Clinical characteristics of patients with chronic cough in Guangdong, China: a multicenter descriptive study.

BACKGROUND: The clinical characteristics of patients with chronic cough are reported only in single-center survey in China, being significantly different from that in western countries. Here, we performed a multicenter study to describe the clinical characteristics of chronic cough patients. METHODS: A cross-sectional observational survey was conducted in thirteen tertiary hospitals of Guangdong, South China. Relevant data were recorded using a standardized questionnaire and analyzed, including demographics, educational attainment, cough features, and concomitant symptoms. RESULTS: Of 933 patients in this study, the median age was 40.0 (IQR 31.0-52.0) years with a peaked age of 30-39 years. The proportion of females (487, 52.2 %) was comparable to that of males (446, 47.8 %). Up to 81.9 % of the patients were non-smokers. More than two-thirds of the subjects with chronic cough had a low educational level. The median cough duration was 6.0 (IQR 3.0-24.0) months, and 73.0 % of chronic cough patients presented with dry cough. Laryngeal paresthesia was the most common concomitant symptom (704, 75.5 %), followed by rhinitis/sinusitis-related (350, 37.5 %) and respiratory symptoms (322, 34.5 %). Rhinitis/sinusitis-related symptoms more frequently occurred in patients with productive cough than in those with dry cough (49.0 % vs. 33.0 %, P < 0.001). Moreover, female patients displayed an older age and a higher prevalence of nocturnal cough compared to male patients (both P < 0.05). CONCLUSIONS: Our results show an equal gender, young profile and laryngeal paresthesia in patients with chronic cough, and different clinical features between females and males.

Single Dose Steroid Injection After Loss of Signal (LOS) During Thyroid Surgery is Effective to Recover Electric Signal Avoiding Vocal Cord Palsy and the Need of Staged Thyroidectomy: Prospective Evaluation on 702 Patients.

BACKGROUND: Steroids are often used for the management of vocal cord palsy after thyroid surgery. There are no reports in the current literature of their intraoperative use, immediately after a loss of signal during neuromonitoring (LOS). We evaluate the impact of a single dose of 4 mg of dexamethasone on laryngeal nerve function, administrated at the time of a LOS during a nerve-monitored thyroidectomy. METHODS: A prospective not randomized study was performed, dividing patients in two groups, when a LOS was detected. LOS was defined as an electromyographic signal (EMG) inferior to 100 µV when stimulating the inferior laryngeal nerve, according to international guidelines. In group 1 (G1), surgeon waits for signal's recovery up to 20 min. Absence of a detectable signal after 20 min was predictive of vocal cord palsy; if it affected the first side of surgery the procedure was interrupted to avoid the risk of bilateral nerve palsy. In group 2 (G2), 4 mg of dexamethasone were injected within 10 min from a detected LOS, waiting 10 min for its effects. An EMG value > to 200 µV within 20' after steroid administration was predictive of full recovery and normal post-operatory vocal cord function. Vocal cords motility was checked at postoperative day 1 in all patients by an experienced ENT. RESULTS: Between January 2017 and December 2018, 702 patients underwent thyroid surgery under intermittent intraoperative nerve monitoring by two expert surgeons. A LOS was found in 22 patients in G1 and 16 in G2. Four patients in G1 spontaneously recovered electric signal (18.2%), while in G2 a signal was recovered in 14/16 patients (87.5%) (p < 0.001). This immediate effect was monitored by EMG, showing the increase in potentials at 10, 15 and 20 min after injection. ENT evaluation found vocal cord palsy, respectively, in 18/22 and 1/16 patients (G1 vs G2, p < 0.001). One of the patients in G2 who recovered electric signal presented transient palsy, fully recovered at 2 months, while the two patients who had a signal < 200 µV did not present postoperative cord palsy. In G1, 10/18 palsy were definitive. No permanent palsies were presents in G2. CONCLUSION: A single 4 mg iv dexamethasone injection within 10 min form a LOS during thyroid surgery exerts a therapeutic action, measurable by EMG modifications. It avoids vocal nerve palsy and the need of a staged thyroidectomy. It may also protect from permanent cord palsy, but the mechanism is unknown.

