Characteristics of Nonidiopathic Occult Lesions Causing Facial Paralysis Compared With Bell’s Palsy

Introduction: Occult lesions involving the facial nerve, such as cranial nerve schwannomas and parotid gland tumors, may be misdiagnosed as idiopathic facial paralysis or Bell’s palsy. Our goal was to characterize clinical features and diagnostic findings of patients with idiopathic/viral etiologies vs non-idiopathic, occult etiologies of facial paralysis (FP).

Methods: The records of 276 patients referred for surgical management of FP at two major academic institutions were reviewed retrospectively. Of them, 40 patients with traumatic, iatrogenic, or congenital etiologies were excluded.

Results: A total of 176 patients had idiopathic/viral etiologies of FP and 60 patients had non-idiopathic etiologies of FP, including malignancies (50/60), benign neoplasms/nerve sheath tumors (8/60), and systemic/CNS disorders (2/60). Non-idiopathic causes of FP were 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 therapy to steroids and/or antiviral medications (71.4% vs 28.7%; p < 0.01). Past medical history of skin cancer (36.4% vs 7.26%; p < 0.01) and salivary gland cancer (23.3% vs 0.57%; p < 0.01) were also more common in patients with non-idiopathic FP. Rates of facial pain, numbness, paresthesias/dysesthesias, hearing loss, and vertigo did not differ significantly between the groups. Dysgeusia (2.78% vs 12.2%; p = 0.04) was more frequently associated with idiopathic/viral FP. 9/60 (15%) patients with non-idiopathic FP experienced a diagnostic delay of greater than 6 months.

Conclusions: Facial paralysis that is gradual onset (>72 hours), progressive, irreversible/flaccid, and does not respond to medication therapy should be further evaluated for occult neoplastic and systemic/CNS causes. It is especially critical to evaluate patients with history of skin cancer or salivary gland cancer for malignant lesions. Associated cranial neuropathies may be less important than characteristics of FP and patient past medical history in identifying occult facial nerve lesions.