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The usefulness of electroencephalographic (EEG) monitoring as well as the significance of the period of cross clamping in carotid endarterectomy have not been completely defined. In particular, the clinical importance of major EEG changes has not been fully investigated and some recent studies seem to indicate that the method has little value. As to the duration of cross clamping, there is strong evidence that occlusion times of about 15 minutes are tolerated under general anesthesia, but no information is available regarding longer periods of occlusion. The authors describe a consecutive series of 141 carotid endarterectomies in which the patients with EEG changes were shunted only when occlusion was anticipated to last longer than 30 minutes. Early major EEG changes (during the first 4 minutes) occurred in 14% of the cases. In the absence of EEG changes, long occlusion periods of 40 to 50 minutes were well tolerated. In contrast, the 20 patients with major persistent EEG changes did not tolerate protracted occlusion and three of them had immediate postoperative neurological complications. It seems that, in these circumstances, the incidence of neurological deficit is a function of the duration of cross clamping: these three patients had undergone occlusion for 15 to 30 minutes. Their deficits partially resolved. On the basis of these results it is concluded that: EEG recording is a reliable monitoring system in carotid artery cross clamping. No major strokes due to temporary carotid artery occurred in the series. The clinical significance of major persistent EEG changes is not negligible. Cross clamping for longer than 15 minutes in the presence of significant EEG alterations is potentially dangerous.

The rCBF was evaluated using I-123 HIPDM and single photon emission computed tomography (SPECT) on 14 patients undergoing extracranial-intracranial (EC-IC) bypass surgery because of internal carotid artery (ICA) occlusion. Before surgery, all patients showed cortical areas of hypoperfusion over the affected cerebral hemisphere. Shortly after EC-IC bypass a rCBF increase was observed in six patients. However, at the 6 and 12 month follow-ups, with angiographic control of bypass patency, rCBF studies did not show any significant rCBF change. Long-term noninvasive tomographic monitoring of perfusion changes occurring after EC-IC bypass surgery failed to show a long-lasting improvement in perfusion.

Ventricular concentrations of homovanillic acid (HVA) and 5-hydroxyindole-acetic acid (5HIAA) were measured in 7 patients a few days after a severe traumatic brain injury. Both acid metabolites were elevated in respect to control patients values, however, the rise was more consistent for 5HIAA (258 +/- 86 ng/ml) with a 5HIAA/HVA ratio of 0.85 +/- 0.35. The data support previous hypothesis on the profound involvement of serotoninergic structures in the early stages of acute traumatic brain syndromes and on the role of 5HT in maintaining edema and vasospasm.

10 patients suffering from intracranial aneurysm causing subarachnoid hemorrhage (SAH) have been treated during the acute pre-and postoperatory phase with omega-aminocaproic acid. The blood and the cerebrospinal fluid of the treated patients have been analyzed in order to study fibrin(ogen) degradation products (FDP) and fibrinolytic activity (FA). The results so obtained show only an alteration of local fibrinolytic processes either inside or around the aneurysmatic clot: there were no alterations of the systemic FA. Furthermore, monitoring of FDP and FA was a very useful tool in those patients who took advantage of the treatment with omega-aminocaproic acid which protected them from rebleeding.