How Long Could the Enhancement of Facial Nerve Last in Bell’s Palsy?

Abstract

Background: The brain magnetic resonance imaging (MRI) findings seen in patients with Bell's palsy are abnormal contrast enhancement of affected facial nerves. Previous evaluation included mainly patients who had experienced palsy for several weeks and there are no studies to date on patients with late stage of Bell’s palsy. This study investigated the findings of MRI of Bell's palsy after 3 months of symptom onset to assess how long the enhancement last.Methods: Among the patients with Bell's palsy (idiopathic unilateral facial palsy) who visited the hospital, 9 patients who underwent contrast-enhanced MRI of the internal auditory canal after 3 months of symptom onset were reviewed retrospectively. MRI examination results were investigated along with the patient's clinical symptoms and electrodiagnostic test results. Based on the MRI results, the frequency of abnormal contrast enhancement and contrast-enhanced areas were investigated.Results: 9 patients were included. 6 of them did MRI imaging because of incomplete recovery of facial palsy and the others did because of complication of facial palsy including synkinesis and hemifacial spasm. Time interval between symptom onset and evaluation was 17 months (3-84). Of 9 patients, 2 showed abnormal enhancement of affected nerve and they performed MRI after 5 months and 12 months of symptom onset, respectively.Conclusions: Abnormal enhancement of facial nerve in Bell’s palsy could last up to one year. This awareness can be helpful in interpretation of MRI of Bell’s palsy.