2025 Poster Presentations
P282: TYPE OF ENDOSCOPIC DRILL SHAFT DOES NOT PREDICT NASOSEPTAL FLAP NECROSIS.
Zechariah G Franks, MD, MPH; Vladimir A Ljubimov, MD, MS; Jayakar Nayak, MD, PhD; Michael C Chang, MD; Peter H Hwang, MD; Juan Carlos Fernandez-Miranda, MD; Zara M Patel, MD; Stanford University
INTRODUCTION: The nasoseptal flap (NSF) is the workhorse for reconstruction of complex skull base defects after endoscopic skull base surgery (ESBS), and flap necrosis increases the known risks of ESBS such as cerebrospinal fluid leak, meningitis, and death.?Several factors have been identified that increase rates of NSF necrosis but surgical technique and choice of instrumentation are not often or easily studied. Pressure on or manipulation of the flap pedicle during the case is hypothesized to compromise that blood supply. We aimed to study whether switching from an endoscopic high speed rotating shaft drill to an endoscopic high speed non-rotating shaft drill for resection of skull base bone would lead to a change in risk of necrosis.
METHODS: We performed a retrospective review of all the ESBS cases with NSF reconstruction of a single skull base neurosurgeon and four different rhinologists at our institution over a 4-year period comparing rates of flap necrosis when using a rotating shaft vs a non-rotating shaft drill.
RESULTS: In the first two years of the study, there were 143 NSFs with 6 necrotic flaps (4.2% rate) with the rotating shaft drill. In the latter two years, the non-rotating shaft drill was utilized exclusively and there were 187 NSFs and 6 necrotic flaps (3.2% rate). Although the overall ratio of necrosis to flaps raised was higher with the rotating shaft, when evaluated via chi squared analysis for statistical significance, they were not significantly different (p=0.63). The demographics and past medical history of the 12 patients with necrotic flaps were analyzed in aggregate and their average age was 49, 50% male, had an average BMI of 30, 58% were revision cases with history of prior ESBS tumor resection, 25% had a history of radiation therapy, 25% had a history of diabetes mellitus, and 50% had a history of hypothyroidism. Additionally, the pathology of these patients included 1 pituitary adenoma, 5 craniopharyngiomas, 2 chordomas, 1 chondrosarcoma, 2 meningiomas, and 1 trigeminal nerve schwannoma.
CONCLUSIONS: There are many perceived advantages to the new non-rotating shaft high speed endoscopic drills, but their use does not appear to significantly alter rates of NSF necrosis. Ultimately, this study highlights that NSF necrosis rates are low but present when skull base centers are doing extensive endoscopic dural openings. This is true even with robust otolaryngology and neurosurgery residency and fellowship programs. Higher powered studies are needed to differentiate what specific surgical technique and instrumentation risk factors may predispose to NSF necrosis, but are challenging to perform given the rapid evolution of ESBS. In our cohort of NSF flap necrosis patients, the more likely causes have to do with 1) patient factors that affect viability of NSF pedicles (high rate of previous ESBS), 2) increased risk of poor wound healing (higher rates of obesity, radiation, diabetes, and hypothyroidism), and 3) more complex skull base pathology.