Large Vestibular Aqueduct Syndrome Research Articles

Comparison of 45° Oblique Reformats with Axial Reformats in CT Evaluation of the Vestibular Aqueduct

Measurement of the vestibular aqueduct on CT scans of the temporal bone is important for the detection of large vestibular aqueduct syndrome; typically this is done in the axial plane. We sought to determine the usefulness of reformats performed in the 45 degrees oblique plane for evaluating the vestibular aqueduct. In addition, we provide reference measurements for the vestibular aqueduct in the 45 degrees oblique plane. MATERIALS AD METHODS: We selected 15 subjects referred for reasons other than sensorineural hearing loss, and without radiographic evidence of abnormality of the inner ear. Two neuroradiologists independently evaluated both axial and 45 degrees oblique images for ease in visualizing the vestibular aqueduct. Then, one of the readers (B.O.) performed reference measurements of the diameter at the mouth and midpoint of the aqueduct. Combining the results of both observers, we judged 82% of vestibular aqueducts as well-defined or easily traced on 45 degrees oblique views, whereas we judged only 55% as well-defined or easily traced on axial views. The difference in the degrees of visualization between the 45 degrees oblique and axial reformats was significant for observer 1 (P =.022) and observer 2 (P =.001). Intraobserver agreement about the visibility of the aqueduct was higher on the 45 degrees oblique than the axial views: (kappa = 0.682, SE = 0.171) for 45 degrees oblique reformats; (kappa = 0.480, SE = 0.145) for axial reformats. On the 45 degrees oblique reformats, the mean external aperture dimension of the vestibular aqueduct was measured as 0.616 +/- 0.133 mm, and the postisthmic segment had a mean width of 0.482 +/- 0.099 mm. The 45 degrees oblique plane gives a more reliable depiction of the vestibular aqueduct than the axial plane in CT evaluation of the temporal bone. This technique can be useful in cases of borderline enlargement of the vestibular aqueduct.

Clinical Investigation and Mechanism of Air-Bone Gaps in Large Vestibular Aqueduct Syndrome

Patients with large vestibular aqueduct syndrome (LVAS) often demonstrate an air-bone gap at the low frequencies on audiometric testing. The mechanism causing such a gap has not been well elucidated. We investigated middle ear sound transmission in patients with LVAS, and present a hypothesis to explain the air-bone gap. Observations were made on 8 ears from 5 individuals with LVAS. The diagnosis of LVAS was made by computed tomography in all cases. Investigations included standard audiometry and measurements of umbo velocity by laser Doppler vibrometry (LDV) in all cases, as well as tympanometry, acoustic reflex testing, vestibular evoked myogenic potential (VEMP) testing, distortion product otoacoustic emission (DPOAE) testing, and middle ear exploration in some ears. One ear with LVAS had anacusis. The other 7 ears demonstrated air-bone gaps at the low frequencies, with mean gaps of 51 dB at 250 Hz, 31 dB at 500 Hz, and 12 dB at 1,000 Hz. In these 7 ears with air-bone gaps, LDV showed the umbo velocity to be normal or high normal in all 7; tympanometry was normal in all 6 ears tested; acoustic reflexes were present in 3 of the 4 ears tested; VEMP responses were present in all 3 ears tested; DPOAEs were present in 1 of the 2 ears tested, and exploratory tympanotomy in 1 case showed a normal middle ear. The above data suggest that an air-bone gap in LVAS is not due to disease in the middle ear. The data are consistent with the hypothesis that a large vestibular aqueduct introduces a third mobile window into the inner ear, which can produce an air-bone gap by 1) shunting air-conducted sound away from the cochlea, thus elevating air conduction thresholds, and 2) increasing the difference in impedance between the scala vestibuli side and the scala tympani side of the cochlear partition during bone conduction testing, thus improving thresholds for bone-conducted sound. We conclude that LVAS can present with an air-bone gap that can mimic middle ear disease. Diagnostic testing using acoustic reflexes, VEMPs, DPOAEs, and LDV can help to identify a non-middle ear source for such a gap, thereby avoiding negative middle ear exploration. A large vestibular aqueduct may act as a third mobile window in the inner ear, resulting in an air-bone gap at low frequencies.

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.

