Abstract
Background:
Cholesterol granulomas are benign cystic lesions arising in the petroclival region. Petroclival cholesterol granulomas (PCCGs) can be treated via traditional approaches such as infralabyrinthine, transcanal infracochlear, translabyrinthine, middle cranial fossa, and retrosigmoid routes or through less invasive endoscopic-assisted endonasal transphenoidal approaches. The latter approach requires access to the sphenoid sinus, visualization of the clival recess and bony landmarks to access the petrous apex (PA). However, in patients with poorly pneumatized (choncal) sphenoid sinus, access to the sphenoid sinus using the endoscopic endonasal transphenoidal approach is technically difficult and may not be feasible, necessitating an alternative approach.
Methods:
In this report, we present a case of a low-lying petroclival cholesterol granuloma in a patient with a conchal sphenoid and describe an alternative access corridor via an upper nasopharyngeal exposure that facilitated an endoscopic-assisted fenestration and drainage of the lesion.
Presentation:
A 55-year-old woman presented with hearing loss and tinnitus. CT showed a conchal sphenoid and a large lytic expansile mass with soft tissue density centered in the right PA with osseous remodeling. (Fig. 1–C) MRI showed a nonenhancing right PA mass that measured 22 ×18 ×19 mm with increased T1 and T2 signal, consistent with PCCG. (Fig. 1 D–F). A transclival endoscopic-assisted approach was planned.
Operative Technique:
A standard image-guided approach including a right maxillary antrostomy, uncinectomy, and middle turbinectomy was performed. The upper nasopharyngeal mucosa and adenoid bed were then completely removed using coblation. A pedicled nasoseptal flap was harvested and mobilized toward the right maxillary sinus. A transclival exposure was performed with a high-speed diamond drill located inferior and medial to the vidian nerve. Intraoperative ultrasound and neuronavigation confirmed the course of the petroclival internal carotid arteries. Dissection of paraclival structures proceeded in a standard fashion until the cyst contents were reached. Following cyst evacuation, extensive drilling was performed medially, superiorly, and inferiorly to enlarge the size of the outflow tract and facilitate placement of the nasoseptal flap. Successful resection was verified by postoperative CT and MRI. (Fig. 2) Postoperative nasal endoscopy verified mucosalization of the drainage tract.
Conclusion:
In patients with a conchal sphenoid, an upper nasopharyngeal corridor provides adequate visualization for an endoscopic-assisted transclival approach, which was successfully used to treat a PCCG.
Fig. 1
Preoperative CT showing lytic expansile soft tissue mass (A–C) and preoperative MRI (D–F) showing T1–T2 hyperintensity consistent with cholesterol granuloma.
Fig. 2
Postoperative CT and MR imaging showing postsurgical changes and resection cavity.