Surgical Management and Outcome Experience of 53 Cerebellopontine Angle Meningiomas

Abstract

Background Meningiomas follow schwannomas as the second most common cerebellopontine angle (CPA) tumors. We investigate the diagnosis, management, and prognosis of this disease. Methods We reviewed the cases with the CPA meningiomas in our institution in Shaanxi, China from January 2012 to December 2015. Charts were retrospectively examined and patients were divided into two groups: 1) surgical treatment with a retrosigmoid approach for tumor resection and 2) stereotactic radiosurgery treatment only. Patients were followed up and outpatient records were also reviewed. Results Forty-nine patients underwent surgical resection via the retrosigmoid approach, while the other four underwent Gamma Knife® stereotactic radiosurgery (Elekta AB, Stockholm, Sweden) only. The most common presenting symptoms included hearing loss/tinnitus, vertigo, and headache; only 8.2% were asymptomatic. The largest diameter and base of each tumor varied from 4.0 to 5.5 cm and 3.0 to 5.0 cm, respectively. The tumors extended into different directions, mainly towards the tentorium and internal acoustic meatus (IAM). Eighty-three percent of surgical patients had a gross total resection. One death occurred due to pulmonary inflammation. Tumor recurrence was noted in 6.1% of patients. Postoperative trigeminal disturbance, facial nerve palsy, and hearing deterioration or loss were the most common immediate and delayed postoperative complications; most patients partially or completely recovered after hospital discharge. Intraoperative neuro-electrophysiological monitoring, complete resection, and postoperative radiation were key factors for reducing complications and recurrence. Conclusions The retrosigmoid approach offers an ideal visual field for exposing and resecting CPA meningiomas in a large series of cases. In our experience, it is one of the most useful and commonly used surgical approaches for removing meningiomas of this region.

Keywords: cerebellopontine angle; meningioma; retrosigmoid approach; surgical resection.

Figure 1. Resection Grade and Pathology of the Surgical Patients

Figure 2. Preoperative MRI with Contrast Demonstrating the Origins and Extensions of Cerebellopontine Angle Meningiomas

(A) Tumor with a wide base origin at the tentorium cerebelli (arrow) and an extension to the tentorium cerebelli hiatus compressing the pons. (B) The rodent-tailed sign of this tumor (arrow) revealed a larger origin from the tentorium and petrous bone. (C) The coarse base indicated that the tumor originated largely at the back of petrous bone (arrow) and partially at the tentorium cerebelli (arrowhead). MRI: magnetic resonance imaging

Figure 3. Reactive Thickening of the Petrous Bone

MRI with contrast and CT demonstrating the location of the CPA meningioma and its petrous reactive changes in a 46-year-old female The CPA meningioma (star, left) was associated with a thickened petrous bone (arrow, right), but no dilated IAM. CPA: cerebellopontine angle; CT: computerized tomography; IAM: internal acoustic meatus; MRI: magnetic resonance imaging

Figure 4. Feeding Vessels

MRI with contrast demonstrating the blood supply to the meningioma in a 36-year-old male. This CPA meningioma had many adjacent vessels (short arrow) and perforating vessels (long arrow). CPA: cerebellopontine angle; MRI: magnetic resonance imaging

Figure 5. Total and Subtotal Resections

MRI with contrast demonstrating the surgical removal of a CPA meningioma from two patients via a retrosigmoid approach. Upper row: a 36-year-old male who had total removal of his tumor (star). Lower row: a 48-year-old female with near total removal of her tumor (star). A small residual was left at the tumor origin at the back surface of the petrous bone. CPA: cerebellopontine angle; MRI: magnetic resonance imaging

Figure 6. Partial Resection

Contrast MRI demonstrating radiosurgery for residual from a CPA meningioma in a 47-year-old female presenting with left oculomotor palsy. Preoperative images revealed a straddle meningioma across the petrous apex (A, arrow). Partial removal of the tumor was achieved via a retrosigmoid approach. Residual tumor at its invasion of the cavernous sinus (B, arrow) was treated with Gamma Knife stereotactic radiosurgery (16 Gy) a month post-operation. Contrast MRI two years later showed obvious shrinkage of the residual tumor (C, arrow). CPA: cerebellopontine angle; MRI: magnetic resonance imaging

Figure 7. Intraoperative Exposure of Cranial Nerves

Photograph of the intraoperative demonstration of anatomical preservation of the cranial nerves. (A) The left CPA meningioma was totally removed and the trigeminal (short arrow) and abducens (long arrow) nerves were anatomically preserved. (B) The trigeminal (short arrow) and facial/vestibulocochlear nerves (long arrow) were anatomically preserved following total removal of a right CPA meningioma. The brainstem (star) and cerebellum (round) were clearly seen. CPA: cerebellopontine angle

Figure 8. Application of Radiosurgery to Residual Tumor

MRI with contrast of postoperative radiotherapy for the residual tumor. The residual of the CPA meningioma (upper row, arrow) underwent 16 Gy stereotactic radiosurgery 30 days after operation, and it disappeared two years later (lower row). CPA: cerebellopontine angle; MRI: magnetic resonance imaging