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Journal of Neurological Surgery. Part B, Skull Base logoLink to Journal of Neurological Surgery. Part B, Skull Base
. 2020 Mar 6;82(Suppl 3):e172–e178. doi: 10.1055/s-0040-1702218

Endoscope-Assisted Middle Fossa Approach: Optimizing the Surgical Corridor for the Resection of Multicompartmental Chordomas

André Beer-Furlan 1,2,3,, Eduardo de Arnaldo Silva Vellutini 1,2, Leonardo Balsalobre 1,4, Aldo Cassol Stamm 1,4
PMCID: PMC8289554  PMID: 34306933

Abstract

Background  Skull base chordomas are a major therapeutic challenge. The surgical management involves selecting an approach that will offer the patient the best chance of largest/complete removal while minimizing morbidity and mortality.

Methods  Medical records and imaging review of two skull base chordomas involving the middle fossa and posterior fossa that were successfully treated with an endoscope-assisted middle fossa approach.

Results  The use of angled endoscopes provided better identification of anatomical landmarks and improved tumor resection when compared with the microscopic surgical exposure. The approach selection, anatomical landmarks, and technical aspects of the intraoperative setting of the endoscope-assisted approach are discussed.

Conclusion  Endoscopic assistance in the middle fossa approach is a safe and valuable tool for maximizing the reach of the surgical corridor when treating skull base chordomas.

Keywords: endoscope-assisted approach, transcranial endoscopy, middle fossa, subtemporal, chordoma, skull base chordoma

Introduction

Skull base chordomas are a major therapeutic challenge. Despite being considered histologically low-grade malignancies 1 and having a slow growth, chordomas are locally aggressive and carry a poor prognosis even after treatment. 2

They are derived from embryonic notochordal tissue and nearly always arise within the bone, mainly in the sacrum, clivus, or cervical vertebrae. Approximately 25% of them are located at the clivus constituting approximately 0.15% of all primary intracranial tumors. 3 4

Surgical resection associated with adjuvant radioproton beam therapy seems to offer the best results. 5 6 7 8 Operative management involves selecting an approach that will offer the best chance of maximal tumor removal while minimizing morbidity and mortality. 9

The development expanded endoscopic endonasal approaches (EEAs) and associated surgical tools have pushed the limits of ventral skull base chordoma management. Endoscopes have the ability to optimize the reach of a surgical approach by allowing “around the corner” visualization, improve illumination, and image magnification in deep cavities. 10 11 12 13 14 The endoscope has proven its value in transnasal surgery; however, its potential has not been explored in depth in skull base chordomas that treated through transcranial approaches. 15

We report two cases of multicompartmental skull base chordomas in which an endoscope-assisted middle fossa approach was performed. The approach selection, anatomical landmarks, and intraoperative technical nuances of the endoscope application in a middle fossa transcranial approach are discussed in detail.

Case Illustration

Case 1

A 52-year-old woman presented in 2014 with worsening right facial hypoesthesia associated with pain at maxilar (V2) and mandibular (V3) nerve territories. The patient had history of a petroclival chordoma with two subtotal resections (1998 and 2008) through a right suboccipital retrosigmoid approach. After the second surgery, the patient worsened a preexisting right abducens nerve (CN IV) palsy, developed a new right side facial hypoesthesia (V2/V3 territories), House–Brackmann grade 2 facial palsy, and complete sensorineural hearing loss (anacusis). A small residual tumor was intentionally left adherent at the posterior wall of the right cavernous sinus.

The yearly follow-up with magnetic resonance imaging (MRI) did not show signs of residual tumor growth until the new complaints of facial pain and worsening facial hypoesthesia. New MRI showed significant tumor growth compared with the prior year. Imaging of tumor extending into the middle fossa and posterior fossa with hyperintensity on T2-weighted (T2W) images, hypo/isointensity on T1-weighted (T1W) images, and no contrast enhancement were compatible with prior diagnosis of the chordoma ( Fig. 1 ).

Fig. 1.

Fig. 1

Preoperative MRI. ( A and B ) coronal T2W images; ( C and D ) axial T2W images; ( E–H ) axial T1W images. MRI, magnetic resonance imaging; T1W, T1-weighted; T2W, T2-weighted.

An endoscope-assisted middle fossa approach was performed ( Fig. 2 ). The postoperative course was uneventful and the immediate MRI showed radical resection of the tumor and the fat graft filling up the surgical cavity ( Fig. 3 ). The patient had complete improvement of the trigeminal pain and her facial hypoesthesia returned to baseline. Pathology confirmed chondroid chordoma again. No brachyury was performed for this case; however, pathology showed both chordoid and chondroid areas with an epithelial phenotype and stained strongly for cytokeratin, as well as S-100.

