Voice Center

The Role of Bilateral Superior Laryngeal Nerve Block in Managing Refractory Chronic Cough

Refractory chronic cough is defined as a cough persisting longer than 8 weeks that has failed to resolve with medical management or behavioral therapy. Among patients who have undergone comprehensive workup in the effort to rule out aerodigestive, allergic, and neurologic sources for their cough, the etiology remains unclear. Possible mechanisms underlying the development of refractory chronic cough include neuronal hypersensitivity, which is characterized by an exaggerated cough response to mechanical, thermal, or chemical triggers. More specifically, hypersensitivity of the larynx resulting from post-viral damage to the internal branch of the superior laryngeal nerve (SLN) is thought to contribute to this disease process.¹ Developing theories of a neurogenic source have cultivated novel targets for the treatment of refractory chronic cough, such as the SLN block. Two prior studies have demonstrated effectiveness of a unilateral SLN block with a 1:1 mixture of long-acting corticosteroid and local anesthetic.² ³ Recently, 3 laryngologists at Cleveland Clinic’s Head & Neck Institute began offering bilateral SLN block as an option for treatment for these patients, largely utilizing a 1:1 mixture of Kenalog-40 and 1% lidocaine without epinephrine. Each patient had a thorough multidisciplinary workup before considering this treatment option.

Eighty-seven patients with refractory chronic cough underwent bilateral SLN block at Cleveland Clinic’s Voice Center between November 2018 and August 2021. Most patients had failed treatment for acid suppression and pulmonary contributions, as well as prior therapies including neuromodulators, tramadol, codeine, Tessalon Perles, steroids, behavioral cough suppression therapy, and Botox® injections. Following bilateral SLN block, 67 patients (78.8%) reported some improvement, and 18 patients (21.2%) reported no improvement. Patients were asked to assign a value for percent improvement in their cough, and on average, patients reported 57.3% improvement in their symptoms on initial review. In addition, patients reported that their cough improved for a duration of 4.7 weeks on average following injection. Notably, 3 patients had previously undergone unilateral SLN block at other institutions without success but had marked subjective improvement with this procedure utilizing the bilateral approach. Additionally, most patients received multiple injections following subjective improvement with initial injection. Each procedure was well tolerated. There were no immediate complications, but 3 patients who underwent multiple injections developed purpura and skin fragility on the upper extremities. Further study is needed to understand optimal dosing and frequency of injection.

References
  1. Altman KW, Noordzij JP, Rosen CA, Cohen S, Sulica L. Neurogenic cough. Laryngoscope. 2015 Jul;125(7):1675-1681.
  2. Simpson, CB, Tibbetts KM, Loochtan MJ, Dominguez LM. Treatment of chronic neurogenic cough with in‐office superior laryngeal nerve block. Laryngoscope. 2018 Aug;128(8): 1898-1903.
  3. Dhillon VK. Superior laryngeal nerve block for neurogenic cough: A case series. Laryngoscope Investig Otolaryngol. 2019 Jul 5;4(4):410-413.