Efficacy of SLN Block for Chronic Cough

This is a research study to find out if superior laryngeal nerve blocks are an effective way to reduce cough when compared to placebo (a substance without any medical value). Eligibility for the study include the following: age \>18, cough history suggestive that the nerve to the voice box is overactive, non-smoker, Patients will be followed over time and assigned to either the treatment or placebo group at random. The treatment would be four superior laryngeal nerve blocks and the placebo would be four saline injections (the inactive substance). Study team will measure if the injection improved cough and ask patients to keep a log of symptoms and fill out questionnaires at each visit. After the four injections, patients will follow up in 3 months to see if cough has returned and if so, how severe the cough is.