Magnetic resonance imaging of patients with large vestibular aqueducts

3D-real IR MRI detects serendipity of inner ear in enlarged vestibular aqueduct syndrome

BACKGROUND

Although, the diagnostic criteria for enlarged vestibular aqueduct syndrome (EVAS) were determined by years. On the shoulders of predecessors, we still detected some new discoveries about EVAS by using 3D-real IR MRI.

AIMS/OBJECTIVES

To analyze the signal intensity of membranous and osseous labyrinths of vestibular aqueduct (VA) and endolymphatic sac (ES) in EVAS using three-dimensional real inversion recovery (3D-Real-IR) magnetic resonance imaging (MRI) after intratympanic injection of gadolinium.

MATERIAL AND METHODS

The study is a prospective trial, diagnosed EVAS patients (n = 10) and none- patients (n = 10) were included. 3D-real-IR MRIs were performed to assess the endolymphatic hydrops (EH) and differentiated the endolymphatic and perilymphatic signal intensities of VA and ES.

RESULTS

Compared to control group, EVAS group had VA osseous labyrinths middle diameter >1.5 mm different from membranous labyrinths. The cochlear EH was correlated with Mondini malformation and irrelation with the level of hearing loss (HL).

CONCLUSIONS AND SIGNIFICANCE

Interspace of osseous labyrinths of VA and ES are much larger than their membranous labyrinths, which is not consistance with previous research. And cochlear Mondini malformation may cause endolymphatic fluid malabsorption, inducing cochlear EH. Osteal ampliative of VA and ES and cochlear EH, which are morphogenetic anomalies, may not the direct cause of HL in EVAS.

Vestibular Dysfunction in Patients with Enlarged Vestibular Aqueduct

OBJECTIVE

Enlarged vestibular aqueduct (EVA) is the most common inner ear malformation. While a strong correlative relationship between EVA and hearing loss is well established, its association with vestibular dysfunction is less well understood. In this study, we examine the effects of EVA on the vestibular system in patients with EVA.

STUDY DESIGN

Prospective, cross-sectional study of a cohort ascertained between 1999 and 2013.

SETTING

National Institutes of Health Clinical Center, a federal biomedical research facility.

SUBJECTS AND METHODS

In total, 106 patients with unilateral or bilateral EVA, defined as a midpoint diameter greater than 1.5 mm, were referred or self-referred to participate in a study of the clinical and molecular aspects of EVA. Clinical history was ascertained with respect to the presence or absence of various vestibular signs and symptoms and history of head trauma. Videonystagmography (VNG), cervical vestibular evoked myogenic potential (cVEMP), and rotational vestibular testing (RVT) were performed to assess the vestibular function.

RESULTS

Of the patients with EVA, 45% had vestibular signs and symptoms, and 44% of tested patients had abnormal VNG test results. An increased number of vestibular signs and symptoms was correlated with the presence of bilateral EVA (P = .008) and a history of head injury (P < .001). Abnormal VNG results also correlated with a history of head injury (P = .018).

CONCLUSION

Vestibular dysfunction is common in patients with EVA. However, not all patients with vestibular signs and symptoms have abnormal vestibular test results. Clinicians should be aware of the high prevalence of vestibular dysfunction in patients with EVA.

SLC26A4 genotype, but not cochlear radiologic structure, is correlated with hearing loss in ears with an enlarged vestibular aqueduct

OBJECTIVES/HYPOTHESIS

Identify correlations among SLC26A4 genotype, cochlear structural anomalies, and hearing loss associated with enlargement of the vestibular aqueduct (EVA).

STUDY DESIGN

Prospective cohort survey, National Institutes of Health, Clinical Center, a federal biomedical research facility.

METHODS

Eighty-three individuals, 11 months to 59 years of age, with EVA in at least one ear were studied. Correlations among pure-tone hearing thresholds, number of mutant SLC26A4 alleles, and the presence of cochlear anomalies detected by computed tomography or magnetic resonance imaging were examined.

RESULTS

Linear mixed-effects model indicated significantly poorer hearing in ears with EVA in individuals with two mutant alleles of SLC26A4 than in those with EVA and a single mutant allele (P = .012) or no mutant alleles (P = .007) in this gene. There was no detectable relationship between degree of hearing loss and the presence of structural cochlear anomalies.

CONCLUSIONS

The number of mutant alleles of SLC26A4, but not the presence of cochlear anomalies, has a significant association with severity of hearing loss in ears with EVA. This information will be useful for prognostic counseling of patients and families with EVA.

