The Erroneous Appearance of Silver Nitrate on CT Imaging in Patients
with Severe Otitis Externa; A Case Series
Abstract
Introduction Silver nitrate is commonly used within otolaryngology to
treat granulation tissue in severe otitis externa. It appears
radio-opaque on CT (computed tomography) imaging and therefore can mimic
bony fragments and foreign bodies. This is particularly cumbersome when
the phenomena correlates to the clinical complaint. Discussion We report
two cases of 73-year-old and 75-year-old males who presented with
chronic otalgia and discharge. Granulation tissue in the external
auditory canal was identified and chemically cauterised with silver
nitrate. Subsequent CT petrous bones demonstrated an unidentified
foreign body in the canal with extensive soft tissue swelling giving an
impression of a wick in situ and “minor bony erosion in the left
external acoustic canal” respectively. An additional CT of a
57-year-old female who had been treated with silver nitrate for
granulomatous tissue reported “multiple highly radiopaque foci in the
external auditory canal, suggestive of foreign body”. Though relatively
unknown, this phenomenon has been reported in literature. However, there
are few reports of silver nitrate artefacts in CT images of the head no
cases in the context of otitis externa. Our patients avoided further
imaging or surgery following clarification with the radiologists and
symptomatic improvement with long-term intravenous antibiotics.
Conclusion Given the prevalence of CT imaging and cauterization in
otolaryngology, we recommend contemporaneously documenting the use of
silver nitrate and highlighting this on request forms to avoid alarming
erroneous reports, unnecessary investigation and surgical procedures. We
also recommend, where clinically acceptable, to use silver nitrate prior
to imaging.