A 56-year-old female presented with subacute right-sided frontal and vertex headaches, accompanied by ipsilateral otalgia and mild disequilibrium. She denied auditory symptoms, vertigo, facial numbness, weakness, or diplopia. Her audiogram revealed pure tone averages and speech discrimination within normal limits bilaterally. MRI revealed an expansile, lobulated, hyperintense lesion on both T1- and T2-weighted sequences localized to the right petrous apex (Figure 1A). Computed tomography (CT) imaging demonstrated bony remodeling with thinning of the posterior carotid canal wall, consistent with a benign etiology (Figure 1B). The radiographic appearance was characteristic of a cholesterol granuloma (CG).1, 2 Given the lesion's anatomic location, and course of the carotid artery and jugular bulb, a standard transcanal infracochlear approach was contraindicated due to carotid artery proximity (Figure 1C).3 Similarly, the lesion was not sufficiently anteroinferior to be reached via a transsphenoidal route. However, superior extension and remodeling of the lateral skull base floor made the petrous apex potentially accessible via a middle fossa extradural approach (Figure 1D).4, 5 Case report was exempt and formal review was waived by the UMass Chan Institutional Review Board. The patient underwent a right-sided endoscope-assisted middle fossa craniotomy under general anesthesia with intraoperative facial nerve monitoring (Figure 2A). Computer-assisted stereotactic navigation was employed for precise localization of the petrous apex and to avoid injury to adjacent structures (Figure 2C and D). After elevation of the temporal lobe dura, the arcuate eminence and petrous ridge were identified and location of the lesion was confirmed with navigation, followed by an endoscopically assisted petrous apicotomy using a high-speed diamond bur (Figure 2B). The granuloma cavity contained a fibrous inflammatory tissue consistent with cholesterol granulomas (Figure 2B‴). The cavity was marsupialized and packed with Floseal and Surgicel to promote hemostasis and prevent recurrence. A controlled durotomy was performed at the beginning of the case to allow cerebrospinal fluid (CSF) egress and facilitate brain relaxation. A DuraMatrix graft was placed over the middle fossa floor to reinforce any potential dural defects. Closure was performed in layers, including reapproximation of the temporalis muscle and layered skin closure. The patient tolerated the procedure well without complications. At follow-up, she reported improvement in right-sided headache and otalgia. There were no new neurological deficits, and her hearing remained stable (Figure 1F). Postoperative MRI imaging 1 year after surgery confirmed stable, successful drainage of her CG (Figure 1A and E). Cholesterol granulomas of the petrous apex are benign cystic lesions that can present with nonspecific symptoms including headache, facial pain, or cranial neuropathies. Surgical management is indicated when symptomatic, enlarging, or causing compressive effects. Traditional approaches to the petrous apex—transmastoid infralabyrinthine, infracochlear, or endonasal transsphenoidal—can be limited by anatomical constraints, particularly in relation to the carotid artery and cochlea. This case illustrates a novel application for the endoscope during a middle fossa craniotomy combined with navigation-assisted techniques for marsupialization of a petrous apex CG. The middle fossa route, traditionally used for tumors like vestibular schwannomas or facial nerve decompression, offers direct extradural access to the superior petrous apex while preserving cochlear and labyrinthine structures. The incorporation of endoscopy enhanced visualization of the lesion cavity, and enabled precise drilling, minimizing the risk of injury to surrounding neurovascular structures. The approach is particularly advantageous when lesions are medially or anteriorly situated beyond the reach of transmastoid or transcanal subcochlear corridors and not accessible transnasally. This case underscores the importance of individualized surgical planning for petrous apex cholesterol granulomas. For lesions in challenging anatomical locations, a middle fossa craniotomy augmented by intraoperative endoscopy and navigation provides a safe, effective, and minimally invasive alternative to traditional approaches. The use of the endoscope in middle fossa craniotomy can expand the armamentarium for skull base surgeons managing petrous apex pathology. Reef Al-Asad, data curation, investigation, resources, writing (original draft, editing, review); Abel P. David, data curation, clinical management, investigation, resources, review and editing of manuscript; Daniel Lee, data curation, clinical management, investigation, supervision, resources, review and editing of manuscript; Judith Kempfle, conceptualization, investigation, clinical management, supervision, resources, writing original draft, editing, review. Daniel Lee: Consultant for Auregen, Korro Bio, 3NT Medical, Skylark Bio, Spiral Therapeutics. Judith Kempfle: Consultant: Zeiss Meditec. None.
Al‐Asad et al. (Thu,) studied this question.