Lateral Semicircular Canal and Vertigo in Patients With Large Vestibular Aqueduct Syndrome

Enlarged vestibular aqueduct as a cause of postneonatal deafness

INTRODUCTION

The enlarged vestibular aqueduct (EVA) is the most frequent malformation of the inner ear associated with sensorineural hearing loss (5-15%). It exists when the diameter in imaging tests is greater than 1.5 mm at its midpoint. The association between hearing loss and EVA has been described in a syndromic and non-syndromic manner. It can appear as a familial or isolated form and the audiological profile is highly variable. The gene responsible for sensorineural hearing loss associated with EVA is located in the same region described for Pendred syndrome, where the SCL26A4 gene is located.

OBJECTIVE

To describe a series of children diagnosed with EVA in order to study their clinical and audiological characteristics, as well as the associated genetic and vestibular alterations.

METHOD

Retrospective study of data collection of children diagnosed with EVA, from April 2014 to February 2023.

RESULTS

Of the 17 cases, 12 were male and 5 were female. 5 of them were unilateral and 12 bilateral. In 5 cases, a cranial traumatism triggered the hearing loss. Genetic alterations were detected in 3 cases: 2 mutations in the SCL26A4 gene and 1 mutation in the MCT1 gene. 13 patients (76.5%) were rehabilitated with hearing aids and 9 of them required cochlear implantation.

DISCUSSION

The clinical importance of AVD lies in the fact that it is a frequent finding in the context of postneonatal hearing loss. It is convenient to have a high suspicion to diagnose it with imaging tests, to monitor its evolution, and to rehabilitate early.

Vestibular dysfunction in lateral semicircular canal dysplasia

Introduction

Lateral semicircular canal (LSCC) dysplasia is the most common inner ear malformation. The severity of dysplasia can appear in various spectrums, from a short and broad LSCC with normal or small-sized central bony island (CBI) to a single fluid-filled cavity confluent with the vestibule without CBI. However, reports on the association between LSCC dysplasia and the loss of vestibular function are still lacking. In this study, the results of vestibular function tests [caloric test and video-head impulse test (vHIT)] in patients with LSCC dysplasia were analyzed and compared between groups with and without CBI.

Methods

This study retrospectively enrolled 17 patients (23 ears) who had LSCC dysplasia following computed tomography or magnetic resonance imaging and underwent vestibular function tests.

Results

LSCC dysplasia was observed unilaterally in 11 patients and bilaterally in six patients. Nine of 23 ears had CBIs, and 14 ears had no CBI. Three of 17 patients experienced dizziness. Abnormal caloric tests were detected in 11 of the 16 patients who underwent the caloric tests (69%); in contrast, 11 of 12 patients who underwent the vHIT (92%) had normal LSCC vestibulo-ocular reflex (VOR) gain on vHIT. A significant correlation was found between the maximum slow-phase velocity of the caloric test and LSCC VOR gain of the vHIT (correlation coefficient 0.792, p = 0.004). The CBI-absent group showed significantly lower SPV and LSCC VOR gains than the CBI-present group (p = 0.001 and 0.004, respectively).

Discussion

LSCC dysplasia impairs VOR function, especially in the absence of CBI.

Prognostic changes after sudden deafness in patients with inner ear malformations characterized by LSCC: a retrospective study

Introduction

This study aimed to investigate the clinical features and prognosis of sudden sensorineural hearing loss in patients with lateral semicircular canal (LSCC) malformation.

Methods

This study enrolled patients with LSCC malformation and sudden sensorineural hearing loss (SSNHL) who were admitted to Shandong ENT Hospital between 2020 and 2022. We collected and analyzed data on examinations of audiology, vestibular function, and imaging records of patients and summarized the clinical characteristics and prognosis of these patients.