Inter-rater reliability of seven neurolaryngologists in laryngeal EMG signal interpretation.

PURPOSE: Laryngeal electromyography (LEMG) has been considered as gold standard in diagnostics of vocal fold movement impairment, but is still not commonly implemented in clinical routine. Since the signal interpretation of LEMG signals (LEMGs) is often a subjective and semi-quantitative matter, the goal of this study was to evaluate the inter-rater reliability of neurolaryngologists on LEMGs of volitional muscle activity. METHODS: For this study, 52 representative LEMGs of 371 LEMG datasets were selected from a multicenter registry for a blinded evaluation by 7 experienced members of the neurolaryngology working group of the European Laryngological Society (ELS). For the measurement of the observer agreement between two raters, Cohen's Kappa statistic was calculated. For the interpretation of agreements of diagnoses among the seven examiners, we used the Fleiss' Kappa statistic. RESULT: When focusing on the categories "no activity", "single fiber pattern", and "strongly decreased recruitment pattern", the inter-rater agreement varied from Cohen's Kappa values between 0.48 and 0.84, indicating moderate to near-perfect agreement between the rater pairs. Calculating with Fleiss' Kappa, a value of 0.61 showed good agreement among the seven raters. For the rating categories, the Fleiss' Kappa value ranged from 0.52 to 0.74, which also showed a good agreement. CONCLUSION: A good inter-rater agreement between the participating neurolaryngologists was achieved in the interpretation of LEMGs. More instructional courses should be offered to broadly implement LEMG as a reliable diagnostic tool in evaluating vocal fold movement disorders in clinical routine and to develop future algorithms for therapy and computer-assisted examination.

Innervation of the human cricopharyngeal muscle by the recurrent laryngeal nerve and external branch of the superior laryngeal nerve.

PURPOSE: The major component of the upper esophageal sphincter is the cricopharyngeal muscle (CPM). We assessed the contribution of the laryngeal nerves to motor innervation of the CPM. METHODS: We performed an intraoperative electromyographic study of 27 patients. The recurrent laryngeal nerve (RLN), vagus nerve, external branch of the superior laryngeal nerve (EBSLN), and pharyngeal plexus (PP) were stimulated. Responses were evaluated by visual observation of CPM contractions and electromyographic examination via insertion of needle electrodes into the CPM. RESULTS: In total, 46 CPMs (24 right, 22 left) were evaluated. PP stimulation produced both positive visual contractions and electromyographic (EMG) responses in 42 CPMs (2080 ± 1583 µV). EBSLN stimulation produced visual contractions of 28 CPMs and positive EMG responses in 35 CPMs (686 ± 630 µV). Stimulation of 45 RLNs produced visible contractions of 37 CPMs and positive EMG activity in 41 CPMs (337 ± 280 µV). Stimulation of 42 vagal nerves resulted in visible contractions of 36 CPMs and positive EMG responses in 37 CPMs (292 ± 229 µV). Motor activity was noted in 32 CPMs by both RLN and EBSLN stimulation, 9 CPMs by RLN stimulation, and 3 CPMs by EBSLN stimulation; 2 CPMs exhibited no response. CONCLUSIONS: This is the first study to show that the EBSLN contributes to motor innervation of the human CPM. The RLN, EBSLN, or both of the nerves innervate the 90, 75, and 70 % of the CPMs ipsilaterally, respectively.

Effects of transcutaneous electrical stimulation on vocal folds adduction.

According to most previous studies, inducing movements in internal laryngeal muscles by transcutaneous electrical stimulation (TES) was impossible. However, the movements have been reported after using needle electrodes inserted into the internal superior laryngeal nerve (ISLN). Herein, we aimed to apply an innovative TES protocol to cause movements in vocal folds. A short duration and high frequency electrical current was applied by two surface electrodes just above the entrance of ISLN to larynx. The subjects were 32 normal participants (mean age = 23.87; SD = 3.43). During TES application, the vocal folds' movements were examined by flexible videonasolaryngoscopy. Statistical paired t test was used to analyze the differences of vocal folds opening angle, in degrees, during rest and TES periods. Furthermore, the movements were judged by seven experienced speech pathologists via a 9-point rate scale from -1 (any abduction) to 8 (complete adduction). The mean vocal folds adduction increased by 35.68° (t = 9.35, p > 0.001) due to TES application. The mean qualitative scores assigned by raters to each subject were between 6 and 7 points, which indicate an acceptable adduction in vocal folds through TES. Unlike previous studies, the applied TES protocol in this research induced significant vocal fold movements. This might be attributed to our different stimulation parameters, which were designed to penetrate deeply and stimulate ISLN specifically. It is worth noting that we introduced a novel TES protocol, which should be confirmed and then examined as a complementary therapy for neurologic voice disorders in future studies.

