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.