Meatal Ganglionitis: Clinical Pathologic Correlation in Idiopathic Facial Paralysis (Bell’s Palsy)

<i>Hypothesis:</i> Present evidence which supports the concept that inflammation of the facial nerve (FN) meatal ganglion (MG) is the site of virus accumulation in idiopathic facial paralysis (IFP). <i>Materials and Methods: </i>Four bodies of evidence are used to support the hypothesis. (1) A case report of a 51-year-old female with left IFP is representative of a series with 5 patients who were monitored with MRI. Sequential MRI of the FN at 1, 8 and 15 weeks after onset of IFP monitored the inflammatory process in the FN. (2) A human temporal bone (TB) taken from an 81-year-old female who recovered from IFP 3 years before death was examined in the light microscope. (3) Eleven reports of MRI in patients with IFP were reviewed. (4) The data from 2 human TB studies describing the MG in normal and abnormal FN are summarized. <i>Results:</i> (1) The MRI of the FN in the majority of imaging reports of patients with IFP demonstrated enhancement of the meatal segment of the FN as the earliest focus in IFP. (2) The meatal FN segment was the earliest site of enhancement in our series of 5 patients with IFP. (3) The TB from the patient who recovered from IFP demonstrated degenerated cells in the MG and degeneration of vestibular neurons innervating cristae. (4) TB studies describe the occurrence of the MG in human FN. In the majority of FN (80%), the MG is represented by a smaller ganglion than the geniculate one. However, the MG equals or exceeds in size the geniculate ganglion in 20% of TB. A second TB study demonstrated ganglion cell lesions consistent with virally induced pathology in the MG and vestibular nerve (and ganglion) in a high percentage of TB. <i>Conclusions:</i> Clinical, radiologic and anatomical evidence supports meatal ganglionitis as a pathologic correlate in IFP.