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In Vivo Morphometric Analysis of Human Cranial Nerves Using Magnetic Resonance Imaging in Menière's Disease Ears and Normal Hearing Ears
Published on: February 21, 2018
Radiologic detectability and anatomic course of Arnold's nerve on temporal bone HRCT: A cross-sectional study
Masato Suzuki1, Makiko Obara2, Iori Kusaka1
1Department of Otolaryngology-Head-Neck Surgery, Iwate Medical University School of Medicine, 2-1-1 Idai Dori, Yahaba, Iwate, 028-3695, Japan.
Summary
High-resolution CT can detect the auricular branch of the vagus nerve (ABVN) within the temporal bone in a significant minority of patients. Its course relative to the chorda tympani is classifiable, aiding surgical planning.
Area of Science:
- Radiology
- Anatomy
- Neuroscience
Background:
- The auricular branch of the vagus nerve (ABVN), also known as Arnold's nerve, plays a role in auricular vagus nerve stimulation.
- Understanding its intraosseous course within the temporal bone is crucial for surgical interventions and interpreting stimulation outcomes.
Purpose of the Study:
- To assess the radiologic detectability of the ABVN on temporal bone high-resolution CT (HRCT).
- To classify the ABVN's course relative to the chorda tympani.
- To analyze age- and sex-related distributions of the ABVN.
Main Methods:
- Retrospective review of 1854 temporal bone HRCTs from 958 patients (2019-2023).
- Defined ABVN positivity by a continuous osseous canal from the jugular fossa to the tympanomastoid fissure, crossing the facial canal.
- Classified ABVN course (Types A-C) based on crossing height relative to the chorda tympani.
Main Results:
- The intraosseous ABVN was identified in 13.8% of ears (255/1854).
- Detection rates were similar between sexes (14.0% males, 13.5% females) and higher in adults (15.3%) vs. <20 years (8.7%).
- Courses were classified as Type A (40%), Type B (59%), and Type C (1%); mean measurements to surgical landmarks were recorded.
Conclusions:
- Temporal bone HRCT can delineate an intraosseous ABVN in a clinically relevant proportion of individuals.
- A classification system based on the chorda tympani relationship provides reproducible anatomical data.
- This classification may enhance preoperative planning for procedures involving the ABVN and improve the interpretation of auricular vagus stimulation outcomes.
