Brain oedema and intracranial pressure in superior sagittal sinus balloon occlusion. An experimental study in pigs

About 2/3 of all patients with thrombosis of the superior sagittal sinus (SSS) develop signs of increased ICP and/or brain oedema (BE). The time of onset and the spectrum of symptoms in SSS thrombosis vary extremely. This variability might be caused by differences in pathomechanism like BE and rise of ICP, parameters studied in the present contribution. 10 domestic pigs received a standardized occlusion of the SSS with two different balloon types (spherical and cylindrical). They were monitored for several systemic and intracranial pressures. After 4 hours of occlusion the brains were examined for BE (Evans blue, water content). They were compared with those of 4 sham-operated control animals. 4 animals underwent cerebral angiography. Within 4 hours ICP rose to 60 mm Hg in the group with the spherical balloon. Normal ICP of 5-10 mm Hg was seen in the group with the cylindrical balloon and in the sham-operated controls. The water content of the white matter was elevated in both occlusion groups differing significantly from the control group. Haemorrhagic infarction of the frontal parts of the cerebrum occurred in animals with concomitant obliteration of bridging and cortical veins. We conclude from our experiments that SSS occlusion may initiate a multitude of possible pathomechanisms depending on the involvement of bridging veins, cortical veins and inner brain veins.