Perineural Invasion of the Facial Nerve Presenting as Rapid-Onset Excruciating Facial Pain and Paralysis

Objective: This case report describes an 82-year-old female presenting with sudden onset, total right-sided facial paralysis, later diagnosed as metastatic squamous cell carcinoma (SCC) with perineural invasion of the facial nerve. The case highlights the diagnostic challenges of facial paralysis with associated pain in elderly patients and underscores the importance of recognizing subtle imaging findings suggestive of malignancy. Methods: A retrospective review of the patient’s clinical presentation, imaging studies, surgical intervention, and pathological findings was conducted. Results: The patient developed right-sided facial paralysis ten months prior to presentation, followed by progressive hearing loss, imbalance, and excruciating facial pain. Initial treatment, including intratympanic dexamethasone injections, failed to alleviate symptoms. Examination revealed a central tympanic membrane perforation, complete flaccid facial paralysis (House-Brackmann grade 6), and sensorineural hearing loss. Imaging showed subtle widening of the labyrinthine segment of the right facial nerve and geniculate ganglion on CT, with corresponding enhancement and a filling defect in the internal auditory canal (IAC) on MRI. The differential diagnosis included facial nerve schwannoma, hemangioma, atypical Ramsay Hunt syndrome, and metastatic SCC. Imaging findings prompted surgical biopsy via a transcanal endoscopic approach, which confirmed metastatic SCC. Despite targeted radiation therapy, the patient developed failure to thrive, transitioned to hospice, and passed away. Conclusion: This case emphasizes the need for thorough evaluation of atypical facial paralysis, particularly in elderly patients with a history of cutaneous malignancy. The presence of facial pain, progressive hearing loss, and imaging abnormalities should prompt consideration of perineural tumor spread. Early recognition and multidisciplinary management are critical for timely intervention and improved palliative care outcomes.