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Topic

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Left Vertebral Artery (Intracranial Part)

The intracranial part of the left vertebral artery is the segment that extends from the foramen magnum entry of the artery to its union with the contralateral vertebral artery to form the basilar artery. It travels posterolaterally along the medulla oblongata, lying ventral to the cerebellar hemisphere and lateral to the medulla, within the subarachnoid space.

This segment gives rise to important branches, including the posterior inferior cerebellar artery (PICA), which supplies the posterior inferior cerebellum and medulla oblongata, and small medullary perforators supplying the medulla. The intracranial vertebral artery is tortuous, especially in elderly individuals, and is surrounded by cerebrospinal fluid (CSF) within the cisterna magna. Understanding its precise course and relationships is crucial for neurologists, neurosurgeons, and interventional radiologists for procedures, aneurysm evaluation, and posterior circulation stroke assessment.

Function

  • Supplies posterior brain structures, including the medulla, cerebellum, and spinal cord segments

  • Contributes to posterior circulation of the brain via the basilar artery

  • Gives off branches such as PICA and medullary perforators

  • Ensures adequate perfusion of posterior fossa structures, critical for vital functions and balance

Synonyms

  • Intracranial left vertebral artery

  • Intradural left vertebral artery

  • Left VA (intracranial segment)

MRI Appearance

T1-weighted images:

  • The vessel wall is low signal intensity, surrounded by high signal CSF in the subarachnoid space

  • The lumen may appear iso- to hyperintense on flow-sensitive sequences depending on flow direction and velocity

  • T1 post-contrast sequences enhance the vessel wall, particularly in cases of dissection, inflammation, or atherosclerotic plaque

T2-weighted images:

  • The lumen appears flow-void (hypointense) due to rapid arterial blood flow

  • CSF surrounding the artery is hyperintense, providing clear contrast

  • Tortuosity and stenosis may be identified indirectly as areas of signal alteration

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, leaving the artery flow-void and hypointense, while highlighting surrounding edema or inflammatory changes if present

  • Useful in arterial wall pathology, vasculitis, or compressive lesions

T1 Post-Contrast (Gadolinium-enhanced):

  • Normally, the arterial lumen may enhance minimally

  • Pathological conditions such as dissection, aneurysm, or inflammatory arteritis show focal or circumferential enhancement of the vessel wall

  • Enhances adjacent dural or meningeal vessels if secondary pathology exists

CT Appearance:

  • On non-contrast CT, the artery is not directly visible, but calcified atherosclerotic plaques in its wall appear hyperdense

  • On CT angiography (CTA), the lumen is well-opacified by contrast, clearly showing the course from foramen magnum to the basilar artery, including the origin of PICA

  • CTA is excellent for evaluating stenosis, aneurysms, occlusions, and vessel tortuosity

MRI images

Left vertebral artery (intracranial part) mri coronal image -img-00000-00000

MRI images

Left vertebral artery (intracranial part)