Introduction: Chronic refractory cough is defined as cough lasting greater than 8 weeks and with an unclear etiology. Blockade of the internal branch superior laryngeal nerve (iSLN) has been shown to be safe and effective in the treatment of chronic cough. It remains unknown, however, if underlying comorbidities impact patient response to iSLN blockade.
Methods: A total of 44 patients aged 18 years and older were seen at our institution's Laryngology clinics between 2019 and 2022 and treated with iSLN blockade. Patient demographics, comorbidities, and pre- and post-treatment cough severity index (CSI) scores were collected from electronic medical records. Two-tailed independent T tests were used to compare CSI scores between groups with and without 4 underlying comorbidities: GERD, pulmonary history, smoking history, and evidence of vocal fold paresis or asymmetry on stroboscopy.
Results: Patients with a history of GERD or smoking and those with evidence of glottic insufficiency had similar improvements in CSI compared to those who did not (22.5 ± 26.4 vs 45.0 ± 47.1, P = .36; 32.7 ± 27.8 vs 29.0 ± 38, P = .85; 41.3 ± 18.8 vs 27.2 ± 37.7, P = .195). Patients with underlying pulmonary conditions had a significantly reduced response to iSLN blockade than did patients without underlying disease (9.85 ± 15.0 vs 47.4 ± 38.1, P = .028).
Conclusion: Underlying lung pathology may contribute to decreased iSLN blockade efficacy in the treatment of chronic refractory cough from laryngeal hypersensitivity and its treatment is likely necessary for optimal symptom reduction. Characterizing patient comorbidity profiles can help guide patient counseling on expected treatment efficacy.
Keywords: comorbidities; laryngeal hypersensitivity; nerve block; refractory cough; superior laryngeal nerve.