Topics

Topic

design image
Labyrinthine artery

The Labyrinthine artery is a small but critical vessel supplying the inner ear structures. It plays a pivotal role in the vascularization of the cochlea and vestibular apparatus, both essential for hearing and balance. Its clinical significance is highlighted by its susceptibility to vascular compromise, which can lead to sudden sensorineural hearing loss or vertigo. Though rarely visualized directly on imaging due to its minute size, understanding its origin, course, and potential imaging findings is vital for diagnosing inner ear pathologies.

Synonyms:

  • Internal auditory artery

  • Auditory artery

Origin:

  • Most commonly arises from the anterior inferior cerebellar artery (AICA) (about 85% of cases)

  • Less commonly, it may arise directly from the basilar artery or from a common trunk with the AICA

Course:

  • Travels with the facial (CN VII) and vestibulocochlear (CN VIII) nerves within the internal auditory canal (IAC)

  • Enters the internal auditory meatus along with these nerves

  • Divides into two main branches:

    • Cochlear branch: supplies the cochlea

    • Vestibular branch: supplies the vestibular apparatus (utricle, saccule, semicircular canals)

Function:

  • Supplies arterial blood to the structures of the inner ear

    • Cochlea (hearing)

    • Vestibular apparatus (balance)

  • Is an end artery (no significant collateral supply), so its occlusion can cause acute inner ear dysfunction

MRI Appearance:

  • Not directly visualized due to its very small caliber

  • Can be inferred by flow voids in high-resolution MRI sequences within the internal auditory canal

  • Pathology may present as:

    • Inner ear ischemia: Loss of normal high signal within cochlea/vestibule on T2-weighted images

    • Labyrinthine infarct: Restricted diffusion on DWI in the cochlea or vestibule in acute phase

CT Appearance:

  • Not directly visualized on routine CT due to small size

  • High-resolution CT may show bony canal of internal auditory canal through which the artery passes, but not the vessel itself

  • Indirect signs in pathology:

    • Labyrinthine ossificans (chronic sequela of infarct): Abnormal calcification within cochlea/vestibule on CT

MRI images

Labyrinthine artery MRI 3T axial t2 image