Major patterns of laryngeal electromyography and their clinical application

Physiological Effects of Voice Therapy for Aged Vocal Fold Atrophy Revealed by EMG Study

OBJECTIVES

Age-related voice changes are characterized as breathy, weak and strained, and a deterioration in vocal function in the elderly has been putatively linked to a reduced intensity of speech. They contribute to undesirable voice changes known as presbyphonia. These changes are caused by histological alterations in the lamina propria of the vocal fold mucosa and atrophy of the thyroarytenoid muscle, as well as by decreased respiratory support. There are several clinical studies on presbylarynx dysphonia showing the effectiveness of voice therapy. However, physiological changes of the presbylarynx following voice therapy have not been verified. The purpose of this prospective study was to demonstrate the clinical effectiveness of voice therapy for rehabilitating presbylarynx dysphonia, using vocal function assessments and thyroarytenoid muscular activity detection on laryngeal electromyography (LEMG).

METHODS

10 patients who were diagnosed with aged vocal fold atrophy from ages 60 to 87 years (mean age: 72 years) underwent approximately 12 weeks of voice therapy, mainly using forward-focused voice and vocal resistance training. Stroboscopic examination, aerodynamic assessment, acoustic analysis, Voice Handicap Index (VHI)-10, and LEMG were performed pre- and post-voice therapy. Vocal fold vibratory amplitude (VFVA) was measured by image analysis from the stroboscopic examinations. Turns analysis during steady phonation on LEMG was also assessed.

RESULTS

Maximum phonation time, subglottic pressure, jitter, shimmer, VFVA, and VHI-10 significantly improved after voice therapy. The number of turns per second on LEMG also significantly increased.

CONCLUSION

Our data suggest that voice therapy may improve vocal function and thyroarytenoid muscle activity in patients with aged vocal fold atrophy.

LaDIVA: A neurocomputational model providing laryngeal motor control for speech acquisition and production

Many voice disorders are the result of intricate neural and/or biomechanical impairments that are poorly understood. The limited knowledge of their etiological and pathophysiological mechanisms hampers effective clinical management. Behavioral studies have been used concurrently with computational models to better understand typical and pathological laryngeal motor control. Thus far, however, a unified computational framework that quantitatively integrates physiologically relevant models of phonation with the neural control of speech has not been developed. Here, we introduce LaDIVA, a novel neurocomputational model with physiologically based laryngeal motor control. We combined the DIVA model (an established neural network model of speech motor control) with the extended body-cover model (a physics-based vocal fold model). The resulting integrated model, LaDIVA, was validated by comparing its model simulations with behavioral responses to perturbations of auditory vocal fundamental frequency (fo) feedback in adults with typical speech. LaDIVA demonstrated capability to simulate different modes of laryngeal motor control, ranging from short-term (i.e., reflexive) and long-term (i.e., adaptive) auditory feedback paradigms, to generating prosodic contours in speech. Simulations showed that LaDIVA’s laryngeal motor control displays properties of motor equivalence, i.e., LaDIVA could robustly generate compensatory responses to reflexive vocal fo perturbations with varying initial laryngeal muscle activation levels leading to the same output. The model can also generate prosodic contours for studying laryngeal motor control in running speech. LaDIVA can expand the understanding of the physiology of human phonation to enable, for the first time, the investigation of causal effects of neural motor control in the fine structure of the vocal signal.

Vocal fold immobility with normal LEMG: A range of possibilities

OBJECTIVE

The objective of this paper is to study the etiology of vocal fold immobility with non-pathological LEMG.

METHODS

A retrospective study was performed on patients who presented with vocal fold immobility and underwent LEMG from 2009 to 2017. Those patients with normal LEMG findings were selected. The different causes of vocal fold impairment were studied.

RESULTS

Of the 120 patients included in this study, 15 had a normal LEMG recording. The different etiologies of vocal fold immobility were idiopathic, central nervous system damage, iatrogenic, and external compression.

CONCLUSIONS

Vocal fold immobility and vocal fold paralysis are not equal terms. Vocal fold immobility with normal LEMG has a heterogeneous group of causes. It is not correct to assume that the major cause of immobility in patients with normal LEMG is always cricoarytenoid joint fixation.

Vocal fold immobility with normal LEMG: A range of possibilities

OBJECTIVE

The objective of this paper is to study the etiology of vocal fold immobility with non-pathological LEMG.

METHODS

A retrospective study was performed on patients who presented with vocal fold immobility and underwent LEMG from 2009 to 2017. Those patients with normal LEMG findings were selected. The different causes of vocal fold impairment were studied.

RESULTS

Of the 120 patients included in this study, 15 had a normal LEMG recording. The different etiologies of vocal fold immobility were idiopathic, central nervous system damage, iatrogenic, and external compression.

CONCLUSIONS

Vocal fold immobility and vocal fold paralysis are not equal terms. Vocal fold immobility with normal LEMG has a heterogeneous group of causes. It is not correct to assume that the major cause of immobility in patients with normal LEMG is always cricoarytenoid joint fixation.

Vocal cord paralysis following general anesthesia with endotracheal intubation: a clinical review on 43 cases

Background

Vocal cord paralysis (VCP) is one of the most stressful experiences for patients undergoing general anesthesia. Moreover, it is a risk factor for aspiration pneumonia and may increase morbidity and mortality. We examined several clinical features of the condition by reviewing the medical records of patients who experienced VCP following general anesthesia.

Methods

We reviewed the medical records of 321 patients who consulted an otolaryngologist owing to hoarseness, sore throat, throat discomfort, or dysphagia after general anesthesia. Among these, we included in the present study 43 patients who were diagnosed with VCP by laryngoscopy, who did not have symptoms of suspected VCP before surgery, who had no past history of VCP, and for whom endotracheal intubation was not continued after surgery.

Results

The mean age of patients with VCP was 51.3 years. With respect to surgical site, the most common was upper limb surgery, performed in 12 cases (9 cases were performed in sitting posture. With respect to surgical duration, only 11 cases lasted less than 3 h, whereas 32 cases required a surgical duration longer than 3 h. The most common symptom of VCP was hoarseness. Nine of the patients with VCP recovered spontaneously, but VCP persisted in 13 cases until the final follow-up examination.

