Injection Laryngoplasty on Cough Strength and Swallowing Safety in Treating Glottal Insufficiency

ImportanceGlottal competence and cough effectiveness are associated with aspiration. In unilateral vocal fold paralysis (UVFP), injection laryngoplasty (IL) is the mainstay treatment for those with dysphonia and dysphagia. However, few data exist explaining how IL exerts its effects on aspiration prevention.ObjectiveTo evaluate the effect of IL on voluntary cough strength, glottal closure, and swallowing function. Furthermore, the effects were compared between patients with active treatment/disease and those without.Study DesignProspective cohort study.SettingLaryngology clinic of single tertiary hospital.ParticipantAdult patients underwent IL for UVFP between January 2021 and April 2023.Main Outcome MeasuresMaximum volitional cough pressure (MCoughP) was quantified before and after IL, as well as clinical voice outcomes and normalized glottal gap area. For those with a complaint of aspiration, the Eating Assessment Tool (EAT-10) questionnaire and Penetration-Aspiration Scale (PAS) were also evaluated.ResultsForty-one patients were included (26M:15F; age range 32 to 80 years old, mean age 58.7). Clinical voice outcomes and glottal closure were significantly improved in all patients, as well as EAT-10 score (16.22 ± 11.83 at pre-IL and 10.83 ± 11.17 at post-IL, P = .008) and PAS [2 (IQR 1.25, 2) at pre-IL and 1 (IQR 1, 2) at post-IL with 20 mL bolus, P = .02; 2 (IQR 2, 4) at pre-IL and 2 (IQR 1, 2) at post-IL with cup-sipping, P = .007]. Twelve patients had ongoing treatment/systemic diseases, who had significant improvement in voice and glottal closure but not in PAS. MCoughP was significantly increased in ongoing treatment/systemic diseases (-) group [42.90 ± 20.17 cmH₂O at pre-IL, 51.33 ± 21.15 at post-IL, 95% CI (-16.63, -0.23), P = .04] but decreased in ongoing treatment/systemic diseases (+) group [67.98 ± 40.06 cmH₂O at pre-IL, 55.32 ± 31.68 at post-IL, 95% CI (1.37, 23.97), P = .03].Conclusions and RelevanceIL significantly improved glottal competence and voice outcomes. However, increased volitional cough pressure and improved swallowing safety were only demonstrated in patients without ongoing treatment or systemic diseases. Patient's general condition may contribute to the observed effect of IL on dysphagia. Rehabilitation to optimize cough strength and prevent aspiration is beneficial for patients with deteriorating general conditions.