable MD in situation of medical treatment failure longer than 6 months were included between 1998 and 2013 in this case control study. A 2-year follow-up was performed after the last intratympanic gentamicin performed with the titration technique. A vestibular assessment was applied before and after 2 years of treatment with a functional level score using the AAOHNS vertigo scale and multifrequency vestibular assessment: skull vibration-induced nystagmus test (SVINT), head-shaking test (HST) and caloric test (CaTe). The correlation between the results of the questionnaire and the level of the deafferentation as evaluated by the tests was analyzed with the Spearman test. Among the 64 included patients, 56 (87.5 %) described vertigo control. There was a correlation (=-0.33 [-0.53; -0.09], p = 0.008) between subjective improvement (AAO -HNS 1 or 2) and the degree of vestibular deafferentation as evidenced by a destructive nystagmus (beating toward the safe side) with the HST and the SVINT, as well as a caloric hypofunction >90 % with the CaTe. The present study demonstrates that a profound vestibular deafferentation confirmed with multifrequency test evaluation is needed to have a subjective improvement in the treatment of unilateral disabling MD with intratympanic gentamicin.

"Gauze Technique" in the Treatment of the Fungus Ball of the Maxillary Sinus: A Technique as Simple as It Is Effective.

Fungus ball of maxillary sinus generally affects immunocompetent and nonatopic subjects. Although endoscopic removal is the current gold standard treatment, removal is at times difficult due to an accumulation of fungal elements in the anterior ad inferior recesses. Aim. To present our experience of maxillary fungus ball treated by the "gauze technique" that avoids these removal difficulties. Materials and Methods. A retrospective, cross-sectional, and descriptive study of 25 patients affected by maxillary fungus ball was carried out: 19 were treated by the "gauze technique" and 6 were treated without "gauze technique." Results. A comparison was made between the two groups for surgery procedure time, length of hospitalization, time from surgery to nasal unpacking, complications, and postsurgical patient satisfaction. The only statistically significant difference observed was a shorter surgical procedure time (p < 0.05) for the "gauze technique." Conclusions. The data obtained in this study demonstrated that the "gauze technique" is a safe, simple, and quick technique, able to reduce surgery procedure time whilst providing excellent functional outcomes and patient satisfaction.