Contralateral Transmaxillary Approach for a 13-Year-Old Boy with a Petrous Apex Cholesterol Granuloma: A Case Report Open Access

Surgical extirpation of a cholesterol granuloma of the petrous apex, located dorsal to the petrous part of the internal carotid artery (ICA), can be challenging. An infrapetrous approach combined with the lateralization of the ICA or an open approach are generally required [1, 2]. However, these approaches are invasive, particularly in pediatric cases. In this report, we described the use of an endoscopic contralateral transmaxillary (CTM) approach [2], which is relatively less invasive than the aforementioned approaches. This is the first reported pediatric case of a cholesterol granuloma of the petrous apex excised using the endoscopic contralateral approach.

A 13-year-old boy presented with left-sided headache. He had no previous history of physical or mental illness, nor any developmental disorders. Neurological examination revealed slight hypoesthesia in the left V1 area and severe neuralgia in the left auriculotemporal, resulting in an inability to attend school. The patient had no hearing loss, vertigo, abnormal eye movements, or facial paralysis.

Magnetic resonance imaging (MRI) revealed a high-intensity mass on TI-weighted images without gadolinium enhancement (shown in Fig. 1). The patient’s headache was unresponsive to acetaminophen, nonsteroidal anti-inflammatory drugs, pentazocine, carbamazepine, or prednisolone.

We diagnosed the lesion as a cholesterol granuloma and considered middle fossa and other endoscopic approaches, including an infrapetrous approach, for its extirpation; however, the patient’s parents requested for a less-invasive technique. Because of various anatomical conditions, such as the location of the carotid artery and a high jugular vein, we did not select the transcanal infracochlear or infralabyrinthine approaches. After a meticulous analysis, we selected an endoscopic CTM approach via the contralateral maxillary sinus (shown in Fig. 2).

The bilateral ethmoid and sphenoid sinuses were explored through nasal endoscopy. Hemifacial degloving [3] was performed with an incision made at the right piriform aperture and sublabium (shown in Fig. 3a).

The anterior and medial walls of the right maxillary sinus were resected to secure a pathway to the sphenoid sinus (CTM approach). Using a diamond burr, a portion of the anterior wall of the petrous part of the ICA was drilled through the left sphenoid sinus to expose the petrous part of the left ICA.

The posterior petrous bone adjacent to the ICA was then drilled through the right maxillary sinus using a 15° curved bur. The cyst wall of the cholesterol granuloma was opened widely (shown in Fig. 3b) and, using a navigation system, was confirmed to be adjacent to the internal auditory canal (IAC). The ICA surfaces and cystic orifice were covered with a pedicled miniflap comprising sphenoid sinus mucosa and free femoral fascia. A polyvinyl chloride stent was inserted into the cystic orifice. Postoperatively, the patient did not experience headache or associated neurological complications. The medication was reduced and stopped over a period of 1 month. MRI at 46 months postoperatively revealed no recurrence of the cholesterol granuloma (shown in Fig. 4), and no esthetic changes were observed.

A cholesterol granuloma is a chronic inflammatory lesion consisting of a cystic cavity filled with brownish fluid. The approach to a lesion in the petrous apex depends on the anatomical areas involved and the remaining functions of the seventh and eighth cranial nerves.