Conclusions

We hope that this study might call attention to the occurrence of VCP following general anesthesia. Moreover, it is necessary to further evaluate the reasons for the higher incidence of VCP in upper limb surgery performed in sitting posture.

Comparison between Intramuscular Multichannel Electrodes and Supramysial Multichannel Electrodes via EMG Measurements for Potential Use as Larynx Stimulation Electrodes: In Vivo Animal Analysis

One of the most common causes for larynx paralysis is the injury of the recurrent laryngeal nerve which, among others, causes the paralysis of the posterior cricoarytenoideus muscle (PCA). Electrical stimulation of PCA offers an approach to retaining the function of the paralyzed larynx muscle. The study aim was to test the applicability of an intramuscular multichannel array electrode as a measuring electrode for myoelectrical potentials and as a possible electrode for stimulation, e.g., posterior cricoarytenoideus muscle stimulation. For this purpose, two different kinds of electrodes were compared. 42 intramuscular multichannel array electrodes and 11 supramysial multichannel electrodes were implanted into the triceps brachii muscle of rats. The triceps brachii muscle of rats is suitable to serve as a substitute muscle for the human PCA muscle in an in vivo animal model. It has the same striated muscle cells, is of comparable size, and fundamentally serves a similar function to the human PCA muscle during normal respiration. Walking and breathing are circular functions that cause minimal muscle fatigue when carried out steadily. In total, the myoelectrical activity of 6703 steps could be recorded, allowing a comparison and statistical analysis of the EMG amplitudes and EMG activation patterns. Small differences can be detected between the EMG signals of both electrode types which, however, can be explained physiologically. Both electrode types reveal the basic characteristics of the triceps brachii muscle activity, namely the muscle contraction strength and the coordination pattern. This indicates that the intramuscular electrode may be applied for a detailed analysis of the human larynx.

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.

Practice Parameter: Laryngeal Electromyography (An Evidence-Based Review)

This paper reports on an evidence-based review of laryngeal electromyography (EMG) as a technique for use in the diagnosis, prognosis, and treatment of laryngeal movement disorders including the laryngeal dystonias, vocal fold paralysis, and other neurolaryngological disorders. The authors performed a systematic review of the medical literature from 1944 through 2001 on the clinical application of EMG to laryngeal disorders. The review yielded 584 articles of which 33 met the predefined inclusion criteria. The evidence demonstrated that in a double-blind treatment trial of botulinum toxin versus saline, laryngeal EMG used to guide injections into the thyroarytenoid muscle in persons with adductor spasmodic dysphonia was beneficial. A cross-over comparison between laryngeal EMG-guided injection and endoscopic injection of botulinum toxin into the posterior cricoarytenoid muscle in abductor spasmodic dysphonia found no significant difference between the 2 techniques and no significant treatment benefit. Based on the evidence, laryngeal EMG is possibly useful for the injection of botulinum toxin into the thyroarytenoid muscle in the treatment of adductor spasmodic dysphonia. There were no evidence-based data sufficient to support or refute the value of laryngeal EMG for the other uses investigated, although there is extensive anecdotal literature suggesting that it is useful for each of them. There is an urgent need for evidence-based research addressing other applications in the use of laryngeal EMG for other applications. (Otolaryngol Head Neck Surg 2004;130: 770-9.)

Diagnostic Laryngeal Electromyography: The Wake Forest Experience 1995–1999

BACKGROUND:

Laryngeal electromyography (LEMG) is a valuable diagnostic/prognostic test for patients with suspected laryngeal neuromuscular disorders.

OBJECTIVE:

To report our experience with diagnostic LEMG at the Center for voice Disorders of Wake Forest University and to evaluate the impact of LEMG on clinical management.

METHODS:

Retrospective chart review of 415 patients who underwent diagnostic LEMG over a 5-year period (1995–1999).

RESULTS:

Of 415 studies, 83% (346 of 415) were abnormal, indicating a neuropathic process. LEMG results altered the diagnostic evaluation (eg, the type of radiographic imaging) in 11% (46 of 415) of the patients. Unexpected LEMG findings (eg, contralateral neuropathy) were found in 26% (107 of 415) of the patients, and LEMG results differentiated vocal fold paralysis from fixation in 12% (49 of 415). Finally, LEMG results altered the clinical management (eg, changed the timing and/or type of surgical procedure) in 40% (166 of 415) of the patients.

CONCLUSIONS:

LEMG is a valuable diagnostic test that aids the clinician in the diagnosis and management of laryngeal neuromuscular disorders.

Value of Laryngeal Electromyography in Diagnosis of Vocal Fold Immobility

Objectives:

We sought to determine the value of laryngeal electromyography (LEMG) and evoked LEMG in the diagnosis of vocal fold immobility.

Methods:

We analyzed 110 cases of vocal fold immobility by their clinical manifestations and LEMG characteristics, including spontaneous potential activity, motor unit potential measurement, recruitment pattern analysis, and evoked LEMG signals.

Results:

With LEMG, we identified 87 patients with neuropathic laryngeal injuries. Neurogenic vocal fold immobility showed a wide variety of abnormal activity. Fibrillation potentials and positive sharp waves were found in patients with laryngeal nerve injuries. For laryngeal paralysis, there was no reaction with LEMG and evoked LEMG. For incomplete laryngeal paralysis, decreased evoked LEMG signals were also seen with delayed latency (thyroarytenoid muscle, 2.2 ± 1.0 ms, p < 01; posterior cricoarytenoid muscle, 2.4 ± 1.0 ms, p < .05) and lower amplitude (thyroarytenoid muscle, 0.9 ± 0.7 mV, p < .05; posterior cricoarytenoid muscle, 1.2 ± 1.0 mV, p < .01). Nineteen patients with vocal fold mechanical limitations generally had normal LEMG and evoked LEMG signals. Four patients with neoplastic infiltration of the laryngeal muscles demonstrated abnormal LEMG signals but nearly normal evoked LEMG signals.