Results

Fourteen patients were enrolled. Patients with LSCC malformation was noted in 0.42% of all SSNHL cases during the same period. One patients had bilateral SSNHL and the rest had unilateral SSNHL. Of them, eight and six patients had unilateral and bilateral LSCC malformations, respectively. Flat hearing loss was noted in 12 ears (80.0%) and severe or profound hearing loss was noted in 10 ears (66.7%). After treatment, the total efficacy rate of SSNHL with LSCC malformation was 40.0%. Vestibular function was abnormal in all patients, but only five patients (35.7%) had dizziness. There were statistically significant differences in the vestibular functions between patients with LSCC malformation and matched patients without the malformation hospitalized during the same period (p < 0.05).

Conclusion

Patients with SSNHL and LSCC malformation had flat-type and severe hearing loss and worse disease prognosis compared to those with SSNHL without LSCC malformation. Vestibular function is more likely to be abnormal; however, there was no significant difference in vestibular symptoms between patients with and without LSCC malformation. LSCC is a risk factor for the prognosis of SSNHL.

Clinical Implication of Caloric and Video Head Impulse Tests for Patients With Enlarged Vestibular Aqueduct Presenting With Vertigo

Background: By examining the clinical features and results of video head impulse test (vHIT) and caloric tests in patients with enlarged vestibular aqueduct (EVA) presenting with vertigo, we aimed to investigate the function of angular vestibulo-ocular reflex (VOR) and its clinical implications.

Methods: Nine patients with EVA manifesting with vertigo were enrolled. The medical history, audiological examination, imaging, and the results of the caloric test and the vHIT were analyzed.

Results: Of the nine patients with EVA (eight bilateral and one unilateral case), five were pediatric cases. All 17 ears exhibited sensorineural hearing loss (SNHL). Enlarged vestibular aqueduct patients can present with recurrent (seven cases) or single (two cases) vertigo attack, trauma-induced (two cases), or spontaneous (seven cases) vertigo. Diminished caloric responses were observed in 77.8% (7/9) of the patients (four cases unilaterally and three bilaterally), while unilateral abnormal vHIT results in 11.1% (1/9) patients. Abnormal caloric and normal horizontal vHIT responses were found in 66.7% (6/9) of EVA patients.

Conclusions: Vestibular manifestations in EVA are diverse. Enlarged vestibular aqueduct patients with vertigo can present with a reduced caloric response and normal horizontal vHIT, and this pattern of angular VOR impairment was also found in other hydropic ear diseases.

Nystagmus in patients with lateral semicircular canal dysplasia

BACKGROUND

Dizziness is not a common symptom in the lateral semicircular canal (LSCC) dysplasia, and nystagmus findings has been rarely described in LSCC dysplasia.

OBJECTIVE

To investigate the characteristics of spontaneous and positional nystagmus in patients with LSCC dysplasia.

METHODS

Patterns of spontaneous and positional nystagmus of twelve patients with LSCC dysplasia, who visited our clinic with a chief complaint of dizziness, were investigated.

RESULTS

LSCC dysplasia was observed unilaterally in 4, and bilaterally in 8 patients. Non-rotatory dizziness with various onset times was the most common description of dizziness, and unilateral caloric weakness was observed in 82% of patients. Direction-fixed nystagmus, in which the direction of spontaneous nystagmus was same with that of positional nystagmus, was observed in 9 patients, and direction-changing positional nystagmus, in which the direction of nystagmus was changed from that of spontaneous nystagmus by positioning maneuvers, was observed in 3 patients, of whom down-beating or direction-changing spontaneous nystagmus was observed in one patient each.

CONCLUSION

While direction-fixed horizontal nystagmus is the most commonly observed type of nystagmus in LSCC dysplasia, atypical spontaneous nystagmus, such as down-beating nystagmus or direction-changing spontaneous nystagmus, may be observed in patients with bilateral LSCC dysplasia.

