Arterial Supply to the Pons in Infarction
A left hemipons infarct is supplied by perforating branches from the basilar artery, specifically the paramedian and short circumferential branches that arise directly from the basilar artery.
Vascular Anatomy of the Pons
The pons receives its blood supply from the basilar artery through several types of branches:
- Paramedian branches penetrate directly from the basilar artery to supply the medial pontine structures including the corticospinal tracts, medial lemniscus, and pontine nuclei
- Short circumferential branches supply the lateral portions of the pons
- Long circumferential branches (anterior inferior cerebellar artery and superior cerebellar artery) supply the lateral and dorsolateral pons
For a hemipons infarct specifically affecting one side, the involved vessels are the ipsilateral paramedian and short circumferential perforating arteries arising from the basilar artery.
Clinical Considerations
Anatomical Localization
- The basilar artery runs along the ventral surface of the pons and gives off multiple small perforating branches bilaterally
- Unilateral pontine infarcts typically result from occlusion of these small penetrating vessels rather than the main basilar trunk
- A left hemipons infarct would involve the left-sided perforating branches
Related Vascular Territories
While the posterior inferior cerebellar artery (PICA) can supply the lower pons in some cases, this is uncommon and typically involves the ponto-medullary junction rather than the mid-pons 1. PICA occlusion more characteristically causes lateral medullary syndrome with possible extension to the lower pons.
Clinical Pitfalls
- Pontine compression from mass effect can lead to ophthalmoparesis, breathing irregularities, and cardiac dysrhythmias, which should be distinguished from direct ischemic injury 2
- Initial CT imaging can be normal in up to 25% of patients with posterior circulation strokes, so clinical suspicion and MRI may be necessary 2
- Peak swelling occurs several days after onset, requiring monitoring for deterioration 2