Conclusions:

We conclude that LEMG and evoked LEMG behavior plays a crucial role in the diagnosis of vocal fold immobility. The decreased recruitment activities on LEMG and the decreased evoked LEMG signals with longer latency and lower amplitude reflect the severity of neuropathic laryngeal injury.

Multi-Motor Unit Potential Analysis and Other Quantitative Techniques for Laryngeal Electromyogram

Reference values for motor unit potentials of laryngeal muscles, the thyroarytenoid (TA) and cricothyroid (CT) muscles, have been collected using multi-motor unit potential quantitative electromyogram analysis technique with concentric quantitative electromyogram-needle electrode type in 40 healthy volunteers. The method is well tolerated, easy to perform, and examination of one muscle takes usually around 5 minutes. The mean motor unit potential amplitude of both muscles was significantly larger in men than in women. The method can safely be used in clinical routine. Other quantitative electromyogram methods are also shortly reviewed.

Superior laryngeal nerve injury: effects, clinical findings, prognosis, and management options

PURPOSE OF REVIEW

The superior laryngeal nerve (SLN) provides motor innervation to the cricothyroid muscle. However, the functions of this muscle and the anatomic variations of the nerve that supplies it are not fully understood. SLN paresis and paralysis (SLNp) is difficult to diagnose because of a lack of consistent laryngeal findings, and its effects on the voice likely go beyond simple pitch elevation control.

RECENT FINDINGS

Although SLNp has traditionally been thought to lead to voice pitch limitation, recent research findings reveal multiple roles for this nerve in voice and speech. Cricothyroid muscles are the primary controls of fundamental frequency of voice. SLNp can lead to significant contraction of pitch range, vocal fold vibratory phase asymmetry, and acoustic aperiodicity, thus leading to an overall poor vocal quality. In addition, cricothyroid muscles may also play a role in pitch lowering and shifting from voiced to unvoiced sounds during speech.

SUMMARY

Subtle signs, symptoms, and diagnostic findings associated with SLNp make this disorder difficult to characterize clinically. Lack of treatment methodologies to restore the dynamic action of the cricothyroid muscles poses difficulties in treating patients with this condition. A more thorough understanding of the effects of SLNp will improve diagnosis and treatment.

Voice outcomes after total thyroidectomy, partial thyroidectomy, or non-neck surgery using a prospective multifactorial assessment

BACKGROUND

Voice alteration remains a significant complication of thyroid surgery. We present a comparison of voice outcomes between total thyroidectomy (TT), partial thyroidectomy (PT), and non-neck (NN) surgery using a multifactorial voice-outcomes classification tool.

STUDY DESIGN

Patients with normal voice (n = 112) were enrolled between July 2004 and March 2009. The patients underwent TT (n = 54), PT (n = 35), or NN (n = 23) surgery under general endotracheal anesthesia as part of a prospective observational study involving serial multimodality voice evaluation preoperatively, and at 2 weeks, 3 months, and 6 months postoperatively. Patients with adverse voice outcomes were grouped into the negative voice outcomes (NegVO) category, including patients with objective (abnormality on videolaryngostroboscopy and substantial voice dysfunction) and subjective (normal videolaryngostroboscopy but with notable voice impairment) NegVO. Voice outcomes were compared among study groups.

RESULTS

Negative voice outcomes occurred in 46% (95% CI, 34-59%) and 14% (95% CI, 6-30%) of TT and PT groups, respectively. No NegVOs were observed after NN surgery. Early NegVOs were more common in the TT group than in the NN or PT groups (p < 0.001). Most voice disturbances resolved by 6 months (TT 84%; PT 92%) with no difference in NegVO among all groups (p = 0.23). Black race and significant changes in certain voice outcomes measures at the 2-week follow-up visit were identified as predictors of late (3 to 6 months) NegVO.

CONCLUSIONS

This comprehensive voice outcomes study revealed that the extent of thyroidectomy impacts voice outcomes in the early postoperative period, and identified risk factors for late NegVO in post-thyroidectomy patients who should be considered for early voice rehabilitation referral.

Characteristics of Vocal Fold Immobility following Endotracheal Intubation

Objectives:

We investigated the clinical and laryngeal electromyography (LEMG) characteristics and the outcome of closed reduction of arytenoid cartilage dislocation in patients with vocal fold immobility (VFI) following endotracheal intubation.

Methods:

Sixty patients with VFI following endotracheal intubation were included. Closed reduction was performed under local anesthesia in 54 cases. Another 6 patients did not undergo an intervention. Laryngeal behaviors and voice function were evaluated. Forty-five patients underwent LEMG testing.

Results:

All patients complained of persistent hoarseness immediately following surgery. The LEMG results for 29 of 45 patients showed normal patterns (15 cases) or mildly abnormal patterns (14 cases) on the affected side. Sixteen cases displayed apparent abnormal LEMG patterns on the affected side. The voices of all 54 patients improved after reduction. The movement of the affected vocal folds recovered to normal in 51 cases. One month after reduction, neuromuscular function had improved in 29 of 30 cases. Among the 6 patients who did not undergo intervention, 3 had normal or slightly hoarse voices, and 3 experienced moderate hoarseness.

Conclusions:

Vocal fold immobility following endotracheal intubation is typically caused by arytenoid dislocation. Some instances were accompanied by an abnormality of the recurrent laryngeal nerve. A timely closed arytenoid reduction should be performed to restore patients' normal voices and vocal fold mobility. Our reduction technique under local anesthesia can be performed easily and obtains satisfactory outcomes within 6 weeks after endotracheal intubation.

