The lower posterior cerebellar artery is discharged, one on hay. and one on the left. side, from the vertebral artery when it has entered the cranial cavity and just before the vertebral arteries of the two sides join to form the anterior basal artery. In medical contexts, the abbreviation "PICA" is sometimes used (taken from the English language Posterior Inferior Cerebellar Artery). The artery supplies parts of the cerebellum and of the brainstem. In stroke that affects PICA, an injury picture called "Wallenberg syndrome" is obtained.
Wallenberg syndrome means, in the typical case, that the affected person becomes dizzy, strongly nauseous, vomits, flares uncontrollably with the gaze (nystagmus), loses balance and falls over to the side where the injury is located. At the same time, pain and temperature sensitivity in the face on the injury side and over the rest of the body on the opposite side deteriorates.