Microsurgical removal of posterior petrosal and petroclival meningiomas: A report of 8 cases

Abstract

Background: Posterior petrosal and petroclival meningiomas are rare, benign tumors, representing difficult tumours to be treated by microsurgery: for often significant space-occupying effect, brain stem compression, frequent tight brain stem adherence, as well as encasement of the basilar artery, its perforators and cranial nerves. 
Methods: We report our experience referring on 6 cases of posterior petrosal and 2 cases of petroclival meningiomas operated in the last 5 years; retrospectively analyzed, including: the history, clinical data, imaging studies, surgical & histological records, follow-up records. All patients were woman, The main age was 56 years (range 34-72 years). Bony changes at the petrous apex was seen in one case with petroclival meningioma. 
Results: Gross total resection was achieved in 7 of 8 patients Simson gr.1-2., using a conventional retromastoid, retrosigmoid approach and in one case a petrosal approach. Retromastoid - retrosigmoid approach was preferred approach for removing posterior petrous meningiomas, used also in one case of petroclival meningioma; especially if preoperative hearing is intact. In all cases the establishment of an arachnoid plane was critical for separating the tumor from the cerebellum and brainstem as well as microdissection of the neurovascular structures. Once the tumor was excised, its dural attachment was removed or coagulated and hyperostotic bone was drilled away. Tumor histology was fibrous, meningothelial and psammomatous meningioma. After surgery two patients had a transitory palsy of the third (extrinsec) and the seventh nerve, installed immediately after operation, but one patient with a petroclival meningioma operated using the posterior petrosal approach died after a hemorrhagic infarct in the midbrain. No recurrence or progression of disease occurred one year after. 
Conclusions: A variety of techniques have been advocated for complete resection of posterior petrosal and petroclival meningiomas, with minimal brain retraction. For each case planning the safest approach should be sustaind on: detailed radiologic studies to define tumor size, location and extensions, the attachment of the tumor to the dura overlying the posterior face of the petrous apex, tumor encasement of the basilar and pontine perforators, venous anatomy delineation (especially the anatomy of the vein of Labbé). the consistency of the tumor, the operative distance to the tumor and neurovascular structures, minimal brain retraction, good visualization and lighting. The posterior petrosal approach is safe for total removal of clival and petroclival tumor, also for selected cases of petroclival meningioma even a retromastoid-retrosigmoid approach can be suitable.