Tracking voice change after thyroidectomy: application of spectral/cepstral analyses

This study evaluates the utility of perioperative spectral and cepstral acoustic analyses to monitor voice change after thyroidectomy. Perceptual and acoustic analyses were conducted on speech samples (sustained vowel /α/ and CAPE-V sentences) provided by 70 participants (36 women and 34 men) at four study time points: prior to thyroid surgery and 2 weeks, 3 months and 6 months after thyroidectomy. Repeated measures analyses of variance focused on the relative amplitude of the dominant harmonic in the voice signal (cepstral peak prominence, CPP), the ratio of low-to-high spectral energy, and their respective standard deviations (SD). Data were also examined for relationships between acoustic measures and perceptual ratings of overall severity of voice quality. Results showed that perceived overall severity and the acoustic measures of the CPP and its SD (CPPsd) computed from sentence productions were significantly reduced at 2-week post-thyroidectomy for 20 patients (29% of the sample) who had self-reported post-operative voice change. For this same group of patients, the CPP and CPPsd computed from sentence productions improved significantly from 2-weeks post-thyroidectomy to 6-months post-surgery. CPP and CPPsd also correlated well with perceived overall severity (r = -0.68 and -0.79, respectively). Measures of CPP from sustained vowel productions were not as effective as those from sentence productions in reflecting voice deterioration in the post-thyroidectomy patients at the 2-week post-surgery time period, were weaker correlates with perceived overall severity, and were not as effective in discriminating negative voice outcome (NegVO) from normal voice outcome (NormVO) patients as compared to the results from the sentence-level stimuli. Results indicate that spectral/cepstral analysis methods can be used with continuous speech samples to provide important objective data to document the effects of dysphonia in a post-thyroidectomy patient sample. When used in conjunction with patient's self-report and other general measures of vocal dysfunction, the acoustic measures employed in this study contribute to a complete profile of the patient's vocal condition.

Anatomic direction of entry for botulinum toxin injection to treat the adductor spasmodic dysphonia in Thais

Background: Botulinum toxin injections into the thyroarytenoid (TA) muscle of the larynx is the most popular treatment for adductor spasmodic dysphonia. Injection is usually done by percutaneous transcricothyroid membrane with either electromyography (EMG) or fiberoptic laryngoscopy (FOL) to verify placement of the needle within the TA muscle. This procedure requires a working knowledge of three-dimensional anatomy of the larynx to establish the direction for the accurate placement of the needle. Objective: Find out the appropriate angles and depth of the needle for placement of percutaneous transcricothyroid membrane method of botulinum toxin injection by means of studying the larynges of Thai cadavers. Methods: The descriptive study was performed in 45 Thai freshly thawed cadavers. The angle of the needle from midline sagittal plane, the angle in superior relation to tracheal plane, and the depth from midline cricothyroid (CT) membrane to midlength of TA muscle were measured from the two views of photographs, anteroposterior and lateral. Results: The mean angle of 24.2±6.76° (mean±SD) from the midline sagittal plane in male and 24.9±7.6° in female were worked out. A mean angle in superior relation to the tracheal plane was 47.7±7.8° and 51.4±9.6° in male and female, respectively. The mean depth was 1.7±0.2 and 1.4±0.1 cm in male and female, respectively. Conclusion: The mean angles and depth of the needle insertion from the midline of CT membrane to the center of TA muscle in Thai laryngeal specimens were evaluated. These values were different from the studies in Caucasians, but it could provide a direct relationship to the build of the races. This knowledge may help laryngologists do this procedure more accurately with better outcome, especially in hospitals that have no EMG or FOL guide.

Evaluation of peripheral vocal cord paralysis by electromyography

OBJECTIVE

To analyze the predictive value of electromyography (EMG) after peripheral vocal cord paralysis and to estimate regeneration time.

STUDY DESIGN

Retrospective study based on electromyographic data and medical chart review of university based ENT hospitals.

METHODS

EMG results of 448 patients were classified into neuropraxia, axonotmesis/neurotmesis, or not classifiable and followed until final outcome. Final outcome was classified electromyographically into restitutio ad integrum, defective healing, or not classifiable.

RESULTS

The etiology of the paralysis was thyroid gland surgery in 42.9% and other iatrogenic lesions in 11.8%. Idiopathic paralysis was found in 20.3%. Mean follow-up time was 4.8 months. Initial EMG findings were neuropraxia in 31.0%, axonotmesis/neurotmesis in 40.8%, and not classifiable in 28.1%. Restitutio ad integrum was detected by EMG in 17.6% and defective healing in 43.3%. In 39.1%, the outcome could not be classified. The positive predictive value of EMG was 97% and the negative predictive value 60%. The outcome depended significantly on the initial EMG result (P < .0001) but not on the etiology (P = .737) of the paresis. Regeneration time after neuropraxia was 4.0 months and after axonotmesis/neurotmesis 5.6 months.

CONCLUSION

Laryngeal EMG has a high predictive value for acute peripheral vocal cord paralysis. The outcome can be predicted more reliably by means of EMG than by analysis of the etiology of the lesion.

Isolated bilateral vocal cord paralysis with intermediate syndrome after organophosphate poisoning

INTRODUCTION

Muscular weakness affecting predominantly the proximal limb muscles and neck flexors is the cardinal feature of intermediate syndrome with cranial nerve palsies occasionally accompanied. Following acute cholinergic phase of organophosphate poisoning (OPP), only a few isolated cases of vocal cord paralysis have been reported in the past. We describe a case of bilateral vocal cord paralysis which occurred in the wake of a clinical recovery from acute cholinergic crisis in OPP.

CASE REPORT

A 32-year-old woman presented with severe cholinergic crisis after ingestion of an unknown amount of dichlorvos in a suicide attempt. The patient was improved from cholinergic crisis by administration of antidotes. On day 4, she complained of progressive dyspnea and dysphonia after removal of the endotracheal tube. Needle electromyography for neuromuscular confirmation was normal. However, laryngeal electromyography (LEMG) findings were consistent with bilateral laryngeal paralysis suggesting the vagus nerve involvement. Her vocal cord movements were restored to near normal with time and she was discharged on the 20th day after admission.

CONCLUSIONS

Physicians should account for the neurotoxic effects of organophosphate poisoning during the first line management of exposed patients. Isolated bilateral vocal cord paralysis (BVCP) should be excluded as a cause, if dysphonia or respiratory distress occurs after extubation in patients with intermediate syndrome. LEMG in such cases can be an important diagnostic adjunct.

Management of Neurologic Disorders of the Larynx

Objectives:

I review the literature on management of neurologic disorders of the larynx.

Methods:

I reviewed the literature on laryngeal physiology, clinical evaluation of laryngeal function, and the clinical presentation and treatment of neurologic disorders that frequently affect the larynx.

