[Persistent primitive first cervical intersegmental artery (proatlantal artery II) with occlusion of the basilar artery--a case report].

A rare case of persistent primitive first cervical intersegmental artery (proatlantal artery II) is reported. A 58-year-old man was admitted to our hospital with dysarthria and left hemiparesis. On admission he was stuporous with bilateral gaze palsy and left hemiparesis. CT scan on admission showed low density areas in the right cerebellar hemisphere and ventricular part of the pons. Right retrograde brachiography revealed occlusion of the basilar artery, aplasia of the right vertebral artery and an abnormal vessel connecting the right external carotid artery and the right vertebral artery. This anastomotic vessel was thought to be a persistent primitive first cervical intersegmental artery (Proatlantal artery II). Left carotid angiography revealed the left posterior cerebral artery was visualized through the posterior communicating artery, leading from the internal carotid artery. Left retrograde brachial angiography showed that the left vertebral artery terminated just distal from the branching of the left posterior inferior cerebellar artery. After admission the left hemiparesis deteriorated gradually and tracheotomy was done due to respiratory difficulties. The patient was then transferred to the rehabilitation center on his 34th day in hospital with neurological deficits.