Function-saving microsurgery in suboccipital removal of large acoustic neuromas

Various successful approaches are available for acoustic neurinoma surgery, permitting total tumor removal and preservation of cranial nerve function. In smaller and medium sized tumors excellent results can be achieved with respect to facial and cochlear nerve function using the transtemporal approach. For larger tumors similar results can be achieved by the suboccipital approach. The results of 45 completely removed large acoustic neurinomas all operated upon via the suboccipito-lateral approach with microsurgical techniques and neurophysiological monitoring are presented. The average tumor size, excluding the portion within the internal auditory canal was 3 cm. Anatomical preservation of the VIIth cranial nerve was achieved in nearly all cases. Satisfactory to excellent facial nerve function was preserved in 70% of all cases. Initial hearing was preserved in 29%. However delayed postoperative hearing loss was encountered in 13%. Therefore definite hearing preservation was achieved in 16% of the cases. Intraoperative monitoring, especially of auditory evoked potentials, was very helpful in achieving these functional results.