Results:

Laryngeal function is complex, as this organ is important in breathing, speech, and swallowing. Coordination of these roles is very susceptible to disruption by neurologic disorders. Diagnosis of neurologic disease is primarily based on history and physical examination; however, the diagnosis of laryngeal dysfunction is frequently overlooked, because the larynx is not easily accessible to examination by non-otolaryngologists. Evaluation of laryngeal function includes listening to the voice, systematic observation of the larynx during speech and nonspeech tasks, and, sometimes, ancillary tests. Neurologic disorders that affect laryngeal function include Parkinson's disease, essential tremor, stroke, amyotrophic lateral sclerosis, multiple sclerosis, and dystonia. The otolaryngologist can sometimes provide treatment to specifically improve symptoms of laryngeal involvement.

Conclusions:

Otolaryngology consultation is important in the diagnosis and treatment of neurologic disorders that affect laryngeal function. The otolaryngologist should be able to perform a systematic evaluation of laryngeal and pharyngeal function, and should be aware of the clinical presentation of neurologic disorders that affect the larynx.

Neurolaryngologic evaluation of the performer

Numerous neurologic diseases affect voice production either through direct effects on the larynx or by affecting muscles involved with support or resonation of the voice. Voice changes can be the initial presenting symptoms of neurodegenerative disorders, especially in patients who have increased awareness of their vocal quality. Some patients present to the otolaryngologist before the neurologist. The otolaryngologist must have an understanding and familiarity with laryngeal manifestations of neurodegenerative diseases to make the appropriate diagnosis in a timely fashion. Moreover, the otolaryngologist can play a significant role in the care of patients who have neurodegenerative disease. Video procedures for neurolaryngologic evaluation accompany this content online.

The role of laryngeal electromyography in the diagnosis of vocal fold immobility in children

INTRODUCTION

Pathology may affect the muscles that control vocal function directly by affecting peripheral function or indirectly by affecting the central nervous system. Clinically, muscle function can be assessed by observing the movements of the structures themselves or by recording the electrical activity of the muscles (electromyography, EMG). Since EMG is an invasive technique, it has enjoyed limited use in the diagnosis and management of voice disorders, especially in children. Laryngeal EMG may be helpful in those patients with voice problems of suspected neurological or neuromuscular etiology.

OBJECTIVE

The purpose of this paper is to study the role of laryngeal EMG in the clinical evaluation of unilateral vocal fold immobility in children.

MATERIALS AND METHODS

Twenty-five children with unilateral vocal fold paralysis were studied. Twenty-five patients with vocal pathologies secondary to vocal abuse and misuse were studied as controls. The sensitivity and specificity of the EMG as a diagnostic marker for vocal fold paralysis were obtained. Additionally, nine patients with traumatic arytenoid dislocation were also studied. All patients were subjected to laryngeal EMG. EMG showed a sensitivity of 100%, and specificity of 92%. Only two patients, present with a functional voice disorder, showed abnormalities in the EMG recordings. In the nine patients with arytenoid dislocation, EMG showed normal parameters.

CONCLUSION

EMG seems a safe and reliable test for evaluating patients with vocal fold immobility. Moreover, the EMG recordings were helpful in differentiating vocal fold paralysis from arytenoid dislocation. EMG can provide useful data concerning muscle denervation, and more importantly, reinnervation. Besides its utility for the diagnosis, serial EMG can be useful for monitoring recovery and for establishing a reliable prognosis, and hence, an adequate treatment plan.

The Value of Laryngeal Electromyography in the Evaluation of Laryngeal Motion Abnormalities

SUMMARY

Laryngeal electromyography (EMG) functions routinely as a prognostic tool in the evaluation of vocal fold paralysis, as a guide for therapeutic injections into the laryngeal muscles, and more recently as an assessment tool in the evaluation of vocal fold paresis. This study investigates the clinical utility of laryngeal EMG as a diagnostic aid in the evaluation of movement disorders of the larynx in patients complaining of dysphonia. A retrospective chart review of all laryngeal EMGs performed at a tertiary laryngology referral center over a 13-month period was performed. All laryngeal EMGs were performed to evaluate laryngeal motion abnormalities in dysphonic patients. Thirty-seven laryngeal EMGs were completed during this study period. Analysis of the data revealed that the medical treatment plan changed as a result of findings on laryngeal EMG in 10/37 patients (27.0%); laryngeal EMG guided and/or confirmed the course of treatment in 12/37 patients (32.4%) and did not change the treatment plan in 15/37 patients (40.5%). Laryngeal EMG is a useful diagnostic tool that, in this study, contributed significantly to and helped guide the evaluation and management of motion disorders in the larynx of dysphonic patients.

Mild Vocal Fold Paresis: Understanding Clinical Presentation and Electromyographic Findings

The implications of mild vocal fold hypomobility are incompletely understood. This study describes the clinical, electromyographic, and probable etiologic findings in patients who presented with complaints of dysphonia and whose physical examination revealed vocal fold paresis as a factor possibly contributing to their voice complaints. A retrospective chart review of all patients who presented to a tertiary laryngology referral center over a 13-month period, who had a clinical diagnosis of mild vocal fold hypomobility and who underwent laryngeal electromyography, were included in the study. A total of 22 patients completed the medical evaluation of their voice complaint. Of these patients, 19 (86.4%) were found to have evidence of neuropathy on laryngeal electromyography. The clinical picture indicated the following probable origins for the vocal fold paresis: goiter/thyroiditis (7/22 or 31.8%), idiopathic (4/22 or 18.2%), viral neuritis (4/22 or 18.2%), trauma (3/22 or 13.6%), and Lyme's disease (1/22 or 4.5%). This article describes the clinical entity of mild vocal fold hypomobility and associated flexible laryngoscopic, rigid strobovideolaryngoscopic, and laryngeal electromyographic findings.

