Unilateral Laryngoscopic Findings Associated With Response to Gabapentin in Patients With Chronic Cough.

Importance: Chronic cough is a debilitating, often multifactorial problem. Vagal neuropathy has been proposed as a cause for a fraction of these cases. There are certain features that support the clinical diagnosis of vagal neuropathy. It is hypothesized that patients with neurogenic cough who have vocal fold motion asymmetry (VFMA) on laryngoscopy will be more likely to respond to gabapentin.

Objective: To evaluate the association between the history, physical and videostroboscopic examinations, and clinical response to gabapentin.

Design, Setting, and Participants: In a retrospective cohort study, patients with chronic cough visiting an academic tertiary laryngology clinic from January 1, 2013, to September 1, 2015, were identified through International Classification of Diseases, Ninth Revision. Of those who had a chronic cough (>8 weeks), 27 patients who received a prescription for gabapentin were included. Patients without videostroboscopy, who did not complete voice therapy, or those without a follow-up examination more than 1 month from the initial evaluation were excluded. Initial history, physical and videostroboscopic examinations, and follow-up evaluations, were performed in a multidisciplinary laryngology clinic including a speech-language pathologist. Documented VFMA by a multidisciplinary team was decided by consensus after review of videostroboscopy recording at the time of the visit.

Main Outcomes and Measures: Response to gabapentin was defined by physician-documented subjective patient report of improvement in cough symptoms.

Results: Follow-up data were available on 25 of the 27 patients (15 [60%] women; mean [SD] age, 57 [11.8] years). Therapy was initiated in patients with chronic cough with gabapentin, 100 mg twice daily, which was titrated to response or adverse effects. The maximum daily dose was 1800 mg. Partial or complete response to gabapentin was noted in 16 (64%) patients. Vocal fold motion asymmetry was noted in 20 (80%) patients. Fifteen of 16 (94%) responders had VFMA compared with 5 of 9 (56%) nonresponders. The difference in the frequency of VFMA between responders and nonresponders was 38% (95% CI, 18%-58%). Adverse effects limited the gabapentin dose in 4 of 9 (44%) nonresponders and 4 of 16 (25%) responders (odds ratio, 2.5; 95% CI, 0.42-13.6).

Conclusions and Relevance: In patients with chronic cough suspected to be related to vagal neuropathy, the odds of response to gabapentin are higher with the presence of VFMA noted on videostroboscopy.