Endoscopic Access to the Infratemporal Fossa and Skull Base a Cadaveric Study

ORIGINAL ARTICLE Endoscopic Access to the Infratemporal Fossa and Skull Base A Cadaveric Study

Christopher J. Hartnick, MD; John S. Myseros, MD; Charles M. Myer III, MD

Objectives: To demonstrate that the regions of the in- Endoscopic visualization and instrumentation was then fratemporal fossa and skull base at the level of the fora- performed. The infratemporal fossa was readily identi- men ovale can be visualized endoscopically and that struc- fied. The skull base at the level of the foramen ovale and tures can be manipulated within these regions using the branches of the third division of the trigeminal nerve endoscopic instruments. were seen distinctly. A probe was placed with ease within the foramen ovale itself. Methods: Cadaveric dissection of 3 human cadavers using an endoscopic optical dissector. In all, 6 endoscopic Conclusions: Endoscopic access to the infratemporal infratemporal fossa and skull base approaches were per- fossa is readily accomplished, with excellent visualiza- formed. tion and instrumentation ability. This novel technique provides access to this remote region for evaluation, pos- Setting: Human temporal bone laboratory. sible biopsy, and potential treatment of infratemporal fossa lesions. Results: A Gillies incision was coupled with a lateral brow incision, and then subperiosteal planes were developed. Arch Otolaryngol Head Neck Surg. 2001;127:1325-1327

HE INFRATEMPORAL fossa is lymphoma, and juvenile nasopharyngeal a relatively remote region angiofibroma. Many of these tumors can beneath the skull base. Ac- undergo biopsy at some other, more readily cess to this region requires accessible area, or the diagnosis is se- thorough knowledge of the cured using imaging studies (computed anatomyT of the region itself and of the sur- tomography or magnetic resonance rounding structures. Surgical procedures imaging). For a small subset of infratem- to gain access to this region have been well poral masses, biopsy results before a ma- described by Fisch1-4 and Sekhar5,6 and jor operative procedure might prove use- their colleagues, among others; these pro- ful in guiding management. cedures are major surgical endeavors that This study arises from preliminary require precision and planning. work9 in which endoscopic access was The anatomy of the infratemporal gained to the region of the infratemporal fossa was well described by Grant7 in 1972. fossa to facilitate diagnosis of a cerebro- The superior border is composed of the spinal fluid leak at the region of the fora- greater wing of the sphenoid bone and the men ovale. Having gained access to visu- temporal fossa containing the temporalis alize this region, the question arises muscle, and the medial border is formed whether this region can be accessed en- by the lateral pterygoid plate. The infra- doscopically such that manipulations such temporal fossa is bounded laterally by the as biopsies can be performed safely with- From the Departments of mandibular ramus, extends anteriorly to out injuring neighboring structures. This Pediatric Otolaryngology the posterior wall of the maxillary sinus, study presents initial cadaveric dissec- (Drs Hartnick and Myer) and and opens inferiorly into the parapharyn- tions that demonstrate such an ability. Pediatric Neurosurgery geal space. (Dr Myseros), Children’s Hospital Medical Center, A host of neoplasms can either arise RESULTS Cincinnati, Ohio. Dr Hartnick from or extend into the infratemporal 8 is now with the Department of fossa. Specific to the realm of pediatric Figure 4 shows the incised periosteum, Otolaryngology, Massachusetts otolaryngology, neoplasms found in this and the muscles in the infratemporal fossa Eye and Ear Infirmary, Boston. region can include rhabdomyosarcoma, are clearly displayed. By remaining on the

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Three fresh frozen cadaver heads were used for the dissections, which took place in the Temporal Bone Laboratory, Department of Otolaryngology–Head and Neck Surgery, University of Cincinnati, Cincinnati, Ohio. The infratemporal fossa was endoscopically identified on both sides of each head, for a total of 6 dissections. On 2 dissections, the zygomatic arch was removed after the endoscopic approach was performed to confirm the anatomical features that had been visualized endoscopically. A craniotomy was then performed on this cadaver head to further confirm the identification of the foramen ovale. Figure 2. An endoscopic optical dissector in position through one incision The endoscopic approach proceeded as fol- (large arrow) and a suction elevator in position through the other incision lows. Two separate 2-cm incisions were made (one (small arrow). at the lateral rim and one just anterior to the temporal hairline) and carried down through the pericra- nium (Figure 1). An optical dissector with a distal spatula (Karl Storz Endoscopy-America Inc, Culver City, Calif) was placed through one incision, and a suction catheter (Karl Storz Endoscopy-America Inc) was placed in the other (Figure 2). Using endoscopic periosteal elevators and the suction freer elevator, the perisosteum was elevated to the level of the zygomatic arch, which was palpated using the endoscopic instruments (Figure 3). Inferiorly, subperiosteal elevation was performed to the region of the infratemporal fossa. Once the infratemporal fossa was accessed, the foramen ovale and the third division of the fifth cranial nerve could be identified. Figure 3. Endoscopic optical dissector instruments. The inset shows the spatula and the 30° scope at its distal tip.

