Post - Operative Facial Nerve Preservation after Vestibular Schwannoma (vs) Resection: A Comparative Meta-Analysis of Endoscopic vs. Open Resection Surgery

Introduction: At the beginning of the last century, surgeons were content when they merely managed to save the life of the vestibular schwannoma patient. During the last few decades, the remarkable improvement in technology has shifted the focus to facial nerve preservation and preservation of serviceable hearing; and to the target of gross total tumor removal.

Objectives: To determine whether patient outcomes and complications differ depending on surgical approach of either endoscopic or open resection methods for the removal of Vestibular Schwannoma. The primary Outcome is to determine the rate of facial nerve preservation or injury between two approaches. Other outcomes such as rate of GTR and hearing preservation had been looked as secondary outcome.

Methods: Pubmed review for all papers about vestibular schwannoma from 1996 to 2011

Inclusion Criteria:

• Case series with > 20 adult patients

• Endoscopic or open resection

• Retrosigmoid incision and craniotomy

• Adult patients

• English language.

Exclusion Criteria:

• Studies describing other approaches: eg: translabyrinthine, middle fossa

• Animal, cadaver, and basic science studies

• Studies don't address the primary outcome, i.e: facial nerve function

• Comparative studies.

We use House and Brakman classification for facial nerve outcome, and divided the analysis to the following: grade 1 and 2 is good, 3 and 4 moderate, and 5 and 6 bad. In regard hearing outcome, We include “serviceable” and “some” i.e PTA less than 80 db and speech discrimination more than 20%, in one group, we call it functional or meaningful hearing. Two independent reviewers review all articles, by title and abstract first, then the whole article if need. We assumed that there is between-study heterogeneity due to the limitations inherent in the nature of the study design as being case-series. Percentages with 95% confidence intervals are reported

Results: We found 1861 articles. Both observers (AA and MA) excluded 1730 articles, and both of them included 44 articles. The disagreement was the flowing: AA excluded and MA included 53 articles, and AA included and MA excluded 32 articles. After review and discussion with the senior author (KR), we end up including 25 articles: 4 endoscopic and 21 open. The total population of patients was: 3026 for open, 790 for endoscopic.

A summary of the results is in the table:

Outcome measure	Open surgery % (95% CI)	Endoscopic surgery % (95% CI)
Weighted mean tumor size	2.5 cm	2.7 cm
Facial nerve outcome: Good	67.0% (61–73%)	94% (92–95%)
GTR	91% (80–98%)	97% (92–99%)
cochlear nerve: functional hearing	22.6% (10.4–37.6%)	46% (38–54%)
CSF leak	8.2% (4.8–12.3%)	4.6% (2.3–7.2%)
Wound infection	1.3% (0.6–2.3%)	2.6% (1.5–4.0%)
Recurrence	5.4% (1.8–10.1%)	2.2% (1.3–3.4%)
Death	0.9% (0.3–2%)	0%

Conclusions: We acknowledge the limitation of our study, but at least we can say: endoscopic is not inferior to standard open approach. With expert hand; endoscopic can offer result as good as open, with potential benefits, such as: less pain and shorten length of stay in hospital. There is a need for more control studies for definitive comparison.