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

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.

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

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.

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.