Cochlear abnormalities associated with enlarged vestibular aqueduct anomaly

Third window lesions of the inner ear: A pictorial review

PURPOSE

Radiographic review of pathologies that associate with third window syndrome.

METHODS

Case series and literature review.

RESULTS

Eight unique third window conditions are described and illustrated, including superior, lateral, and posterior semicircular canal dehiscence; carotid-cochlear, facial-cochlear, and internal auditory canal-cochlear dehiscence, labyrinthine erosion from endolymphatic sac tumor, and enlarged vestibular aqueduct.

CONCLUSION

The present study highlights the characteristic imaging features and symptoms to differentiate third window pathologies for expedient diagnosis and management planning.

Vestibular anomalies and dysfunctions in children with inner ear malformations: A narrative review

About 20% of children with congenital hearing loss present malformations of the inner ear. In the past few years much has been understood about the morphology and function of the anterior part of the labyrinth, since hearing loss may have a dramatic effect on the overall development of a child. Nowadays, for most of them, a chance for hearing rehabilitation is available, making hearing loss a treatable condition. The anomalies range from the lack of development of the whole inner ear to specific anomalies of isolated structures. Despite the frequent concomitant involvement of the posterior part of the labyrinth, this part of the inner ear is frequently neglected while discussing its morphology and dysfunction. Even though vestibular and balance function/dysfunction may have a significant impact on the global development of children, very little is known about these specific disorders in patients with inner ear malformations. The aim of this review is to summarize the available literature about vestibular anomalies and dysfunctions in children with inner ear malformations, discussing what is currently known about the topic.

Retrospective Review of Midpoint Vestibular Aqueduct Size in the 45° Oblique (Pöschl) Plane and Correlation with Hearing Loss in Patients with Enlarged Vestibular Aqueduct

BACKGROUND AND PURPOSE

Vestibular aqueduct measurements in the 45° oblique (Pöschl) plane provide a reliable depiction of the vestibular aqueduct; however, adoption among clinicians attempting to counsel patients has been limited due to the lack of correlation with audiologic measures. This study aimed to determine the correlation between midpoint vestibular aqueduct measurements in the Pöschl plane in patients with an enlarged vestibular aqueduct with repeat audiologic measures.

MATERIALS AND METHODS

Two radiologists independently measured the midpoint vestibular aqueduct diameter in the Pöschl plane reformatted from CT images in 54 pediatric patients (77 ears; mean age at first audiogram, 5 years) with an enlarged vestibular aqueduct. Four hundred nineteen audiograms were reviewed, with a median of 6 audiograms per patient (range, 3-17; mean time between first and last audiograms, 97.4 months). The correlation between midpoint vestibular aqueduct size and repeat audiologic measures (pure tone average, speech-reception threshold, and word recognition score) using a linear mixed-effects model was determined.

RESULTS

The mean midpoint vestibular aqueduct size was 1.78 mm (range, 0.81-3.46 mm). There was excellent interobserver reliability with intraclass correlation coefficients for the 2 readers measuring 0.92 (P < .001). Each millimeter increase in vestibular aqueduct size was associated with an increase of 10.5 dB (P = .006) in the pure tone average, an increase of 14.0 dB (P = .002) in the speech-reception threshold, and a decrease in the word recognition score by 10.5% (P = .05).

CONCLUSIONS

Midpoint vestibular aqueduct measurements in the Pöschl plane are highly reproducible and demonstrate a significant correlation with audiologic data in this longitudinal study with repeat measures. These data may be helpful for clinicians who are counseling patients with an enlarged vestibular aqueduct using measurements obtained in the Pöschl plane.

Unilateral Enlarged Vestibular Aqueduct Syndrome and Bilateral Endolymphatic Hydrops

Enlarged vestibular aqueduct (EVA) syndrome is a common congenital inner ear malformation characterized by a vestibular aqueduct with a diameter larger than 1.5 mm, mixed or sensorineural hearing loss that ranges from mild to profound, and vestibular disorders that may be present with a range from mild imbalance to episodic objective vertigo. In our study, we present the case of a patient with unilateral enlarged vestibular aqueduct and bilateral endolymphatic hydrops (EH). EH was confirmed through anamnestic history and audiological exams; EVA was diagnosed using high-resolution CT scans and MRI images. Therapy included intratympanic infusion of corticosteroids with a significant hearing improvement, more evident in the ear contralateral to EVA. Although most probably unrelated, EVA and EH may present with similar symptoms and therefore the diagnostic workup should always include the proper steps to perform a correct diagnosis. Association between progression of hearing loss and head trauma in patients with a diagnosis of EVA syndrome is still uncertain; however, these individuals should be advised to avoid activities that increase intracranial pressure to prevent further hearing deterioration. Intratympanic treatment with steroids is a safe and well-tolerated procedure that has demonstrated its efficacy in hearing, tinnitus, and vertigo control in EH.

