Surgical Experiences of Transpetrosal Approach in Petroclival Lesions

ABSTRACT

This is a report of 15 consecutive cases of petroclival lesions performed by transpetrosal approach over five years. Pathologies from these cases include 13 cases of tumors and two cases of aneurysms. All cases of tumors were over 4.5cm in size. Two cases of very low-lying basilar bifurcation aneurysms and one case of facial schwanoma extended to the petrosal tip and temporal fossa were operated with anrerior transpetrosal approach, where as nine cases of petroclival tumor which was localized in the posterior fossa were operated via posterior transpetrosal approach. Of these nine cases, one case with lower clival extension was removed totally by adding a retrosigmoid dural opening. Remaining three cases extended to the Meckel's cave or cavernous sinus were operated by combined anterior-posterior transpetrosal approach. Of the 12 cases done with posterior transpetrosal or combined approach, nine cases with preserved serviceable hearing were approached by retrolabylinthine technique and remaining three cases without preservation of serviceable hearing were operated via retrolabylinthine technique. Total removal was achieved in 9 of 13 tumor cases. Of two cases, aneurysmal neck of the first case was clipped completely but was clipped together with right posterior cerebral artery in second case. There was no operative mortality. Immediate postoperative neurological dysfunction were appered in 12 cases. These were significantly improved by the time of follow up examination. Permanent postoperative dysfunction was present in 6 cases, hemiparesis in 2, facial paralysis in 2 and hearing impairment in 2 cases. These results suggest that when selecting the surgical approach to the petroclival lesions, the size, location, extent of the lesion and preoperative status of the hearing were important factors to be considered. We recommend combined anterior-posterior transpetrosal approach for the complex lesions in the petroclival area which extends into the middle fossa(Meckel's cavum or cavernous sinus). Also, we recommend combining with retrosigmoid dural opening or a far lateral type of suboccipital exposure in cases of complex petroclival lesions involving the entire clivus or foramen magnum. In cases with brain stem invasion by tumor, vascular encasement or cavernous sinus invasion without cranial nerve involvement, we recommend subtotal resection of the tumor and radiosurgery to prevent permanent postoperative sequele.