This group from the Netherlands looks at the finding of vascular loops found on MRI IAMs requested for tinnitus. It is a common finding for all who request such imaging. This work adds to the body of evidence that such vascular loops should be regarded as an incidental finding. It occurred in 23% of patients scanned (321 patients). There was a 41% rate of abnormalities on MRI, which were not the cause of tinnitus. This is a familiar situation I face on a regular basis and deciding what requires further evaluation and what can be left alone safely without causing undue anxiety to the patient. Interestingly, their protocol scans for bilateral tinnitus (51% of patients), which in a cash strapped NHS is difficult to justify. Not unsurprisingly, unilateral tinnitus had a significantly higher chance of finding pathology that may account for the tinnitus (p=0.044). Two acoustic neuromas were found (1.7%) and both cases had hearing loss in addition. A discussion regarding whether unilateral tinnitus on its own merits an MRI is presented. It depends on your point of view but in my opinion it does not, and further clinical / audiometric signs are usually present. Rarely would I expect to find significant pathology (e.g. a large acoustic neuroma) warranting treatment, with symptoms of unilateral tinnitus, symmetrical hearing and no other clinical signs. Definitely worth a read and discussing with your radiology department to come up with your own guidelines for MRI IAM requests. 

Diagnostic yield of a routine magnetic resonance imaging in tinnitus and clinical relevance of the anterior inferior cerebellar artery loops.
Hoekstra CE, Prijs VF, van Zanten GA.
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Anand Kasbekar

BMedSci, DOHNS, FRCS (ORL-HNS), DM, Nottingham University Hospitals NHS Trust; Associate, The University of Nottingham; Otology and Hearing Group, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, UK.

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