Postviral Vagal Neuropathy: What Is the Role of Laryngeal Electromyography in Improving Diagnostic Accuracy?

Phenotypic Characterization of Laryngospasm: The Utility of Laryngeal Neurophysiological Studies

OBJECTIVE

To determine the existence of laryngeal neuropathy and the influence of gastroesophageal reflux in patients with episodic laryngospasm.

STUDY DESIGN

Single -center, observational study with prospective clinical collection.

STUDY SETTING

Prospective analysis of 18 Spanish patients with episodic laryngospasm in a Spanish Public Center collected by otolaryngologist. The recruitment dates were from January 2019 to December 2019.

METHODS

Data collection of 18 patients with episodic laryngospasm. Clinical characteristics, laryngeal neurophysiological studies and reflux esophageal testing were analyzed.

RESULTS

All patients have a trigger for the laryngospasms, being the most prevalent adopting the supine position (27.7%). EMG and ENG were pathological in 83.3 and 63.6 % respectively. Chronic bilateral denervation (increased amplitude and duration of potentials) with signs of reinnervation in the non-active chronic phase (large polyphasia), was the most prevalent finding. Evidence of gastroesophageal reflux either by pH meter, Gastroscopy or both was found in 38.8 % of patients.

CONCLUSIONS

Neurophysiological studies have confirmed the existence of laryngeal neuropathy in the majority of patients with laryngospasm. A substantial percentage of patients (38.8%) with laryngospasm had objective GERD and improved with PPIs. Laryngeal EMG and ENG can establish a more accurate diagnostic for episodic laryngospams and may supports treatment with neuromodulators.

Evaluation methods and influencing factors of cough sensitivity

Increased cough sensitivity is an important mechanism of chronic cough, and the evaluation of cough sensitivity helps understand the mechanism of cough and explore better methods to reduce cough. Evaluation methods may be direct or indirect. Direct methods include mechanical stimulation and chemical stimulation, and indirect methods include laryngeal reflex test, questionnaires, and brain functional magnetic resonance imaging (fMRI). Chemical stimulation is the most common method, while the capsaicin cough challenge test is proven and widely used. In this article, we will compare evaluation methods and explore influencing factors of cough sensitivity.

Randomized double blind trial of amitriptyline versus placebo in treatment of chronic laryngopharyngeal neuropathy

OBJECTIVE

A neuropathic etiology has been suggested for patients with chronic laryngopharyngitis symptoms without visible structural pathology. Prior studies have shown that treatment with neuro-modulating medications is beneficial, but it is unknown if this was due to placebo effect. Our objective was to compare the efficacy of amitriptyline versus placebo in treating chronic laryngopharyngeal neuropathy.

STUDY DESIGN

Prospective, randomized placebo-controlled trial.

METHODS

Patients were randomized to receive placebo or amitriptyline for 8weeks. Primary outcome was change in modified Reflux Symptom Index (mRSI) score. Secondary outcomes were change in Voice Handicap Index-10 (VHI) scores, rates of adverse effects, and overall symptom severity.

RESULTS

Eighteen patients completed the study. The average difference in mRSI and VHI-10 scores after treatment were not significantly different between study arms. However, more subjects taking amitriptyline felt their symptoms had subjectively improved (6 out of 9, 67%), while the remainder noted no change. In the placebo group, only 4 out of 9 subjects (44%) felt their symptoms were better and 2 felt worse. Subjects took an average of 25mg of amitriptyline or placebo daily by the end of the 8-week treatment period. No serious adverse effects were noted.

CONCLUSION

Although there was a trend toward greater subjective improvement in overall symptoms with amitriptyline, interpretation is limited due to the small sample size. Larger randomized controlled trials to determine the efficacy of neuro-modulating agents in the treatment of chronic laryngopharyngeal neuropathy, as well as better metrics to characterize this disorder, are warranted.

Laryngeal electromyographic changes in postthyroidectomy patients with normal vocal cord mobility

Thyroidectomy has been used for the treatment of thyroid disease for more than 100 years. In spite of the advancement of surgical techniques, there is still a risk of laryngeal nerve injury. The risk of partial or complete injury still depends on some surgical and disease-related factors. The aim of this study is to show the partial injury and to establish these risk factors via laryngeal electromyographic analysis (LEMG) in postthyroidectomy patients with normal vocal cord motion and mucosal anatomy. Patients who had undergone thyroid surgery were enrolled in this prospective study. LEMG analysis was performed to all patients with normal vocal cord mobility preoperatively and was repeated after the first and the third months of surgery. Thyroarytenoid (TA) and cricothyroid (CT) muscles were used to evaluate recurrent and external branch of superior laryngeal nerves, respectively. Four of the 32 patients had mild-to-moderate degrees of partial LEMG changes during preoperative LEMG analysis of TA and CT muscles on each side. After 3 months of surgery, there was a statistically significant worsening of LEMG findings in the right and left external branches of superior and left recurrent laryngeal nerves. Disease and surgery-related risk factors were analyzed. However, there was no significant relationship on the progression of LEMG findings according to these parameters. This is the first prospective study which supports the risk of progression of LEMG changes in patients with normal laryngoscopic examination after thyroid surgery. No reliable significant risk factor was found influencing the LEMG progression.