An Extended Endaural Subtemporal (E-East) Approach to the Petrous Apex and Posterior and Infratemporal Fossae

Introduction/Background: Traditional approaches to the petrous apex and/or infratemporal fossa require a large exposure. Petrous apicectomy may be performed through an extended middle fossa approach (aka Kawase), and for the exposure of the infratemporal fossa this may require inferior mobilization of the temporalis muscle and zygomatic osteotomies (aka Fisch B or C). We demonstrate the feasibility of a minimally invasive approach to the petrous apex and infratemporal fossa using an expanded version of our previously presented endaural subtemporal (EAST) approach.[1]

Methods: This study is an anatomic study performed on embalmed and latex injected cadaveric heads.

Results: Dissection was performed on four cadaver heads including three injected with colored latex and one uninjected, embalmed head. The initial step in the exposure is an endaural incision beginning on the medial aspect of the tragus at its inferior border with the ear lobule and extending through the incisura of the ear to hug the superior border of the pinna ([Fig. 1A]). Dissection is carried down anterior to the tragal cartilage to the root of the zygoma; temporalis muscle and the temporalis fascia investing the zygoma are dissected anteriorly exposing both the zygomatic root and the squamous temporal bone ([Fig. 1B]). The temporomandibular ligament is elevated allowing the temporomandibular joint capsule to be mobilized inferiorly. A bur hole is placed in the squamosal temporal bone and the dura elevated off the middle cranial fossa floor ([Fig. 2A]). Using a reciprocating saw, osteotomies are then made to elevate the glenoid fossa of the mandible en bloc to facilitate reconstruction of the same ([Fig. 2B]). Under the operative microscope, the temporal bone may be drilled as far as the petrous apex ([Fig. 3A]) allowing good visualization of intradural contents of the posterior fossa ([Fig. 3B]). The glenoid is repositioned in place with screws and miniplates ([Fig. 4]).

Discussion/Conclusion: We provide a stepwise description of a novel approach to the petrous apex and the infratemporal fossa, including a method of reconstruction of the glenoid fossa. This approach is a potential alternative to maximally invasive traditional approaches to the petrous apex and infratemporal fossa. Clinical corroboration of cadaveric studies is required and will necessitate careful patient selection.

The authors wish to thank individuals who donate their bodies and tissues for the advancement of education and research.

Fig. 1 (A) The skin incision and (B) the bony exposure of the root of zygoma after soft tissue dissection.

Fig. 2 (A) A bur hole is placed above the root of the zygoma; the location of the osteotomies for the glenoid fossa are marked on the zygoma in blue; (B) Exposure after en bloc removal of the glenoid.

Fig. 3 (A) CT of the cadaver head; with the extent of petrous apicectomy shaded in yellow; (B) microscope view of extent of posterior fossa contents visualized including trigeminal nerve, superior cerebellar artery and brainstem.

Fig. 4 Photograph of glenoid reconstruction.

Publication History

Article published online:
05 February 2024

• References

• 1 Olszewski A. et al. Endaural Subtemporal Approach for Middle Fossa Encephalocele and CSF Leak Repair. Poster, NASBS; 2023