Background Retromastoid transmeatal approach is currently the most commonly used surgical corridor
to remove vestibular schwannomas (VS) with intracanalicular extension. To expose this
component and intracanalicular portions of cranial nerves VII and VIII, posterior
wall of the internal auditory canal (IAC) needs to be drilled. Opened air cells of
the temporal bone following drilling the posterior wall of the IAC may lead to postoperative
leakage of CSF. The aim of this report is to highlight the importance of using endoscope
in management of the opened air cells at the posterior wall of the IAC.
Methods A consecutive series of 138 patients who received a retrosigmoid transmeatal microsurgical removal of VS (group A) was compared with a consecutive series of 33 patients who
received an endoscopic-assisted retrosigmoid transmeatal removal of VS (group B), in regard of postoperative CSF
fistula. In both groups, the drilled area of the IAC was closed at the end of surgery
with muscle and fibrin glue (group A) or with bone wax with or without muscle and
fibrin glue under direct endoscopic visualization (group B).
Results CSF fistula occurred in 16 out of 138 cases of group A (11.6%). In 15 of these 16
cases, CSF drainage was sufficient to treat the CSF leak, and one patient needed surgery.
Out of the 33 patients of group A, one patient developed CSF leak (3%) and needed
lumbar drain. No patient needed surgery. Closure of opened air cells with bone wax
under direct endoscopic view was able to reduce the risk of CSF leak from 11 to 3%
in this comparative retrospective series.
Conclusion Endoscopic guidance allows a detailed insight in the anatomy of the internal meatus
down to its fundus. It is helpful in the identification of exposed cells which are
missed with operating microscope, and it also improves closure of the cells thus decreasing
the risk of CSF fistula.
