Extra-axial cavernoma (EAC) at the cerebellopontine angle (CPA) is a rare clinical entity that can mimic radiologically several lesions encountered at this location. We report a case of EAC-CPA and present a review of the literature.
A PubMed research was conducted looking for EAC-CPA lesions described in literature. After reviewing all the relevant articles, the following data were extracted and organized into a single table: patients' symptoms, radiological characteristics, surgical procedure, histopathology, and outcome.
Eighteen cases (including ours) were identified from these reports. Mean age at diagnosis was 42 with a male:female ratio of 2.6:1. The most commonly involved cranial nerves were the vestibulocochlear complex followed by the trigeminal nerve. The lesions were iso-to hypodense on computed tomography. On magnetic resonance imaging, the EAC-CPA can be solid or cystic. All lesions were approached using retrosigmoid craniotomies. Histologically, both intra- and extra-axial cavernomas are identical, consisting of devoid vascular sinusoids with endothelial lining. The outcome was favorable in 16/18 of the described cases. One case presented a worsened facial paresis and 1 patient died from excessive intraoperative bleeding and subsequent complications.
Despite the fact that EAC-CPA are rarely encountered, it should be kept in mind in the list of differential diagnosis, preparing both the surgeon and anesthesiologist for the surgery of a vascular lesion. Specific radiological features, especially an associated developmental venous anomaly could point to the diagnosis.