Long-Term Follow-up of Hearing Loss in Children and Young Adults With Enlarged Vestibular Aqueducts: Relationship to Radiologic Findings and Pendred Syndrome Diagnosis

OBJECTIVE

To describe the long-term audiologic findings in pediatric patients with enlarged vestibular aqueducts (EVAs). The relationship between the hearing loss (HL) and the dimensions of the EVA, enlarged endolymphatic duct (EED), or enlarged endolymphatic sac (EES) was also investigated. The influence of a Pendred syndrome (PS) diagnosis on the audiologic phenotype was also examined.

STUDY DESIGN

Retrospective analysis of case notes and imaging records, including measurement of the dimensions of the EVA, EED, and EES.

SETTING

Tertiary referral center.

PATIENTS

Twenty-seven patients (21 female, 6 male) had an EVA in at least one ear. Eighty-five percent had bilateral enlargements. Median age at onset of follow-up was 5.0 years, and median follow-up was 9.7 years.

MAIN OUTCOME MEASURES

Hearing thresholds at the start and end of follow-up, rate of progression of HL, history of sudden drops in hearing.

RESULTS

: All ears with an EVA had HL. Average HL at the start and end of follow-up was severe. Thirty-seven percent of patients had progressive HL, and 33% reported sudden drops in hearing. Progression was significantly associated with a history of sudden drops. PS patients had worse hearing at the end of follow-up as compared with nonsyndromic patients. There was no evidence of a relationship between the dimensions of the EVA, EED, or EES and the severity or progression of HL.

CONCLUSIONS

Patients with EVAs should be advised to avoid known trigger factors for sudden drops in hearing (e.g., minor head trauma). A diagnosis of PS may be associated with a worse audiologic prognosis.

Imaging and clinical findings in large endolymphatic duct and sac syndrome

OBJECTIVE

Large endolymphatic duct and sac syndrome (LEDS) is known as the most common kind of inner ear malformations, which is radiologically detectable. Nevertheless, nowadays many questions are not fully cleared and LEDS is relatively unknown among general radiologists. The aim of this study was to evaluate the incidence of LEDS in the own patient population and to present our experiences regarding imaging findings, clinical presentation and follow up.

MATERIALS AND METHODS

Based on a complete recording of all patients, sent from ENT department to radiology, we identified all radiological diagnosed cases of inner ear malformations including LEDS and all patients in whom an inner ear malformation was clinically suspected. The retrospective study included clinical records, HR-CT and MRI performed between 1994 and 2002.

RESULTS

Among 169 patients (338 ear), 17 of patients (median age: 12 years) and 28 ears, respectively, had enlarged endolymphatic structures. In 10 patients - 6% - (15 ears), no other abnormalities were detected, called isolated LEDS, seven patients showed additional inner ear abnormalities. One patient showed a labyrinthine hemorrhage after sudden hearing loss. Audiometric data revealed sensorineural hearing loss in 22 ears, deafness in 5 ears and normal hearing in 1 case of 28 ears. In 10 (67%) of 15 ears with isolated LEDS, the hearing loss was downward-fluctuating progressive. Twelve patients (eight with isolated LEDS) had partly repeated sudden hearing losses. A trigger for worsening of hearing was found in five patients. A correlation between the severity of morphological changes on imaging and the degree of hearing disturbances could not be detected. Only four young patients underwent a radiological examination within the first or second year after onset of hearing loss. Three patients received a cochlear implant.

CONCLUSIONS

LEDS might be the cause of progressive hearing loss and repeated acute hearing losses in children and young adults. Imaging plays an important role in making the diagnosis.

Computed tomography of the inner ear: size of anatomical structures in the normal temporal bone and in the temporal bone of patients with Menière's disease

The purpose of the study was to obtain reference values for the sizes of anatomical structures of the inner ear on computed tomography (CT) images and to compare these values with those obtained from patients with Menière's disease. CT images of the temporal bone of 67 patients without inner ear pathology and 53 patients with Menière's disease have been evaluated. CT was performed in the sequential mode (1-mm slice thickness, 120 kV, 125 mA). Anatomical structures, such as the length and the width of the cochlea and of the vestibule, the height of the basal turn, the length and the width of the cochlear, the vestibular and the singular aqueduct and the internal auditory meatus and the diameter of the semicircular canals, were measured, using a dedicated postprocessing workstation. Reference values from the control group could be obtained. In the patients with Menière's disease, the length and the width of the vestibular aqueduct were smaller, compared with the values from the control group. The values obtained from the control group can serve as reference values for adult patients. The different sizes of anatomical structures of the control group and of patients suffering from Menière's disease suggest that functional impairment might be related to subtle morphological changes.

