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SPECIAL NI FEATURE - OPERATIVE NUANCES: STEP BY STEP
Year : 2020  |  Volume : 68  |  Issue : 1  |  Page : 20-25

Anterior Transpetrosal Approach for Petroclival Meningioma: Operative Nuances


1 Department of Neurosurgery, Apollo Hospital, Seshadripuram, Bengaluru, Karnataka, India
2 Department of Neurosurgery, All India Institute for Medical Sciences, Bhopal, Madhya Pradesh, India

Date of Web Publication28-Feb-2020

Correspondence Address:
Dr. Suresh Nair
AIIMS, Saket Nagar, Bhopal - 462 020, Madhya Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.279689

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 » Abstract 


Petroclival meningiomas are unique neurosurgical challenges that require planning an approach to the retrosellar and upper and mid retroclival locations. The classical subtemporal-transtentorial approach went into disrepute due to excessive brain retraction. To resolve this challenge Buchenek and Kukwa introduced extradural approach with drilling of the petrous bone and called it the extended middle fossa approach. It was Kawase et al who modified the extended middle fossa approach initially for dealing with basilar trunk aneurysms. This anterior transpetrosal approach has been described below for dealing with the petroclival meningiomas.


Keywords: Anterior petrosectomy, Kawase's approach, petroclival meningiomas
Key Messages: The Kawase‘s anterior transpetrosal approach is an optimal approach for tumors that do not extend deep into the posterior fossa. A thorough understanding of the anatomy of the petrous temopral bone helps in providing a safe passage to the tumors of this region like petroclival meningiomas.


How to cite this article:
Rao RM, Shrivastava A, Nair S. Anterior Transpetrosal Approach for Petroclival Meningioma: Operative Nuances. Neurol India 2020;68:20-5

How to cite this URL:
Rao RM, Shrivastava A, Nair S. Anterior Transpetrosal Approach for Petroclival Meningioma: Operative Nuances. Neurol India [serial online] 2020 [cited 2020 Mar 29];68:20-5. Available from: http://www.neurologyindia.com/text.asp?2020/68/1/20/279689




To gain access to the retrosellar and upper and mid retroclival lesions located close to the midline, Drake[1] described the sub-temporal transtentorial approach. Soon this went to disrepute because of the unacceptable brain retraction which many a time resulted in temporal lobe injury including the vein of Labbe. As the main anatomic obstacle to a good exposure of these areas is the temporal bone, soon approaches with partial or complete resection of the petrous pyramid was described. Transpetrosal approaches have evolved to offer advantages over traditional operative corridors, such as retromastoid, middle fossa, and pterional trajectories for exposing lesions within the petroclival area. In 1975 Buchenek and Kukwa[2] modified the original extradural middle fossa approach to the internal auditory canal by combining with drilling of the petrous bone and called it the extended middle fossa approach. Even though this extradural approach minimised the risk of injury to the temporal bridging veins and gave extra space below the level of superior petrosal sinus, it often involved opening the semicircular canals which resulted in hearing loss. Kawase et al.[3] described a modification of the extended middle fossa approach for treating basilar trunk aneurysms by restricting the drilling of the petrous bone to the apical area only which contains no neurovascular structures and this gave access to the prepontine region between the trigeminal and facial nerves without sacrificing hearing. The anterior transpetrosal Kawase approach is used to treat a variety of pathological entities not only in the petrous apex, retrosellar and mid clival areas but also to intrinsic lateral pontine lesions.


