Sonography of the extratemporal facial nerve

Introduction:

The technical advances in sonography enable the visualization of peripheral nerves. The possibility of visualizing the facial nerve (FN) has been considered, but not jet proven scientifically. This study describes the first systematic evaluation of the whole extratemporal facial nerve.

Methods:

8 cadaveric hemifaces were evaluated by means of high frequency ultrasound with two linear (13 MHz and 22 MHz) and a convex transducer (6.6 MHz), in order to detect the extratemporal course of the FN starting from its exit at the stylomastoid foramen: the main trunk, the parotid plexus between the 2 parts of the parotid gland, the distal branches terminating into the orbicularis oculi and the zygomatic major muscle. Ultrasound-guided color injections and FN dissection were performed to confirm the results.

Results:

The main trunk of the FN, as it exits the stylomastoid foramen, was correctly stained in 6/8 cases, the parotid plexus in 8/8 cases. The branches innervating the orbicularis oculi muscle were stained in 7/7 and the branches innervating the zygomatic major muscle in 6/7 hemifaces, after 1 was withdrawn due to insufficient image quality.

Conclusions:

Through our novel approach of high-resolution ultrasonography we could identify the various portions of the extratemporal FN, including its main trunk leaving the stylomastoid foramen, in an accurate and reproducible way.

Publication History

Publication Date:
18 April 2018 (online)