Method to test the long-term stability of functional electrical stimulation via multichannel electrodes (e.g., applicable for laryngeal pacing) and to define best points for stimulation: in vivo animal analysis.

The study aim was to identify and analyze intramuscular electrically sensitive points. Electrically sensitive points are herein defined as positions, which allow muscles stimulation with a minimum possible fatigue for a maximum amount of time. A multichannel array electrode was used which could be interesting to retain the function of larynx muscle after paralysis. Eight array electrodes were implanted in the triceps brachii muscle of four rats. While being under anesthesia, the animals were intramuscularly stimulated at 16 different positions. Sihler's staining technique was used to make visible the nerves routes and the intramuscular position of the individual electrode plate. The positions of the motor end plates were determined by means of multichannel-electromyography. The positions that allow longest stimulation periods are located close to the points where the nerves enter the muscle. Stimulation at the position of the motor end plates does not result in stimulation periods above average. Locations initially causing strong muscle contractions are not necessarily identical to the ones allowing long stimulation periods. The animal model identified the stimulation points for minimal possible muscle fatigue stimulation as being located close to the points of entrance of the nerve into the muscle. Stimulation causing an initially strong contraction response is no indication of optimal location of the stimulation electrode in terms of chronic stimulation. The array electrode of this study could be interesting as a stimulation electrode for a larynx pacemaker.

The role of laryngeal electromyography in vagus nerve stimulation-related vocal fold dysmotility.

Vagus nerve stimulation (VNS) is a useful tool for drug-resistant epilepsy, but it induces known laryngeal side effects, with a significant role on patients' quality of life. VNS patients may show persistent left vocal fold (LVF) palsy at rest and/or recurrent LVF adduction during stimulation. This study aims at electromyographically evaluating laryngeal muscles abnormalities in VNS patients. We compared endoscopic laryngeal evaluation data in six VNS patients with laryngeal muscle electromyography (LMEMG) carried out on the thyroarytenoid, cricothyroid, posterior cricoarytenoid, and cricopharyngeal muscles. Endoscopy showed LVF palsy at rest in 3/6 patients in whom LMEMG documented a tonic spastic activity with reduced phasic modulation. In four out of six patients with recurrent LVF adduction during VNS activation, LMEMG showed a compound muscle action potential persisting for the whole stimulation. This is the first LMEMG report of VNS-induced motor unit activation via recurrent laryngeal nerve and upper laryngeal nerve stimulation. LMEMG data were could, therefore, be considered consistent with the endoscopic laryngeal examination in all patient.

Carotid endarterectomy significantly improves postoperative laryngeal sensitivity.