Speech development after cochlear implantation in infants with isolated large vestibular aqueduct syndrome

Background: Few studies on speech performance of children after cochlear implantation (CI) described isolated large vestibular aqueduct syndrome (LVAS). Objective: To investigate speech developmental trajectories of infants with LVAS after CI, and to compare with those who have structurally normal inner ears. Materials and methods: 1112 infants with congenital severe to profound hearing loss participated in this study. 150 infants in group A were diagnosed with LVAS, 962 infants in group B with structurally normal inner ear. The speech performance was assessed via the Meaningful Use of Speech Scale (MUSS). The evaluations were performed pre-implant, 1, 3, 6, 9, 12, 24, 36, 48 and 60 months after CI. Results: The mean scores of the MUSS improved over a 5-year period after implantation in both groups A and B. The LVAS group presented similar speech developmental trajectory to the non-LVAS group at each assessment interval, except pre-operation. There were significant differences in mean scores between vocalizing behavior and oral communication skills, clarification skills of infants in both two groups. Conclusions and significance: Speech performance of infants with LVAS developed rapidly after CI and was similar to infants with structurally normal inner ear. For infants with isolated LVAS, CI had a significant effect and should be recommended as a therapeutic option.

Enlarged vestibular aqueduct: Audiological and genetical features in children and adolescents

BACKGROUND

Enlarged Vestibular Aqueduct (EVA) is one of the most common congenital malformations associated with sensorineural or mixed hearing loss. The association between hearing loss and EVA is described in syndromic (i.e. Pendred Syndrome, BOR, Waardenburg) and non-syndromic disorders, as isolate or familiar mutations of the SLC26A4 gene. The audiological phenotype of the EVA syndrome is heterogeneous, the type and entity of hearing loss may vary and vertigo episodes might also be present.

OBJECTIVE

The aim of this retrospective study was to describe the clinical and genetic features of a group of adolescent subjects presenting an EVA clinical profile, considering the presence of SLC26A4 gene mutations.

METHODS

14 Caucasian patients were assessed (24 ears in total; 4 patients presented a monolateral EVA), 10 females and 4 males. Their age at the time of diagnosis was between 1 and 6 years (mean age 2.5 years). Subjects were assessed by an ENT microscopy evaluation with a complete audiometric assessment, CT & MRI scans and genetic tests for the evaluation of the pendrin gene mutations (SLC26A4).

RESULTS

Considering the presence of SLC26A4 mutations and thyroid function, we could identify three sub-groups of patients: group 1, non syndromic EVA (ns EVA, no SLC26A4 mutation and no thyroid dysfunction); group 2, EVA with DFNB4 (single SLC26A4 gene mutation and no thyroid dysfunction); group 3, EVA with Pendred Syndrome (two pathological mutation of SLC26A4 and thyromegaly with thyroid dysfunction). Patients of group 1 (ns-EVA) showed various degrees of hearing loss from mild (55%) to severe-profound (45%). In groups 2 (DFNB4) and 3 (PDS), the degree of hearing loss is severe to profound in 70-75% of the cases; middle and high frequencies are mainly involved.

CONCLUSIONS

The phenotypic expressions associated with the EVA clinical profile are heterogeneous. From the available data, it was not possible to identify a representative audiological profile, in any of the three sub-groups. The data suggest that: (i) a later onset of hearing loss is usually related to EVA, in absence of SLC26A4 gene mutations; and (ii) hearing loss is more severe in patients with SLC26A4 gene mutations (groups 2 and 3 of this study).

Position of the Internal Aperture of Vestibular Aqueduct in Patients With Enlarged Vestibular Aqueduct

OBJECTIVE

To investigate the position of the internal aperture of vestibular aqueduct and its relationship to hearing level in patients with enlarged vestibular aqueduct (EVA).

METHODS

The size of the common crus and the position of the internal aperture of vestibular aqueduct were compared among control subjects, EVA patients with and without other inner ear malformations. Auditory steady-state response thresholds were compared between EVA patients with different positions of internal apertures.

RESULTS

The common crus in EVA patients was shorter than in control subjects (p < 0.05). The internal aperture of the vestibular aqueduct opened solely into the common crus in control subjects, simultaneously into the common crus and vestibule in almost 45% of EVA patients, solely into the common crus, and the vestibule in almost 30 and 25% of EVA patients, respectively. Auditory steady-state response thresholds at 2000 and 4000 Hz were higher in EVA patients whose internal apertures of vestibular aqueducts opened simultaneously into the common crus and vestibule than in those whose internal apertures opened solely into the common crus.

