Clinical and radiological findings of facial paralysis in multiple sclerosis

Background: Diagnosis of central or peripheral facial palsy (FP) is traditionally based on clinical evaluation. This study aims at investigating the relationship between clinical evaluation of FP and lesion location as visible on Magnetic Resonance Imaging (MRI) in patients with Multiple Sclerosis (MS) for the purpose of adding supporting evidence to the diagnosis of central or peripheral FP in these patients. Methods: A retrospective study was conducted on data from patients who underwent MS treatment between January 2016 and January 2019 at the MS Center of Wayne State University, MI, USA, and presented with at least one episode of FP during the observational period. The following data was collected from each patient: demographics, time from MS onset, side of FP, FP type (central or peripheral, as clinically evaluated), FP onset, FP treatment, amount of recovery of normal facial movements, time elapsed from beginning of FP treatment, number of FP recurrences, lesions presence/absence and location as visible on MRI. Correlation analysis was performed to assess to which extent clinical evaluation of FP correlated with presence of MRI lesions in different locations. Results: Eighteen patients were included in this study. In thirteen patients (72.2%) FP was classified as peripheral. Among them only five (38.4%) displayed one or more lesions in the pons. Correlation between presence of lesions in the pons and presence of peripheral FP was statistically significant (p=0.02). Correlation between presence of lesions in the cortex (observed in 61.5% of patients with FP clinically evaluated as peripheral) and presence of FP clinically evaluated as peripheral was also statistically significant (p=0.01). Finally, presence of lesions in the cortex was significantly correlated with presence of FP clinically evaluated as central (p=0.02). Conclusions: FP clinically classified as peripheral may be caused by central lesions in the cortex or pons and not only by peripheral facial nerve damage. In MS patients, FP may appear at the onset of the disease and be misdiagnosed as Bell ’s palsy. Clinicians should carefully approach FP diagnosis and perform a brain as well as temporal bone MRI before pursuing pharmacological treatment.