Trumpeted internal acoustic meatus sign

Last revised by Henry Knipe on 17 Dec 2019

A trumpeted internal acoustic meatus (IAM) is an indirect sign of a vestibular schwannoma and is useful in helping to differentiate between one and other cerebellopontine angle entities, especially from a meningioma which typically does not extend into the meatus and is more often associated with hyperostosis 1.

It is characterized by widening of the medial end of the internal acoustic canal and porus acusticus resulting in an appearance reminiscent of a trumpet.

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Cases and figures

  • Figure 1: trumpet (photo)
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  • Case 1
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  • Case 2: trumpeted IAM
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  • Case 2: normal IAM for comparison
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