CONCLUSION

The common crus is shorter in EVA patients than in control subjects. The internal aperture of the vestibular aqueduct opens solely into the common crus in control subjects. It opens simultaneously into the common crus and vestibule in almost half of the EVA patients. The EVA patients whose internal apertures of vestibular aqueducts open solely into the common crus may have better hearing than those whose internal apertures open simultaneously into the common crus and vestibule.

Ratio of Vestibular Endolymph in Patients with Isolated Lateral Semicircular Canal Dysplasia

PURPOSE

Isolated vestibular-lateral semicircular canal dysplasia (LSCCD) is one of the most common anomalies of the inner ear. However, endolymphatic size in LSCCD is unknown. We measured the size of the endolymph in the vestibule of patients with LSCCD and compared it with that measured in patients without LSCCD.

METHODS

We extracted 1102 magnetic resonance (MR) studies for the evaluation of endolymphatic hydrops (EH) from our database of radiology reports. Among these, we found 15 ears from 11 patients with LSCCD; 4 patients had bilateral abnormalities. Seven of the 15 ears demonstrated aplasia and 8 ears, hypoplasia of the lateral semicircular canal (LSCC). The control group consisted of 26 ears from 13 randomly selected patients without LSCCD. We measured the area of endolymph in the vestibule (ELA), total area of vestibular lymph fluid (TLA), and area of the central bony island (CBI) of the LSCC from axial MR images obtained after intratympanic or intravenous administration of gadolinium-based contrast material. The ratio of endolymphatic area to total lymphatic area (%EL) was defined as %EL = ELA/TLA × 100.We evaluated the correlation between %EL and the area of the CBI and compared age, %EL, degree of cochlear EH, hearing level, and presence of rotating vertigo among the 3 groups (aplasia, hypoplasia, control).

RESULTS

The mean %EL was 76.7% in the aplasia group, 50.0% in the hypoplasia group, and 27.8% in the control group (P < 0.001). There was a relatively strong linear correlation between the area of the CBI and %EL (r = -0.767). Patient age, mean hearing level, degree of cochlear EH, or presence of vertigo attacks did not differ significantly among the groups (P > 0.05).

CONCLUSION

The size of vestibular endolymph was larger in the groups with aplasia or hypoplasia than the control group. Thus, the current diagnostic cut-off value for significant vestibular EH (>50%) might not be appropriate for ears with LSCCD.

Enlarged vestibular aqueduct (EVA) related with recurrent benign paroxysmal positional vertigo (BPPV)

The vestibular aqueduct is a bony canal related to the bony labyrinth of the inner ear and represents the non-sensory components of the endolymph-filled, closed, membranous labyrinth. The association of congenital sensorineural hearing loss with a large or enlarged vestibular aqueduct is well known as the large vestibular aqueduct syndrome (LVAS). The enlarged VA (EVA) comprises abnormalities not only in the structure of the inner ear, but also in the physiology of the auditory and vestibular systems. The clinical picture of this clinical entity is variable [Yetiser S, Kertment M, Ozkaptan Y. Vestibular disturbance in patients with Large Vestibular Aqueduct Syndrome (LVAS). Acta Otolaryngol (StochK) 1999;119: 641-646]. Signs and symptoms of the auditory impairment are more commonly described in the literature: hearing loss ranges from mild to profound, arising from fluctuating to stepwise progressive or sudden. Vestibular disturbances, ranging from mild imbalance to episodic vertigo, are rarely described in the literature. Benign paroxysmal positional vertigo (BPPV) is a labyrinthine disorder with a typical behavior: intense crises of rotational vertigo induced by postural changes of the head, with short duration and usually good responsiveness to rehabilitative maneuvers. These maneuvers are effective in about 80% of patients with BPPV. BPPV often recurs. About 1/3 of patients have a recurrence in the first year after treatment, and by five years, about half of all patients have a recurrence. Vestibular aqueduct has been demonstrated by conventional tomography and computed tomography (CT), however, CT scans cannot show the membranous labyrinth itself. On MR images it is not the vestibular aqueduct that is visualized but its contents, the endolymphatic duct and sac, and can show the abnormalities of the fluid spaces related to the membranous labyrinth. It is proposed that recurrent benign paroxysmal positional vertigo (BPPV) is related with volumetric abnormalities of vestibular aqueduct. This verifiable hypothesis tries to define this rapport and explore new diagnostic and therapeutic possibilities.