Fig. 2.

Fig. 2

Endoscopic view of the surgical field. ( A and B ) narrow surgical corridor between V1 and V2. Bimanual dissection and resection of the tumor created a cavity where the infiltrate petrous bone is visualized; ( C ) bone drilling under endoscopic visualization of the surgical field; ( D ) visualization of the ascending segment of the cavernous ICA, temporal and posterior fossa dura mater. ICA, internal carotid artery; pet.bone, petrous bone; PFD, posterior fossa dura; TD, temporal dura; Tu, tumor; V1, ophthalmic nerve.

Fig. 3.

Fig. 3

Postoperative MRI. ( A and B ) axial T1W images; ( C and D ) coronal T2W images with fat suppression. T1W, T1-weighted; T2W, T2-weighted.

There were no perioperative complications. Patient underwent subsequent intensity-modulated radiation therapy with total dose of 67.84 Gy in 32 fractions. There were no signs of tumor recurrence in the 5-year follow-up.

Case 2

A 46-year-old male presented, 2 years after surgery for a petroclival tumor, with new face hypoesthesia. The patient had a previous history of partial abducens nerve (cranial nerve [CN] VI) palsy secondary to a petroclival region chordoma. He underwent an EEA to the clivus with subtotal tumor resection. After surgery, patient improved completely CN VI palsy and a small residual tumor was left at the right Meckel's cave. Intensity-modulated radiation therapy was performed and a total dose of 54 Gy was delivered to the residual tumor.

Imaging follow-up revealed residual tumor growth until the new complaints of hypoesthesia on the right side of his face. New MRI showed tumor growth with hyperintensity on T2W images, hypo/isointensity on T1W images, and heterogeneous contrast enhancement, compatible with the previous diagnosis of chordoma. The tumor was located in the Meckel's cave and extended into the posterior cranial fossa along the trigeminal nerve ( Fig. 4 ).

Fig. 4.

Fig. 4

Coronal T1W with gadolinium images. ( A ) preoperative; ( B ) post-EEA resection; ( C ) 3 months after middle fossa approach. EEA, endoscopic endonasal approach; T1W, T1-weighted.

An endoscope-assisted middle fossa approach was performed. The postoperative course was uneventful and the immediate MRI showed complete resection of the tumor ( Fig. 5 ). Pathology was consistent with prior diagnosis of chordoma with immunohistochemistry positive for cytokeratin, S-100, and brachyury. The patient developed an expected permanent right face hypoesthesia due to intraoperative confirmation and resection of tumor invading the trigeminal nerve. There were no signs of recurrence in the 6-year follow-up.

Fig. 5.

Fig. 5

( A ) T2W images showing tumor recurrence at the middle and posterior fossa; ( B and C ) Intraoperative endoscopic images demonstrating the gain in caudal reach of the middle fossa approach; ( D ) Postoperative T2W showing complete tumor resection of its caudal extension into the posterior fossa. The arrows are indicating CNVII/VIII and AICA. AICA, anterior inferior cerebellar artery; CN, cranial nerve; T2W, T2-weighted.

Endoscope-Assisted Middle Fossa Approach

A lumbar drain was inserted preoperatively for cerebrospinal fluid (CSF) drainage and facilitation of temporal lobe retraction. Patient was placed in the supine position, with the head slightly extended and rotated 30 degrees to the contralateral side. A classic low-set temporal craniotomy was performed with epidural dissection of the middle fossa and intradural exposure of the trigeminal nerve. Epidural retraction of the temporal lobe was secured with 4–0 nylon sutures and a Leyla retractor (Aesculap, Tuttlingen, Germany).

The tumor bulged and displaced the Gasserian ganglion and V1 laterally, and V2 inferolaterally. Although the tumor infiltrated the anterior petrous bone, the anatomical landmarks of the middle fossa were preserved. Identification and dissection of the middle meningeal artery at the foramen spinosum, V3 at the foramen ovale, and V2 at foramen rotundum were performed.

Epidural exposure and drilling of the petrous bone at the Kawase's triangle 16 were performed with microsurgical techniques. Anterior petrous bone infiltrated by tumor was drilled maximizing the rostrocaudal window for intradural dissection. Besides the Kawase's triangle, the anteromedial (between V1 and V2) and anterolateral (between V2 and V3) triangles were also used as surgical corridors for tumor resection. 16 In both cases, petrous and cavernous segments of the internal carotid artery (ICA) and CN VI were identified for safe tumor removal.

