IATROGENIC VERTEBROBASILAR INSUFFICIENCY AFTER SURGERY OF THE SUBCLAVIAN OR BRACHIAL-ARTERY - REVIEW OF 3 CASES

OBJECTIVE AND IMPORTANCE: Vertebrobasilar insufficiency resulting from disease of the subclavian artery is well recognized. Usually, this oc curs as the ''subclavian steal'' syndrome in the context of chronic su bclavian stenosis and is consequently well tolerated because of collat eralization, Acute disruption of the hemodynamics of the aortic arch v essels, however, can produce disastrous sequelae. CLINICAL PRESENTATIO N: We present three cases of iatrogenic vertebrobasilar insufficiency sustained as complications of surgery of the left subclavian artery or its distal continuation. The cases were chosen from a review of appro ximately 400 emergency neurosurgery consultations requested at the Los Angeles County Hospital between November 1995 and February 1996. INTE RVENTION: The first patient underwent repair of a traumatic brachial a rtery occlusion and awoke postoperatively with bilateral cortical blin dness, right hemiparesis, and multiple cranial nerve deficits that wer e mast likely caused by acute subclavian steal. The second underwent r emoval of a subclavian embolus and developed bilateral cerebellar infa rction leading to persistent coma, possibly from inadvertent embolizat ion of the vertebral artery during surgery. The third underwent resect ion and bypass grafting of a subclavian aneurysm. Good backflow was re ported when the vertebral artery was disarticulated from the subclavia n artery, and this vessel was not reimplanted into the graft. The pati ent suffered massive cerebellar infarction reading rapidly to brain de ath. CONCLUSION: There are myriad ways in which the inherent redundanc y of the vertebrobasilar system may be jeopardized, and when this prot ective mechanism fails, the results can be disastrous. Flow through th e vertebral arteries may be compromised by thrombosis, embolization, d issection, inappropriate ligation, excessive head rotation, hypotensio n, vasospasm, or acute subclavian steal. These examples illustrate the importance of understanding the complex physiology of posterior fossa circulation as the basis of pre-, intra-, and postoperative managemen t of patients undergoing surgery of the subclavian artery.