Longitudinal Follow-up of Superior Laryngeal Nerve Block for Chronic Neurogenic Cough

Outcomes of a step-up approach to the treatment of neurogenic cough

INTRODUCTION

Neurogenic cough (NC) is thought to be related to sensory neuropathy in the hypopharynx and larynx. Defined as a cough persisting longer than 8 weeks refractory to standard therapy, it is a diagnosis of exclusion when other common etiologies (asthma, gastroesophageal reflux disease (GERD), medication side effects) are ruled out. It affects roughly 11 % of Americans and can negatively impact quality of life.

METHODS

Following institutional review board approval, we evaluated the medical records of adult patients seen at the University of Arizona's tertiary laryngology center from 2018 to 2023. Patients were included if their cough persisted for >8 weeks, and they either did not respond to prior proton pump inhibitor and asthma therapy or had GERD and asthma ruled out. These patients underwent a progressive escalation of therapy, which included neuromodulators with or without cough suppression therapy, superior laryngeal nerve (SLN) block, and laryngeal botulinum toxin injections. The primary outcome was patient-reported improvement in cough symptoms rated on a 1-5 scale: 1 = no response, 2 = mild improvement, 3 = moderate improvement, 4 = significant improvement, 5 = complete resolution.

RESULTS

A total of 56 patients were included. Mean (SD) age was 64.6 (14.8) years, and 66 % were female. Overall, 42 patients (75.0 %) responded to treatment. Among responders, 7 (16.7 %) experienced mild improvement, 14 (33.3 %) experienced moderate improvement, 17 (40.5 %) experienced significant improvement, and 4 (9.5 %) experienced complete resolution of their cough. 33 patients (58.9 %) were managed exclusively with neuromodulators ± cough suppression therapy; 27 responded, with an average response rating of 3.0 (SD = 1.2). 11 patients (19.6 %) failed medical therapy and underwent SLN block without subsequent botox treatment; 7 responded, with an average response rating of 2.5 (SD = 1.4). 9 patients (16.1 %) failed all previous therapies and underwent laryngeal botulinum toxin injections; 6 responded with an average response rating of 2.4 (SD = 1.3). The remaining 3 patients underwent cough suppression therapy alone, with 2 responding and an average response rating of 3.3 (SD = 1.7).

CONCLUSIONS

Neurogenic cough can be effectively treated with a stepwise multimodal approach, including neuromodulators, cough suppression therapy, SLN block, and laryngeal botulinum toxin injections.

Chronic Cough: Evaluation of Patients' Motivation to Undergo Cough Suppression Therapy

INTRODUCTION

Chronic cough is a persistent cough lasting greater than eight weeks. The prevalence rate is estimated to be 9% to 33% in the United States. There are several treatment modalities described in current literature including medical, surgical, and behavioral interventions. Behavioral intervention with a speech-language pathologist (SLP) includes education on laryngeal hygiene and the voluntary control of cough as well as respiratory retraining to suppress or reduce the duration of cough. Cough suppression therapy, like other behavioral therapies, requires patient motivation and commitment to participation and completion in therapy.

METHODS

This study was a prospective cross-sectional survey at a single academic institution. Adult patients evaluated by a laryngologist for chronic cough regardless of their primary etiology were included. Patients who were tracheostomy dependent, on oxygen therapy, had vocal fold paralysis/immobility, or had undergone previous laryngeal surgery were excluded. Patients were surveyed at the end of the initial clinic visit or at the beginning of the first cough suppression therapy session. Subjects reported their motivational factors for undergoing cough suppression therapy.

RESULTS

The majority of patients, 21 (58.33%), identified as female, 15 patients (41.20%) identified as male, and no patients identified as transgender, nonbinary, and/or other gender. The patients in this study had a mean age of 57.75 (12.12) years. 35 patients (97.22%) were interested in cough suppression therapy. The mean presenting cough severity index (CSI) was 19.39 (10.28) with the mean cough duration of 8.69 (12.10) years.

CONCLUSIONS

Patients primarily sought cough suppression therapy due to intrinsic factors rather than extrinsic influence. By understanding the relationship between symptomatology and patient motivation, clinicians can better counsel their patients and improve methods to assess candidacy for behavioral treatment.

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

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.