The middle fossa, infralabyrinthine, infracochlear, and transsphenoidal approaches are generally selected to preserve hearing [4, 5]. In cases of severe hearing loss, the translabyrinthine approach may be useful [6]. In our case, the patient’s chief complaint was a headache without other neurological symptoms; therefore, a function-preserving approach was desired. We chose the endoscopic transsphenoidal approach, first reported by Fucci et al. [7], for the extirpation of the granuloma. However, lesions in the lateral petrous apex positioned dorsal to the ICA generally require exposure and displacement of the petrous part of the ICA or excision using an infrapetrous approach [1, 2]. Paluzzi et al. [1] proposed an algorithm for selecting the best surgical approach to cholesterol granulomas of the petrous apex. The selection is based on the V angle, formed by the lacerum segment of the ICA and the most medial edge of the tumor, with the lateral edge of the contralateral pyriform aperture as the apex [1]. Cholesterol granulomas that extend medially (V angle ≥5°) are a good indication for the transclival (i.e., endoscopic transsphenoidal) approach [1], whereas for those with a V angle of <5°, a combined infrapetrous approach is recommended. Extreme lateral cholesterol granulomas (with negative V angles) often require an open approach. In our case, the V angle was approximately 1°; therefore, an infrapetrous approach was required (shown in Fig. 5). In this approach, the risk of injury to the eustachian tube and vidian nerve is relatively high compared to other approaches. Therefore to minimize invasiveness, an endoscopic approach through the contralateral maxillary sinus was considered. Patel et al. [2] first described the anatomical basis and efficacy of a CTM approach to the petrous apex. This approach enables the drill to reach areas of the petrous apex posterior and lateral to the petrous part of the ICA, which are generally not accessible via the endonasal route without extensively dissecting and mobilizing the ICA. They concluded that the CTM approach was most useful for excising less-expansive cholesterol granulomas or clival tumors (chordomas and chondrosarcomas) located posterolateral to the ICA. Although some reports have described the use of a CTM approach for chordoma, chondrosarcoma, cholesteatoma, and pituitary adenoma [2, 8‒14], its use for cholesterol granuloma has been reported in only 1 case, with short-term follow-up outcomes [15]. In our case, the CTM approach with a V angle of 4° at the apex of the lateral edge of the contralateral maxillary sinus window (shown in Fig. 6) allowed us to perform the surgery with a good view; thus, favorable outcomes were achieved. An improvement in the patient’s headache was the greatest consequence of the surgery, and the symptom was presumed to have ceased with the resolution of inflammation of the trigeminal nerve. This is the first reported pediatric case of a cholesterol granuloma extirpated using an endoscopic CTM approach, demonstrating that it can be performed safely without causing any esthetic concerns over 4 years. The endoscopic CTM approach is noninvasive and considered the technique of choice for treating tumors of the pyramidal apex in pediatric patients. One limitation of our approach is the inability to perform osteotomies immediately dorsal to the ICA in the petrous part adjacent to the IAC (shown in Fig. 6), though previous studies have reported access to the contralateral IAC to be possible with this technique [16]. This limitation may be attributed to an inadequate lateral maxillotomy for esthetic reasons. If preservation of the sphenopalatine artery is not prioritized for reconstruction, drilling the pterygoid base on the approach side may facilitate access to the petrous apex via a direct CTM approach [17].

Eytan et al. [18] reported that an endoscopic surgical intervention resolved symptoms in 90% of patients with petrous apex cholesterol granulomas; however, the restenosis rate was 7.5%. Efforts to prevent recurrence, including stent detention or insertion of a vascularized pedicled “miniflap” of nasoseptal mucoperiosteum, have been recognized and reported [1, 19].

In our case, no symptom recurrence was reported 46 months postoperatively. The use of a pedicled sphenoid sinus mucosal flap and free femoral fascia, along with the placement of a stent tube with packing material in the open lumen, likely contributed to the favorable outcome.

The CTM approach can be used for excising cholesterol granulomas of the petrous apex located posterior to the petrous part of the ICA without causing severe complications. This approach can be considered ideal for pediatric cases in which granulomas are not accessible via the transnasal endoscopic transsphenoidal approach.

We would like to thank Editage (www.editage.jp) for English language editing.

Ethical approval was not required for this study in accordance with the national guidelines. The authors affirm that the parents of the patient provided written informed consent for participation on this study. The authors affirm that the parents of the patient provided written informed consent for publication of this case report and any accompanying images.

The authors have no conflicts of interest to declare.

This study was not supported by any sponsor or funder.

Yasuhiro Arai drafted the manuscript. Yasuhiro Arai and Jun Suenaga conceptualized and designed the study and reviewed and revised the manuscript. Yasuhiro Arai drafted the manuscript, analyzed the data, and reviewed the literature. Yasuhiro Arai, Jun Suenaga, Mitsuru Sato, Daisuke Sano, Tetsuya Yamamoto, and Nobuhiko Oridate critically reviewed the manuscript, approved the final version for submission, and agreed to be accountable for all aspects of this study.

All data generated or analyzed during this study are included in this article. Further inquiries can be directed to the corresponding authors.