Expanding the endoscopic transpterygoid corridor to the petroclival region: anatomical study and volumetric comparative analysis

Restricted access

OBJECTIVE

The endoscopic endonasal transmaxillary transpterygoid (TMTP) approach has been the gateway for lateral skull base exposure. Removal of the cartilaginous eustachian tube (ET) and lateral mobilization of the internal carotid artery (ICA) are technically demanding adjunctive steps that are used to access the petroclival region. The gained expansion of the deep working corridor provided by these maneuvers has yet to be quantified.

METHODS

The TMTP approach with cartilaginous ET removal and ICA mobilization was performed in 5 adult cadaveric heads (10 sides). Accessible portions of the petrous apex were drilled during the following 3 stages: 1) before ET removal, 2) after ET removal but before ICA mobilization, and 3) after ET removal and ICA repositioning. Resection volumes were calculated using 3D reconstructions generated from thin-slice CT scans obtained before and after each step of the dissection.

RESULTS

The average petrous temporal bone resection volumes at each stage were 0.21 cm3, 0.71 cm3, and 1.32 cm3 (p < 0.05, paired t-test). Without ET removal, inferior and superior access to the petrous apex was limited. Furthermore, without ICA mobilization, drilling was confined to the inferior two-thirds of the petrous apex. After mobilization, the resection was extended superiorly through the upper extent of the petrous apex.

CONCLUSIONS

The transpterygoid corridor to the petroclival region is maximally expanded by the resection of the cartilaginous ET and mobilization of the paraclival ICA. These added maneuvers expanded the deep window almost 6 times and provided more lateral access to the petroclival region with a maximum volume of 1.5 cm3. This may result in the ability to resect small-to-moderate sized intradural petroclival lesions up to that volume. Larger lesions may better be approached through an open transcranial approach.

ABBREVIATIONS ET = eustachian tube; IAC = internal acoustic canal; ICA = internal carotid artery; PPF = pterygopalatine fossa; PPG = pterygopalatine ganglion; TMTP = transmaxillary transpterygoid.

Article Information

Correspondence A. Samy Youssef, Department of Neurosurgery, University of Colorado, 12631 E 17th Ave., C307, Aurora, CO 80045. email: samy.youssef@ucdenver.edu.

INCLUDE WHEN CITING Published online July 21, 2017; DOI: 10.3171/2017.1.JNS161788.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    Brainlab neuronavigation was used during the cadaveric dissections to assist in the standardization of dissection boundaries. As an example, the probe pointing to the lower extent of exposure (jugular foramen) is shown in the sagittal (A), coronal (B), and axial (C) planes.

  • View in gallery

    Left TMTP approach. A: Pre-ET resection and pre-ICA mobilization. The left lateral clivus has been drilled to allow better, albeit minimal, access to the anterior-most portion of the petrous apex. Endoscopic scissors are used to release the fibrocartilaginous attachments of the lacerum segment of the ICA as well as the pharyngobasilar fascia attachments to the anterior genu to prepare for mobilization. The yellow circle indicates the area of focus. B: Curette pointing at superior portion of the cartilaginous ET. C: Post-ET resection and pre-ICA mobilization. The transpterygoid approach has been performed, and the cartilaginous ET has been removed, creating a large space (blue shading) for infrapetrous access to the lower petrous apex as indicated by the red arrows. D: Post-ET resection and post-ICA transposition with dissector (static vascular retractor can also be used as shown in Fig. 3), revealing more of the upper half of the petrous apex, which has been drilled in part (red arrows). E: Dural margins of the posterior and middle fossae are demonstrated after removal of ET and drilling of lower petrous apex. F: Minimal lateral retraction of the anterior genu after removal of the posterior fossa dura demonstrating the left abducens nerve in the prepontine cistern. AG = anterior genu of the ICA; AICA = anterior inferior cerebellar artery; BA = basilar artery; CET = cartilaginous eustachian tube; Cliv = clivus; CN6 = cranial nerve VI; CS = medial cavernous sinus dura; D = dissector; FL = foramen lacerum; FR = foramen rotundum; MFD = middle fossa dura; PCA = distal horizontal petrous carotid artery; PCCA = paraclival carotid artery; PFD = posterior fossa dura; SPA = sphenopalatine artery; TT = torus tubarius; V2 = maxillary nerve.