 » Case Study Top


The authors describe with intraoperative photographs the surgical tenets of anterior petrosal approach to resect an upper and mid petroclival meningioma. Patient, a middle-aged lady with no co-morbidities presented with a 3-year history of numbness and paresthesia of left half of the face and left-sided trigeminal neuralgia over all the divisions of the fifth nerve. On examination, the patient had mild sensory loss over all the three divisions with subtle weakness of temporalis and masseter muscles of the left side. She also had grade 2 House–Brackmann left facial weakness. Magnetic resonance (MR) imaging revealed an upper and mid clival contrast-enhancing true left petroclival meningioma deforming the pons and midbrain which was hyperintense on T2WI. Tumour was abutting the left Meckel's cave and there was minimal extension over the tentorium [Figure 1].
Figure 1: (a-c) Axial, sagittal, coronal post-contrast MRI images showing an extra-axial mass with uniform contrast enhancement, lobulated surface in the left upper and mid-clival region and petrous apex suggestive of a left petroclival meningioma. (d) is the postop CT scan of the brain showing total excision of the petroclival meningioma by the anterior trans-petrosal approach and the extent of left petrous apex resection. (e-f) postop contrast MRI showing no residual tumor and re-expansion of the pons

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Operative steps of anterior transpetrosal approach

As some degree of temporal lobe retraction is required, the use of a lumbar drain is highly advised, especially for lesions on the dominant side. The patient is positioned supine on the operating table [Figure 2]. A shoulder roll is placed under the patient's shoulder, and the head rotated until the sagittal suture is parallel to the floor. A lateral position is used for obese to avoid venous compromise. A temporal craniotomy is fashioned two thirds in front and one third behind the external auditory canal and the basal temporal bone is drilled to the level of the floor of the middle fossa [Figure 3]. If a zygomatic osteotomy is also planned to gain more space for a temporal muscle to be reflected downward, one can use a frontotemporal incision and in this case, the craniotomy can be expanded more anteriorly which is often required for approaching lesions extending to the cavernous sinus and extending above the tentorium. The temporal lobe dura is elevated in a posterior to anterior fashion. Foramen spinosum and ovale are skeletonized and the middle meningeal artery is coagulated and divided [Figure 4]. Care should be taken to see that middle meningeal artery is not divided close to the foramen spinosum to prevent retraction of the improperly coagulated proximal stump resulting in torrential bleeding. The dura propria is elevated from the trigeminal second and third division using a sharp dissection using a no 15 blade. The greater superficial nerve and location of geniculate ganglion is ascertained avoiding any traction to these structures [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]. The petrous ridge is identified medially and after placing tapered retractors. The  Eustachian tube More Details and tensor tympani muscle lie lateral to a greater superficial petrosal nerve (GSPN) [Figure 11]. The internal auditory canal (IAC) is exposed medially first by drilling the porus acousticus and then proceeding laterally. Many techniques are described for the approximate location of the IAC. The bisection angle between GSPN and arcuate eminence approximates the lie of IAC [Figure 12]. The absence of neurovascular structures at the porus makes this area relatively safe for bone removal. Once the dura of the IAC is seen, the exposure continues laterally toward the fundus.
Figure 2: The patient is supine on table and head turned to right side so that the sagittal suture is parallel to the floor. A shoulder pad is placed under the left shoulder. A square flap is shown here two-thirds in front of the external auditory meatus

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Figure 3: A temporal craniotomy is done reaching middle fossa base, 2/3rds in front of external auditory meatus and 1/3rd behind it

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Figure 4: The middle meningeal artery (MMA) entering intracranially via foramen spinosum. The location of foramen spinosum is at the level of posterior root of zygomatic process. The MMA is coagulated and cut

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Figure 5: The arcuate eminence overlies the superior semicircular canal. The greater superficial petrosal nerve (GSPN) emerges out of the facial canaliculus on the anterior surface of the eminence and travels in a bony groove towards the V3, where it meets the deep petrosal nerve and enters the vidian canal as the vidian nerve

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Figure 6: The GSPN is confirmed by stimulating it and eliciting facial nerve responses

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Figure 7: The lesser superficial petrosal nerve coalesces from the tympanic plexus on the promontory and emerges out of the tympanic cavity onto the MCF base lateral to GSPN

