The Utility of Facial Nerve Ultrasonography in Bell’s Palsy

Objective This study aimed to investigate the utility of facial nerve ultrasonography in the functional and structural assessment of early‐stage Bell’s palsy and the prognostic value of facial nerve ultrasonography in Bell’s palsy. Study Design Prospective longitudinal study. Setting Single center, a university‐affiliated neurology clinic. Subjects and Methods Patients with unilateral Bell’s palsy who had visited our clinic within 3 days of symptom onset were enrolled in this study. Demographic information and House‐Brackmann grade were collected. Electrophysiologic studies and facial nerve ultrasonography were then performed. The facial nerves on each side were scanned longitudinally with a 5‐ to 12‐MHz probe. The diameter of the facial nerves with and without the sheath was measured at the proximal and distal portions. Follow‐up examinations, including House‐Brackmann grade analysis, electrophysiologic studies, and facial nerve ultrasonography, were performed after 2 months. Results Fifty‐four patients with unilateral Bell’s palsy were enrolled, and 22 underwent the follow‐up examinations. The diameters of the facial nerves were larger on the affected side than on the unaffected side at the proximal and distal portions ( P <. 01). On the affected side, the enlarged facial nerve at the proximal portion had decreased in size after 2 months ( P <. 05). The initial ultrasonography findings were positively correlated with the initial severity of Bell’s palsy, but they did not predict prognosis. Conclusion Ultrasonography could be a useful tool for evaluating the facial nerve in Bell’s palsy. Nevertheless, further studies are needed to demonstrate its prognostic value.