Hyperperfusion Syndrome after High Flow Bypass and Carotid Endarterectomy

Abstract

It is well known that hyperperfusion syndromes sometimes occur after high flow bypass or carotid endarterectomy (CEA). In this paper we discuss cases that showed hyperperfusion syndrome after CEA and high flow bypass using radial artery graft (RA graft).
Twenty cases that were treated between April 1993 and January 1996 were selected for this study. All patients complained of TIA, RIND, or minor completed stroke. Their cerebral angiograms demonstrated severe stenosis or occlusion in the ipsilateral internal carotid artery or middle cerebral artery. The regional cerebral blood flow (rCBF) was measured with ¹²³I-IMP single emission computed tomography (SPECT), and measured after administration of 1 gram of acetazolamide intravenously. For these 20 patients 15 cases of CEA and 5 cases of RA graft were performed.
Three cases of hyperperfusion syndrome were observed: 1 case was seizure after RA graft, and 2 cases were hemorrhage (1 patient was after CEA and the other was after RA graft). This hyperperfusion syndrome group (H group) showed hypoperfusion at rest and markedly decreased acetazolamide reactivity before operation.
On the other hand the rCBF was not decreased in non-hyperperfusion group (N group) after acetazolamide administration. In the N group all patients were uneventful after surgery.
According to Kuroda's classification, the cases who have decreased resting rCBF and impaired acetazolamide reactivity are classified as“Type 3.”In our study the H group cases showed markedly decreased acetazolamide reactivity compared with the“Type 3”cases of the N group. The cerebral blood vesseles of this H group may be paralytic and have no vasocontraction ability.
We propose the“vasoparalytic type”for these cases. They have decreased resting rCBF and severely impaired acetazolamide reactivity.
For these patients superficial temporal artery-middle cerebral artery anastomosis or PTA should be performed prior to CEA and RA graft.