Clinical Implication of Magnetic Resonance Imaging in Bell's Palsy

Lee, Ho Ki; Moon, Sang Woo; Lee, Jeong Joon; Choi, Jae Young; Kim, Tae Man; Kim, Seong Gook; Yoon, Poeyng Ho

Abstract

BACKGROUND AND OBJECTIVES
Magnetic resonance imaging(MRI) with gadolimiun, an intravenous paramagnetic agent, shows non-enhancement of the cranial nerves in normal subjects. In the presence of inflammation or edema, gadolinium is absorbed into these tissues, resulting in enhancement on T1-weighted images. The purpose of this study was to evaluate the clinical implication of gadolinium-enhanced MRI in Bell's palsy.
MATERIALS AND METHODS
From 1994 to 1998, 19 patients with Bell's palsy were evaluated to assess the efficacy of gadolinium-enhanced MRI in determining the frequency, the site of facial nerve enhancement, and the relationship between electroneuronography(ENoG) findings and gadolinium-enhanced MRI. The data was compared to 40 patients with sudden sensorineural hearing loss who had temporal bone MRI.
RESULTS
On gadolinium-enhanced MRI, 16 of 19 patients had abnormal contrast enhancement of the facial nerve, but nobody had abnormal contrast enhancement of the facial nerve in the control group. In particular, facial nerve enhancement was identified in the distal portion of the internal auditory canal, geniculate ganglion, labyrinthine segment (n=10), tympanic segment (n=10), and mastoid segment (n=7) of the facial nerve. The facial nerve was enhanced more frequently in patients in whom the degeneration of ENoG was more than 50%. The facial nerve was more frequently enhanced in patients who had a higher House-Blackmann grade.
CONCLUSION
Gadolinium-enhanced MRI plays a important role in diagnosing Bell's palsy and in predicting the location of pathology of the facial nerve.