Experimental models of subarachnoid hemorrhage in the rat: a refinement ofthe endovascular filament model

The rat endovascular filament model has been utilized to study subarachnoid hemorrhage (SAH). Because the severity of the hemorrhage with this model h as proven difficult to modulate, we attempted to vary the hemorrhage by mod ifying filament size, and compared this model to the blood injection method with regards to acute physiological responses and hemorrhage size. SAH was achieved using either a 3-0 or 4-0 filament, or by injecting 0.3 cc of aut ologous blood into the cisterna magna. Peak ICP elevations were lowest in t he 4-0 filament group. CBF decreased acutely and rose from its nadir in ail three models with the injection model demonstrating the earliest recovery. In the injection group, mean arterial blood pressure rose acutely and rema ined elevated, whereas in the 3-0 group, MABP rose transiently and in the 4 -0 group it did not rise significantly. Histologically, there was less suba rachnoid blood in the 4-0 group vs. the injection or 3-0 groups and a diffe rent distribution of blood in the two experimental models. Varying filament size provides a method to modulate the severity of SAH in the filament mod el. In addition, the rat endovascular filament and blood injection models p roduce different distribution of blood and physiological responses. (C) 200 0 Published by Elsevier Science B.V. All rights reserved.