Custom-tailored transdural anterior transpetrosal approach to ventral pons and retroclival regions

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The extradural anterior petrosectomy approach to the pons and midbasilar artery (mid-BA) has the main disadvantage that the extent of resection of the petrous apex cannot be as minimal as desired given that the surgical target field is not visible during bone removal. Unnecessary or excessive drilling poses the risk of injury to the internal carotid artery, vestibulocochlear organ, and seventh and eighth cranial nerves. The use of a custom-tailored transdural anterior transpetrosal approach can potentially avoid these pitfalls.


A technique for a transdural anterior petrosectomy was developed in the operating theater and anatomy laboratory. Following a subtemporal craniotomy and basal opening of the dura mater, the vein of Labbé is first identified and protected. Cerebrospinal fluid ([CSF] 50–100 ml) is drained via a spinal catheter. The tent is incised behind the entrance of the trochlear nerve toward the superior petrosal sinus (SPS), which is coagulated and divided. The dura is stripped from the petrous pyramid. Drilling starts at the petrous ridge and proceeds laterally and ventrally. The trigeminal nerve is unroofed. The internal acoustic meatus is identified and drilling is continued laterally as needed. The bone of the Kawase triangle toward the clivus can be removed down to the inferior petrosal sinus if necessary. Anterior exposure can be extended to the carotid artery if required. It is only exceptionally necessary to follow the greater superior petrosal nerve toward the geniculate ganglion and to expose the length of the internal acoustic canal.

The modified transdural anterior petrosectomy exposure has been used in nine patients—two with a mid-BA aneurysm, two with a dural arteriovenous fistula, one with a pontine glioma, three with a pontine cavernoma, and one with a pontine abscess. In one patient with a mid-BA aneurysm, subcutaneous CSF collection occurred during the postoperative period. No CSF fistula or approach-related cranial nerve deficit developed in any of these patients. There was no retraction injury or venous congestion of the temporal lobe nor any venous congestion due to the obliteration of the SPS or the petrosal vein.


The custom-made transdural anterior petrosectomy appears to be a feasible alternative to the formal extradural approach.

Abbreviations used in this paper:AICA = anterior inferior cerebellar artery; AVF = arteriovenous fistula; BA = basilar artery; CA = carotid artery; CSF = cerebrospinal fluid; GG = geniculate ganglion; GSPN = greater superficial petrosal nerve; IAC = internal auditory canal; ICA = internal carotid artery; IPS = inferior petrosal sinus; SPS = superior petrosal sinus; SSC = superior semicircular canal.

Article Information

Address reprint requests to: Hans-Jakob Steiger, M.D., Neurochirurgische Universitätsklinik, Moorenstrasse 5, D-40225 Düsseldorf, Germany. email:

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    Artist’s rendering of the surgical field after subtemporal exploration on the right side. A: The entrance of the fourth cranial nerve at the tentorial edge is identified, and the tent is incised behind the entrance toward and crossing the SPS. The sinus is coagulated and/or plugged with a small piece of Surgicel or comparable material. B: Perspective of the surgical field after stripping the dura from the petrous pyramid and completing the removal of the petrous apex. Bone removal is terminated as soon as sufficient exposure of the surgical field has been achieved. MMA = middle meningeal artery; V. Labbé = vein of Labbé; III, IV, V, VII, and VIII = third, fourth, fifth, seventh, and eighth cranial nerves, respectively.

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    Photographs obtained during a cadaveric dissection of the transdural anterior petrosectomy on the right side. The initial step of the subtemporal craniotomy is shown in Fig. 1. A: After basal opening of the dura, the vein of Labbé is first identified. The arcuate eminence is located at the posterior limit of the petrosectomy. B: Following subtemporal exploration, the entrance of the trochlear nerve into the cavernous sinus and the median tip of the petrous apex are defined. The median limit of the petrous apex cannot be seen from the transdural perspective and must be identified by probing with a dissector. The medial limit of the osseous resistance of the petrous ridge can be reliably felt. The tentorial edge (tent) is subsequently incised behind the entrance of the trochlear nerve. C: The incision is extended laterally toward the SPS. The incision should cross the petrous ridge at the midpoint between the tip of the petrous apex and the anterior limit of the arcuate eminence. The SPS is divided, and the dura on the petrous apex is then incised in an anterolateral direction and stripped from the petrous apex. If greater exposure is required, the incision crosses the GSPN. D: Drilling starts at the petrous ridge and proceeds laterally and anteriorly. E: The trigeminal nerve is unroofed. Posterolaterally, the internal acoustic meatus should be identified at this stage, and drilling continued in this direction as needed. F: The bone that lies between the third branch of the trigeminal nerve anteriorly, the CA and cochlea laterally, the IPS medially, and the IAC posteriorly can now be removed. G and H: This exposure provides access to the BA and the ventral pons down to the seventh and eighth cranial nerves. AE = arcuate eminence; CB = cochlear block; VI = sixth cranial nerve.

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    Case 2. A and B: Anteroposterior and lateral digital subtraction angiograms showing a 4-mm proximal aneurysm (arrows) of the left AICA in a 73-year-old patient with severe subarachnoid hemorrhage. C and D: Postoperative native computerized tomography scans showing a titanium clip (arrow) and a partial left petrosectomy (arrows), respectively.

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    Case 4. A: A computerized tomography scan revealing an acute pontine hemorrhage. B: Right external carotid artery angiogram obtained after spontaneous pontine and ventricular hemorrhage in a 40-year-old man, demonstrating a dural AVF originating from the SPS. C: Photograph obtained during a right subtemporal approach, showing division of the tent and stripping of the dura from the petrous apex (arrow). D: Photograph obtained after drilling the petrous apex was sufficient to safely divide the draining vein (arrows). DV = draining vein (divided); PA = petrous apex; SCA = superior cerebellar artery.



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