Letter to the Editor: Anterior petrosal approach

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To The Editor: We enjoyed reading the article by Gupta and Salunke2 (Gupta SK, Salunke P: Intradural anterior petrosectomy for petroclival meningiomas: a new surgical technique and results in 5 patients. Technical note. J Neurosurg 117:1007–1012, December 2012), in which they present a variation of the seminal anterior petrosectomy described by Kawase et al.5,6 We also read with great interest the Letter to the Editor by Tatagiba et al. on this article.8

Gupta and Salunke described 5 patients with petroclival meningiomas who underwent an intradural

To The Editor: We enjoyed reading the article by Gupta and Salunke2 (Gupta SK, Salunke P: Intradural anterior petrosectomy for petroclival meningiomas: a new surgical technique and results in 5 patients. Technical note. J Neurosurg 117:1007–1012, December 2012), in which they present a variation of the seminal anterior petrosectomy described by Kawase et al.5,6 We also read with great interest the Letter to the Editor by Tatagiba et al. on this article.8

Gupta and Salunke described 5 patients with petroclival meningiomas who underwent an intradural anterior petrosectomy tailored according to tumor extension. They claimed that bone removal was significantly minimized, which was addressed in their anatomical study.2 We believe the advantage of intradural (subdural) drilling of the petrous apex is that the surgeon can see the tumor and its extension prior to anterior petrosectomy. The surgeon can map the operative field and minimize the drilling area, thereby decreasing the risk of drilling-related injury. Since the extradural approach results in a formal anterior petrosectomy, which may be too extensive and pose an unnecessary risk to critical structures, the authors propose that in some cases, drilling of the entire anterior petrous bone may not be required. The authors stated that the extradural approach has some risks, such as traction injury of the greater superficial petrosal nerve (GSPN), leading to facial nerve palsy, interference with the vein of Labbé, and excessive bone removal, thereby increasing the risk of injury to the cochlea, semicircular canals, and petrous internal carotid artery (ICA).2,7 However, based on our experience of more than 100 cases of anterior petrosectomies spanning 10 years, we point out the risks of extradural anterior petrosectomy indicated by Gupta and Salunke, and the difference between the intradural and extradural approaches.

As opposed to what is indicated by Gupta and Salunke in their article, we show that the risk of damage to the seventh and eighth cranial nerves is very low in the extradural approach. In more than 100 cases of anterior petrosectomy performed at our institution for different pathologies,1,3 such as petroclival meningioma, epidermoid tumors, trigeminal schwannoma, and abducens schwannoma, we experienced only 3 cases of transient facial nerve paresis postoperatively. Two of these cases resolved after 2 weeks, and the third resolved after 1 year (unpublished data).

The GSPN is identified and preserved in most cases by using the correct maneuver. The GSPN is the most reliable landmark of Kawase's triangle and is useful in identifying the geniculate ganglion and internal auditory canal. Semicircular canals are also preserved in all cases. Although the eminentia arcuata as a landmark is not always identified clearly, careful drilling at the posterior margin of Kawase's triangle can preserve this bone structure. Intraoperative navigation system assistance is helpful in preventing injury to the bony structures.

The risk of injury to the vein of Labbé is quite low in the anterior petrosal approach because the extradural anterior petrosectomy makes a surgical corridor with minimal temporal lobe retraction. Moreover, we can retract the temporal lobe on the dura after cutting the tentorium. The vein of Labbé and temporobasal vein injury are not involved in this maneuver. Our approach requires a small temporal craniotomy and is less invasive than an orbitozygomatic craniotomy. Epidural drilling of the petrous bone is safer than subdural drilling. There are many important structures around the anterior part of the tentorial incisura exposed during subdural drilling. They are at a higher risk of injury during subdural drilling.

We can modify dural cutting and the extradural anterior petrosectomy (Kawase's approach) in cases with specific venous drainage patterns from the superficial middle cerebral vein (SMCV), for example, the sphenopetrosal sinus route (8%–19%) and sphenobasal vein pattern (18%–31%),4 to preserve the venous drainage route and avoid the risk of venous congestion. The SMCV drainage route should be determined preoperatively and preserved if at all possible. There is a risk of brain injury caused by wide opening of the sylvian fissure and venous congestion or thrombosis by cutting the drainage route of the SMCV to the sphenoparietal sinus. Since the SMCV and sphenoparietal sinus are important drainage routes in some cases, we would like to know how often Gupta and Salunke cut the route to the SMCV in their procedure.