Large Vestibular Aqueduct Syndrome: A Human Temporal Bone Study

Large vestibular aqueduct syndrome (LVAS) is one of the common causes of hearing loss (HL). All prior studies have reported some anomalies associated with LVAS by imaging techniques. This study was undertaken to determine prevalence of LVAS in our temporal bone (TB) collection and its relationship to other systemic or otologic anomalies. Retrospective, TB histopathologic study. Anteroposterior diameters of internal (IA) and external (EA) apertures were measured in 40 normal TBs (40 cases). TBs were considered as large vestibular aqueduct (LVA) if width of apertures was 95% greater than "normals." Systemic and otologic anomalies and histopathology of ears with LVAS were noted. Of 1,608 non-"normal" TBs, 63 had LVA. There was negative correlation between IA and EA in 48 TBs with only enlarged IA. Fifteen TBs with enlarged EA always had enlarged IA and were therefore considered as LVAS. The most common pathologic condition was congenital heart anomaly. The most common syndrome or dysplasia was Mondini's. The most common anomalies of external and middle ears were dehiscent facial nerves, low set auricles, and ossicular deformities. Inner ear anomalies included modiolar deficiencies, hair cell loss, interscalar septum defects, and strial atrophy. There was no record of family history of HL, head injury, or craniofacial, branchial, or thyroidal abnormalities. Because HL associated with LVAS may be attributed to other ear anomalies, it is important to investigate other inner ear problems and system diagnoses that may indicate a syndrome in patients with radiologically diagnosed LVAS.

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

To evaluate the hypothesis that there are differences in the morphology of the lateral semicircular canal (LSCC) between patients with large vestibular aqueduct syndrome (LVAS) and control subjects and to investigate the clinical implications of these differences. Retrospective case review. Tertiary referral center. Nine patients (two male patients and seven female patients; age range, 8-54 yr) with LVAS (one patient had unilateral LVAS, and eight patients had bilateral LVAS). Five patients had vertigo, and four patients, including the one with unilateral LVAS, did not have vertigo. The area of the LSCC was traced on the magnetic resonance imaging console and compared between LVAS patients and 12 control subjects who did not have sensorineural hearing loss. The LSCC fluid-containing area was divided by the sum of the LSCC inner area and the LSCC fluid-containing area for evaluation of the degree of the LSCC dysplasia. The LSCC fluid-containing ratio was significantly larger in LVAS patients than in control subjects. Moreover, the LSCC fluid-containing ratio was significantly larger in the eight ears with vertigo than in the nine ears without vertigo. There was no relationship between hearing level and the LSCC fluid-containing ratio. Patients with LVAS may have disturbed morphogenesis of both membranous and bony labyrinths. Our results reveal that the morphology of semicircular canals is clinically associated with vertigo.

Surgical Results of Cochlear Implantation in Malformed Cochlea

To report the surgical aspects of cochlear implantation in malformed cochlea. Tertiary care center. Retrospective case review. Between November 1997 and October 2004, 20 patients with inner ear malformations were implanted in our department. The age range was between 2 and 37 years (average, 8.8 yr). The anomalies were classified according to Sennaroglu and Saatci classification. There were two patients with common cavity deformity, four cases of incomplete partition (IP) type I (cystic cochleovestibular malformation), four cases of IP type II (classical Mondini's deformity), nine patients with large vestibular aqueduct (LVA) syndrome, and one patient with X-linked deafness. Standard transmastoid facial recess approach was used in 17 patients (three patients with IP I, four patients with IP II, and nine patients with LVA syndrome). In the remaining patient with IP I, because of the dehiscent and anteriorly located facial nerve, the surgical approach had to be modified, and an anteroposterior approach was used. After elevating the tympanomeatal flap, the electrode was inserted through the ear canal and then transferred to the mastoid through a full-length cut produced in the ear canal. The flap then returned to its place. In the patients with common cavity deformity, the electrode was inserted by the transmastoid labyrinthotomy approach. Facial nerve had an abnormal course in four patients, but no patient had facial weakness postoperatively. Cerebrospinal fluid gusher was encountered in four patients, whereas oozing was present in five patients. It seems that a slightly larger cochleostomy may reduce postoperative rhinorrhea. The patient with common cavity deformity showed abnormal vestibular stimulation which decreased and was totally abolished during a 3-month period. Based on these findings, cochlear implantation is surgically feasible in patients with common cavity, IP types I and II, and LVA. The surgeon should be ready to make modifications in the surgical approach because of the abnormal course of the facial nerve and be ready to produce special precautions to cerebrospinal fluid gusher.

