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 »  Abstract
 »  Introduction
 »  Material and methods
 »  Discussion
 »  References

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Year : 1999  |  Volume : 47  |  Issue : 4  |  Page : 300-3

Pure extradural approach for skull base lesions.


Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India.

Correspondence Address:
Department of Neurosurgery, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India.

  »  Abstract

Lesions in the parasellar and paracavernous regions can be removed by various skull base approaches involving basal osteotomies. A major complication of intradural skull base approaches is CSF leak and associated meningitis. We have managed 5 patients with skull base lesions with a pure extradural approach using wide basal osteotomies. The operative techniques are described.

How to cite this article:
Gupta S K, Khosla V K, Sharma B S. Pure extradural approach for skull base lesions. Neurol India 1999;47:300


How to cite this URL:
Gupta S K, Khosla V K, Sharma B S. Pure extradural approach for skull base lesions. Neurol India [serial online] 1999 [cited 2021 Jan 20];47:300. Available from: https://www.neurologyindia.com/text.asp?1999/47/4/300/1585




   »   Introduction Top


Lesions of the skull base in the suprasellar, parasellar, cavernous sinus and paracavernous regions are traditionally approached via frontal, pterional or temporal routes. These conventional approaches have gainfully been replaced by skull base approaches, namely, supraorbital, supraorbital-pterional and fronto-orbito-zygomatic. These approaches minimize brain retraction, shorten the dissection distance and provide multiple entry points for tumour resection.[1] A major disadvantage of intradural skull base approaches is CSF leak and meningitis, as dural repair in such cases is problematic.[2] In this communication, we present our initial experience of surgical management of a variety of skull base lesions, via basal pure extradural approach.


   »   Material and methods Top


The clinical features, radiological findings, surgical approaches and follow up of cases are depicted in [Table I].

Operative technique

1. Fronto-orbito-zygomatic
a) Unilateral: [Figure - 1] The skin incision begins in front of tragus about 1.5 cm below the zygomatic arch and curves anteriorly within the hairline, across the midline to the contralateral midpupillary line. The scalp flap is reflected using sharp dissection with knife to expose the supraorbital rim, the glabella, the zygomatic process of frontal bone, the malar prominence and the zygomatic arch. The temporalis muscle and fascia are cut along the innominate line and reflected posteriorly. The fascial attachment on both the superior and inferior surfaces of zygomatic arch is dissected to expose the zygomatic arch. The periorbita is separated from the superior and lateral orbital wall. Burr holes are made and bony osteotomies are performed through the roof and lateral wall of orbit, the posterior end of zygomatic arch and the malar prominence. The sphenoid ridge is drilled and the free bone flap is removed as a single piece. The temporal muscle is reflected with fish hooks and the bone of middle fossa floor is rongeured. This exposes cavernous sinus dura, optic nerve, the 2nd division of fifth nerve and the superior orbital fissure.
b) Bilateral [Figure. 2]: The steps described above are performed on both sides. Additionally the osteotomies of the orbital roofs are extended medially and also through the nasion to the cribriform plate and the bone flap is removed as a single piece.
2. Fronto-temporo-orbito-suboccipito-zygomatic : The skin incision used is shown in [Figure. 3] and the bony removal is depicted in [Figure. 4]. This exposure in fact combines the fronto-orbito-zygomatic and the trans-petrosal approach. After the bone flap is removed, the mastoidectomy is completed and the petrosal bone is drilled away.


   »   Discussion Top


Bony osteotomy is an important component of a basal approach to skull base juxtasellar and paracavernous lesions. The advantages of a fronto-orbito-zygomatic bony removal has been discussed in detail.[1],[3],[4],[5],[6] This provides a direct and a wide angle surgical field and effectively makes a deep lesion superficial. For trigeminal schwannomas of the middle fossa, the preferred route is intradural subtemporal.[3] We used an extradural approach without transgressing the dura in the present series, achieving total excision without any postoperative morbidity. This avoids or reduces significantly, the complications related with brain retraction, vascular and neural injuries and CSF leak, thus reducing the post-operative morbidity. For dumbell tumours extending into both middle and posterior fossa, a combined subtemporal intradural transtentorial approach may be necessary for total extirpation. A major portion of these tumours can also be removed through a purely extradural approach using large and extensive basal osteotomies combined with petrosectomy. However, for removal of the inferior posterior fossa portion of the tumour in the region of lower cranial nerves, an intradural approach is desirable. Large tumours (case 2) extending from the orbital apex to the brainstem, invading the cavernous sinus and the lower cranial nerves, are a surgical challenge and total removal may not be feasible without significant postoperative morbidity. In such cases, the small residual tumour can be managed by postoperative radiosurgery.[7]

Various extra and intradural approaches described for cavernous sinus lesions include intradural superior, lateral or combined approaches, inferior subtemporal infratemporal extradural approach, medial extradural approach and anterolateral extradural approach.[8] A fronto-orbito-zygomatic craniotomy with bone removal of the middle cranial fossa floor upto the cavernous sinus dura gives an excellent exposure and allows excision of the lesions of this region without dural opening. Our experience with this approach is limited. The bilateral fronto-orbito-zygomatic approach, described here may be considered as a further modification of the extended frontal approach. The advantages of this approach are: a single flap bony removal which can be easily replaced, achieving a superior cosmesis and a very wide basal exposure of the paranasal sinuses, orbits, both the cavernous sinuses and infratemporal fossae.

It is concluded that appropriately tailored basal craniotomy, osteotomy and purely extradural approach for skull base lesions, reduces postoperative morbidity.

 

  »   References Top

1.Al-Mefty O : Surgical techniques for the juxtasellar area. In : Surgery of the cranial base. Al-Mefty O. (Ed). Kluwer Academic Publishers, Boston, 1989; 73-89.   Back to cited text no. 1    
2.Sekhar LN, Moller AR : Operative management of tumours involving the cavernous sinus. J Neurosurg 1986; 64 : 879-889.   Back to cited text no. 2    
3.McCormick PC, Post KD : Trigeminal neurinomas. In : Neurosurgery (2nd edn). Wilkins RH, Rengachary SS (Eds). McGraw Hill, New York, 1996; 1545-1552.   Back to cited text no. 3    
4.Jackson IT, Marsh WR, Bite U et al : Craniofacial osteotomies to facilitate skull base tumours resection. Br J Plas Surg 1986; 39 : 153-160.   Back to cited text no. 4    
5.Jane JA, Park TS, Pobereskin LH et al : The supraorbital approach: Technical note. Neurosurgery 1982; 11 : 537-542.   Back to cited text no. 5    
6.Sekhar LN, Nanda A, Sen CN et al : The extended frontal approach to tumour of the anterior, middle and posterior skull base. J Neurosurg 1992; 78 : 198-203.   Back to cited text no. 6    
7.Pollock BE, Kondziolka D, Feickinger JC et al : Preservation of cranial nerve function after radiosurgery for nonaccoustic schwannomas. Neurosurgery 1993; 33 : 597-601.  Back to cited text no. 7    
8.Patel SS, Sekhar LN : Surgical treatment of tumours involving the cavernous sinus. In : Neurosurgery (2nd edn). Wilkins RH, Rengachary SS (Eds). McGraw Hill, New York, 1996; 1683-1694.  Back to cited text no. 8    

 

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