Basilar artery occlusion.

Twenty patients with basilar artery occlusion and three patients with bilateral vertebral artery occlusions have been studied. The clinical data at the time of the ictus and the long-term follow-up data have been correlated with the site and extent of the basilar artery occlusion and the type of collateral flow. Patients with hypertension and with coma at the outset have a grave prognosis. The presence of surface collateral flow may not indicate adequate perfusion of the paramedian penetrating branches of the basilar artery or the thalamoperforating branches of the posterior communicating or posterior cerebral arteries. It is these vessels which supply the territory regulating the level of consciousness and containing some of the control mechanisms for respiratory function.