Microscope was used until maximal visualization of deep surgical field was achieved. The caudal reach of the microscopic subtemporal approach was limited by two factors: the petrous ICA and temporal lobe. The petrous ICA was the lateral boundary of bone resection at the petrous apex, creating a pivoting point for surgical instruments and limiting light reach to the caudal aspect of deep surgical field. The temporal lobe also limited caudal reach by blocking instruments and illumination on the superficial surgical plane. Likewise, working in a deep field through narrow corridors, such as the anteromedial and anterolateral triangles, created blind spots that could not be directly visualized. The combination of narrow and deep surgical field, crowding of surgical instruments, and external light source prevent adequate visualization of a straight instrument's tip.

At this point, the endoscope improved illumination and visualization of the deep surgical field. The assisting surgeon handled the endoscope (4 mm/18 cm; 45 degrees) with two hands. The dominant hand held the endoscope camera, while the other hand was placed at the edge of the craniotomy holding the endoscope shaft. Bimanual handling of the endoscope enabled quick, safe, and stable movements.

The endoscope was inserted at the edges of the craniotomy in an oblique angled toward the surgical target. Having the superficial planes of the middle fossa dissected at the epidural space helped to protect the temporal when driving the endoscope in and out of the surgical field. If the primary surgeon needed better caudal visualization, the angled endoscope was placed at the opposite (rostral) aspect of the field with its lens directed toward the area of interest. Similar strategy of positioning the endoscope in the opposite location of the area of interest was used in the ventral and dorsal directions and provided sufficient space for bimanual dissection and drilling.

We noted a significant amount of tumor outside the microscope's line of sight that became visible and reachable with the endoscope. Having the “around the corner” visualization optimized use of straight instruments and allowed angle dissectors and suctions to reach blind spots ( Figs. 2 and 5 ). For CSF leak prevention, autologous fat graft and fibrin glue were used for closure of the surgical cavity.

Discussion

Surgical management of chordomas is among the most challenging tasks in skull base surgery. Gross total resection is difficult in the majority of cases, 17 and the best surgical strategy involves choosing an approach that will offer the best chance of largest/complete removal while minimizing morbidity and mortality.

Transclival EEA has already proven itself as it revolutionized management of ventral skull base chordomas by optimizing surgical resection while minimizing the surgical morbidity.

The use of rigid endoscopes in transcranial lateral approaches has been shown advantageous by improving the visualization of the anatomic structures without the need for an extensive exposure and brain retraction. 18 19 20 21 22 23 24 25 26 27 It has been used in the treatment of epidermoid tumors, 28 29 cholesteatoma, cholesterol granuloma, 30 and vestibular schwannomas. 31 32 However, it has never been described in the management of skull base chordomas.

Surgical Approach Selection

Three surgical routes were considered for these petroclival chordomas: EEA, suboccipital retrosigmoid approach, and a middle fossa (subtemporal) approach.

The EEA offers good exposure at the midline petrous apex/clival region, and the posterior fossa component of the tumor. However, the middle fossa portion of the lesion would be difficult to remove due to its lateral extension and location posterior and superior to the cavernous ICA.

Similarly, the suboccipital retrosigmoid approach offers good access to the inferior component of the tumor (petrous apex/clival region and posterior fossa). Although it is possible to reach the middle fossa through a retrosigmoid suprameatal approach, the lateral reach is somewhat limited. Furthermore, the retrosigmoid working corridor to the middle fossa is long and narrow (in between cranial nerves), posing an additional risk of morbidity.

The epidural subtemporal approach offers direct and better access to the middle fossa component of the tumor and anterior petrous bone region. On the other hand, this approach requires temporal lobe retraction, which is a disadvantage and could hinder the exposure of the rostral extension of a lesion. The petrous ICA is also a limitation to the caudal exposure of the posterior fossa after anterior petrosectomy. Nevertheless, considering the middle fossa component and the caudal extent of the posterior fossa component, we opted for the subtemporal approach. The endoscopic assistance was used as a tool to overcome the potential rostral–caudal exposure limitations of the approach.

Transpetrosal approaches are alternative surgical routes in patients without serviceable hearing. However, they are time consuming and we believe similar or better anatomical exposure may be obtained with a single or combination of more pragmatic approaches such as retrosigmoid, subtemporal, and EEA.

