Has management of epidermoid tumors of the cerebellopontine angle improved? A surgical synopsis of the past and present

Abstract

We compared the surgical outcomes of recent patients with cerebellopontine angle (CPA) epidermoids treated with advanced surgical tools with those of patients treated in earlier series. From November 2000 to June 2004, we treated 12 patients with epidermoid tumors. One patient had a strict CPA lesion. Tumors extended into the prepontine region in seven cases and supratentorially in two. In two cases the CPA was involved bilaterally. All patients but one underwent a lateral suboccipital approach in a semi-sitting position with microsurgical technique. Endoscopic assistance was used in cases with extensions beyond the CPA. In one case, a subtemporal route was used. The mean follow-up was 27 months (range, 8 to 50 months). There were no deaths. Total removal was achieved in 7 of the 10 patients with unilateral CPA epidermoids. Preoperative status improved in eight (80%) patients, particularly the function of cranial nerves (CNs) V and VII. Only two patients had permanent CN deficits. Complete excision with preservation of CN function should be the goals of management of epidermoids of the CPA. In some cases, these goals can be difficult to achieve, even with contemporary surgical equipment. Bilateral and extensive tumors should be removed in staged procedures. The function of CN V and CN VII may recover after decompression, but the outcome of symptoms related to CN VIII is less certain. The endoscope is a reliable tool for assessing the extension of epidermoids, but it cannot be used for tumor removal.

Keywords: Epidermoid; cerebellopontine angle; cranial nerve deficits; suboccipital; subtemporal.

Figure 1

Preoperative (A) sagittal T1-weighted and (B) axial T2-weighted magnetic resonance (MR) images show a CPA epidermoid mass dislocating the brainstem and extending to the prepontine region and temporal fossa. Postoperative (C) sagittal T1-weighted and (D) axial T2-weighted MRIs show the decompression of neurovascular structures and confirm removal of the infratentorial component. The lesion site has filled with cerebrospinal fluid. The right temporal remnant of the tumor was stable at the patient's 24-month follow-up examination.

Figure 2

(A) Preoperative axial T2-weighted image shows a CPA epidermoid mass compressing the brainstem and extending to the basilar artery. (B) Postoperative axial T2-weighted MRI shows the decompression of neurovascular structures and confirms the complete removal of the lesion 24 months after surgery.

Figure 3

(A) Microscopic intraoperative photograph shows the pearly appearance of a CPA epidermoid. (B) Partial resection of the tumor reveals the CN VII and CN VIII cranial nerve complex. (C) The surgical field after its removal. CN V, CN VII, and CN VIII were preserved.

Figure 4

Microscopic intraoperative photographs show (A) CPA epidermoid with a thick bright capsule, (B) the surgical field during its removal, and (C) the involvement of CN VI. (D) A view “around the corner” was obtained by using an angulated mirror. (E) The lesion was removed, and CN VII, CN VIII, and the lower CNs were preserved.

Figure 5

(A) Microscopic intraoperative photograph shows a CPA epidermoid and (B) the surgical field during its removal. CN V is visible in the background. (C) An endoscope provides a different angle of view.