Superior Laryngeal Nerve Block Response Rates in 54 Neurogenic Cough Patients

Abstract

ObjectiveNeurogenic cough related to hypersensitivity of the internal branch of the superior laryngeal nerve (SLN) is often treated with neuromodulating medications, which can cause considerable side effects. An alternative therapy is steroid and local anesthetic injection of the SLN (“SLN block”), initially proposed to benefit those with lateralizing symptoms (tenderness over the thyrohyoid membrane or unilateral cough source). Our objectives are to determine if SLN block produces subjective symptomatic improvements and if repeat injections further improve symptoms, and evaluate clinical factors potentially predictive of response.MethodsRetrospective chart review of 54 patients receiving SLN blocks at a tertiary medical academic center from January 2010 to June 2020. Medical history and anticipated predictors of positive response, including stigmata of laryngeal hypersensitivity, were recorded. Outcomes included symptomatic response, number of injections required, and side effects. Response was defined subjectively by asking patients whether the injection was beneficial and objectively by using CSI scores.ResultsFifty‐four patients met the inclusion criteria. Thirty‐eight patients (70.4%) endorsed improvement. No variables were identified as positive predictors of response. Thirty‐two of the 38 (84.2%) endorsed improvement after one injection. Six of 15 (40%) patients who failed the first injection had positive response to the second. No significant side effects were reported.ConclusionNo localizing symptoms, specific cough features, or aspects of the medical history helped predict response, suggesting that a broader range of patients may be offered the intervention. The majority of patients reported symptomatic improvement and repeat injections may benefit patients with initial nonresponse.Level of Evidence4 Laryngoscope, 133:2647–2653, 2023

The Impact of Medical Comorbidities on Cough Improvement Following Superior Laryngeal Block

“…8,14 In 2018, Simpson et al 14 demonstrated significant improvement in cough in a cohort of 23 patients treated with iSLN blockade using a combination of local anesthetic and corticosteroid. Since then, similar results have been reported by several groups, 8,15 -17 and iSLN blockade has been shown to be effective in reducing Cough Severity Index (CSI) scores as long as 10 months post-procedure. 18 While these studies have largely characterized iSLN blockade as safe and efficacious, there is currently a lack of consensus on whether patients might differentially benefit from iSLN block.…”

“…18 While these studies have largely characterized iSLN blockade as safe and efficacious, there is currently a lack of consensus on whether patients might differentially benefit from iSLN block. Duffy et al, 15 for example, found that only patients with vocal fold abnormalities had a statistically significant improvement in short-term CSI score after iSLN block, while Talbot et al 16 found no positive predictors of response to iSLN blockade in a cohort of 54 patients. Thus, more work remains to thoroughly characterize which patients will benefit most from iSLN blockade.…”

Efficacy of Botulinum A Injection to the Laryngeal Adductor Compartment for Treatment of Cough

“…SLN block for CC is more recently described with reduction in CSI scores greater than 10 in several studies 13‐18 . Two of these studies, however, excluded patients with medical comorbidities that could account for cough.…”

“…Superior laryngeal nerve (SLN) block via lidocaine and corticosteroid injection conceptually reduces neuroinflammation in the laryngeal afferents and has shown efficacy for cough reduction with minimal side effects. [13][14][15][16][17][18] Percutaneous onobotulinumtoxinA (BTxA) injection to the TA/LCA has also been described as effective. [19][20][21] Similarly, transendoscopic supraglottic BTxA injection to the false vocal folds has shown favorable results.…”

The Therapeutic Landscape in Chronic Cough

“…The experience of superior laryngeal nerve block by the injection of local anaesthetic agents and corticosteroids has been described retrospectively following implementation in several clinics [ 38 – 40 ]. Recently, a small single-blind placebo-controlled study was performed comparing this treatment in 10 patients injected with active treatment and 7 with placebo, finding improvements in cough VAS and LCQ scores.…”