Learning objectives:
-
1. Learn about the MRI features of the temporal bone post SP BSC.
-
2. Understand more about the behaviour of the temporal bone when it has been isolated from the external environment.
-
3. Understand the role of MRI in surveillance of the temporal bone post SP BSC.
Introduction: Long term follow up is recommended following subtotal petrosectomy (SP) with cavity obliteration and blind sac closure (BSC) of the external auditory canal to detect recurrent or iatrogenic cholesteatoma and chronic otitis media (COM). Follow up has historically been a challenge both clinically and radiologically. Recent advances in MRI have transformed our ability to survey patients post SP BSC. The objectives of this study were to: i. Characterise the MRI features post SP BSC; ii. Assess the behaviour of the temporal bone and disease persistence/progression post SP BSC; iii. Classify the radiological features and define their consequences for clinical care.
Methods: Retrospective case note review was performed in a tertiary referral hospital of 23 patients who underwent SP BSC between November 2004 and October 2013. MRI surveillance was carried out over a mean follow up period of 48 months (range 14–116). MRI features over time were compared to clinical course and surgical findings.
Results: Otitis media with effusion is a common finding in the unventilated temporal bone but appears to have little if any clinical consequence. Revision surgery was performed on clinical grounds in four patients (17%) and concerning imaging features but no clinical concerns in three patients (13%). Radiological findings correlated with operative and histological findings for cholesterol granuloma and mucosal COM but there was discrepancy in the diagnosis of cholesteatoma.
Conclusions: The MRI features of the temporal bone post SP BSC are described. A grading system for radiological findings is proposed to guide surveillance and possible further surgical intervention.