Endoscopic Epidural Middle Fossa Approach

The endoscopic epidural middle fossa approach through small or keyhole craniotomies has been described previously in cadavers. 20 21 22 23 24 25

The principles of the exclusively endoscopic approach are the same used for the microscopic procedure; a low-set temporal craniotomy, epidural dissection, and drilling/flattening of the middle fossa floor. The middle meningeal artery is usually cut at foramen spinosum to facilitate dural detachment and temporal lobe retraction. Initial epidural dissection goals are to expose the arcuate eminence and the greater superficial petrosal nerve (landmark to the petrous ICA located inferomedial to the nerve). Further exposure will allow access to V3, where an interdural dissection or middle fossa peeling is started, exposing the Meckel's cave, V1, V2, and V3 ( Fig. 6 ).

Fig. 6.

Fig. 6

Endoscopic cadaveric dissection and anatomical landmarks of the middle fossa. ( A ), Dural detachment after section of the MMA; ( B ) exposure of the petrous ICA; ( C ) anterior exposure of the middle fossa; ( D ) exposure of the trigeminal nerve after peeling the dura mater over the trigeminal nerve. Arc, arcuate eminence; CS, cavernous sinus; FR, foramen rotundum; FO, foramen ovale; GG, Gasserian gangion; GSPN, great superficial petrosal nerve; MMA, middle meningeal artery; pet. ICA, petrous internal carotid artery; TD, temporal dura; V1, ophthalmic nerve; V2, maxillary nerve; V3, mandibular nerve.

The Role of Endoscopic Transcranial Surgery

It is natural that the clinical application of new techniques and concepts are introduced in a gradual manner, due to the greater surgical difficulties encountered in vivo when compared with cadaveric dissections. The endoscopic assistance in transcranial approaches is the first step on the transition from a microsurgical approach to an exclusively endoscopic approach. This transition was successfully made in endonasal approaches, and some keyhole operations of the suprasellar region and cerebellopontine angle. 28

In these cases of endoscope-assisted middle fossa approach, we observed significant improvement in tumor exposure and resection through the small surgical corridors. Damage of tissue proximal to the tip of the endoscope was not an issue when working at the epidural space on the superficial planes of the approach. We found that 45-degree endoscope are initially more challenging to maneuver in the surgical field due to image distortion. However, this issue is quickly solved with practice and the 45 degrees provided versatility and better reach when working in blind spots. Additionally, the angled scope permitted positioning of its shaft at the edge of the craniotomy, leaving more space for bimanual dissection and drilling at the center of the field.

It is also important to have appropriate surgical instrumentation to take advantage of the wide and angled view. The initial work with the endoscopic assistance is done with straight instruments, since it permits better visualization than the microscope in the deep surgical field. Further dissection with angled instruments is crucial to better access and remove tumor from those blind spots. We used angled microsurgical instruments designed for endoscopic endonasal surgery; however, the development of better instrumentation for transcranial endoscopic surgery may optimize the benefits to its maximum.

The decision of using the endoscope in transcranial or keyhole approach must always be weighed against its potential drawbacks. Loss of three-dimensional stereoscopic vision, heat-related tissue damage associated with the light source, tissue damage when entering and exiting the surgical cavity, and movement proximal to the endoscope lens may all pose limitations. Fortunately, it all may be overcome with routine use of the endoscope and with a second surgeon handling and controlling it.

Conclusion

Our experience has shown that endoscopic assistance in middle fossa approach is a safe tool for maximizing the reach of the surgical corridor when treating skull base chordomas. It is particularly valuable when working through narrow corridors to reach deep and blind spot areas of the surgical field.

Footnotes

Conflict of Interest None declared.