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

OBJECTIVES

Studies examining electromyography (EMG)-guided laryngeal onobotulinumtoxinA (BTxA) injection for chronic cough reveal promising efficacy, however, are limited by small cohorts and absent quantifiable outcomes. It further remains unclear if pulmonary disease limits efficacy, or if vagal motor neuropathy prognosticates response. We hypothesize BTxA injection results in qualitative improvement in cough, decrease in Cough Severity Index (CSI), no change in Voice Handicap Index-10 (VHI-10), and complication rates comparable to historical data. We also examine the correlation of pulmonary comorbidities and vocal fold hypomobility with treatment efficacy.

STUDY DESIGN

Retrospective review.

METHODS

Charts for patients receiving percutaneous adductor compartment BTxA injection for cough were reviewed for the binary outcome of patient-reported presence or absence of improvement. Generalized estimating equations regression models were used to analyze the change in CSI (ΔCSI) and the correlation of ΔCSI with qualitative outcomes. Multivariable analyses were used to examine correlation of vocal fold hypomobility and pulmonary disease with qualitative outcomes and ΔCSI.

RESULTS

Forty-seven patients underwent 197 BTxA injections from June 2012 to June 2022. A statistical proportion of 0.698 (0.599-0.813, p < 0.0001) or 69.8% of injections resulted in subjective improvement. Mean ΔCSI was -2.12 (0.22-4.02, p < 0.05), indicating overall improvement. With and without subjective improvement, estimated ΔCSI was -4.43 and +2.68, respectively (p < 0.0001). VHI-10 did not change (0.69, p = 0.483). Neither pulmonary disease nor vocal fold hypomobility correlated with subjective improvement or ΔCSI. Dysphagia occurred following 15 (7.6%) injections with no aspiration pneumonia or hospitalization.

CONCLUSIONS

BTxA injection to the laryngeal adductors may effectively treat cough with limited risk for serious complications.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:1749-1756, 2024.

Indications and Short-Term Outcomes for In-Office Therapeutic Superior Laryngeal Nerve Block

OBJECTIVE

Superior laryngeal nerve (SLN) block consists of injection of steroid and anesthetic at the internal branch of the SLN entry site. Prior case series have demonstrated beneficial effects on neurogenic cough. SLN blocks have also recently shown benefit for paralaryngeal pain. We describe short-term outcomes for multiple symptoms of irritable larynx syndrome (ILS) including neurogenic cough, dysphonia related to laryngeal hypersensitivity, inducible laryngeal obstruction (ILO), paralaryngeal pain, and isolated globus.

METHODS

Retrospective review from 2 institutions of patients undergoing a single SLN block for the indications listed. Variables include age, sex, indication(s), known vagus neuropathy, and patient-reported outcomes at short-term follow-up.

RESULTS

A total of 209 patients were included (59 males, 150 females; age: 58 ± 13 years). Twenty-six patients (12%) had a history of a vagus nerve injury. Indications included neurogenic cough (n = 149), dysphonia related to laryngeal hypersensitivity (n = 66), paralaryngeal pain (n = 50), ILO (n = 23), and isolated globus (n = 3). Some patients had multiple indications. Significant improvements in patient-reported measures occurred after a single SLN block within 2 to 4 weeks for neurogenic cough (cough severity index; 25.2 ± 11.2 to 19.0 ± 12.8; P < .001), dysphonia (voice handicap index-10; 22.1 ± 12.2-18.0 ± 13.3; P = .005), and ILO (dyspnea index; 21.0 ± 14.9-14.7 ± 15.7; P = .017). Subjective pain improved in 23 of 39 patients with paralaryngeal pain. There was no observed improvement for isolated globus. Presence of known vagal neuropathy or therapy around the time of SLN block did not affect outcome.

CONCLUSION

SLN block can be an effective component of treatment for a variety of ILS symptoms. Patients may experience some improvement after 1 injection.

LAY SUMMARY

Symptoms of irritable larynx syndrome, such as neurogenic cough, paralaryngeal pain, inducible laryngeal obstruction, and dysphonia related to laryngeal hypersensitivity can be challenging to manage. In-office Superior Laryngeal Nerve blocks can serve as a quick, well tolerated, adjunctive treatment with positive short-term outcomes.

LEVEL OF EVIDENCE

4.