Disclosure

The authors report no conflict of interest.

References

  • 1

    Fukaya RYoshida KOhira TKawase T: Trigeminal schwannomas: experience with 57 cases and a review of the literature. Neurosurg Rev 34:1591712010

  • 2

    Gupta SKSalunke P: Intradural anterior petrosectomy for petroclival meningiomas: a new surgical technique and results in 5 patients. Technical note. J Neurosurg 117:100710122012

  • 3

    Ichimura SKawase TOnozuka SYoshida KOhira T: Four subtypes of petroclival meningiomas: differences in symptoms and operative findings using the anterior transpetrosal approach. Acta Neurochir 150:6376452008

  • 4

    Ichimura SYoshida KKagami HInaba MOrii MToda M: Epidural anterior petrosectomy with subdural visualization of sphenobasal vein via the anterior transpetrosal approach— technical case report. Neurosurg Rev 35:6096132012

  • 5

    Kawase TShiobara RToya S: Anterior transpetrosal transtentorial approach for sphenopetroclival meningiomas: surgical method and results in 10 patients. Neurosurgery 28:8698761991

  • 6

    Kawase TToya SShiobara RMine T: Transpetrosal approach for aneurysms of the lower basilar artery. J Neurosurg 63:8578611985

  • 7

    Miller CGvan Loveren HRKeller JTPensak Mel-Kalliny MTew JM Jr: Transpetrosal approach: surgical anatomy and technique. Neurosurgery 33:4614691993

  • 8

    Tatagiba MAcioly MARoser F: Petroclival tumors. J Neurosurg 119:5265282013. (Letter)

Response

I have read with interest the views expressed by Tomio et al. Kawase's approach is one of the most elegant skull base surgical techniques. However, for tumors that have a large suprasellar extension, we find it difficult to reach the superior-most extent of the tumor. Many petroclival meningiomas in this region are fibrous and are not easily suckable or amenable to removal by CUSA (Cavitron Ultrasonic Surgical Aspirator). This requires tumor manipulation, and the vessels and nerves on the medial and superior aspect of the lesion, which are hidden from the surgeon's view, may be stretched and at risk of injury. In addition, tumors that extend superiorly more than 2 cm from the tentorial edge may require more temporal extension, putting draining veins at risk of injury. In the intradural approach, the surgical corridor is along the long axis of the tumor and structures on both the medial and lateral aspects of the tumor are visible.

We agree with Tomio et al. that in about 10% of patients the venous drainage can be through the sphenopetrosal sinus and cutting the superficial middle cerebral vein may lead to venous congestion. Luckily in our short series of 5 cases, we did not encounter this problem. We believe that preoperative assessment of venous drainage pattern should be done in all patients before planning the surgical approach.

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Article Information

Please include this information when citing this paper: published online March 21, 2014; DOI: 10.3171/2013.10.JNS132121.

© AANS, except where prohibited by US copyright law.

Headings

References

1

Fukaya RYoshida KOhira TKawase T: Trigeminal schwannomas: experience with 57 cases and a review of the literature. Neurosurg Rev 34:1591712010

2

Gupta SKSalunke P: Intradural anterior petrosectomy for petroclival meningiomas: a new surgical technique and results in 5 patients. Technical note. J Neurosurg 117:100710122012

3

Ichimura SKawase TOnozuka SYoshida KOhira T: Four subtypes of petroclival meningiomas: differences in symptoms and operative findings using the anterior transpetrosal approach. Acta Neurochir 150:6376452008

4

Ichimura SYoshida KKagami HInaba MOrii MToda M: Epidural anterior petrosectomy with subdural visualization of sphenobasal vein via the anterior transpetrosal approach— technical case report. Neurosurg Rev 35:6096132012

5

Kawase TShiobara RToya S: Anterior transpetrosal transtentorial approach for sphenopetroclival meningiomas: surgical method and results in 10 patients. Neurosurgery 28:8698761991

6

Kawase TToya SShiobara RMine T: Transpetrosal approach for aneurysms of the lower basilar artery. J Neurosurg 63:8578611985

7

Miller CGvan Loveren HRKeller JTPensak Mel-Kalliny MTew JM Jr: Transpetrosal approach: surgical anatomy and technique. Neurosurgery 33:4614691993

8

Tatagiba MAcioly MARoser F: Petroclival tumors. J Neurosurg 119:5265282013. (Letter)

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