Article
Microsurgical petrosal vein occlusion and alternative venous draining pathways: An anatomic study
Alternative venöse Drainagewege nach intraoperativem Verschluss der Vena petrosa: Eine anatomische Studie
Search Medline for
Authors
Published: | April 11, 2007 |
---|
Outline
Text
Objective: Aim of the present anatomic study is to demonstrate alternative draining pathways of the petrosal vein, who allow compensation in case of surgical sacrifice.
Methods: In three formaldehyde fixed specimens (technique according to Tutsch) the petrosal vein has been selectively injected via the superior petrous sinus with a silicon mixture in two different colours. 14 days later the posterior fossa nervous structures were removed in toto epidurally from the skull and then further fixed (14 days) in 4% formaldehyde. The dura was opened ventrally to the brainstem and under microscopic guidance the nervous and vascular structures were dissected, measured and photographed. Special attention was paid to the venous system. Beside conventional micro- and macroscopic photography, 3D-photographs were elaborated.
Results: The petrosal vein was present in all cases and joined the superior petrous sinus laterally to the trigeminal nerve always as a single trunk. We identified four times the intermediate, once the medial and once the lateral type according to the classification of Rhoton. The petrous vein was composed four times by two, once by three and twice by four feeding veins (vein of the cerebellopontine fissure 1,57-2,12mm, transverse pontine vein 0,64-1,28mm, anterior lateral marginal vein 1,12-1,27mm, pontotrigeminal vein 0,71-1,98mm, vein of the middle cerebellar peduncle 0,88-1,3mm, middle anterior hemispheric vein 1,25-1,32mm). There was no passage of the coloured silicon mixture to the contralateral venous brainstem territory. However, the ipsilateral anastomoses to the deep supratentorial venous system – peduncular, anterolateral pontomesencephalic, lateral mesencephalic veins, and the tectal veins in connection with the pontotrigeminal vein – filled in all six cases with the selectively injected coloured silicon.
Conclusions: Although the present anatomical model does not reflect physiological aspects of vascular dynamics, we documented an apparently compensatory venous blood drainage occurring via anastomotic pathways directed to the ipsilateral supratentorial venous system. These findings present an interesting aspect for preoperative image-guided planning in cerebello-pontine angle surgery.