petroclival meningiomas: quo vadis?

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Perspectives

Madjid Samii, M.D., Ph.D.

President, International Neuroscience Institute (INI)

Petroclival Meningiomas: Quo Vadis?

Commentary on:A Comparative Anatomic Study of aModified Temporal-Occipital TranstentorialTranspetrosal-Ridge Approach and aTranspetrosal Presigmoid Approachby Lin and Zhao pp. 495-502.

Madjid Samii and Venelin M. Gerganov

P etroclival meningiomas are still regarded as one of the mostformidable challenges in skull base surgery. These tumorsmay have various extension patterns and relations to sur-

ounding structures. The management of patients with petroclivaleningiomas should be therefore individualized, taking into account

heir biological age, general condition, neurologic status, and expec-ations as well as the tumor characteristics.

he natural history of petroclival meningiomas is unpredictable andrequently characterized by progressive growth and neurologic de-erioration. Treatment goal should be complete resection of theseenign tumors, which is the only potentially curative option. Extentf tumor removal is the most important predictor of outcome, andvery effort should be made to remove the tumor completely at

nitial surgery. We know, however, that even total tumor removaloes not preclude late recurrences. Hence, preservation of neuro-

ogic functions and of life quality after surgery should have the high-st priority. Leaving a small part of the tumor or of the tumor capsule

s consequently reasonable, if the attempt to remove it completelyould cause injury to essential neural and vascular structures.

he history of petroclival meningioma surgery reflects to a large ex-ent the evolution of skull base surgery. Various extensive cranialase approaches were elaborated or modified with the goal of com-lete exposure of the tumor and its surrounding neural and vasculartructures. Visualization of these structures was regarded as arerequisite for achieving a more radical and safer tumor resection.

he possibility to remove the tumor completely, however, is relatedainly to the tumor characteristics. The main reason for subtotal

emoval of petroclival meningiomas, regardless which skull baseechnique is used, is the lack of a dissection plane or infiltration ofranial nerves, brainstem, or major vessels. These extensive ap-

Key words� Anatomy� Petroclival region� Presigmoid approach� Temporal occipital transtentorialtranspetrosal-ridge approach

424 www.SCIENCEDIRECT.com WO

proaches are related, furthermore, to unacceptably high approach-related mortality, with a high rate of facial nerve palsy, hearing loss,cerebrospinal fluid leaks, and vascular—in particular venous—injuries.

We believe that meningiomas that are confined to the petroclivalarea are best removed via the simple and safe retrosigmoid ap-proach. If additional exposure is required, the petrous apex may beresected intradurally. In 1982, the senior author introduced the tech-nique of the intradural resection of the petrous apex via the retro-sigmoid route—the so-called retrosigmoid intradural suprameatalapproach, or Samii approach. Currently, this is our favored approachfor all tumors in the petroclival area. In tumors extending supraten-torially into the middle cranial fossa, additional resection of tento-rium is performed. Endoscopic inspection is used to inspect hiddenareas for tumor remnants, reducing the amount of bone resection orthe retraction of neural structures. In tumors with a particularly largesuprasellar part, such as the sphenopetroclival meningiomas, en-gulfing the optic nerve and carotid artery, we prefer operating instages using two simple approaches. Initially, the infratentorial tu-mor part in the cerebellopontine angle, clivus, and/or Meckel’s caveis removed via a retrosigmoid–suprameatal approach. The brain-stem is decompressed and the risk of severe neurologic deteriora-tion is thus prevented. The remaining supratentorial component isremoved via the frontotemporal approach at a second stage.

H. Lin and G. Zhao presented the modified temporal occipitaltranstentorial transpetrous-ridge approach and evaluated its “ana-tomic features” on cadaver heads. They found that although itrequires a smaller bone window compared to the presigmoidapproach, the exposure of the middle of the brainstem is muchgreater. The benefits of the approach, especially in terms of mor-bidity and outcome, have still to be validated clinically.

From the International Neuroscience Institute (INI),Hannover, Germany

To whom correspondence should be addressed: Madjid Samii, M.D., Ph.D.[E-mail: Samii@ini-hannover.de]

Citation: World Neurosurg. (2011) 75, 3/4:424.DOI: 10.1016/j.wneu.2010.12.035

Journal homepage: www.WORLDNEUROSURGERY.org

Available online: www.sciencedirect.com

1878-8750/$ - see front matter © 2011 Elsevier Inc. All rights reserved.

RLD NEUROSURGERY, DOI:10.1016/j.wneu.2010.12.035