Cerebral perfusion defects, dysautoregulation and carotid stenosis.

Single Photon Emission Computed Tomography (SPECT), imaging of cerebral blood flow was carried out in ten patients with haemodynamically significant carotid stenosis. Before and after carotid endarterectomy each patient was investigated by 3--dimensional SPECT brain scanning using technetium--hexamethyl propyleneamine oxine (99 mTcHMPAO, ceretec). Brain blood flow was normal before and after operation in 3 patients whose autoregulation was kept intact. Seven patients received acetazolamide to limit cerebral vascular reactivity and in four of these, preoperative perfusion defects were visible. After carotid endarterectomy the ipsilateral perfusion defects were abolished and it is concluded that carotid stenosis can reduce perfusion in the dysautoregulation brain and that carotid reconstruction can restore normal flow.