  • View in gallery

    A step-by-step illustration of the key steps of the approach with emphasis on ET resection and ICA mobilization for exposure of the petroclival region. A: Sharp transection of the fibrocartilaginous attachments of the lacerum segment of the ICA and the pharyngobasilar fascia attachments to the anterior genu is performed, thus untethering in preparation for transposition. B: Removal of the nasopharyngeal, pterygoid, and lacerum cartilaginous ET segments. The tensor veli palatini (TVP) and levator veli palatini (LVP) attachments are removed along with the ET. The torus tubarius is spared, as removal does not improve ipsilateral approach or access to the petrous apex. If a contralateral approach is desired, the torus tubarius can be removed, or the drill can be used to easily displace it inferiorly. C: Lateral mobilization of the paraclival ICA using a static vascular retractor revealing more of the upper petrous apex. The endonasal high-speed drill using a round diamond bur is used for petrous apex removal. D: The exposed petrous apex and posterior fossa dura have been removed, revealing the intradural exposure. a. = artery; AICA = anterior inferior cerebellar artery; m. = muscle; n. = nerve; II = optic nerve; VI = abducens nerve; VII = facial nerve; VIII = vestibulocochlear nerve; V2 = second branch (maxillary division) of the trigeminal nerve. Artist: David Aten. Published with permission from A. Samy Youssef, MD, PhD.

  • View in gallery

    Magnified intradural view of the left petroclival region after maximal lateral ICA retraction and dural resection using 0° (A) and 30° (B) endoscopes. Medially, the basilar artery (BA) is exposed, posterolaterally the CN VII/VIII complex (CN7&8) can be seen within the IAC, superiorly the top of the pons is exposed, and inferiorly the top of CN IX (CN9) is seen exiting the brainstem. PCS/DC = posterior cavernous sinus/Dorello’s canal.

  • View in gallery

    3D reconstructions of the left temporal bone from one of the cadaver dissections in which the TMTP approach was performed. The petrous apex was drilled before and after ET resection and paraclival ICA mobilization. Light blue represents the volume of petrous apex drilled via a medial transsphenoidal approach with a small amount of lateral clivus removed but before ET resection or ICA mobilization. Red demonstrates the amount of the petrous apex accessed after ET resection. Yellow demonstrates additional apiceal volume drilled after ET resection and carotid mobilization. Different views include posterior (A), anterior (B), anterior oblique (C), and posterior oblique (D) with a representative body figure in the bottom right corner of each quadrant to demonstrate head positioning.

  • View in gallery

    3D bar graph demonstrating resection volumes at each stage of the resection of 5 cadavers with each side denoted by R (right) or L (left). Prior to ET resection, the right side was drilled in all 5 cadavers with volumes shown in blue. After ET (red) and after ICA mobilization (green), both the right and left sides were drilled in all 5 cadavers (10 sides).

  • View in gallery

    Prior to dissection/petrous apex drilling, an initial fine-cut CT scan of one of the cadaver heads was imported into the Sectra Table (Sectra AB) to produce 3D axial (A) and coronal (B) reconstructions of the petrous temporal bone (light blue). After the TMTP approach, ET resection, ICA mobilization, and petrous apex drilling, the same cadaveric head was again scanned into the Sectra Table to produce 3D reconstructions of the drilled petrous temporal bone in the axial (C) and coronal planes (D). The empty space created by bilateral drilling of the petrous apex is demonstrated in black with red outline.

References

  • 1

    Battaglia PTurri-Zanoni MDallan IGallo SSica EPadoan G: Endoscopic endonasal transpterygoid transmaxillary approach to the infratemporal and upper parapharyngeal tumors. Otolaryngol Head Neck Surg 150:6967022014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Boari NRoberti FBiglioli FCaputy AJMortini P: Quantification of clival and paraclival exposure in the Le Fort I transmaxillary transpterygoid approach: a microanatomical study. J Neurosurg 113:101110182010

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3

    Cavallo LMMessina ACappabianca PEsposito Fde Divitiis EGardner P: Endoscopic endonasal surgery of the midline skull base: anatomical study and clinical considerations. Neurosurg Focus 19(1):E22005

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 4

    Cavallo LMMessina AGardner PEsposito FKassam ABCappabianca P: Extended endoscopic endonasal approach to the pterygopalatine fossa: anatomical study and clinical considerations. Neurosurg Focus 19(1):E5

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Chatrath PNouraei SADe Cordova JPatel MSaleh HA: Endonasal endoscopic approach to the petrous apex: an image-guided quantitative anatomical study. Clin Otolaryngol 32:2552602007

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    DeFreitas JLucente FE: The Caldwell-Luc procedure: institutional review of 670 cases: 1975–1985. Laryngoscope 98:129713001988

  • 7

    Freeman JLSampath RCasey MAQuattlebaum SCRamakrishnan VRYoussef AS: Transposition of the paraclival carotid artery: a novel concept of self-retaining vascular retraction during endoscopic endonasal skull base surgery technical report. Acta Neurochir (Wien) 158:162516292016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Gu YYu YZhang XHu FWang XXu W: Endoscopic endonasal transmaxillary transpterygoid approach to Meckel cave: anatomical study and preliminary clinical results. J Neurol Surg A Cent Eur Neurosurg 76:2052102015

