Computerized Tomography in the Operative Treatment of Cerebrovascular Disease

Abstract

The indication and timing for carotid endarterectomy or extra-intracranial arterial bypass (EIAB) surgery in patients suffering from occlusive cerebrovascular disease has come mainly from clinical follow-ups and angiographic findings up to the present. Difficult questions were, on the one hand to decide on surgery in patients with partial recovery of completed stroke and, on the other hand, to assess the blood-brain-barrier (BBB) damage with regard to operative timing. Visualization of cerebral infarcts was rendered possible for the first time by computerized tomography (CT). The early visualization of infarcts depends on the amount of water in the tissue, in that a 3% increase in water content gives a fall in the absorption coefficient of 2 Houndsfield Units (4). A contrast medium enhancement in the infarcted area is detectable by CT in 40% of patients in the first stages, rising to 70% by the 3rd week and decreasing continuously until the 6th week. The existence of a hypodense lesion is found in 18% of the patients with a transient ischemic attack (TIA), in 76% of the patients with prolonged reversible ischemic neurological deficit (PRIND) and in 95% of the patients with completed stroke (CS) (3).