Prevalence of labyrinthine ossification in CT and MR imaging of patients with acute deafness to severe sensorineural hearing loss

Objective: To evaluate the prevalence of labyrinthine ossification, and especially cochlear ossification, in a cohort of patients with unilateral sudden deafness or severe sensorineural hearing loss. Design: Retrospective data collection. Study sample: Sixty-four consecutive patients with unilateral sudden deafness or severe sensorineural hearing loss and either high-resolution CT (HRCT) of the temporal bone (isotropic spatial resolution <= 0.8 mm; n = 18) or high resolution CISS MRI (isotropic spatial resolution <= 1 mm; n = 55) were included. Nine patients underwent both imaging modalities. A standardized reading regarding labyrinthine ossifications was performed by an experienced head and neck radiologist blinded to clinical symptoms. Results: Radiologic signs of cochlear ossification were present in 14 patients (12 CT and 2 MRI). Eight patients showed unilateral and six patients bilateral signs of cochlear ossification. In all except one of the unilateral cases, the deafened ear was affected. Conclusions: Signs of cochlear ossification were found in an unexpectedly high rate (14/64, 22%) of patients with acute deafness. The data suggest HRCT of the temporal bone to be more sensitive to detect labyrinthine ossification than MRI. HRCT of the temporal bone should therefore be considered in patients with impaired recovery of acute deafness to exclude cochlear ossification; if present, and, in cases of early signs, the patient should be evaluated further to facilitate early cochlear implantation before progression impedes electrode insertion, reflecting latest developments considering cochlea implants for single-sided deafness to be effective.