PRESENT STATUS OF COMPUTERIZED-TOMOGRAPHY AND ANGIOGRAPHY IN THE DIAGNOSIS OF CEREBRAL THROMBOPHLEBITIS CAVERNOUS SINUS THROMBOSIS EXCLUDED

In order to evaluate the contribution of computerized tomography (CT) to the diagnosis of cerebral thrombophlebitis, a series of 28 cases wa s reviewed and compared with data from the literature. In an examinati on carried out 4 to 5 days of its constitution the thrombus may be dir ectly, visualized as a spontaneous hyperdensity. This early but very t ransient sign, called <<cord sign>>, can easily be overlooked, which e xplains why it was found in only 5 of our 28 cases and in 2 % of the l argest series of the literature. The thrombus thereafter becomes hypod ense and can be intensified by peripheral contrast enhancement which p roduces the classical <<delta sign>>. This sign is more frequent: 13/2 8 in our series and 16 to 30 % in published cases. It is usually found in the superior sagittal sinus and must be distinguished from anatomi cal variations which are common at that level. These two direct signs acquire a grater value when associated with such indirect signs as dif fuse or localized cerebral oedema (12 to 52 %) and venous ischaemia (2 2 to 59 %). Venous ischaemia is characterized by its strong bleeding p otential (more than 50 % of the cases) and by its usually favourable c ourse; these two elements and its site differentiate it from arterial ischaemia. Finally, venous stasis is responsible, in 5 to 19 % of the cases, for intense enhancement of the tentorium cerebelli: this sign i s not specific but easy to evidence and of great value when associated with a direct sign. Dilatation of cortical veins, found in 4 of our 2 8 cases, also seems to be an interesting sign which, to our knowledge, has not yet been mentioned in the literature. Since in 3.6 to 26 % of the cerebral thrombophlebites the CT scan is normal, a negative CT ex amination does not rule out this disease, and in many cases the explor ation must be rapidly completed by angiography or MRI. Because it is n on-invasive and very sensitive to flows, MRI has become the kev examin ation to assert the diagnosis. Angiography is now restricted to those cases where cases where MRI cannot be performed promptly or to certain , purely cortical thrombophlebites which might pass unnoticed at MRI. When carried out and interpreted cautiously, angiography always shows the venous thrombosis, its exact size and its suppletive network. The results of this study show that MRI alone can diagnose cerebral thromb ophlebitis in most patients, that CT well done and interpreted often p rovides useful but seldom sufficient in&ces, and that angiography shou ld be reserved for difficult cases.