Cerebrospinal Fluid Leak in Cochlear Implantation: Enlarged Cochlear versus Enlarged Vestibular Aqueduct (Common Cavity Excluded)

Objective. To share our experience of cerebrospinal fluid gusher in cochlear implantation in patients with enlarged cochlear or vestibular aqueduct. Study Design. Case series with comparison and a review of the literature. Methods. A retrospective study was performed. Demographic and radiological results of patients with enlarged cochlear aqueduct or enlarged vestibular aqueduct in 278 consecutive cochlear implant recipients, including children and adults, were evaluated between January 2000 and December 2015. Results. Six patients with enlarged cochlear aqueduct and eight patients with enlarged vestibular aqueduct were identified. Cerebrospinal fluid gusher occurs in five subjects with enlarged cochlear aqueduct and in only one case of enlarged vestibular aqueduct. Conclusion. Based on these findings, enlarged cochlear aqueduct may be the best risk predictor of cerebrospinal fluid gusher at cochleostomy during cochlear implant surgery despite enlarged vestibular aqueduct.

Relationship between multidetector CT imaging of the vestibular aqueduct and inner ear pathologies

This study investigated the relationships between morphological changes in the vestibular aqueduct (VA) in different inner ear pathologies. Eighty-eight patients (34 males and 54 females, ranging from seven to 88 years of age; average age 49.2 years) with cochleovestibular disorders underwent temporal bone CT (with a 64-channel helical CT system according to temporal bone protocol parameters; 0.6 mm slice thickness, 0.6 mm collimation, bone reconstruction algorithm). All patients with cochleovestibular disorders who underwent temporal bone CT had been previously divided into six different suspected clinical classes: A) suspected pathology of the third window; B) suspected retrocochlear hearing loss; C) defined Ménière's disease; D) labyrinth lithiasis; E) recurrent vertigo. On CT images we analyzed the length, width and morphology of the VA, contact between the VA and the jugular bulb (JB), the thickness of the osseous capsule covering the semicircular canals, the pneumatization rate of the temporal bone and the diameter of the internal auditory canal. At the end of the diagnostic work-up all patients were grouped into six pathological classes, represented as follow: 1) benign paroxysmal positional vertigo (BPPV), 2) recurrent vertigo (RV), 3) enlarged vestibular aqueduct syndrome (EVAS), 4) sudden or progressive unilateral sensorineural hearing loss (SNHL), 5) superior semicircular canal dehiscence syndrome (SSCD), 6) recurrent vestibulocochlear symptoms in Ménière's disease. We evaluated 176 temporal bones in 88 patients. The VA was clearly visualized in 166/176 temporal bones; in ten ears the VA was not visualized. In 14 ears (11 patients, in three of whom bilaterally) we found an enlarged VA while in 31 ears the VA was significantly narrower. In 16 ears a dehiscence of the JB with the vestibular or cochlear aqueduct was noted. In all six patients with suspected EVAS we found a AV wider than 1.5 mm on CT scans; moreover CT identified four patients with large VA and ill-defined clinical symptoms. Most patients with BPPV (11 patients, Class 1) we did not find any VA abnormalities on CT scans, confirming the clinical diagnosis in ten patients; in the remaining patients we found an enlarged VA, not clinically suspected. In the RV class (eight patients, Class 2) we found three patients with negative CT scans, two patients with narrow aqueduct and subsequently reclassified as Ménière's disease patients, and three patients with ectasic JB dehiscence with the VA. In patients suffering from SNHL we found no statistically significant correlation with the morphological abnormalities. The clinical suspicion of SSCD was confirmed by CT in 11/13 patients (84.6 %); in addition another seven patients showed a thinning or dehiscence of the superior semicircular canals as the prevailing alteration on CT scans, and were reclassified in this group. Ménière's disease symptoms were correlated with a VA alteration in more than half of the cases; the most striking finding in this class was that the VA was significantly narrower (21 patients). Our study demonstrates that alterations of the VA morphology are not only related to EVAS but are also found in other inner ear pathologies such as Ménière's disease. Furthermore, MDCT may confirm the presence of correlations between the morphology of inner ear structures such as VA, semicircular canals or JB dehiscence, and alterations of vestibulocochlear function.