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Figure 8: The mandibular division of Trigeminal nerve is seen entering foramen ovale. The GSPN passes under the V3 and it overlies the petrous carotid artery (Horizontal segment)

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Figure 9: The dura propria of the temporal lobe is peeled back from dural cover over V3. This is interdural dissection. The limit of this dissection is tentorial edge and exposes Meckel's cave

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Figure 10: Continuing the interdural dissection anteriorly, the Maxillary nerve (V2) is exposed entering foramen rotundum

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Figure 11: Drilling of middle fossa base lateral to GSPN, exposes the eustachian tube with overlying tensor tympani muscle. These structures are parallel to and lateral to petrous carotid which lies underneath GSPN. Usually this drilling is not required

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Figure 12: Bisection of the long axis of GSPN and arcuate eminence, indicates the lie of internal auditory meatus. This is confirmed by facial nerve stimulation

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At the fundus, bone resection is limited anteriorly by the basal turn of the cochlea and posteriorly by the ampulla of the SSC and the vestibule. Injury to either structure results in hearing loss [Figure 13]. Therefore, the dural exposure is narrowed as the dissection proceeds laterally. Drilling in the angle between the GSPN and the IAC can easily perforate the underlying cochlea [Figure 12] and [Figure 13]. The Kawase rhomboid is bound by the GSPN laterally, the petrous ridge medially, the IAC axis posteriorly, and V3 anteriorly. The limits of the extended middle fossa exposure are the inferior petrosal sinus inferiorly, the middle ear ossicles laterally, the  Gasserian ganglion More Details anteriorly and the superior semicircular canal (SSC) posteriorly [Figure 14], [Figure 15], [Figure 16], [Figure 17]. Drilling the petrous apex exposes the superior petrosal sinus (SPS) and dura of the posterior fossa inferiorly to the level of the inferior petrosal sinus. The lateral border of the Kawase's triangle is the pregasserian petrous carotid artery and the lesser and greater GSPN running close to the carotid artery.
Figure 13: The dura of Internal auditory canal (IAC) is exposed. The cochlea lies in premeatal location between the IAC and petrous carotid. The semicircular canals lie behind the IAC

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Figure 14: Drilling beneath and lateral to GSPN exposes the internal carotid artery in the horizontal portion of petrous canal, which is confirmed by doppler. The tegmen tympani is a thin plate of bone roofing the tympanic cavity lateral to arcuate eminence

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Figure 15: By drilling underneath GSPN, the petrous carotid is exposed which forms the lateral boundary of Kawase's quadrangle. The posterior boundary is IAC. The anterior boundary is posterior border of V3. The GSPN and petrous carotid pass forwards underneath V3

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Figure 16: The landmarks for drilling Kawase's quadrangle are identified

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Figure 17: Kawase's triangle/quadrangle is the petrous bone bounded laterally by petrous carotid artery, anteriorly by posterior border of V3, posteriorly by the anterior border of IAC. This bone is devoid of neurovascular structures and is removed to gain access to posterior fossa

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Drilling should not be extended lateral to the carotid artery lest the eustachian tube may get inadvertently opened or damage the overlying tensor tympani muscle [Figure 11]. Next step is opening of the temporal lobe dura mater basally in a linear fashion above and parallel to the SPS thus exposing the tentorium [Figure 18] and [Figure 19]. Temporal lobe is gently retracted to identify the tentorial edge as well as the trochlear nerve in its subarachnoid course running parallel to the tentorial edge. Another dural incision is made in the exposed posterior fossa dura parallel and inferior to the SPS. SPS is then divided between two hemoclips as far as posterior taking care to avoid damage to underlying trigeminal nerve [Figure 17], [Figure 18], [Figure 19], [Figure 20]. This dural opening in the area of petrous apicectomy exposes the anterolateral aspect of the pons. The dural incision around is extended laterally to unlock the dura of Meckel's cave [Figure 21]. In the classical Kawase approach, the tentorium is cut towards its edge behind the entry point of trochlear nerve, which then allows full communication between the intradural middle and posterior fossa compartments [Figure 22]. The only two structures crossing the field of view are the fourth cranial nerve medially and the fifth nerve laterally [Figure 21] and [Figure 22]. Elevating the divided edges of the tentorium with retention sutures provides wide exposure of the petroclival region, comfortably to midclivus, that is, level with the porus acousticus. Although all of the middle fossa approaches are designed to preserve hearing, sacrifice of the labyrinth and thus hearing can sometimes be used to allow additional exposure of the posterior fossa.[4],[5],[6],[7],[8],[9],[10],[11]
Figure 18: Drilling of petrous apex exposes superior petrosal sinus, inferior petrosal sinus, dura of IAC