The Efficacy of Superior Laryngeal Nerve Block for Neurogenic Cough: A Placebo-Controlled Trial

OBJECTIVES

Chronic cough is a common and debilitating problem. The objective of this study is to assess the efficacy and safety of superior laryngeal nerve (SLN) block for neurogenic cough through a placebo-controlled, prospective trial.

METHODS

Patients were recruited in an outpatient tertiary care center. Inclusion criteria included a history consistent with neurogenic cough and age ≥ 18. Exclusion criteria included patients with untreated other etiologies of chronic cough (i.e., uncontrolled reflux) and current neuromodulating medication use. Patients were randomized into the treatment (1-2 mL of a 1:1 triamcinolone 40 mg: 1% lidocaine with 1:200,000 epinephrines) or placebo (saline) group and received two unilateral injections at approximately 2-week intervals. Outcomes were measured primarily by the Leicester Cough Questionnaire (LCQ) and a patient symptom log including a visual analog scale of cough severity.

RESULTS

17 patients completed the study, including 10 in the treatment group and seven in the placebo group. Eight (80%) patients in the treatment group reported improvement with at least one of the injections, whereas only 1 (14.3%) patient reported improvement in the placebo group (p < 0.0001). Average total LCQ scores increased in the treatment group from 10.09 to 13.15 (p = 0.03), with the most change occurring in the social domain. There was no statistically significant change in LCQ scores for the placebo group. There were no serious adverse events.

CONCLUSION

An SLN block is a safe and efficacious procedure for the treatment of neurogenic cough. Further studies are needed to optimize treatment protocol and assess long-term follow-up of patient outcomes.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:3068-3074, 2023.

Anesthetic management of airway stent placement by rigid bronchoscopy with superior laryngeal nerve block while preserving spontaneous breathing: A case report

Key Clinical Message

The combination of superior laryngeal nerve block can reduce the respiratory depression that occurs during management under total intravenous anesthesia.

Abstract

Anesthetic management of endobronchial stent placement by rigid bronchoscopy requires the maintenance of spontaneous breathing while suppressing upper airway reflexes. The combination of superior laryngeal nerve block (SLNB) can reduce the respiratory depression that occurs during management under total intravenous anesthesia. The patient was diagnosed as having lung cancer with invasion into the right middle bronchus and stenosis of the right main bronchus on chest computed tomography, and emergency airway stent placement was performed. Sedation was initiated with propofol and dexmedetomidine, and ultrasound-guided SLNB was performed after local anesthetic spraying into the oral cavity and trachea. Bucking was minimally controlled during insertion of the rigid bronchoscope. The patient's intraoperative hemodynamics remained stable, and there were no hypoxic events. SLNB can provide the suppression of the upper airway reflex while minimizing effects on spontaneous breathing, and may be useful for achieving balanced anesthesia during rigid bronchoscopy.

Supraglottic Botulinum Toxin Improves Symptoms in Patients with Laryngeal Sensory Dysfunction Manifesting as Abnormal Throat Sensation and/or Chronic Refractory Cough

Laryngeal sensory dysfunction (LSD) encompasses disorders of the vagal sensory pathways. Common manifestations include chronic refractory cough (CRC) and abnormal throat sensation (ATS). This study examined clinical characteristics and treatment outcomes of LSD using a novel approach of laryngeal supraglottic Onabotulinum toxin Type A injection (BTX). This was a retrospective review of clinical data and treatment outcomes of supraglottic BTX in patients with LSD. Between November 2019 and May 2021, 14 patients underwent 25 injection cycles of supraglottic BTX for treatment of symptoms related to LSD, including ATS and CRC. Primary outcome measures included the Newcastle Laryngeal Hypersensitivity Questionnaire (LHQ), Cough Severity Index (CSI), Reflux Symptom Index (RSI), and Voice Handicap Index-10 (VHI-10) at baseline and within three months of treatment. Pre- and post-treatment data were compared using a linear mixed model. After supraglottic BTX, LHQ scores improved by 2.6. RSI and CSI improved by 8.0 and 5.0, respectively. VHI-10 did not change as a result of treatment. Short-term response to SLN block was significantly associated with longer term response to BTX treatment. These findings suggest that LSD presents clinically as ATS and CRC along with other upper airway symptoms. Supraglottic BTX injection is a safe and effective technique in the treatment of symptoms of LSD.