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There have been years of debate about the appropriate imaging strategy for children with bilateral sensorineural hearing loss. For those children undergoing cochlear implant surgery, CT may provide some assistance to surgical planning, although this is not necessary in children with normal anatomy. It is recognised that radiation CT (of sufficient dose) increases the relative risk of leukaemia and brain tumours. For this reason, the prevailing practice in the UK is for initial imaging with MRI. Furthermore, MRI is preferable for the assessment of the cochlear nerves (CT relies on the presence or absence of the bony cochlear nerve canal). This article builds on this debate. It reports the experience of children who have had both modalities of imaging at Texas Children’s Hospital, Emery University and the Cleveland Clinic. The headline figure is that CT has a higher diagnostic yield than MRI. This is therefore worth interrogating further, as it has the potential to change practice. The usual cautions apply. This is a retrospective series. It is relatively likely that those patients with particular comorbidities were preferentially scanned with both modalities. This will skew the results. Of over 2000 patients with hearing loss, only just over 300 had both imaging modalities; this demonstrates significant patient selection. Nevertheless, the results deserve closer investigation. Clearly it is important to see the kinds of anomalies that CT detected and MRI missed. MRI was clearly better at finding cochlear nerve hypoplasia or aplasia, but it seems confusing that CT detected none of the 18 cases that MRI detected. Stenosis or absence of the bony cochlear nerve canal, which can be seen on CT, may be enough to infer absence of the cochlear nerve. MRI protocols were not standardised, or elaborated upon, which does not help shed light on the disparity in positive findings of cochlear anomalies – not an area in which MRI is generally considered to be inferior to CT. It is also confusing why MRI cannot detect IAC hypoplasia with any reliability. These findings make the lack of illustrations more than frustrating. Studies reporting imaging findings are greatly enhanced by illustrative examples showing why CT or MRI can or cannot detect clinically relevant anomalies. This study’s results have the potential to make us re-evaluate imaging protocols but, without illustration, the article may not be able to change practice.

Imaging in pediatric bilateral sensorineural hearing loss: Diagnostic yield with computed tomography versus magnetic resonance imaging.
Zhang J, Sawaf T, Anne S, et al.
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Robert Nash

BM BCh, MA(Oxon), MRCS, MA, DOHNS, FRCS (ORL-HNS), Great Ormond Street Hospital, London, UK.

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