Ultrastructural study of brain microvessels in patients with traumatic cerebral contusions

Brain tissue from 11 patients with traumatic cerebral contusions submitted to surgery was studied. Control biopsy specimens were obtained from 5 patients undergoing ventriculo-peritoneal shunts for "communicating" hydrocephalus. After collection, the small fragments were fixed by immersion in glutaraldehyde-osmium and embedded in Epon. Semi-thin sections stained with toluidine blue were observed with the light microscope. Thin sections stained with lead citrate and uranyl acetate were observed using a Jeol electron microscope. In tissues from patients with head trauma a clear space most probably corresponding to fluid accumulation was systematically observed around microvessels. Ultrastructurally endothelial cells from these specimens exhibited signs of marked intracellular oedema, tight junctions being intact. Pinocytotic activity was increased, mainly at the abluminal surface. Swelling of astrocytic perivascular processes and the appearance of macrophagic cells with voluminous lysosomes were also observed. The authors conclude that the oedema of endothelial cells probably represent a central fact in the pathophysiology of traumatic brain oedema and speculate on the putative involvement of stretch-activated receptors in this condition.