Imaging of deafness and tinnitus

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Acquired deafness and tinnitus are common problems and patients should be carefully selected for imaging. Conductive deafness is best imaged with high resolution CT and sensorineural deafness with T2 weighted 3D MRI. Additional MRI sequences including contrast are used for indeterminate and abnormal cases. Radiologists should be familiar with the common causes of conductive deafness; cholesteatoma, ossicular fixation, ossicular erosion, traumatic subluxations and dislocations and otospongiosis which can cause mixed deafness when the pericochlear region is involved. Investigation of acquired sensorineural deafness mainly revolves around excluding vestibular schwannoma and differentiating this from other causes of CP angle masses, particularly meningiomas, epidermoids and metastases. Rarely post traumatic labyrinthitis ossificans or in children, widened vestibular aqueduct syndrome can be the causes of acquired deafness. Pulsatile tinnitus is best investigated using contrast enhanced CT, looking for venous and arterial anomalies, glomus tumours and rarely dural arteriovenous (AV) fistulae or arterial stenoses. Dural AV fistulae may sometimes only be detected at conventional cerebral angiography. Deafness and tinnitus are common clinical problems but only some patients require imaging. The clinical features which suggest that imaging is warranted are reviewed here. Imaging of deafness can be broadly determined according to whether the patient has sensorineural (investigated with MRI) or conductive (investigated with CT) deafness. This article reviews the imaging features of common causes of acquired conductive deafness, including cholesteatoma, the sequelae of chronic otitis media, trauma and otospongiosis. The imaging features of the main causes of sensorineural deafness are also reviewed, with particular focus on imaging vestibular schwannoma. The pathologies that result in tinnitus overlap with those causing sensorineural deafness. This article pays particular attention to the imaging of tinnitus caused by glomus tumours and vascular causes, such as aberrant vessels and arteriovenous malformations.