gms | German Medical Science

Objective: There is a multitude of experimental subarachnoid hemorrhage models with uncertainty which one to prefer. Recently a modification of the classic endovascular perforation model with a monofilament has been published (modification with a tube-tungsten wire construction). To clarify the pathological pattern of each technique we assessed both (classic vs. modified) defining successful induction of SAH without collateral pathologies as the primary endpoint.

Method: Rats (Sprague Dawley, weight: 300- 400g) were randomly assigned to receive classic endovascular perforation (n=19) or modified perforation technique (n=19). Regional cortical blood flow (rCBF), intracranial pressure (ICP) and blood pressure (BP) were recorded during intervention and 3h afterwards. Induction of SAH was defined as drop in CBF bilaterally and parallel sharp increase of ICP with verification by typical macroscopic pattern afterwards. Animals were sacrificed either 6 or 24h after surgery. The successful SAH-induction was assessed by the means of macroscopic occurrence of additional pathologies and territorial ischemia. Statistical analysis was performed using IBM SPSS statistical software version 21.

Results: Success of SAH-induction (overall 86.8%) was statistically independent from type of technique (p=0.631); intervention failed to induce SAH in 5 cases (classic technique: n=3, modified technique: n=2). There was no significant difference concerning case fatality rate (classic technique: 36.8%; modified technique: 21%; p=0.283) nor occurrence of territorial ischemia (52.6% vs. 32.6%; p=0.184). However, the incidence of collateral intracranial hemorrhage (ICH) (26.3% vs. 0%; p=0.016) and subdural hematoma (SDH) (57.9% vs. 21.1%; p=0.020) was significantly higher with the classic technique. Induction of SAH without collateral ICH or SDH was possible in 31.6% with the classic and in 73.7% with the modified technique. Peak ICP levels differed significantly between the two groups (classic technique: 91.3 ± 23.1mmHg; modified technique: 59.7 ± 19.6mmHg).

Conclusions: Both tested techniques have proven successful to produce SAH. However, the induction of SAH without collateral pathologies was met more reliable by the modified technique. If, from the experimental point of view, higher ICP levels are required the classic method might be more appropriate. Apart from that the modified technique seems favorable in respect to long-term examination.