Diagnostic Delay of Unilateral Facial Paralysis Caused by Occult Malignancy: A Scoping Review

OBJECTIVE: This scoping review aims to evaluate the clinical characteristics, diagnostic challenges, and histopathology of unilateral facial paralysis due to occult malignancy. DATA SOURCES: A systematic search of EBSCO and Embase databases was performed. REVIEW METHODS: Studies reporting patients with unilateral facial paralysis initially associated with negative work-up or diagnostic delay and ultimately attributed to biopsy-proven malignancy of the facial nerve were included. Two reviewers independently screened titles, abstracts, and full texts, with disagreements resolved by a third reviewer. Clinical features, imaging study quantity and type, diagnostic delay, method of tissue acquisition, malignancy type, and cancer history were retrieved. RESULTS: Twenty-seven studies, comprising 66 patients, met inclusion criteria. All studies were case series or case reports. The mean patient age was 62 years (range, 33-89), and 76% were male. All patients presented with progressive facial paralysis. Trigeminal symptoms were reported in 35 cases (53%), and additional cranial nerve involvement in 15 cases (22%). The mean diagnostic delay was 21 months (range, 1-180). MRI was the most common imaging modality (54%). Surgical biopsy was utilized for diagnosis in 76% of patients. Squamous cell carcinoma was the most common malignancy (38%), frequently associated with prior regional cutaneous disease. CONCLUSION: Occult malignancy is a rare but clinically significant cause of unilateral facial paralysis and is frequently associated with prolonged diagnostic delay. Progressive paralysis, lack of recovery, trigeminal symptoms, additional cranial neuropathies, or a history of skin cancer should prompt repeat imaging and consideration of biopsy, even in the setting of negative initial imaging. LEVEL OF EVIDENCE: N/A.