Even the most careful mode of extirpation of a vestibular schwannoma by the extended middle cranial fossa approach (subtemporal extradural) has its pitfalls. The authors describe two cases of the lateral variant of a tumour filling the inner auditory meatus, originating from the lower vestibular branch with caloric normoflexion in the ENG image. In the first case the preoperative hearing threshold was normal however without any response in the BERA tracing, with the temporal bone extremely pneumatized ending by postoperative deafness. In the second case the preoperative hearing was acceptable the V wave was, as compared with the sound side, delayed by 0.5 ms and the temporal bone lacked any pneumatization. Hearing was preserved at the preoperative level. The authors describe technical problems with which the surgeon must cope under these conditions and discuss prognostic factors which could influence the surgeon’s and patient’s decision as regards surgical intervention.

        Key words: vestibular schwannoma, extended middle fossa approach.