Estimation of the endolymphatic sac and vestibular aqueduct using magnetic resonance imaging

OBJECTIVE

To evaluate the diagnostic accuracy of magnetic resonance imaging for assessment of the endolymphatic sac and vestibular aqueduct.

STUDY DESIGN

Imaging and histological study of the cadaver.

METHODS

Five cadavers were studied by a 1.5-T magnetic resonance imaging system with a 3-inch-diameter surface coil. Magnetic resonance imaging scans were obtained with proton density-weighted and T2-weighted fast spin-echo sequences. Histological sections were made with an epoxy resin-embedding method and were compared with magnetic resonance imaging scans.

RESULTS

The visibility of the endolymphatic sac on both sequences corresponded well to the presence of the endolymphatic sac on histological sections. On the histological sections, the width of the external aperture of vestibular aqueduct (endolymphatic sac including surrounding connective tissue) was 0.96 +/- 0.18 mm (mean +/- SD) and the width of lumen of endolymphatic sac at the same point was 0.47 +/- 0.17 mm. The width of the endolymphatic sac was 1.02 +/- 0.19 mm on proton density-weighted images and was 0.81 +/- 0.15 mm on T2-weighted images. The widths of endolymphatic sac measured on proton density-weighted image and those of vestibular aqueduct on histological section did not show statistically significant differences (P >.05). On the other hand, the endolymphatic sac as measured on T2-weighted image tended to be smaller than the vestibular aqueduct (P <.05) and tended to be larger than the lumen of the endolymphatic sac (P <.0005).

CONCLUSION

Both sequences can precisely depict the endolymphatic sac; however, the proton density-weighted image is a more appropriate indicator of the actual anatomical configuration of the endolymphatic sac with surrounding connective tissue and vestibular aqueduct.

Large vestibular aqueduct syndrome treated by hyperbaric oxygen

We report the case of a 14-year-old girl with a large vestibular aqueduct (LVA) in whom hyperbaric oxygen (HBO) therapy was effective for the treatment of sensorineural hearing loss. The patient was referred to Nagoya University Hospital for the treatment of hearing loss on 14 September, 1998, because her right hearing level had declined abruptly on 22 August, 1998, and had not changed for 3 weeks since then in spite of steroid and prostaglandin therapy. Her audiogram revealed bilateral profound deafness of more than 110 dB. She had had profound hearing loss on the left side since she was 9 years old. HBO therapy was performed on 22 occasions from 17 September until 19 October, 1998. During the HBO therapy, her right hearing ability returned almost to the level determined prior to the abrupt loss, 60 dB. We therefore recommend HBO therapy for the treatment of sensorineural hearing loss associated with large vestibular aqueduct syndrome if the hearing ability does not recover following conventional treatment.

MR imaging of the cochlear modiolus: area measurement in healthy subjects and in patients with a large endolymphatic duct and sac

PURPOSE

To evaluate the cochlear modiolus with thin-section magnetic resonance (MR) imaging in healthy subjects and patients with a large endolymphatic duct and sac, and to assess whether the cochlea is normal or abnormal in patients with a large endolymphatic duct and sac.

MATERIALS AND METHODS

MR images were obtained in 10 ears in five volunteers (group 1), 40 ears in 20 patients with bilateral sensory hearing loss (group 2), three ears in two patients with Mondini malformation (group 3), and 12 ears in seven patients with a large endolymphatic duct and sac (group 4).

RESULTS

In groups 1 and 2, all modiolar areas were larger than 4.0 mm2. In group 3, each modiolus was smaller than 2.0 mm2. In group 4, modiolar areas were smaller than 2.0 mm2 in eight ears and were larger than 4.0 mm2 in four ears.

CONCLUSION

Findings in this study confirm that a large endolymphatic duct and sac is frequently associated with modiolar deficiency, but the modiolar area is normal in some cases. This result does not support the recently proposed hypothesis that hearing loss with a large endolymphatic duct and sac is caused by the transmission of subarachnoid pressure forces into the labyrinth through a deficient modiolus.