Can a fixed measure serve as a pertinent diagnostic criterion for large vestibular aqueduct in children?

A vestibular aqueduct midpoint width greater than 1.50 mm is currently considered to be pathognomonic for a large vestibular aqueduct syndrome. To analyse the diameter of the vestibular aqueduct in children as a function of age and consequently to determine if a fixed measure could serve as a pertinent diagnostic criterion. This was a retrospective study of 200 high-resolution CT scans of the ear in 100 patients aged 0-16 years and from various paediatric medical departments. On each CT scan, the lateral semicircular canal diameter, the vestibular aqueduct midpoint width between the external aperture and common crus, and the vestibular aqueduct external aperture diameter were measured. Spearman's rank test and the Mann-Whitney correlation test were used for an integrated statistical analysis. There was no statistically significant variability in vestibular aqueduct diameter as a function of age or sex of patients. A CT scan threshold value, fixed and independent of age and sex, is thus legitimate for the diagnosis of vestibular aqueduct dilatation.

Health education on large vestibular aqueduct syndrome

目的 分析大前庭水管综合征(large vestibular aqueduct syndrome,LVAS)患者的发病原因,寻找最好的治疗方法及健康指导方法.方法回顾1994年3月～2004年3月95例(190耳)双侧LVAS患者经过CT扫描,听力及前庭功能检查,诊断明确后所采取的相应治疗措施及健康指导.结果95例LVAS患者就诊时听力均受损,其中36例无听力呈聋哑状态,2例儿童服镇静药,没有收集到听力资料.对患者先积极采用药物治疗,药物治疗3个月后听力无变化,建议患者佩带大功率助听器;佩带3个月后言语效果不满意,而且患者有接受人工耳蜗植入术的愿望,将其纳入耳蜗植入手术适应证.结论对于LVAS患者,采取相应的治疗、护理及与之相适宜的健康指导措施,可延缓病情的发展,若明显听力下降,影响学习,可考虑采用耳蜗植入术。

Relationship between the external aperture and hearing loss in large vestibular aqueduct syndrome

Large vestibular aqueduct syndrome (LVAS) is a major cause of hearing loss in childhood. This study aimed at measuring external aperture of enlargement of the vestibular aqueduct (EVA) and analyzing relationship between the size of external aperture and hearing loss. Diagnostic criteria of LVAS were based on hearing loss and CT images. CT images of temporal bone of 100 LVAS patients were collected and 60 control subjects were reviewed retrospectively in the past 10 years. A battery of audiometric and vestibular function tests were performed. The width of the vestibular aqueduct (VA) was measured on axial CT images of the temporal bone. One hundred patients (65 men, 35 women) were diagnosed as having the isolated EVA. Hearing loss mostly occurred in early childhood. The diagnosis age of LVAS was 7.7 years on average. The causes of hearing loss could not be confirmed by initial consult. Typically, audiometric curve is the high-frequency down-sloping configuration. 92% of the cases had severe or profound sonsorineural hearing loss (SNHL). The mean size of the external aperture was (7.5 +/- 1.2) mm in present LVAS. Statistical analysis showed that the degree of hearing loss is unrelated to the width of VA. LVAS is a distinct clinical entity characterized by fluctuating, progressive SNHL. The degree of hearing loss is unrelated to the size of external aperture of VA. The protective management and hearing aid have become the main therapies. The cochlear implantation might be performed if the hearing loss affected learning at school.

Large vestibular aqueduct syndrome: audiological, radiological, clinical, and genetic features

