Nonvestibular schwannoma tumors in the cerebellopontine angle: a structured approach and management guidelines

Abstract

The most common cerebellopontine angle (CPA) tumor is a vestibular schwannoma, but one in five CPA tumors are not vestibular schwannomas. These tumors may require different management strategies. Compared with vestibular schwannomas, symptoms and signs from cranial nerve VIII are less frequent: other cranial nerve and cerebellar symptoms and signs predominate in patients with these less common CPA tumors. Computed tomography and magnetic resonance imaging often show features leading to the correct diagnosis. Treatment most often includes surgery, but a policy of observation or subtotal resection is often wiser. This review provides a structured approach to the diagnosis of nonvestibular schwannoma CPA lesions and also management guidelines.

Keywords: Cerebellopontine angle; epidermoids; management guidelines; meningiomas; tumors.

Figure 1

Meningioma. A 52-year-old woman complained of tinnitus and right-sided hearing loss for 6 months. Enhanced axial T1-weighted MRI of the posterior fossa shows a 16- × 11- × 18-mm large, heterogeneous, sessile lesion. The lesion extended into the internal auditory canal, but did not widen it.

Figure 2

Meningioma. Same patient as in Fig. 1. Enhanced T1-weighted magnetic resonance image shows “dural tail sign.”

Figure 3

Epidermoid. A 55-year-old man complained of left-sided tinnitus and hearing loss for 2 years. He also experienced severe recurrent dizziness and chronic headache. Enhanced axial T1-weighted magnetic resonance imaging showed a large heterogeneous low-signal intensity tumor with no enhancement. The tumor was removed by the retrosigmoid approach.

Figure 4

Epidermoid. Same patient as in Fig. 3. T2-weighted magnetic resonance image shows an inhomogeneous high-intensity lesion.

Figure 5

Lipoma. A 28-year-old man was referred with a recurrent cyst in the left cerebellopontine angle. He complained of headache, left-sided hearing loss, dizziness, and vision and balance problems. He had a left-sided abducens palsy. Cyst removal had been performed three times previously, but after all operations a small tumor in relation to the cyst was visible on control magnetic resonance imaging. Unenhanced T1-weighted magnetic resonance imaging showed a large cyst in the left CPA and a hyperintense tumor in relation to the cyst and pons. The cyst and tumor were removed by the retrosigmoid approach.