References

  • 1.Mitchell A, Scheithauer B W, Unni K K, Forsyth P J, Wold L E, McGivney D J. Chordoma and chondroid neoplasms of the spheno-occiput. An immunohistochemical study of 41 cases with prognostic and nosologic implications. Cancer. 1993;72(10):2943–2949. doi: 10.1002/1097-0142(19931115)72:10<2943::aid-cncr2820721014>3.0.co;2-6. [DOI] [PubMed] [Google Scholar]
  • 2.Eriksson B, Gunterberg B, Kindblom L G. Chordoma. A clinicopathologic and prognostic study of a Swedish national series. Acta Orthop Scand. 1981;52(01):49–58. doi: 10.3109/17453678108991758. [DOI] [PubMed] [Google Scholar]
  • 3.Sen C, Triana A. Cranial chordomas: results of radical excision. Neurosurg Focus. 2001;10(03):E3. doi: 10.3171/foc.2001.10.3.4. [DOI] [PubMed] [Google Scholar]
  • 4.Sen C N, Sekhar L N, Schramm V L, Janecka I P. Chordoma and chondrosarcoma of the cranial base: an 8-year experience. Neurosurgery. 1989;25(06):931–940. doi: 10.1097/00006123-198912000-00013. [DOI] [PubMed] [Google Scholar]
  • 5.al-Mefty O, Borba L A. Skull base chordomas: a management challenge. J Neurosurg. 1997;86(02):182–189. doi: 10.3171/jns.1997.86.2.0182. [DOI] [PubMed] [Google Scholar]
  • 6.Arnold H, Herrmann H D.Skull base chordoma with cavernous sinus involvement. Partial or radical tumour-removal? Acta Neurochir (Wien) 198683(1,2):31–37. [DOI] [PubMed] [Google Scholar]
  • 7.Colli B, Al-Mefty O. Chordomas of the craniocervical junction: follow-up review and prognostic factors. J Neurosurg. 2001;95(06):933–943. doi: 10.3171/jns.2001.95.6.0933. [DOI] [PubMed] [Google Scholar]
  • 8.Colli B O, Al-Mefty O. Chordomas of the skull base: follow-up review and prognostic factors. Neurosurg Focus. 2001;10(03):E1. doi: 10.3171/foc.2001.10.3.2. [DOI] [PubMed] [Google Scholar]
  • 9.Mangussi-Gomes J, Beer-Furlan A, Balsalobre L, Vellutini E A, Stamm A C. Endoscopic endonasal management of skull base chordomas: surgical technique, nuances, and pitfalls. Otolaryngol Clin North Am. 2016;49(01):167–182. doi: 10.1016/j.otc.2015.09.011. [DOI] [PubMed] [Google Scholar]
  • 10.Chibbaro S, Cornelius J F, Froelich S. Endoscopic endonasal approach in the management of skull base chordomas--clinical experience on a large series, technique, outcome, and pitfalls. Neurosurg Rev. 2014;37(02):217–224. doi: 10.1007/s10143-013-0503-9. [DOI] [PubMed] [Google Scholar]
  • 11.Fernandez-Miranda J C, Gardner P A, Snyderman C H. Clival chordomas: A pathological, surgical, and radiotherapeutic review. Head Neck. 2014;36(06):892–906. doi: 10.1002/hed.23415. [DOI] [PubMed] [Google Scholar]
  • 12.Jahangiri A, Jian B, Miller L, El-Sayed I H, Aghi M K. Skull base chordomas: clinical features, prognostic factors, and therapeutics. Neurosurg Clin N Am. 2013;24(01):79–88. doi: 10.1016/j.nec.2012.08.007. [DOI] [PubMed] [Google Scholar]
  • 13.Koutourousiou M, Gardner P A, Tormenti M J. Endoscopic endonasal approach for resection of cranial base chordomas: outcomes and learning curve. Neurosurgery. 2012;71(03):614–624. doi: 10.1227/NEU.0b013e31825ea3e0. [DOI] [PubMed] [Google Scholar]
  • 14.Saito K, Toda M, Tomita T, Ogawa K, Yoshida K. Surgical results of an endoscopic endonasal approach for clival chordomas. Acta Neurochir (Wien) 2012;154(05):879–886. doi: 10.1007/s00701-012-1317-1. [DOI] [PubMed] [Google Scholar]
  • 15.Koechlin N O, Simmen D, Briner H R, Reisch R. Combined transnasal and transcranial removal of a giant clival chordoma. J Neurol Surg Rep. 2014;75(01):e98–e102. doi: 10.1055/s-0034-1373668. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Drazin D, Wang J M, Alonso F. Intracranial anatomical triangles: a comprehensive illustrated review. Cureus. 2017;9(10):e1741. doi: 10.7759/cureus.1741. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17.Hug E B, Loredo L N, Slater J D. Proton radiation therapy for chordomas and chondrosarcomas of the skull base. J Neurosurg. 1999;91(03):432–439. doi: 10.3171/jns.1999.91.3.0432. [DOI] [PubMed] [Google Scholar]
