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.
Keywords: Bell’s palsy; cranial nerve; facial nerve; ultrasonography.