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Basilar plexus

The basilar plexus, also known as the basilar venous plexus, is a network of small, interconnected venous channels located at the base of the brain, specifically along the clivus within the posterior cranial fossa. It forms part of the intracranial venous system, linking the two inferior petrosal sinuses and providing communication with the cavernous sinuses and internal vertebral venous plexus. Its clinical significance lies in its role in intracranial venous drainage and potential involvement in the spread of infection or tumor, as well as its appearance on neuroimaging.

Synonyms

  • Basilar venous plexus

  • Plexus basilaris

  • Clival venous plexus

Function

  • Provides a venous communication between the two inferior petrosal sinuses

  • Connects with the cavernous sinuses and internal vertebral venous plexus

  • Assists in venous drainage of the posterior cranial fossa

  • May act as a pathway for the spread of infection or tumor from extracranial to intracranial compartments

MRI Appearance

  • T2-Weighted MRI:

    • Appears as a flow void or low signal intensity structure, often linear or plexiform, along the clivus.

    • Sometimes may appear as a small, non-enhancing, serpiginous or reticulated area.

  • T1-Weighted MRI:

    • Typically low to intermediate signal intensity, similar to other venous structures.

    • May be difficult to distinguish from the surrounding bone marrow unless enlarged or prominent.

  • Phase Contrast (PC) 3D MRI:

    • Can show slow venous flow within the plexus as a serpiginous vascular structure.

    • Useful for identifying abnormal venous flow or anatomy.

  • Post-Contrast T1-Weighted MRI:

    • Shows enhancement due to vascular nature, often linear or plexiform enhancement at the clivus.

    • Enhancement is usually symmetric and matches other dural venous sinuses.

CT Appearance

  • Non-Contrast CT:

    • Typically not visible as a distinct structure due to small size and lack of calcification or high density.

    • May occasionally be seen as a faint, low-density linear area along the clivus if enlarged.

  • CT Angiography/Venography:

    • May show as a small, enhancing venous channel at the base of the clivus, connecting the inferior petrosal sinuses.

    • Best visualized with thin-slice, contrast-enhanced imaging protocols.

MRI images

Basilar plexus MRI 3T AXIAL IMAGE