OBJECTIVE: Iatrogenic injury of the vagus nerve or its branches during carotid endarterectomy (CEA) can result in globus sensation, dysphagia, and even vocal fold immobility. Knowledge of morphologic and functional laryngopharyngeal outcomes after CEA is poor. The present study was performed to determine potential iatrogenic damage to the laryngeal innervation after CEA. An area of particular interest was the supraglottic sensory threshold, which was examined by Fiberoptic Endoscopic Evaluation of Swallowing With Sensory Testing (FEESST; Pentax Medical Company, Montvale, NJ), a validated and safe method for the determination of the motor and sensory components of swallowing. METHODS: FEESST was used preoperatively in 32 patients scheduled to undergo CEA and twice postoperatively to examine the motor and sensory components of swallowing. In this endolaryngeal examination, laryngopharyngeal sensory thresholds (in mm Hg) were defined as normal at <4.0 mm Hg air pulse pressure (APP), moderate deficit at 4.0 to 6.0 mm Hg APP, or severe deficit at >6.0 mm Hg APP, with a value >10.0 mm Hg APP indicating abolished laryngeal adductor reflex. Acoustic voice parameters were also analyzed for further functional changes of the larynx. RESULTS: The mean ± standard deviation preoperative FEESST measures showed no significant differences (P = .065) between the operated-on side (6.73 ± 1.73 mm Hg) and the opposite side (5.83 ± 1.68 mm Hg). At 2 days postoperatively, the threshold increased (P = .001) to 7.62 ± 1.98 mm Hg on the operated-on side. A laryngopharyngeal mucosal hematoma on the operated side was endoscopically detectable in eight patients (30.8%); in these patients, we found a markedly elevated (P = .021) measure of 9.50 ± 0.93 mm Hg. On the opposite (nonoperated-on) side of the laryngopharynx, the thresholds remained at the same level as preoperatively over all assessments (P >.05), whereas the differences between the operated and nonoperated-on sides and the hematoma and nonhematoma groups were highly significant (P = .004 and P = .001, respectively). Surprisingly, the sensory threshold on the operated-on side (6.08 ± 2.02 mm Hg) decreased significantly at the 6-week follow-up, even in relation to the preoperative measure (P = .022). With the exception of one patient with permanent unilateral vocal fold immobility, no signs of nerve injury were detected. CONCLUSIONS: In accordance with previous reports, injuries to the recurrent laryngeal nerve during CEA seem to be rare. In most patients, postoperative symptoms (globus, dysphagia, dysphonia) and signs fade within a few weeks without any specific therapeutic intervention. This study shows an improved long-term postoperative superior laryngeal nerve function with regard to laryngopharyngeal sensitivity.

Prospective validation study of Cernea classification for predicting EMG alterations of the external branch of the superior laryngeal nerve.

PURPOSES: Cernea classification is applied to describe the external branch of the superior laryngeal nerve (EBSLN). Using intraoperative neural monitoring we evaluated whether or not this classification is useful for predicting which EBSLN subtype has an increased risk of injury. METHODS: An analysis of 400 EBSLN. The identification of EBSLN was achieved with both cricothyroid muscle twitch and the glottis evoked electromyography response. We defined S1 initial EBSLN stimulation at identification and S2 final nerve stimulation achieved in the most cranial aspect of the nerve exposed above the area of surgical dissection after superior artery ligation. RESULTS: The mean S1 amplitude acquired was 259+/67 (180-421), 321 +/79 (192-391), 371 +/38 (200-551) µV, respectively, for type 1, 2A, 2B (p = 0.08). The S1 and S2 amplitudes were similar in type 1 (p = 0.3). The S1 and S2 determinations changed significantly in type 2A and 2B (p = 0.04 and 0.03). EBSLN which demonstrated a >25 % decreased amplitude in S2 increased significantly from Type 1 (4.9 %) to Type 2A (11.2 %) and 2B (18 %) (p = 0.01). None of type 1, 2.8 % type 2A and 3 % type 2B showed a loss of EBSLN conductivity. The latency determinations did not vary significantly for any parameter compared. CONCLUSIONS: The Cernea classification was, therefore, found to predict the risk of EBSLN stress. We identified amplitude differences between S1 and S2 determinations in type 2A and 2B, thus confirming that surgical dissection in these subtypes is, therefore, extremely difficult to perform.

A comparison of 2 methods of endoscopic laryngeal sensory testing: a preliminary study.

OBJECTIVE: This study examined the association between laryngeal sensory deficits and penetration or aspiration. Two methods of testing laryngeal sensation were carried out to determine which was more highly correlated with Penetration-Aspiration Scale (PAS) scores. METHODS: Healthy participants and patients with dysphagia received an endoscopic swallowing evaluation including 2 sequential laryngeal sensory tests-air pulse followed by touch method. Normal/impaired responses were correlated with PAS scores. RESULTS: Fourteen participants completed the endoscopic swallowing evaluation and both sensory tests. The air pulse method identified sensory impairment with greater frequency than the touch method (P<.0001). However, the impairment identified by the air pulse method was not associated with abnormal PAS scores (P=.46). The sensory deficits identified by the touch method were associated with abnormal PAS scores (P=.05). CONCLUSION: Sensory impairment detected by the air pulse method does not appear to be associated with risk of penetration/aspiration. Significant laryngeal sensory loss revealed by the touch method is associated with compromised airway protection.