  • 18.Gagliardi F, Boari N, Roberti F. Extradural subtemporal transzygomatic approach to the clival and paraclival region with endoscopic assist. J Craniofac Surg. 2012;23(05):1468–1475. doi: 10.1097/SCS.0b013e31825a6497. [DOI] [PubMed] [Google Scholar]
  • 19.Kocaoğullar Y, Avci E, Fossett D, Caputy A. The extradural subtemporal keyhole approach to the sphenocavernous region: anatomic considerations. Minim Invasive Neurosurg. 2003;46(02):100–105. doi: 10.1055/s-2003-39345. [DOI] [PubMed] [Google Scholar]
  • 20.Komatsu F, Komatsu M, Di Ieva A, Tschabitscher M. Endoscopic extradural subtemporal approach to lateral and central skull base: a cadaveric study. World Neurosurg. 2013;80(05):591–597. doi: 10.1016/j.wneu.2012.12.018. [DOI] [PubMed] [Google Scholar]
  • 21.Perneczky A, Fries G. Endoscope-assisted brain surgery: part 1--evolution, basic concept, and current technique. Neurosurgery. 1998;42(02):219–224. doi: 10.1097/00006123-199802000-00001. [DOI] [PubMed] [Google Scholar]
  • 22.Mourgela S, Sakellaropoulos A, Anagnostopoulou S. Middle cranial fossa endoscopy using a rigid endoscope. Minim Invasive Ther Allied Technol. 2007;16(06):355–359. doi: 10.1080/13645700701705328. [DOI] [PubMed] [Google Scholar]
  • 23.Taniguchi M, Perneczky A. Subtemporal keyhole approach to the suprasellar and petroclival region: microanatomic considerations and clinical application. Neurosurgery. 1997;41(03):592–601. doi: 10.1097/00006123-199709000-00017. [DOI] [PubMed] [Google Scholar]
  • 24.Salma A, Wang S, Ammirati M.Extradural endoscope-assisted subtemporal posterior clinoidectomy: a cadaver investigation study Neurosurgery 201067(3, Suppl Operative):ons43–ons48. [DOI] [PubMed] [Google Scholar]
  • 25.Beer-Furlan A, Evins A I, Rigante L, Anichini G, Stieg P E, Bernardo A. Dual-Port 2D and 3D endoscopy: expanding the limits of the endonasal approaches to midline skull base lesions with lateral extension. J Neurol Surg B Skull Base. 2014;75(03):187–197. doi: 10.1055/s-0033-1364165. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Beer-Furlan A, Evins A I, Rigante L. Endoscopic extradural anterior clinoidectomy and optic nerve decompression through a pterional port. J Clin Neurosci. 2014;21(05):836–840. doi: 10.1016/j.jocn.2013.10.006. [DOI] [PubMed] [Google Scholar]
  • 27.Figueiredo E G, Beer-Furlan A, Nakaji P. The role of endoscopic assistance in ambient cistern surgery: analysis of four surgical approaches. World Neurosurg. 2015;84(06):1907–1915. doi: 10.1016/j.wneu.2015.08.031. [DOI] [PubMed] [Google Scholar]
  • 28.de Divitiis O, Cavallo L M, Dal Fabbro M, Elefante A, Cappabianca P.Freehand dynamic endoscopic resection of an epidermoid tumor of the cerebellopontine angle: technical case report Neurosurgery 200761(5, Suppl 2):E239–E240. [DOI] [PubMed] [Google Scholar]
  • 29.Tuchman A, Platt A, Winer J, Pham M, Giannotta S, Zada G.Endoscopic-assisted resection of intracranial epidermoid tumors World Neurosurg 201482(3,4):450–454. [DOI] [PubMed] [Google Scholar]
  • 30.Zhang J, Hua W, Zhang X. Pure endoscopic surgery via subtemporal extradural keyhole approach for middle cranial fossa tumors. World Neurosurg. 2019;130:e487–e497. doi: 10.1016/j.wneu.2019.06.131. [DOI] [PubMed] [Google Scholar]
  • 31.Master A N, Roberts D S, Wilkinson E P, Slattery W H, Lekovic G P. Endoscope-assisted middle fossa craniotomy for resection of inferior vestibular nerve schwannoma extending lateral to transverse crest. Neurosurg Focus. 2018;44(03):E7. doi: 10.3171/2017.12.FOCUS17663. [DOI] [PubMed] [Google Scholar]
  • 32.Montaser A S, Todeschini A B, Harris M S, Adunka O F, Prevedello D M. Role of endoscopy in resection of intracanalicular vestibular schwannoma via middle fossa approach: technical nuances. World Neurosurg. 2018;120:395–399. doi: 10.1016/j.wneu.2018.08.215. [DOI] [PubMed] [Google Scholar]

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