gms | German Medical Science

Objective: Epidermoid tumors grow along the subarachnoid spaces within the cerebellopontine angle (CPA) around neurovascular structures and often extend through reaching the contra-lateral side and/or Meckel’s cave to the middle cranial fossa. The endoscope assisted microscopic technique is used in such lesions with different implementations varying from simple inspection reaching bi-manual excision under endoscopic visualization. The aim the study is to determine the degree of benefit of the use of the microscope and/ or the endoscope with their various implementations with evaluating additional value of the endoscope-assisted microsurgical technique.

Method: All data of the cranial procedures performed in our institute between the years 1998-2013 to manage skull base epidermoid cysts were checked.19 procedures were performed to manage 15 patients with skull base epidermoid tumors in the CPA and the temporomesial regions. In four patients, two-staged procedures were performed to totally excise extensive tumors. All cases were operated upon by the senior neurosurgeon in our institute, as the decision to use the endoscope as an assistant tool intraoperatively was dependent on the surgeon’s preference in accordance to the essentiality of using both microscope and endoscope for better orientation and visualization in each procedure.

Results: Average follow-up period was 65 months. The two-staged surgeries were of 6 months interval in 3 cases. Endoscope-assisted microsurgery was implemented in 16 out of the 19 procedures (84.2%), microscopic in two and merely endoscopic in one procedure.The tumor was totally excised in 11 out of 15 patients. In three cases, a minimal residual (1-3%) was found upon follow-up with stationary course. One case complicated postoperatively with a thalamic hematoma. Temporary facial paresis in two cases and Abducent paresis in one case were detected postoperatively and improved upon follow-up.

Conclusions: The endoscope, with its wide-scale visualization provide a better orientation that may not be available with the microscope, while microscopic three dimensional image allows better dissection. In this series, the use of the endoscope as an assistant tool to the microscope was essential in 84.2% of all cases studied with a favorable outcome. The bi-manual tumor excision was found helpful for better excision of CPA tumors extending through the Meckel’s cave. Staged surgery is helpful in managing extensive tumors with two different approaches for easier accessibility.