Persistent trigeminal artery

Case contributed by Prashant Gupta
Diagnosis certain

Presentation

Non-specific headache

Patient Data

Age: 45 years
Gender: Female

Note: This case has been tagged as "legacy" as it no longer meets image preparation and/or other case publication guidelines.

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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