Cerebral edema associated with craniectomy and arterial hypertension

The present studies were performed to determine whether cerebral edema will develop as a consequence of arterial hypertension and/or craniectomy. Arterial hypertension was induced for 30 minutes by inflation of a balloon catheter situated in the descending aorta, and a parietal craniectomy was performed. The cerebral edema noticed was evaluated by macroscopic and microscopic observations, BBB permeability of HRP and Evans blue and water content. In addition, ICP was measured in the cisterna magna and ICPP by a catheter-tip transducer. In arterial hypertension or craniectomy alone, some small areas of Evans blue extravasation with increased water content were seen in the cortex, which corresponded to the occipito-parietal parts of the arterial boundary zones. In contrast, when arterial hypertension was combined with craniectomy, these lesions extended further into underlying white matter with increased water content. Forty-eight hours later, extensive brain edema with a shift of midline structures developed on the side of craniectomy which differed from that in arterial hypertension or craniectomy alone. It is suggested that some hydrostatic pressure gradients, particularly between blood vessel and surrounding extracellular space and among different areas within the brain parenchyma, may play an important role in the development of brain edema.