Lateral pontine branches of basilar artery

The lateral pontine branches arise from the basilar artery and course laterally around the surface of the pons before giving perforating branches to the pontine tissue. Traditionally, they are divided according to the distance they travel around the circumference of the pons into short circumflex (short circumferential) arteries and long circumflex (long circumferential) arteries.

1. Short circumflex arteries

The short circumflex branches partially surround the pons and typically divide into 2–5 terminal perforators.

Important examples include the superolateral pontine artery and anterolateral pontine artery. The superolateral pontine artery is usually an upper pontine branch, whereas the anterolateral pontine artery typically arises immediately above and before the AICA. The latter contributes to the ventromedial and ventrointermedial pontine regions and areas associated with CN VI and CN VII/VIII.

Please note that there are also arteries that exhibit combine characteristics of paramedian and short circumflex branches, and thus the the distinction is not always absolute.

2. Long circumflex arteries

The long circumflex branches travel farther around the pons toward its lateral and posterolateral aspects. They generally produce relatively few terminal perforators (0–2) and may extend as far as the cerebellopontine angle.

Major examples described in the study are the posterolateral pontine artery, commonly an upper branch near the SCA, and the pontomedullary artery, which is usually a lower branch and commonly arises below the AICA. The latter supplies the inferolateral pontine region. Because of their lateral course, particularly the lower circumflex vessels, these arteries may have close relationships with CN VI, VII and VIII.

Clinical correlates

Occlusion of lateral pontine branches produces different deficits according to the level and territory of the affected vessel.

• Upper posterolateral and superolateral branches may affect trigeminal and sensory pathways and cerebellar connections.

• Occlusion of the anterolateral pontine artery may involve the corticospinal tract together with CN VI/VII and sensory pathways, producing a caudal pontine syndrome.

• Lower long circumflex branches may affect CN VI and VII structures, vestibular pathways, sympathetic fibres, sensory tracts and the middle cerebellar peduncle, producing a caudal pontine tegmental syndrome with combinations of cranial nerve deficits, crossed sensory abnormalities, Horner syndrome, vertigo and ipsilateral cerebellar signs.