Laryngeal electromyography in movement disorders: preliminary data

This study describes preliminary laryngeal electromyography (LEMG) data and botulinum toxin treatment in patients with dysphonia due to movement disorders. Twenty-five patients who had been clinically selected for botulinum toxin administration were examined, 19 with suspected laryngeal dystonia or spasmodic dysphonia (SD), 5 with vocal tremor, and 1 with Gilles de la Tourette syndrome (GTS). LEMG evaluations were performed before botulinum toxin administration using monopolar electrodes. Electromyography was consistent with dystonia in 14 patients and normal in 5, and differences in frequency suggesting essential tremor in 3 and Parkinson tremors in 2. The different LEMG patterns and significant improvement in our patients from botulinum toxin therapy has led us to perform laryngeal electromyography as a routine in UNICAMP movement disorders ambulatory.

Practice parameter: laryngeal electromyography (an evidence-based review)

This paper reports on an evidence-based review of laryngeal electromyography (EMG) as a technique for use in the diagnosis, prognosis, and treatment of laryngeal movement disorders, including the laryngeal dystonias, vocal fold paralysis, and other neurolaryngological disorders. The authors performed a systematic review of the medical literature from 1944 through 2001 on the clinical application of EMG to laryngeal disorders. Thirty-three of the 584 articles met the predefined inclusion criteria. The evidence demonstrated that in a double-blind treatment trial of botulinum toxin versus saline, laryngeal EMG used to guide injections into the thyroarytenoid muscle in persons with adductor spasmodic dysphonia was beneficial. A cross-over comparison between laryngeal EMG-guided injection and endoscopic injection of botulinum toxin into the posterior cricoarytenoid muscle in abductor spasmodic dysphonia found no significant difference between the two techniques and no significant treatment benefit. Based on the evidence, laryngeal EMG is possibly useful for the injection of botulinum toxin into the thyroarytenoid muscle in the treatment of adductor spasmodic dysphonia. There were no evidence-based data sufficient to support or refute the value of laryngeal EMG for the other uses investigated, although there is extensive anecdotal literature suggesting that it is useful for each of them. There is an urgent need for evidence-based research addressing other applications in the use of laryngeal EMG for other applications.

The Role of Laryngeal Electromyography in Vocal Fold Immobility

AIM OF STUDY

To assess the utility of laryngeal electromyography (EMG) as a diagnostic method for patients with immobile vocal folds and to evaluate its possible role as a prognostic indicator in the management of those cases.

METHODOLOGY

The study included 35 patients with unilateral vocal fold immobility (VFI) and 10 normal controls. All patients were subjected to full history taking and thorough clinical examination and radiological investigations. Laryngeal EMG was performed for all the patients and controls.

RESULTS

The specificity of EMG was 100%, while the sensitivity was 65.7% in detecting VFI. Seventeen cases (74%) with abnormal EMG data had a combined lesion of recurrent and superior laryngeal nerves and 6 cases (26%) had isolated recurrent laryngeal nerve lesion. In both groups there was no statistical difference as regards the position of the paralyzed vocal fold in either paramedian or lateral positions. Clinical follow-up with indirect laryngoscopy, 6 months later, revealed recovery in 10 of the 25 cases (40%). None of the recovered patients showed abnormal EMG data at presentation, while 13 out of 15 cases of non-recovered patients showed abnormal EMG data, i.e. the specificity of EMG was 100%, while the sensitivity was 86.6% in predicting recovery in patients with VFI. The quantitative analysis of the interference pattern was more sensitive (65.7 and 86.6%) than the conventional methods of analysis (60 and 80%) in detecting and predicting recovery in patients with immobile vocal folds, respectively.

CONCLUSION

The clinical use of laryngeal EMG is an efficient and objective test in the study of patients with immobile vocal folds and in predicting recovery of those cases. It is also a useful tool in the diagnostic algorithm in vocal fold paralysis.

Neurophysiology of swallowing

Swallowing is a complex motor event that is difficult to investigate in man by neurophysiological experiments. For this reason, the characteristics of the brain stem pathways have been studied in experimental animals. However, the sequential and orderly activation of the swallowing muscles with the monitoring of the laryngeal excursion can be recorded during deglutition. Although influenced by the sensory and cortical inputs, the sequential muscle activation does not alter from the perioral muscles caudally to the cricopharyngeal sphincter muscle. This is one evidence for the existence of the central pattern generator for human swallowing. The brain stem swallowing network includes the nucleus tractus solitarius and nucleus ambiguus with the reticular formation linking synaptically to cranial motoneuron pools bilaterally. Under normal function, the brain stem swallowing network receives descending inputs from the cerebral cortex. The cortex may trigger deglutition and modulate the brain stem sequential activity. The voluntarily initiated pharyngeal swallow involves several cortical and subcortical pathways. The interactions of regions above the brain stem and the brain stem swallowing network is, at present, not fully understood, particularly in humans. Functional neuroimaging methods were recently introduced into the human swallowing research. It has been shown that volitional swallowing is represented in the multiple cortical regions bilaterally but asymmetrically. Cortical organisation of swallowing can be continuously changed by the continual modulatory ascending sensory input with descending motor output.

SIGNIFICANCE

Dysphagia is a severe symptom complex that can be life threatening in a considerable number of patients. Three-fourths of oropharyngeal dysphagia is caused by neurological diseases. Thus, the responsibility of the clinical neurologist and neurophysiologist in the care for the dysphagic patients is twofold. First, we should be more acquainted with the physiology of swallowing and its disorders, in order to care for the dysphagic patients successfully. Second, we need to evaluate the dysphagic problems objectively using practical electromyography methods for the patients' management. Cortical and subcortical functional imaging studies are also important to accumulate more data in order to get more information and in turn to develop new and effective treatment strategies for dysphagic patients.

