Impact of unilateral facial nerve paralysis on nasal airway function.

Abstract

Nasal airway dysfunction in unilateral facial paralysis is underrecognized, and side-specific physiologic data in complete flaccid paralysis remain limited. This study characterized unilateral nasal airflow and mucosal function in complete unilateral facial nerve paralysis and explored associations with disease duration. Twenty-seven adults with complete unilateral facial paralysis were prospectively evaluated at a tertiary clinic (January 2025-January 2026). Assessment included unilateral peak nasal inspiratory flow (PNIF), nasal Schirmer testing, rigid endoscopy with validated nasal valve grading, photographic analysis, Cottle maneuver, and the Thai-NOSE scale. Paralyzed and nonparalyzed sides were compared. The cohort was predominantly female (74.1%; mean age 46.2 ± 14.5 years). Etiologies included tumor resection/radiotherapy (40.7%), trauma (25.9%), and Bell's palsy (14.8%); median paralysis duration was 36 months (IQR 11-144). The paralyzed side showed significantly reduced mucosal secretion (4.74 ± 4.75 vs. 8.37 ± 6.11 mm; p = 0.006) and PNIF (48.21 ± 28.09 vs. 61.17 ± 29.37 L/min; p = 0.005). Subjective obstruction was prevalent (81.5%), yet valve grading remained symmetric (internal p = 0.559; external p = 1.000). Longer paralysis duration correlated with nasal morphologic distortion (r = 0.420, p = 0.029) but not functional impairment (r = -0.010, p = 0.961). Complete unilateral flaccid facial paralysis produces side-specific reductions in nasal airflow and mucosal secretion undetectable by standard valve grading. Morphologic deformity progresses with disease duration, whereas physiologic impairment showed no significant association with the duration categories examined. Side-specific PNIF, nasal Schirmer testing, and validated symptom scores should be integrated into routine evaluation and reconstructive planning.