Transcanal surgery for vestibular schwannomas: a pictorial review of radiological findings, surgical anatomy and comparison to the traditional translabyrinthine approach

The most popular approaches for vestibular schwannoma (VS) removal are retrosigmoid, middle cranial fossa and translabyrinthine (TL). All require a certain degree of invasivity, bone removal, or brain manipulation. Recently, the authors described the transcanal transpromontorial approaches (TTA), which allow the inner ear to be accessed directly through the external auditory canal (EAC), either with a microscopic (Expanded TTA, or ExpTTA) or even an exclusive endoscopic technique (Endoscopic TTA, or EndoTTA). The advantages compared to traditional approaches are a direct view of the internal auditory canal (IAC) from lateral to medial, very little or no superficial tissue dissection and very little petrous bone drilling. In summary, from an anatomical point of view, they could be considered to be minimally invasive approaches. The radiologic outcome and the anatomical correspondence of these new approaches are described so as to share with the readers the possible radiologic findings and to compare and differentiate them from classic transpetrous approaches such as the TL approach. LEVEL OF EVIDENCE 4.