Cochlear modiolus and lateral semicircular canal in sudden deafness

CONCLUSION

This study demonstrated that precise analysis shows that the inner ear shape in sudden deafness (SD) is different from that in controls in that the fluid-filled area of SD labyrinths is significantly larger than that of controls. Reduced cochlear modiolus area and inner area of the lateral semicircular canal (LSCC) may be associated with insufficient maturation of the inner ear.

OBJECTIVE

The aim of this study was to quantify the morphologies of the cochlea and LSCC using magnetic resonance imaging (MRI) and to evaluate their relationships with clinical symptoms in SD.

SUBJECTS AND METHODS

Twenty-six unilateral SD patients with vertigo, 26 unilateral SD patients without vertigo and a matched control group without hearing loss were studied. The areas of cochlear modioli and LSCCs were traced on the MRI console and compared between SD patients with or without vertigo and control subjects. The ratio of the LSCC fluid-filled area to the total LSCC area was used to index the degree of dysplasia.

RESULTS

The cochlear modiolus area was significantly less in SD ears (4.1+/-0.2 mm2) than in controls (4.3+/-0.4 mm2). The LSCC inner area was significantly less in SD ears (6.9+/-1.7 mm2) than in controls (9.1+/-1.8 mm2). These results suggest that the fluid-filled area of SD labyrinths is significantly larger than controls. Morphology did not differ between affected and contralateral sides or between ears with or without vertigo in SD patients.

Vestibular signs and symptoms of volumetric abnormalities of the vestibular aqueduct

Objective:

The objective of this study was to identify a pattern of signs, symptoms and neuroradiological findings which would assist investigation of vestibular function (especially otolith function) in a group of adult patients with anatomical alterations of the endolymphatic aqueduct and sac.

Methods:

Fifteen subjects affected by volumetric abnormalities of the vestibular aqueduct were selected from a cohort of patients referred to a tertiary referral neurotological centre between 1 January 2004 and 30 June 2006. All patients underwent accurate clinical history-taking and were evaluated using a standardised set of bedside and instrumental neurotological tests (i.e. audiometry, auditory brainstem response and vestibular evoked myogenic potentials). After these tests, each patient underwent computed tomography and magnetic resonance imaging in order to accurately evaluate the middle ear, labyrinthine capsule and internal auditory canals. These evaluations confirmed clinical suspicion of volumetric abnormalities of the vestibular aqueduct and endolymphatic sac.

Results:

All the patients with a defined volumetric alteration in the region of the vestibular aqueduct and endolympatic sac reported a typical pattern of symptoms and signs. The most obvious and frequent symptoms in these patients were migraine-related vertigo (using the Neuhauser criteria, 10 of 15, 66.6 per cent), ‘motion sickness’ (12 of 15, 80 per cent), oscillopsia (nine of 15, 60 per cent) and dizziness (14 of 15, 93.3 per cent). Clinical examination results for the selected patients allowed some useful speculative conclusions. During neurotological evaluation, two instrumental methodologies were especially useful diagnostically: vestibular evoked myogenic potentials of the neck, and the mastoid vibration test at 100 Hz.

Conclusions:

Dysfunction of the vestibular aqueduct is suggested by symptomatology characterised by: migraine-related vertigo, unstable or recurring oscillopsia, lowering of the vestibular evoked myogenic potential threshold, hypoacusis, anamnestic report of motion sickness, and nystagmus induced by mastoid vibration and head-shaking. Computed tomography and magnetic resonance imaging are needed in order to confirm clinical suspicions.