Purpose The aim of this study was to analyze the clinical, audiological, radiological, and genetic features of a group of patients affected with large vestibular aqueduct syndrome. Materials and methods Seventeen patients affected with large vestibular aqueduct syndrome (LVAS), diagnosed by means of high-resolution magnetic resonance imaging of the inner ear, with 3-dimensional reconstructions of the labyrinth and by high-resolution spiral computed tomography of the temporal bone, performed only on the oldest patients, have been submitted to a complete audiological evaluation, a thyroid functional and ultrasonographic study, and a molecular study of the PDS gene. Results The clinical presentation of LVAS was very variable in our group of patients. The enlarged vestibular aqueduct was bilateral in 15 cases and unilateral in 2; it was the only malformation of the labyrinth in 12 patients, whereas it was associated with other inner ear anomalies in the other 5. The hearing loss was very variable in degree (from mild to profound), age at onset, and progression. Moreover, among the 17 patients, 10 were clinically affected by Pendred's syndrome (PS), 3 by distal renal tubular acidosis associated with large vestibular aqueduct, whereas in 3 patients the large vestibular aqueduct was not syndromal. Finally, we identified mutations in the PDS gene in 5 of 10 patients with PS. Conclusions Our data underscore the frequent role of the large vestibular aqueduct syndrome in the pathogenesis of sensorineural hearing loss and the overall wide variability in its audiological features. It is also highlighted that LVAS is often part of some syndromal diseases, most of which are PS, which is often misdiagnosed because of the varying degree of thyroid symptoms. This study also underscores the possible role of hydro-electrolyte and acid-base endolymphatic fluid disorders in the pathogenesis of enlarged vestibular aqueduct syndrome.

Large Vestibular Aqueduct Syndrome: A Case Study

A 23-month-old female was referred for hearing aid fitting after failing newborn hearing screening and being diagnosed with significant hearing loss through subsequent diagnostic testing. Auditory brainstem response (ABR) and behavioral testing revealed a moderate-to-severe bilateral mixed hearing loss. Prior to the hearing aid evaluation, tympanostomy tubes had been placed bilaterally with little or no apparent change in hearing sensitivity. Initial testing during the hearing aid fitting confirmed earlier findings, but abnormal middle ear results were observed, requiring referral for additional otologic management. Following medical clearance, binaural digital programmable hearing aids were fit using Desired Sensation Level parameters. Behavioral testing and probe microphone measures showed significant improvements in audibility. Decrease in hearing sensitivity was observed six months following hearing aid fitting. Radiological studies, ordered due to the mixed component and decreased hearing sensitivity, revealed large vestibular aqueduct syndrome (LVAS). Based on the diagnosis of LVAS, a cochlear implant was placed on the right ear; almost immediate speech-language gains were observed.

Considerations for Cochlear Implantation of Children with Sudden, Fluctuating Hearing Loss

The histories of two pediatric patients who received cochlear implants with subsequent partial recovery of hearing in the nonimplanted ear are reviewed. One child had a sudden bilateral hearing loss, presumably secondary to autoimmune ear disease. The other child had a bilateral progressive hearing loss diagnosed as large vestibular aqueduct syndrome (LVAS). The rationale for the timing of the surgical implantation is discussed. Retrospectively, recovery of hearing in the nonimplanted ear suggests the possibility that the implant could have been delayed or eliminated as a treatment option, and that wearable hearing aids may have been appropriate. A number of factors, however, suggest the decision to implant was appropriate. Issues involved in the decision-making process of when to implant are presented and discussed.

The remediation of hearing deterioration in children with large vestibular aqueduct syndrome

Based on imaging findings, large vestibular aqueduct syndrome (LVAS) in early childhood is the most common cause of sensorineural hearing loss. Children with LVAS are at a high risk of suffering sudden deteriorations in hearing. This study was to review treatment of sudden hearing deterioration in children with LVAS who underwent corticosteroid therapy. We conducted a retrospective study of patients presenting to an academic tertiary medical center. Sixteen children of LVAS were evaluated. Corticosteroid therapy (prednisolone 1–2 mg/(kg day) or equal titer's dexamethasone) was administered as soon as sudden hearing loss developed. The pure tone audiometric result improved more than 10 dB at two or more consecutive frequencies and was regarded as a significant response to corticosteroid therapy. Sixteen cases comprising 12 boys and 4 girls were retrospectively analyzed in this study. The mean age at which LVAS was diagnosed was 2.3 years. Mean follow-up for the 16 cases from the first clinic visit to November 2003 was 4.2 years. The initial audiograms varied from down-sloping, valve or rising patterns. In addition, bilateral enlargement of the vestibular aqueduct was found to all children and the mean diameter of right and left ears were 7.23 and 6.83 mm, respectively. Seven children had totally experienced 13 episodes of sudden hearing deterioration. After receiving corticosteroid therapy in time, 11 of 13 episodes had indicated significant responses to treatment, a response rate of 85%. Early detection of LVAS and the timing of treatment are crucial for preventing the residual hearing from deteriorating. As soon as the hearing deterioration of a child with LVAS is recognized, aggressive intervention such as corticosteroid therapy should be performed in no time.

