Three-dimensional Fourier transformation constructive interference in steady state magnetic resonance imaging of the inner ear in patients with unilateral and bilateral Meniere's disease

Objective: In this study, three-dimensional Fourier transformation constructive interference in steady state (3DFT-CISS) magnetic resonance imaging was used to quantify the distance between the vertical part of the posterior semicircular canal and the posterior fossa as a measure of the endolymphatic sac and duct in patients with Meniere's disease. Differences in this distance between affected and unaffected ears, as well as differences between unilaterally and bilaterally affected patients, were studied and compared with a control group. Also, possible correlations between the measured distance and the duration and severity of symptoms, patient age, and average hearing loss were investigated in the group of patients with Meniere's disease. Study Design: Retrospective clinical study. Setting: Tertiary referral center (University Hospital) as part of a large, diagnostic research project on Meniere's disease. Patients: Of the 111 patients with Meniere's disease initially included, 90 patients underwent 3DFT-CISS MRI. Eighty-six of these patients were analyzed in this MRI study. Fifty-six patients had unilateral Meniere's disease, and 30 patients had bilateral Meniere's disease (116 affected and 56 unaffected ears). Sixty-two ears in patients without Meniere's disease were studied as controls. Intervention: The distance between the vertical pail of the posterior semicircular canal and the posterior fossa was determined by 3DFT-CISS MRI. Main Outcome Measures: Contiguous axial 3DFT-CISS MRI slices of 0.7 to 1.0 mm were made by a radiologist according to a strict protocol. Measurements of the distance between the vertical part of the posterior semicircular canal and the posterior fossa were taken by two professionals-a radiologist and an otolaryngologist scan. Results: A significantly smaller distance (2.9 mm) between the vertical part of the posterior semicircular canal and the posterior fossa as visualized on MRI scans was found in the cars of patients with Meniere's disease than in the cars of patients in the control group (3.8 mm, p <0.001). In both uni- and bilaterally affected patients (n = 56 and n = 30, respectively), no significant difference between ears was found (p = 0.44 and p = 0.19, respectively). In bilaterally affected patients, however, this distance (3.2 mm) was significantly greater than the distance in unilaterally affected patients (2.7 mm, p = 0.004). There was no relationship between the MRI-visualized distance between the vertical part of the posterior semicircular canal and the posterior fossa and the duration of disease, average hearing loss, or severity of symptoms in uni- and bilaterally affected patients. Conclusion: The difference in MRI-visualized distances between the vertical part of the posterior semicircular canal and the posterior fossa of uni- and bilaterally affected patients strongly suggests that unilateral and bilateral hearing loss are two different entities in patients with Meniere's disease. The size of the endolymphatic sac seems not to be the only factor in the pathogenesis of Meniere's disease. That the MRI-visualized distance between the vertical part of the posterior semicircular canal and the posterior fossa does not have any relationship to the duration of the disease or to patient age indicates that this distance is a congenital feature.