Abstract
It is generally regarded to be very difficult to establish an experimental animal model of chronic subdural hematoma (CSH).
The subdural space was inoculated with fresh blood in 9 dogs (Group I), blood clot in 10 dogs (Group II), and CSF-blood mixture in 13 dogs (Group III). In both Group I and II, the subdural mass showed high or mixed density in the early stage and the mass showed shrinkage of the volume with decrease of its density in the chronic stage by CT. Histological examination revealed rapid organization process of the mass from granulation tissue to firm fibrous connective tissue. In Group III, inoculated subdural masses showed low or iso-density in the early stage and then, the densities variably reduced afterwards. Histological examination revealed neomembrane formation in the subdural space about 2-3 weeks after the inoculation which were consisted of the sinusoidal channel layer and the fibrous layer. Structures of this neomembrane quite resembled to those of clinical cases of CSH. However, there was no expansive subdural lesions so far. In Group IV of 13 dogs, CSF-blood mixture was inoculated into the subdural space and daily doses of D-Mannitol of 3 g/kg and Heparin of 200u./kg were given intravenously from Day 7 after inoculation. In 10 dogs, the subdural collections diminished with increase of the density. In 2 dogs, however, the subdural mass showed significant expansive character with high density in CT from Day 14 to 21. Pathological examination revealed massive hemorrhage from capillaries of the fibrous layer of the neomembrane into the capsular lumen. In the remaining one dog, the subdural mass showed expanding low density area due to dissolution of the hematoma. These three cases resembled human cases of CSH clinico-pathologically.
The result suggested that subdural collection of mixture of CSF and blood participated in the neomembrane formation of CSH and that enlargement of the content of subdural hematoma was brought forth by hemorrhages from capillaries of the fibrous layer, or by dissolution of the hematoma.