Large vestibular aqueduct syndrome: audiological, radiological, clinical, and genetic features

Large vestibular aqueduct syndrome: audiological, radiological, clinical, and genetic features

Hearing loss in patients with enlarged vestibular aqueduct: Air-bone gap and audiological Bing test

The Bing test is based on the principle that occlusion of the external auditory meatus improves the perception of bone-conducted sounds unless there is a conductive hearing impairment. An air-bone gap has been reported in patients with large vestibular aqueduct (LVA) syndrome without apparent middle ear dysfunction. We therefore performed the Bing test on nine patients with this syndrome to evaluate whether it is associated with an air-bone gap or middle ear dysfunction. Bone conduction thresholds did not change significantly during the Bing test in any patient. Because an air-bone gap is observed in patients with abnormal communication between the inner ear and cerebrospinal fluid through the LVA, dehiscent superior canal, or dilated inner ear meatus; we propose that a ‘three windows’ model (in which the abnormal communication provided by the enlarged endolymphatic duct and sac in LVA acts as the ‘third window’ for sound conductance) might explain the air-bone gap in such patients.

診断が遅延した前庭水管拡大症の２例

We report two cases of large vestibular aqueduct syndrome, a rare congenital malformation of the inner ear originally described by Valvassori and Clemis in 1978.The first case was a 38-year-old woman who had complained of progressive hearing loss since childhood and periodic episodes of recurrent vertigo since 30 years of age. She had been misdiagnosed as having Meniere's disease by previous doctors. The second case was a 9-year-old boy with acute hearing loss several hours after minor head collision. Psychogenic hearing loss was initially suspected, but was eventually ruled out based on diminished auditory brainstem response. When these patients were initially seen in our clinic, both patients showed severe bilateral combined hearing loss on pure tone audiogram. Definitive diagnosis was established by magnetic resonance imaging, which demonstrated expanded endolymphatic ducts and sacs.Clinical characteristics and possible pathogenesis of large vestibular aqueduct syndrome is discussed with a review of the literature.

Large vestibular aqueduct syndrome: CT and MR imaging findings

Large vestibular aqueduct syndrome (LVAS) is an uncommon disorder that manifest as progressive sensorineural hearing loss starting in infancy, early childhood and less commonly in adolescence. We report an 18-year-old girl who had enlarged vestibular aqueduct (VA) on computed tomography (CT) and magnetic resonance (MR) imaging. Axial CT scan shows large bony vestibular aqueduct and its connection to common crus. Axial thin section fast spin-echo MR image demonstrated enlargement of vestibular aqueducts, large endolymphatic duct and connection of duct to common crus.

Cochlear implantation in patients with large vestibular aqueduct syndrome (LVAS)

Cochlear implantation in patients with large vestibular aqueduct syndrome (LVAS)

Cochlear implantation in patients with large vestibular aqueduct syndrome (LVAS)

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Chronological changes of hearing in pediatric patients with large vestibular aqueduct syndrome.

To describe the chronologic changes of hearing in patients with large vestibular aqueduct syndrome (LVAS) and identify the prognostic factors. A retrospective chart-review study. Twelve consecutive patients with LVAS were recruited at Taipei Veterans General Hospital between July 1986 and July 2000. The records of serial pure-tone audiogram and high-resolution computer tomography were collected. The chronologic figures of pure-tone average (PTA) were sketched. The investigated variables included sex, laterality and type of hearing loss (HL), size of vestibular aqueduct, and the chronologic changes and configurations of hearing. Data were analyzed statistically. The degree of HL in early childhood was from moderate to profound. The worst hearing could be estimated by the hearing level in early childhood. Sixteen of 24 ears were stable. Bilateral, chronologically stepwise-downhill hearing occurred in only one patient (1/12) during the follow-up period. Chronologically, high-tone hearings were worse than those of low-tone, but fluctuations of high-tone hearing were smaller than those of low-tone. The sizes of vestibular aqueduct were predictive of the density of major depression and its depth. LVAS, a congenital disease, is characterized by fluctuating sensorineural HL. Most hearing at PTA remained stable at least in one ear chronologically. The standard deviation of hearing at 500 Hz was the only prognostic factor for the progression of PTA. An enlarged vestibular aqueduct affects fluctuations of hearing, but the pathogenesis of HL still remains unclear and deserves further investigations.