Laryngeal electromyography: an evidence-based review

This article reports on an evidence-based review of laryngeal electromyography (EMG) as a technique for use in the diagnosis, prognosis, and treatment of laryngeal movement disorders including the laryngeal dystonias, vocal fold paralysis, and other neurolaryngological disorders. The authors performed a systematic review of the medical literature from 1944 through 2001 on the clinical application of EMG to laryngeal disorders. Thirty-three of the 584 articles met the predefined inclusion criteria. The evidence demonstrated that in a double-blind treatment trial of botulinum toxin versus saline, laryngeal EMG used to guide injections into the thyroarytenoid muscle in persons with adductor spasmodic dysphonia was beneficial. A cross-over comparison between laryngeal EMG-guided injection and endoscopic injection of botulinum toxin into the posterior cricoarytenoid muscle in abductor spasmodic dysphonia found no significant difference between the two techniques and no significant treatment benefit. Based on the evidence, laryngeal EMG is possibly useful for the injection of botulinum toxin into the thyroarytenoid muscle in the treatment of adductor spasmodic dysphonia. There were no evidence-based data sufficient to support or refute the value of laryngeal EMG for the other uses investigated, although there is extensive anecdotal literature suggesting that it is useful for each of them. There is an urgent need for evidence-based research addressing the use of laryngeal EMG for other applications.

Utility of laryngeal electromyography in predicting recovery after vocal fold paralysis

OBJECTIVES

To determine the value of laryngeal electromyography in predicting recovery after vocal fold paralysis and to determine what elements of laryngeal electromyography are most predictive of outcome.

DESIGN

Cohort study with retrospective data review.

SETTING

University voice center.

PARTICIPANTS

Consecutive sample of 31 patients with vocal fold paralysis diagnosed by indirect laryngoscopy, using either nasal insertion with a flexible nasopharyngoscope or peroral with a 70 degrees Hopkins rod. Inclusion criteria were that laryngeal electromyography had to have been performed between 21 days and 6 months from the onset of symptoms and patients must have been followed a minimum of 6 months.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Vocal fold motion at 6 months from onset of symptoms.

RESULTS

Nine subjects (29%) had resolved vocal fold motion, whereas 22 (71%) had persistent vocal fold paralysis. By using our laryngeal electromyography paradigm, 4 of 6 patients with a laryngeal electromyography prognosis of excellent resolved. The predictive value for a negative test was 66.7%. For patients with a fair or poor prognosis, 5 of 25 resolved. The predictive value for a positive test was 80%. Only 8 of 22 patients with persistent vocal fold paralysis had fibrillations, and spontaneous activity was not significantly related to outcome. Patients with absent or greatly decreased motor unit recruitment had a significantly higher proportion of permanent vocal fold paralysis (P<.05). Stepwise forward logistic regression determined that prognosis by laryngeal electromyography and onset time were significant predictors of outcome (P<.01). The model predicted 44.4% of resolved cases, which represents a moderate prediction.

CONCLUSIONS

This study confirms the utility of laryngeal electromyography in assessing prognosis for recovery of vocal fold motion after laryngeal nerve injury. The results support our hypothesis that preset decision rules based on laryngeal electromyography data can be effectively used to determine a prognosis for recovery of vocal fold motion.

Vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma: laryngeal electromyography findings

Laryngeal electromyography was used to study the pattern of neurological injury in three patients with unilateral vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma. The thyroarytenoid and cricothyroid muscles were assessed to give an indication of recurrent and superior laryngeal nerve function. Two patients demonstrated both recurrent and superior laryngeal neuropathy suggesting injury at the skull base. The other patient had only recurrent laryngeal neuropathy indicating more distal involvement. Subclinical neuropathic changes were seen in two cases on the side contralateral to the vocal fold paralysis. These patients may be at increased risk of developing bilateral vocal fold paralysis and potentially life-threatening airway obstruction. Long-term follow-up is recommended for such patients, especially if medialization thyroplasty is being considered. This is the first report describing the use of electromyography to determine the pattern of nerve injury in patients with vocal fold paralysis following head and neck radiotherapy.

Lack of evoked laryngeal electromyography response in patients with a clinical diagnosis of vocal cord paralysis

There has been recent debate about whether patients with vocal cord immobility have a neurologic paralysis or whether synkinesis, the misdirection of axons to competing laryngeal muscles, is responsible for the lack of voluntary vocal cord motion. This issue was studied in 15 patients with vocal cord paralysis who underwent laryngeal reinnervation. Evoked electromyography was performed with a surface electrode endotracheal tube. The recurrent laryngeal nerve (RLN) was identified and stimulated with constant current. Of the 15 patients, only 1 produced a compound muscle action potential upon nerve stimulation. The remaining 14 patients had no evoked response during RLN stimulation. A control group of 8 patients with normal vocal cord mobility was studied, and each had a normal evoked electromyography response after RLN stimulation. These results support the assertion that patients who require treatment for vocal cord paralysis do not have synkinesis produced by RLN reinnervation.

[Use of botulinum toxin in the treatment of laryngeal dystonia (spasmodic dysphonia): preliminary study of twelve patients]

Laryngeal dystonia (spasmodic dysphonia) is a movement disorder characterized by involuntary contractions of laryngeal muscles involved with vocalization. The introduction of botulinum toxin in the treatment of laryngeal dystonia had a major clinical impact due to the striking improvement of symptoms. We report the preliminary results of therapeutical use of botulinum toxin in the treatment of twelve patients with laryngeal dystonia. After an extensive clinical evaluation, the patients underwent a videostroboscopic exam for diagnostic confirmation. Botulinum toxin was injected in the cricothyreoid membrane, directed towards the thyreoaritenoid muscle, with the aid of eletromyography needles. Most of patients who underwent botulinum toxin injection had a significant improvement of their symptoms (83%), with effects lasting for four months in average and without important side effects.

Cricopharyngeal sphincter muscle responses to transcranial magnetic stimulation in normal subjects and in patients with dysphagia

OBJECTIVE

Cricopharyngeal (CP) muscle of the upper oesophageal sphincter (UES) has a significant role in the pharyngo-esophageal phase of deglutition. The linkage between the CP muscle of UES and the motor cortex has not been previously studied electrophysiologically in healthy humans and in patients with neurogenic dysphagia.

METHODS

Needle recordings of EMG responses were carried out from the CP sphincter muscle following transcranial magnetic stimulation (TMS) over the vertex around the Cz electrode position (cortical MEP), and on the parieto-occipital skull and the occiput ipsilaterally (peripheral MEP) in 14 healthy control subjects and in 26 patients with and without neurogenic dysphagia. Needle recordings obtained from the cricothyroid muscle of the larynx were also evaluated in six healthy subjects.