Figure 1. Model of a skull with arrows pointing to the 2 sites of incision (one Figure 4. Endoscopic view at the level of the skull base just medial to the at the lateral rim and one just anterior to the temporal hairline) for the zygomatic arch. The periosteum has been incised, and the infratemporal endoscopic approach to the regions of the infratemporal fossa and skull base fossa musculature is visualized inferiorly; the foramen ovale is in the at the level of the foramen ovale. distance medially.

face of the skull base and continuing to elevate the peri- COMMENT osteum, the foramen ovale and the third division of the fifth cranial nerve are visualized. A probe can then be Modern endoscopic equipment has revolutionized placed that allows for manipulation of the nerves them- many surgical disciplines, including otolaryngology. selves (Figure 5) or for direct access to the foramen ovale Specific to otolaryngology, endoscopes and related itself (Figure 6). After the zygomatic arch is subse- instruments have enabled the development of endo- quently removed and a craniotomy is perfomed, the struc- scopic sinus surgery and endoscopic middle ear otos- tures identified endoscopically are confirmed to be truly copy. The great benefit that using endoscopic equip- representative. ment provides is the ability to avoid open surgical

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©2001 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/28/2021 Figure 5. Endoscopic view showing the tip of a probe adjacent to the fifth Figure 6. Endoscopic view showing the tip of a probe inserted into the cranial nerve. foramen ovale.

maneuvers while still performing safe and effective In conclusion, this study represents a small initial investigations or procedures. investigation concerning a new surgical endoscopic tech- Endoscopic access to the infratemporal fossa may nique. More work will be required first in the cadaveric provide a unique means of visualizing and performing model and then in the clinical realm to define the role of minor biopsies in this region. To date, we have endoscopy in the surgical armamentarium of the otolar- peformed 6 cadaveric and 1 clinical dissection. The yngologist. patient was a child and was placed under general anesthesia for the procedure. Certainly for children, and Accepted for publication June 11, 2001. probably for adults, the procedure requires general Presented at the annual meeting of the American So- anesthesia, because it includes substantial periosteal ciety for Pediatric Otolaryngology, Scottsdale, Ariz, May elevation. As the technique evolves, it may be possible 11, 2001. to perform the procedure on adults with the use of local Corresponding author: Christopher J. Hartnick, MD, anesthesia. Department of Otolaryngology, Massachusetts Eye and Ear The equipment used for these dissections was de- Infirmary, 243 Charles St, Boston, MA 02114 (e-mail: signed initially for brow lifting. As such, the angula- [email protected]). tions of some of the instruments are not conducive to this form of surgery. We are presently developing instru- REFERENCES ments that are specifically designed to navigate around the angles of the skull base. To that end, we are also de- 1. Fisch U. Infratemporal fossa approach to tumours of the temporal bone and base veloping insulated instruments that will allow for elec- of the skull. J Laryngol Otol. 1978;92:949-967. trocautery and may allow for some degree of hemostatic 2. Fisch U, Pillsbury HC. Infratemporal fossa approach to lesions in the temporal control. bone and base of the skull. Arch Otolaryngol. 1979;105:99-107. 3. Fisch U. Infratemporal fossa approach for lesions in the temporal bone and base As stated previously, the procedures for which this of the skull. Adv Otorhinolaryngol. 1984;34:254-266. form of endoscopy might be warranted include those in 4. Fisch U, Fagan P, Valavanis A. The infratemporal fossa approach for the lateral which visualization of the fossa would change manage- skull base. Otolaryngol Clin North Am. 1984;17:513-552. ment or in which a biopsy might be required. Another 5. Sekhar LN, Schramm VL Jr, Jones NF, et al. Operative exposure and management of the petrous and upper cervical internal carotid artery. Neurosurgery. 1986; possible use for this surgical technique may be to pro- 19:967-982. vide a simple and direct route to the foramen ovale. 6. Sekhar LN, Schramm VL Jr, Jones NF. Subtemporal-preauricular infratemporal Procedures such as percutaneous rhizotomy require fossa approach to large lateral and posterior cranial base neoplasms. J Neuro- access to the foramen ovale.10,11 With the percutaneous surg. 1987;67:488-499. approach, a small radiation dose in the form of fluoros- 7. Grant J. An Atlas of Anatomy. Baltimore, Md: Williams & Wilkins; 1972. 8. Cummings CW, Fredrickson JM, Harker LA, et al, eds. Otolaryngology–Head and copy is required to demonstrate the position of the Neck Surgery. 3rd ed. St Louis, Mo: Mosby–Year Book Inc; 1998. needle tip relative to the foramen; an endoscopic 9. Hartnick CJ, Lacy PD, Myer CM III. Endoscopic evaluation of the infratemporal approach might alleviate the need for fluoroscopy and fossa. Laryngoscope. 2001;111:353-355. provide another means of access. Finally, bony deficits, 10. Taha JM, Tew JM Jr. Treatment of trigeminal neuralgia by percutaneous radio- frequency rhizotomy. Neurosurg Clin North Am. 1997;8:31-39. acquired and congenital, associated with cerebrospi- 11. Tew JM Jr, Mayfield FH. Trigeminal neuralgia: a new surgical approach. (Percu- nal fluid fistulae may be directly and noninvasively taneous electrocoagulation of the trigeminal nerve.) Laryngoscope. 1973;83: addressed. 1096-1101.

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