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Figure 19: The temporal dura propria is being opened above and parallel to SPS

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Figure 20: Posterior fossa dura being opened below SPS

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Figure 21: The superior petrosal sinus is ligated and cut. The tentorium is opened exposing the Trigeminal nerve superior to petroclival tumor. The porus Trigeminus is opened to expose trigeminal ganglion in Meckel's cave

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Figure 22: Trochlear nerve exposed coursing over tumor before entering tentorium

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After ensuring adequate brain relaxation with adequate CSF drainage through the lumbar drain, temporal lobe of our patient was retracted gently to access the tumor taking care to avoid damage to the vein of Labbe. The vein of Labbé was followed to its insertion point to ensure that its outflow was not obliterated during retraction of the temporal lobe. The tumor was exposed after ligating the SPS and the cut tentorial edges held back with stay sutures. Extremely care was taken while making the dural incisions in order to protect the trigeminal nerve as it can easily be inadvertently transected due to its displacement by the tumor as it enters the Meckel cave at the porus trigeminus [Figure 19] and [Figure 21]. The Tumour was devascularized by bipolar coagulation along the dural attachment on the petrous ridge and the tentorium. Feeders from meningohypophyseal trunk and external carotid artery were coagulated and cut as they entered the tumor. After inspecting and stimulating the tumour capsule for the presence of any cranial nerves, the tumor was entered and debulked with cavitron and this allowed slackening of the capsule. The tumor capsule was held with tumor forceps and carefully dissected from the surrounding neurovascular structures using the natural arachnoid planes [Figure 23]. Basilar artery was displaced by the tumor to the opposite side.
Figure 23: Complete excision of petroclival tumor achieved, with V nerve lying free in cistern and brainstem exposed. The lower limit of this exposure is the VII-VIII nerve in IAC

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As primary dural closure was difficult, strips of abdominal fat are placed across the dural opening to seal the dural defect. Alternatively, a vascularized muscle flap prepared from the posterior aspect of the temporalis muscle may be rotated to fill the defect in the dura. Before placement of the fat tissue, all air cells including the ones at the mastoid area was meticulously waxed. A lumbar drain was kept for 48 hours after surgery. Our patient had gross total resection [Figure] 1e, [Figure]f and [Figure 23] with preservation of all cranial nerves and had an uneventful postoperative course with total subsidence of trigeminal neuralgia. She was neurologically intact at discharge except for preoperative fifth nerve deficits.

Pearls and pitfalls

Anterior petrosectomy is an optimal approach for tumors that do not extend deep into posterior fossa. And is ideally designed to reach ventral and ventrolateral regions of the upper brainstem or the upper third of the clivus. Tumors that extend to Meckel's cave or cavernous sinus or with contralateral extension can be accessed through this route. This approach is not designed to reach below the IAC. Two significant advantages are the absence of neurovascular structures during extradural bone removal and tackling of tentorial arteries early during dissection. However, sometimes a middle fossa extradural approach has some disadvantages especially when the venous drainage from the superficial middle cerebral vein is through sphenobasal and sphenopetrosal veins[12] instead of the cavernous sinus. It then requires a modified technique for anterior petrosectomy via an intradural route.[13],[14] However, the risk of injury to the temporal bridging veins is higher in this approach than in the epidural approach and also the lack of familial epidural landmarks impair identification of the petrous apex. Hence, imaging of the cerebral vessels can provide crucial information in planning surgical resection. Importance of a slack brain to prevent retraction injury to temporal and the need for intraoperative lumbar drain cannot be overemphasised. The location and displacement/encasement of basilar artery should be carefully ascertained before surgery.


