Time window for clinical effectiveness of mass evacuation in a rat balloonmodel mimicking an intraparenchymatous hematoma

The purpose of this study is to evaluate in a rat model if the early remova l of an experimental intracerebral mass mimicking an extensive subcortical hematoma improves neurological outcome. Fifty six male Wistar rats were stu died. A balloon was placed sterotactically at the level of the striatum. Th e balloon was inflated to 100 mu l for periods of 10, 60 or 130 min (with 1 0 animals in each group). In Ib animals the balloon was not deflated and th ere were four sham operated cases. Neurological deficit was evaluated by a blinded observer by means of a clinical scale from 0 to 8 points at 24 and 72 h after inflation. Three additional animals at each inflation period wer e sacrificed after 6 h for pathological study with hematoxylin-eosin staini ng. Death rate was 9/10 animals who had permanent inflation. 4/10 in those with 2 h inflation, 2/10 for 1 h inflation and 0/10 for 10 min inflation (P <0.01 in chi square test). Many animals developed a particular clinical syn drome not previously described. Mean 72 h clinical scores (0-8 points) were : 7.6 (S.D.: 1.2) for the permanent inflation group, 4.4 (S.D.: 3.2) for 2 h of inflation, 2.3 (S.D.: 3.2) for 1 h and 0.4 (0.9) for 10 min of inflati on (P<0.01 in Kruskal Wallis test). In the pathological study the rate of d amaged neurons was significantly higher in the permanent than in transient inflation groups. In conclusion, in this balloon model evacuation of an ext ensive acute expanding subcortical (hematoma-like) mass must be performed w ithin a limited time window to prevent the development of irreversible neur ological deficits or death. (C) 2000 Elsevier Science B.V. All rights reser ved.