A Multi-Institutional Review of Characteristics of Idiopathic Versus Non-Idiopathic Facial Paralysis.

Objective: Occult lesions involving the facial nerve can be misdiagnosed as idiopathic facial paralysis, also known as Bell's palsy. Our goal was to compare the clinical features of patients with idiopathic/viral versus non-idiopathic facial paralysis and identify predictors of malignant etiologies.

Methods: Retrospective chart review of 276 patients referred for surgical management of facial paralysis at two large facial nerve tertiary care centers.

Results: A total of 176 patients had idiopathic/viral facial paralysis (IFP) and 60 patients had non-idiopathic facial paralysis (non-IFP), including malignancies (50/60), benign neoplasms/nerve sheath tumors (8/60), and systemic/CNS disorders (2/60). Non-IFP was more likely to be characterized by gradual onset (57.4% vs. 10.3%; p < 0.01), progressive course (65.0% vs. 19.8%; p < 0.01), irreversible flaccid paralysis (41.7% vs. 10.4%; p < 0.01), and lack of response to medication therapy (71.4% vs. 28.7%; p < 0.01). A past medical history of skin cancer or pre-cancerous lesions (36.4% vs. 7.26%; p < 0.01) and salivary gland cancer (23.3% vs. 0.57%; p < 0.01) were also associated with non-IFP. Epiphora/tearing, facial pain, and facial numbness were associated with malignant FP. 14/60 (23%) patients with non-IFP experienced a diagnostic delay of greater than 6 months.

Conclusion: Facial paralysis that is gradual onset (> 72 h), progressive, without synkinesis, and unresponsive to medications should be further evaluated for nonidiopathic causes. Malignant lesions may be associated with other symptoms such as facial pain, facial numbness, and epiphora/tearing. Also consider malignant causes of FP in patients with a history of skin or salivary gland cancer.

Level of evidence: 3: