A systematic review on the role of the endoscope in the surgical management of cerebellopontine angle tumors: is it time to draw the conclusion?

Objective: The use of the endoscope has brought major changes in skull base surgery in the last decades. In the cerebellopontine angle (CPA), it has shown few advantages over microscopic surgery alone, evolving towards a full-endoscopic surgery for neurovascular conflicts and tumors. This review aims to systematically analyze the literature about the use of the endoscope in the cerebellopontine angle tumors. Methods: Pubmed/Medline and Embase databases were investigated applying PRISMA guidelines without time restrictions to find all adult patients affected by an extra-axial cerebellopontine angle tumor (vestibular schwannoma, meningioma, epidermoid tumor, or other extra-axial lesions) treated using only the endoscope (full-endoscopic, FE or endoscopic-controlled, EC) or with endoscopic assistance (EA). Results: After article selection, a total of 2489 patients have been treated for a CPA lesion using the endoscope: 2054 vestibular schwannomas (VS), 368 epidermoid tumors (ET), 41 meningiomas and 26 among other pathologies. The retrosigmoid approach was the most frequently employed surgical corridor, irrespective of lesion type, for both full-endoscopic and endoscopic-assisted procedures. Although a great heterogeneity should be highlighted among the selected series of VS (1539), a weighted average of 92.5% of gross total resection (GTR) was obtained and 90% out of 1332 showed a good facial nerve outcome when comparable. Advantages in term of recognition of residuals have been described for the CPA meningiomas and multicompartmental epidermoid tumors with origin from CPA cistern, without increasing the risk of complications. Conclusions: Despite different accepted advantages, the number of tumors in which the endoscope has been included among the surgical armamentarium is still limited compared to the number of the full-microscopic resections. After almost 30 years since its value was recognized, the number of prospective and case-control studies is still scarce to affirm a real benefit leading to its routinary use.