Persistent trigeminal artery

Case contributed by Dr Prashant Gupta


Non-specific headache

Patient Data

Age: 45 years
Gender: Female
Annotated image

Note a flow void connecting carotid and basilar systems on left side consistent with a persistent trigeminal artery. The "tau sign" is best seen on sagittal images.

Case Discussion

The tau sign refers to the unusual configuration of signal voids in the presellar ICA and in a persistent trigeminal artery, as viewed on parasagittal MR images.

The combination of the vertical and horizontal segments of the ICA and the proximal portion of the trigeminal artery creates the outline of the Greek letter "τ".

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Case information

rID: 17846
Published: 18th May 2012
Last edited: 13th Aug 2019
Inclusion in quiz mode: Included