Value of Laryngeal Electromyography in Spasmodic Dysphonia Diagnosis and Therapy.

OBJECTIVE: To investigate the role of laryngeal electromyography (LEMG) in the diagnosis and treatment of spasmodic dysphonia (SD). METHODS: The clinical manifestations, characteristics of motor unit potentials (MUPs), recruitment potentials, and laryngeal nerve evoked potentials (EPs) in LEMG, as well as the changes after botulinum toxin (BTX) treatment, were analyzed in 39 patients with adductor SD. RESULTS: The main clinical manifestations were a strained voice and phonation interruptions; in addition, the patients displayed hyper-adducted vocal folds during phonation. LEMG revealed significantly increased amplitudes of the thyroarytenoid muscle MUPs. The recruitment potentials were in a dense bunch, discharging full interference patterns with significantly increased amplitudes; the mean and maximum amplitude of recruitment potentials were 3090 µV and 5000 µV, respectively. The amplitude of EPs of thyroarytenoid muscle increased significantly; the mean and maximum amplitudes were 10.3 mV and 26.3 mV, respectively. After BTX was injected, the LEMG revealed denervation changes, and the EPs weakened or disappeared in the injected muscle. CONCLUSIONS: SD could be diagnosed, and the therapeutic efficacy of SD treatments could be evaluated based on clinical characteristics combined with LEMG characteristics. The increased amplitudes of the recruitment potentials and EPs of the thyroarytenoid muscle were the characteristic indexes. After BTX was injected, denervated potential characteristics appeared in the muscles.

Intraoperative neural monitoring in thyroid cancer surgery.

BACKGROUND: Intraoperative neural monitoring (IONM) has increasingly garnered the attention of the surgeons performing thyroid and parathyroid surgery around the world. Current studies suggest a majority of general and head and neck surgeons utilize neural monitoring in their thyroid surgical case load in both the US and Germany. PURPOSE: We aim to present an up-to-date review of the application of IONM specifically focusing on its utility in thyroid cancer surgery. Neural monitoring is discussed particularly as it relates to neural prognosis, the issues of staged thyroid surgery for thyroid cancer, and new horizons in the monitoring of the superior laryngeal nerve (SLN) and prevention of neural injury through continuous vagal neural monitoring. CONCLUSION: IONM, as it relates to thyroid surgery, has obtained a widespread acceptance as an adjunct to the gold standard of visual nerve identification. The value of IONM in prognosticating neural function and in intraoperative decision making regarding proceeding to bilateral surgery is also well-known. Initial data on recent extensions of IONM in the form of SLN monitoring and continuous vagal nerve monitoring are promising. Continuous vagal nerve monitoring expands the utility of IONM by providing real-time electrophysiological information, allowing surgeons to take a corrective action in impending neural injury.

Airway protective mechanisms.

Cough and swallow are highly coordinated reflex behaviors whose common purpose is to protect the airway. The pharynx is the common tube for air and food/liquid movement from the mouth into the thorax, has been largely overlooked, and is potentially seen as just a passive space. The thyropharyngeus muscle responds to cough inducing stimuli to prepare a transient holding area for material that has been removed from the subglottic airway. The cricopharyngeus muscle participates with the larynx to ensure regulation of pressure when a bolus/air is moving from the upper airway through to the thorax (i.e., inspiration or swallow) or the reverse (i.e., expiration reflex or vomiting). These vital mechanisms have not been evaluated in clinical conditions but could be impaired in many neurodegenerative diseases, leading to aspiration pneumonia. These newly described airway protective mechanisms need further study, especially in healthy and pathologic human populations.

Laryngeal sensation and pharyngeal delay time after (chemo)radiotherapy.

