gms | German Medical Science

Objective: Postcommunicating (P2), distal anterior pontomesencephalic (S1) and lateral pontomesencephalic (S2) segments aneurysms are uncommon entities, a challenge for both microsurgical and endovascular techniques due to their commonly fusiform and dysplastic pattern, the deep location, the neighboring presence of the posterior thalamic-perforators. Only few reports illustrate single experiences concerning the possibility of direct posterior cerebellar artery (PCA) to superior cerebellar artery (SCA) revascularization prior to aneurysm trapping without need of an extracranial donor vessel.

Method: In the neurovascular research lab of the Heinrich Heine University ten SCA-PCA anastomoses has been performed in 5 cadaveric specimens bilaterally using a subtemporal craniotomy. After flushing of the vessels, the specimens had been treated with Thiel-fixation. Colored red and blue latex has been used to enhance the visualization of the vascular system after revascularization. The side to side anastomoses where constructed with a continuous 10-0 suture.

Results: After dural opening, cisternae interpeduncularis, cruris and ambient has been exposed, the arachnoid removed unveiling basilar tip, superior and posterior cerebellar arteries, posterior thalamo-perforators, posterior communicating artery (Pcom), posteromedial choroidal artery, hippocampal artery, internal temporal artery and the SCA division. Neural structures including III°, IV° nerves, gyrus parahyppocampalis, mesencephalon-pontine junction and venous landmarks has been identified. Five side to side anastomoses has been performed connecting crural (P2A) and distal S1 segments in the cisterna cruris. In the other half of the cases a ambient segment (P2P)-S2 side to side anastomose has been constructed distally in the cisterna ambient. Incision and reflection of tentorial incisura permitted further cranial mobilization of S2 and cerebellomesencephalic (S3) segments from the cerebellar mesencephalic fissure in the ambiens cistern allowed approximation of the vessels for the anastomose.

Conclusions: P2-SCA direct revascularization without need of an extracranial donor vessel in selected cases is a useful revascularization technique, possible even in the ambient cistern. For the first time we describe the incision of the tentorial incisura to achieve the cranial mobilization of the SCA to better approximate the diverging course of the vessels for the anastomose.