Imaging of postoperative middle ear cholesteatoma

Cholesteatoma is often treated surgically using canal wall-preserving techniques. Clinical and otoscopic diagnosis of residual or recurrent disease after this form of surgery is unreliable and thus radiological imaging is often used prior to mandatory “second-look” surgery. Imaging needs to be able to differentiate residual or recurrent disease from granulation tissue, inflammatory tissue or fluid within the middle ear cavity and mastoid cavity. High-resolution computed tomography (HRCT), conventional magnetic resonance imaging (MRI), and delayed contrast MRI have all been used in detecting postoperative cholesteatoma. Although delayed contrast MRI performs better than HRCT and conventional MRI, the sensitivities and specificities of these different imaging methods are relatively poor. Diffusion-weighted MRI (DWI and, in particular, non-echo planar DWI) has been shown to have a high sensitivity and specificity for detecting recurrent cholesteatoma. In this review we provide examples of postoperative imaging appearances following cholesteatoma surgery and we review the relevant literature with an emphasis on studies evaluating the diagnostic accuracy of DWI.

Introduction

A cholesteatoma is a non-neoplastic lesion of the middle ear cleft, or any other pneumatized portion of the temporal bone, that is associated with bony erosion.¹ Histologically, a cholesteatoma is characterized by desquamated debris surrounded by layers of keratinizing squamous epithelium.² Both congenital and acquired forms of cholesteatoma exist.³ Congenital cholesteatoma is relatively rare with a reported incidence of 0.12 per 100,000.⁴ Classically, congenital cholesteatoma develops behind an intact tympanic membrane without evidence of previous middle ear infection and is likely to be caused by the persistence of foetal epidermoid tissue.⁵ Acquired cholesteatoma is more common and usually a consequence of chronic middle ear inflammation. Although the exact incidence is unknown, European epidemiological studies quote an incidence of 9.2 per 100,000.1, 6 The classical clinical presentation of cholesteatoma is an offensive otorrhoea associated with a conductive hearing loss due to ossicular erosion. Less commonly, it may be asymptomatic or present with complications such as vertigo, facial paralysis, mastoiditis, or meningitis. Given the severity of potential complications that may ensue from untreated cholesteatoma and the lack of successful medical treatment, surgical intervention is offered to all patients able to tolerate general anaesthesia.