Endoscopy of the posterior fossa and dissection of acoustic neuroma.

Abstract

The authors evaluated the importance of endoscopes in eliminating the disadvantages of the posterior fossa approach, such as the lack of adequate visualization of the lateral aspect of the internal acoustic canal (IAC). Between 1989 and 1998, 32 patients underwent removal of acoustic neuroma (AN) via a combined retro-sigmoid-retrolabyrinthine approach. 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 in which a standard retrosigmoid-retrolabyrinthine approach was used. Standard sinus endoscopes of 0 degree, 30 degrees, 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 the AN and surrounding structures were evaluated. The IAC was inspected for residual tumor, and if any was found, endoscopically guided tumor dissection was performed. Endoscopes have facilitated an understanding of the anatomy between an AN and neighboring neurovascular structures. For surgery in which the posterior fossa approach is used, endoscopes can make operations safer by eliminating the disadvantages of the approach. In addition to allowing inspection of the fundus, it is possible to perform endoscopically guided tumor dissection within the IAC.