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Hofstetter CPSingh AAnand VKKacker ASchwartz TH: The endoscopic, endonasal, transmaxillary transpterygoid approach to the pterygopalatine fossa, infratemporal fossa, petrous apex, and the Meckel cave. J Neurosurg 113:9679742010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Jacquesson TBerhouma MTringali SSimon EJouanneau E: Which routes for petroclival tumors? A comparison between the anterior expanded endoscopic endonasal approach and lateral or posterior routes. World Neurosurg 83:9299362015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Jacquesson TSimon EBerhouma MJouanneau E: Anatomic comparison of anterior petrosectomy versus the expanded endoscopic endonasal approach: interest in petroclival tumors surgery. Surg Radiol Anat 37:119912072015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Kantola VEMcGarry GWRea PM: Endonasal, transmaxillary, transpterygoid approach to the foramen ovale: radio-anatomical study of surgical feasibility. J Laryngol Otol 127:109311022013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Kasemsiri PSolares CACarrau RLProsser JDPrevedello DMOtto BA: Endoscopic endonasal transpterygoid approaches: anatomical landmarks for planning the surgical corridor. Laryngoscope 123:8118152013

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Kassam ABGardner PSnyderman CMintz ACarrau R: Expanded endonasal approach: fully endoscopic, completely transnasal approach to the middle third of the clivus, petrous bone, middle cranial fossa, and infratemporal fossa. Neurosurg Focus 19(1):E62005

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    Kassam ABVescan ADCarrau RLPrevedello DMGardner PMintz AH: Expanded endonasal approach: vidian canal as a landmark to the petrous internal carotid artery. J Neurosurg 108:1771832008

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

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

  • 17

    Klossek JMFerrie JCGoujon JMFontanel JP: Endoscopic approach of the pterygopalatine fossa: report of one case. Rhinology 32:2082101994

  • 18

    Komatsu FKomatsu MDi Ieva ATschabitscher M: Endoscopic approaches to the trigeminal nerve and clinical consideration for trigeminal schwannomas: a cadaveric study. J Neurosurg 117:6906962012

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Komune NKomune SMatsushima KRhoton AL Jr: Comparison of lateral microsurgical preauricular and anterior endoscopic approaches to the jugular foramen. J Laryngol Otol 129 (Suppl 2):S12S202015

    • Search Google Scholar
    • Export Citation
  • 20

    Lee DLMcCoul EDAnand VKSchwartz TH: Endoscopic endonasal access to the jugular foramen: defining the surgical approach. J Neurol Surg B Skull Base 73:3423512012

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Liu JPinheiro-Neto CDFernandez-Miranda JCSnyderman CHGardner PAHirsch BE: Eustachian tube and internal carotid artery in skull base surgery: an anatomical study. Laryngoscope 124:265526642014

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Maurer AJBonney PAIser CRAli RSanclement JASughrue ME: Endoscopic endonasal infrapetrous transpterygoid approach to the petroclival junction for petrous apex chondrosarcoma: technical report. J Neurol Surg Rep 76:e113e1162015

    • Search Google Scholar
    • Export Citation
  • 23

    Moussazadeh NKulwin CAnand VKTing JYGamss CIorgulescu JB: Endoscopic endonasal resection of skull base chondrosarcomas: technique and early results. J Neurosurg 122:7357422015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Neel HB IIIKeating LWMcDonald TJ: Ventilation in secretory otitis media: effects on middle ear volume and eustachian tube function. Arch Otolaryngol 103:2282311977

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 25

    Schilder AGMBhutta MFButler CCHoly CLevine LHKvaerner KJ: Eustachian tube dysfunction: consensus statement on definition, types, clinical presentation and diagnosis. Clin Otolaryngol 40:4074112015

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 26

    Taniguchi MAkutsu NMizukawa KKohta MKimura HKohmura E: Endoscopic endonasal translacerum approach to the inferior petrous apex. J Neurosurg 124:103210382016

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 27

    Taniguchi MKohmura E: Endoscopic transnasal transmaxillary transpterygoid approach to the parapharyngeal space: an anatomic study. Minim Invasive Neurosurg 53:2552602010

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Van Gompel JJAlikhani PTabor MHvan Loveren HRAgazzi SFroelich S: Anterior inferior petrosectomy: defining the role of endonasal endoscopic techniques for petrous apex approaches. J Neurosurg 120:132113252014

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29

    Zanation AMSnyderman CHCarrau RLGardner PAPrevedello DMKassam AB: Endoscopic endonasal surgery for petrous apex lesions. Laryngoscope 119:19252009

  • 30

    Ziyal IMSalas EWright DCSekhar LN: The petrolingual ligament: the anatomy and surgical exposure of the posterolateral landmark of the cavernous sinus. Acta Neurochir (Wien) 140:2012051998

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation

TrendMD

Cited By

Metrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 390 390 52
Full Text Views 368 305 5
PDF Downloads 184 153 5
EPUB Downloads 0 0 0

PubMed

Google Scholar