Petroclival Meningioma: Anterior Petrosal Approach
Last Updated: March 27, 2020
The topics related to general considerations, clinical presentation, evaluation, and indications for surgery are discussed in the chapter titled Petroclival Meningioma: Posterior Petrosectomy.
In addition, the general resection techniques for removal of petroclival meningiomas are discussed in the Petroclival Meningioma: Posterior Petrosectomy chapter.
With the anterior petrosal approach, the surgeon attempts to expose the upper third of the clivus as the surgical target. This region extends from the tuberculum sella toward the internal auditory canal (IAC). Any portion of the tumor that extends beyond the IAC is not reachable via this approach. For more details about application of this skull base operative corridor, refer to the Anterior Petrosectomy chapter.
The anatomy of the petroclival region is complex. Detailed study of this region in the microsurgical laboratory is mandatory.
RESECTION OF PETROCLIVAL MENINGIOMA: ANTERIOR PETROSAL APPROACH
Before patient positioning, I routinely place a lumbar drain to facilitate extradural drilling and exposure via dural sac decompression. This is an important step for petrous apex drilling. Please see the Anterior Petrosectomy chapter for more details regarding exposure.
Neurophysiologic monitoring, including facial nerve, brainstem auditory evoked responses (BAER), and somatosensory evoked potentials (SSEP), is recommended.
The anterior petrosal approach provides a narrow operative trajectory around CN V for removal of small petroclival meningiomas. This corridor is often inadequate for removal of “true” petroclival meningiomas that most often extend beyond the upper one-third of the clivus. Therefore, the posterior petrosal approach is the most utilized route for removal of petroclival meningiomas.
One of the most important primary concerns during this approach is preservation of CN VI. This tiny, long, and therefore vulnerable nerve is usually displaced by the tumor either inferiorly and medially or superiorly and laterally, and it lies between the surgeon and the deeper sections of the mass. The basilar artery is displaced contralaterally and CN III is usually found supramedial to the pole of the tumor.
A 42-year-old woman presented with progressive double vision and growth of a small upper petroclival tumor.
Once the surgical goals have been achieved, the surgeon’s attention turns to closure. Primary dural closure is impossible, so alternative methods are applied. The available dural flaps are approximated.
Adipose tissue with its globular texture is one of the best barriers against cerebrospinal fluid leakage. Strips of adipose tissue are placed across the dural opening to seal the dural defect. Before placement of the adipose grafts, all exposed air cells are meticulously waxed.
Alternatively, a vascularized tissue/temporalis flap prepared during the exposure may be rotated to fill the defect in the dura. This method is used for cases involving repeat operations or for patients who have a prior history of radiation treatment. The periosteal flap is draped over the drilled petrous surface. The bone flap is replaced and secured using miniplates, and the rest of closure is conducted in standard fashion. For more details, refer to the Anterior Petrosectomy chapter.
The lumbar drain is used to drain 8 cc per hour of cerebrospinal fluid for 48 hours after surgery. Patients are mobilized as soon as possible.
Pearls and Pitfalls
- Petroclival meningiomas are notoriously challenging tumors, and their intrinsic features (density, viscosity, and tenacious adherence to surrounding structures) may render complete resection prohibitively dangerous independent of the surgeon’s skill level.
- The important factors facilitating resection of these tumors relate to 1) intact arachnoid planes separating the tumor capsule from neurovascular structures, 2) texture/consistency of the tumor, and 3) adherence of the tumor to the basilar artery and its perforators.
For additional illustrations of the middle fossa-transpetrous apex approach to the anterosuperior cerebellopontine angle, please refer to the Jackler Atlas by clicking on the image below:
Al-Mefty O. Meningiomas. New York: Raven Press, 1991.
Al-Mefty O. Operative Atlas of Meningiomas. Philadelphia: Lippincott-Raven, 1998.
Cho C, Al-Mefty O. Combined petrosal approach to petroclival meningiomas. Neurosurgery. 2002;51:708-718.
Coppens J. Couldwell W. Clival and petroclival meningiomas, in DeMonte F, McDermott M, Al-Mefty O (eds): Al-Mefty’s Meningiomas, 2nd ed. New York: Thieme Medical Publishers, 2011, 270-282.
Liu J. Couldwell W. Petrosal approach for resection of petroclival meningiomas, in Badie B (ed): Neurosurgical Operative Atlas: Neuro-Oncology, 2nd ed. Rolling Meadows, IL: Thieme Medical Publishers and the American Association of Neurological Surgeons, 2007, 170-179.
Rhoton A Jr. The cavernous sinus, the cavernous venous plexus, and the carotid collar. Neurosurgery. 2002:51(4 Suppl);S1-375-410..
Starke R, Kano H, Ding D, et al. Stereotactic radiosurgery of petroclival meningiomas: a multicenter study. J Neurooncol 2014;119:169-176.
Tew JM, van Loveren HR, Keller JT. Atlas of Operative Microneurosurgery. Philadelphia: Saunders, 1994-2001.
Xu F, Karampelas I, Megerian CA, Selman WR, Bambakidis NC. Petroclival meningiomas: an update on surgical approaches, decision-making, and treatment results. Neurosurg Focus. 2013:35: E11.
Please login to post a comment.