The objective of the study was to evaluate the association between changes in laryngeal sensation and initiation of swallowing reflex or swallowing function before and after (chemo)radiotherapy. A prospective study was conducted in a tertiary referral university hospital. Thirteen patients who received (chemo)radiotherapy for treatment of laryngeal or hypopharyngeal cancer were included. Laryngeal sensation was evaluated at the tip of the epiglottis before and 1, 3 months, and 1 year after (chemo)radiotherapy. Videofluoroscopy was performed at the same time. Quantitative determinations included changes in laryngeal sensation, computed analysis of pharyngeal delay time, the distance and velocity of hyoid bone movement during the phase of hyoid excursion, and pharyngeal residue rate (the proportion of the bolus that was left as residue in the pharynx at the first swallow). Laryngeal sensation significantly deteriorated 1 month after (chemo)radiotherapy, but there was a tendency to return to pretreatment levels 1 year after treatment. Neither pharyngeal delay time nor displacement of the hyoid bone changed significantly before and after (chemo)radiotherapy. In addition, there was no significant difference in the mean velocity of hyoid bone movement and the amount of stasis in the pharynx at the first swallow before and after (chemo)radiotherapy. After (chemo)radiotherapy, laryngeal sensation deteriorated. But, in this study, videofluoroscopy showed that swallowing reflex and function were maintained.

[Case of sudden asystole during direct laryngoscopy].

A 78-year-old man, weighing 74 kg and 172 cm in height suddenly developed asystole during direct laryngoscopy. His heart started beating soon after chest compressions. Direct larygoscopy can stimulate the vagal nerve of the larynx. Although a gradual decrease in heart rate ordinarily occurs prior to asystole, few reports describe the sudden asystole during direct laryngoscopy. Intravenous injection of atropine could avoid the adverse event. Anesthesiologists should pay attention to the occurence of asystole and prepare for resuscitation.

A novel electrodiagnostic assessment of the laryngeal closure reflex.

INTRODUCTION: We describe a novel, clinically applicable conduction study of the laryngeal nerves. METHODS: Seventeen normal volunteer subjects were included. Activation of the sensory territory of the superior laryngeal nerve was performed by administration of low level brief electrical stimuli. The laryngeal closure reflex (LCR) evoked by this stimulus was recorded by needle electrodes. Mean minimal latencies were calculated for each response, and proposed values for the upper limit of normal were determined. RESULTS: Uniform, consistent early ipsilateral responses and late bilateral responses, which exhibit greater variation in latency and morphology, were recorded. Significant side-to-side differences in latencies were observed, consistent with the length discrepancy between right and left recurrent laryngeal nerves. CONCLUSIONS: This technique yields clear, quantifiable data regarding neurologic integrity of laryngeal function, heretofore unobtainable in the clinical setting. This study may yield clinically relevant information regarding severity and prognosis in patients with laryngeal neuropathic injury.

Neuromuscular basis for ventricular fold function.

OBJECTIVES: We sought to examine the neuromuscular basis for ventricular fold function. The primary function of the ventricular folds is to assist in the regulation of intra-abdominal and intrathoracic pressure. They also influence phonation in the setting of vocal fold paralysis or ventricular dysphonia, or after partial laryngectomy. The neuromuscular basis of true vocal fold function has been well studied; however, its neuromuscular correlates in the ventricular folds are ambiguous. The literature is unclear as to whether ventricular fold contraction is passive or active. The musculature and innervation responsible for this action also have not been well defined. The aim of this study was to provide clarity in regard to these mechanisms. METHODS: We examined a whole-organ section of a human larynx from a patient with unilateral vocal fold paralysis. The region of the ventricular folds was compared on both the paralyzed and normal sides. Electrophysiological examination was performed in a porcine model. The superior laryngeal nerve was stimulated, and recording electrodes in both ventricular folds measured the electrical activity. The recurrent laryngeal nerve was then severed, and the experiment was repeated. RESULTS: The histologic slides from the patient with unilateral vocal fold paralysis demonstrated atrophied ventricularis and thyroarytenoid muscles on the paralyzed side. On the unaffected side, these muscles were of normal size. The electrophysiological examination in the porcine model demonstrated findings consistent with innervation of the ventricularis muscle by the recurrent laryngeal nerve. An association of ventricularis muscle activity with ventricular fold contraction also was demonstrated. CONCLUSIONS: Ventricular fold adduction appears to be a result of ventricularis muscle contraction that is mediated by the recurrent laryngeal nerve.