ABSTRACT
Objective To study the microanatomy of the petrosal vein(PV) and discuss the surgical management of the vessel during microvascular decompression.Methods A total of 15 cadaveric(30 PVs) heads were obtained from dead adults.The position,morphology,branches,and variation of the PV,and anatomical relationship between the trigeminal,facial and acoustic nerves and the vessel were observed.Sixty patients with trigeminal neuralgia or hemifacial spasm were also enrolled in this study.Microvascular decompression was performed on the cases,and the PV and its branches were observed during the operation.Results The PV is formed by the union of 2 to 3 branches.It passes through the the subarachnoid space and terminates in the inner two third of the superior petrosal sinus.Classfied by number of the unilateral PVs,3 types of the vessel has been observed:single-stem(9 sides,30.0%),double-stem(17 sides,56.7%) and triple-stem types(4 sides,13.3%).Moreover,according to the anatomical relationship between the end of the PV and auditory meatus,the vein has 3 subgroups:interior-side(17/55,30.9%),intermediate(24/55,43.6%),and exterior-side(14/55,25.5%) subgroups.In our specimens,8 PVs(the main stem or a branch) touched the trigeminal nerve,and 19 PVs were less than 1 mm away from the nerve.None of the PVs connected to the faical and acoustic nerves.In the 60 patients who recieved microvascular decompression,107 PV branches(19 single-stem veins,35 double-stem vessels,and 6 triple-stem veins) were found during the operation,among which 33 belonged to interior-side subgroup,46 were classifed as intermediate type,and 28 were exterior-side veins.Conclusions Management of the PV is the key step for cerebellopontine angle surgery.The vein or its branches can be cut off when they compress the surrounding tissues or obstruct the surgical field.
ABSTRACT
Since April, 1986, 26 cases of trigeminal neuralgia have been treated by microsurgical neurovascu-lar decompression, and the result was excellent in all. The microscopic findings during the operation suggested that the compression on the trigeminal nerve by neighboring vessels was the anatomic cause of trigeminal neuralgia. As the nerve and vessels were fixed by the thickened arachnoid adhesions, thus promoting the compressing effect, inflammation of the arachnoid membrane seemed to be the pathological foundation of trigeminal neuralgia.