Endoscopy of the posterior fossa and endoscopic dissection of acoustic neuroma.

The objective of this study was to evaluate the importance of endoscopes in eliminating the disadvantage of posterior fossa approach-that is, the lack of adequate visualization obtained of the lateral aspect of the internal acoustic canal (IAC). Over a 10-year period 32 patients underwent removal of acoustic neuroma (AN) via a combined retrosigmoid retrolabyrinthine approach (CRSRL). Endoscopes were used at different stages of the operation, and their use was evaluated with regard to elimination of the disadvantages of the posterior fossa approach. All patients in whom AN had been diagnosed underwent surgery. A standard combined retrosigmoid retrolabyrinthine approach was performed. Standard sinus endoscopes of 0, 30, and 70 degrees were introduced into the cerebellopontine angle before debulking the tumor, and the IAC was inspected at the end of the operation. Neurovascular integrity as well as the relationship between AN and surrounding structures were evaluated. The IAC was inspected for residual tumor, and if any was found, endoscopic tumor dissection was performed. Endoscopes have facilitated the understanding of the relationship between AN and neighboring neurovascular structures. The disadvantage of posterior fossa approach can be eliminated by using endoscopes. In surgery in which the posterior fossa approach is performed, endoscopes can be used to make operations safer. In addition to allowing inspection of the fundus, it is possible to perform tumor dissection within the IAC by using the endoscopes.