RESULTS

The cortical motor latency of CP sphincter muscle was 10.7+/-0.5 ms with an amplitude of 0.8+/-0.2 mV in healthy subjects. Both the latency and amplitude of CP-MEP were facilitated during swallowing. The peripheral MEP of the CP muscle was very stable in all normal subjects (5.1+/-0.3 ms; 1.3+/-0.3 mV) and swallowing did not influence these parameters. The cortically elicited CP-MEP was significantly longer than the cortical MEPs obtained from the cricothyroid muscle of the larynx. In 10 dysphagic patients with corticobulbar tract involvement (6 ALS and 4 pseudobulbar palsy) and with pathologic and hyperreflexic EMG of the CP-sphincter muscle, the cortical MEP of CP muscle of the upper esophageal sphincter could not be elicited, although the peripheral CP-MEPs were obtained. TMS never produced a swallowing movement in neither healthy subjects nor patients.

CONCLUSION

The CP muscle of the upper esophageal sphincter can produce MEPs by cortical TMS and by stimulation at the root/nerve levels of vagus nerve. The MEP latency values and central motor delay suggest that there is an oligosynaptic corticobulbar pathway to the motoneurons of CP muscles. When the pathway is affected by a pathology (i.e. ALS or pseudobulbar palsy) the CP sphincter becomes hyperreflexic due to disinhibition and the cortical MEP of the CP muscle disappears due to degeneration of the corticobulbar pathway. These mechanisms appear to be responsible for the pathogenesis of dysphagia.

Nomenclature of voice disorders and vocal pathology

An improved nomenclature framework is crucial to improve communication regarding voice problems and to advance the field of voice disorders. The subjective nature of the voice evaluation process does not lend itself readily to uniformity and most voice-disordered patients demonstrate multiple pathologic processes. In this article, the authors offer a broad-based nomenclature paradigm for the classification of voice disorders and vocal pathology. Four major categories of voice disorders are identified based on pathophysiology and auditory-perceptual and visual-perceptual observations. As the understanding of vocal fold biomechanics and pathophysiology evolves, it is expected that this nomenclature system will also increase in specificity.

Critical evaluation of neurolaryngological disorders

Otolaryngological examinations, videostroboscopic image analysis, and laryngeal electromyography were used as a test battery for a critical evaluation in 80 patients. Vocal fold movements were categorized into mobility, restricted mobility, immobility with different positions, and overactive movement. Laryngeal electromyographic examinations were conducted in all patients, and the results were classified into normal, neuropathic, and myopathic patterns. The electromyographic data were integrated with videostroboscopic findings, interpreted with knowledge of biomechanical and electrophysiological mechanisms of the larynx, and correlated clinically with underlying diseases. It is suggested that neurolaryngological procedures are most clinically useful when dictated by a decision-making algorithm.

Postintubation interarytenoid adhesion

Interarytenoid fibrous adhesion is a poorly recognized complication of intubation and is frequently confused with bilateral vocal cord paralysis. Early diagnosis and treatment is essential for optimal management. Otolaryngologists should constantly remain alert for interarytenoid fibrous scar to establish the diagnosis as early as possible, optimizing the probability of restoring normal breathing and quality of life and avoiding an unnecessary tracheotomy. Surgical laser reduction is appropriate in all cases when other miscellaneous laryngeal injury lesions are eliminated. Direct laryngoscopy with careful examination of the posterior commissure and laryngeal electromyography are the 2 main clinical diagnostic aids contributing to establish the diagnosis.

Laryngeal electromyography: diagnostic and prognostic applications

Laryngeal electromyography is a crucial diagnostic test in laryngology. Laryngeal electromyography is important for the diagnosis of vocal fold paresis and cricoarytenoid joint pathology (e.g., arytenoid dislocation). In addition, laryngeal electromyography offers prognostic information regarding potential vocal fold paralysis recovery, which can improve the management strategies for vocal fold paralysis.

The electromyographic behavior of the thyroarytenoid muscle during swallowing

The electromyographic (EMG) behavior of the laryngeal adductors (e.g., the thyroarytenoid [TA] muscle) during swallowing has been scarcely studied. However, the detailed analysis of TA muscle is important to understand the physiology of swallowing. We investigated 14 healthy adult subjects. Activation of the TA laryngeal adductor muscle was compared with the mechanically measured laryngeal up-down movement and with the onset of excitation of laryngeal elevators, such as submental (SM) muscles, during swallowing. The laryngeal adductor of TA and laryngeal elevators of SM muscles were electromyographically (integrated/rectified) recorded. The vertical laryngeal movements during swallowing were recorded using a piezoelectric sensor. The EMG behavior of the TA muscle revealed three different activities during swallowing. The basic activity was stable; it almost started with the upward movement of larynx and after the SM-EMG onset. A fore-burst was recorded just before the upward movement of the larynx and a late-burst appeared just after the downward movement. The fore-burst was proposed to be related with oral-laryngeal reflexes, and the late-burst could be a rebound activity after a short expiration of swallowing, while the basic activity is accepted to be a part of activity of central-pattern generator of swallowing program.

Botulinum toxin: adjunctive treatment for posterior glottic synechiae

INTRODUCTION

Synechiae formation of the posterior glottis can result in tracheostomy dependence secondary to airway obstruction. Stenosis is caused by total or partial fixation of the vocal folds in adduction resulting from scar contracture. The treatment poses a management dilemma because of recurrent scar formation, made worse by mobility of the vocal folds. Although various treatment options from conservative endoscopic repair to open procedures have been proposed, the results are not satisfactory and patients often require multiple procedures.

METHODS

We present the trial of a conservative approach that includes microscopic CO2 laser resection of the scar with concomitant botulinum toxin injection of the interarytenoid and thyroarytenoid muscles of the more mobile cord. This results in a temporary paresis of the adductor muscles and hence prevents overadduction in the posterior commissure during the postoperative healing period.

STUDY DESIGN

We present the surgical technique and results in three patients who underwent the procedure.

RESULTS

Treatment in all three patients was successful.

CONCLUSIONS

The appropriate use of botulinum toxin may help improve the treatment outcome of posterior synechiae of the larynx without sacrificing any laryngeal components.