Introduction: Microsurgical resection of vestibular schwannomas (VS) poses a significant risk of
injury to cranial nerve VII (facial nerve), which can have substantial negative impact
on patients’ quality of life. Facial nerve preservation is therefore an important
goal of surgery. However, facial nerve outcomes remain challenging to prognosticate,
largely due to a paucity of reported relevant predictive factors.
Objective: We endeavored to design a machine learning algorithm to decipher predictive factors
relevant to facial nerve outcomes following microsurgical resection of VS.
Methods: We constructed a database of patient-, tumor- and surgery-specific features via retrospective
chart review of 138 consecutive patients who underwent microsurgical resection of
VS between 2018 and 2021. This database was then used to train nonlinear supervised
machine learning classifiers to predict facial nerve preservation, defined as House-Brackmann
(HB) I versus facial nerve injury, defined as HB II–VI, as determined at 6-month outpatient
follow-up.
Results: Among the factors evaluated, only age demonstrated a statistically significant association
with facial nerve outcome by independent t-test (mean age: 51.46 functionally preserved vs. 57.35 injured, difference 5.89:
years, 95% CI: 0.7727–11.0073; p = 0.0339). A random forest classifier demonstrated the highest accuracy (85.7%) amongst
algorithms tested for prediction of facial nerve injury, with a sensitivity of 80%
and specificity of 90.1%. We identified age, body mass index (BMI) and intracanalicular
tumor extension as novel prognosticators of facial nerve injury. Importantly, these
same factors were identified when the algorithm was retrained according to facial
nerve status at most-recent follow-up.
Conclusion: Here, we describe the development of a machine learning algorithm to predict the
likelihood of facial nerve injury following microsurgical resection of VS. In addition
to itself serving as a clinical tool, the factors identified can be further developed
as a clinical scoring system for prospective facial nerve prognostication in VS microsurgery.