 » Conclusion Top


The extended middle fossa approach with anterior petrosectomy is an important operative avenue in the operative management of petroclival meningiomas. The surgical nuances of the procedure are described with operative photographs and a short video.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 » References Top

1.
Drake CG. Surgical treatment of aneurysms of the basilar artery: Experience with 14 cases. J Neurosurg 1965;23:457-73.  Back to cited text no. 1
    
2.
Bochenek Z, Kukwa A. An extended approach through the middle cranial fossa to the internal auditory meatus and the Cerebello-pontine angle. Acta Otolaryngol 1975;80:410-4.  Back to cited text no. 2
    
3.
Kawase T, Shiobara R, Toya S. Anterior transpetrosal-transtentorial approach for sphenopetroclivalmeningiomas: Surgical method and results in 10 patients. Neurosurgery 1991;28:869-76.  Back to cited text no. 3
    
4.
Day JD, Fukushima T, Giannotta SL. Microanatomical study of the extradural middle fossa approach to the petroclival and posterior cavernous sinus region: Description of the rhomboid construct. Neurosurgery 1994;34:1009-16.  Back to cited text no. 4
    
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Tummala RP, Coscarella E, Morcos J. Transpetrosal approaches to the posterior fossa. Neurosurg Focus 2005;19:E6.  Back to cited text no. 5
    
6.
Delwe EJ. The anterior transpetrosal- transtentorial approach (Kawase Approach). Contemp Neurosurg 2008;30:1-6.  Back to cited text no. 6
    
7.
Nair S, Rao BR, Menon G. Microsurgical removal of petroclival meningioma-A critical review based on an institutional experience of 83 cases. Asian J Neurosurg 2007;1:16-29.  Back to cited text no. 7
    
8.
Nair S, Gopalakrishnan CV, Vikas V, Abraham M, Rao RM, Menon G, et al. Petroclival Meningiomas: Institutional Experience of 119 cases. Monduzzi Editore International Proceedings Division, Bologna, 2012. p. 51-60.  Back to cited text no. 8
    
9.
Almefty R, Dunn IF, Pravdenova S, Abolfotoh M, Al-Mefty O. True petroclival meningiomas: Results of surgical management. J Neurosurg 2014;120:40-51.  Back to cited text no. 9
    
10.
Abraham M, Nair P, Nair S. Surgical taming of petroclivalmeningiomas: King Cobra of all skull base tumors. Neurol India 2018;60;1309-13.  Back to cited text no. 10
    
11.
Cohen, et al. 'Anterior Petrosectomy' in The Neurosurgical Atlas by Aaron Cohen-Gadol 2018. doi: 10.18791/nsatlas.v5.ch04.3.  Back to cited text no. 11
    
12.
Mizutani K, Toda MM, Yoshida K. The analysis of the petrosal vein to prevent venous complications during the anterior aranspetrosal approach in the resection of petroclival meningioma. World Neurosurg 2016;93:175-82.  Back to cited text no. 12
    
13.
Panigrahi M, Venkateswaraprasanna G. Transpetrosal approach. J Neurosurg 2006;105:336-7.  Back to cited text no. 13
    
14.
Gupta SK, Salunke P. Intradural anterior petrosectomy for petroclivalmeningiomas: A new surgical technique and results in 5 patients. J Neurosurg 2012;117:1007-12.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20], [Figure 21], [Figure 22], [Figure 23]



 

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