The clinical differentiation between vocal cord paralysis and vocal cord fixation using electromyography

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.

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.

Electromyography-guided hyaluronic acid injection laryngoplasty in early stage of unilateral vocal fold paralysis

INTRODUCTION AND OBJECTIVE

To assess the effectiveness of electromyography-guided hyaluronic acid injection laryngoplasty in the early stage of unilateral vocal fold paralysis in terms of patient recovery from dysphonia and quality of life.

METHODS

Between January and December 2014, 28 patients with unilateral vocal fold paralysis underwent electromyography and injection of hyaluronic acid in the thyroarytenoid muscle. We compared the voice handicap index, grade, roughness, breathiness, asthenia, strain scale (GRBAS), videostroboscopic parameters and maximum phonation time assessed before, 15 days and 6 months after the intervention, using the non-parametric Wilcoxon rank test.

RESULTS

Out of the 28 patients, 1 had a haematoma in the injected vocal fold (3.57%) and 6 required second injections. The maximum phonation time of the vowel /e/ increased from 6.07 to 12.14 sec. (15 days post-intervention) and subsequently 12.75 (6 months post-intervention). There was also a significant improvement in the grade, roughness, breathiness, asthenia, strain scale in parameters G, B and A both 15 days and 6 months after the intervention. The voice handicap index score decreased from 58.29 to 37.63 (15 days post-intervention) and 29.64 (6 months post-intervention).

CONCLUSIONS

Electromyography-guided hyaluronic injection laryngoplasty in unilateral vocal fold paralysis enables, in the same intervention, neuromuscular assessment and temporary treatment of glottic insufficiency with a low risk of complications and improvement in patient's quality of life. This may reduce the need for subsequent treatments, but further research is required to confirm these findings.

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 and prognostic contribution of laryngeal electromyography in unilateral vocal-fold immobility in adults

OBJECTIVES

To study the diagnostic and prognostic contribution of laryngeal electromyography in unilateral vocal-fold immobility in adults.

MATERIAL AND METHODS

A retrospective study included patients with unilateral vocal-fold immobility undergoing laryngeal electromyography between 2007 and 2015. Neurogenic, normal or myogenic findings were compared to the clinical aspect. Prognosis for recovery was assessed from motor unit potentials on laryngeal electromyography, and compared to subsequent progress on laryngoscopy.

RESULTS

Sixty-three patients (mean age, 59 years) were initially included; 2 were subsequently excluded from analysis. Mean time from onset of immobility to laryngeal electromyography was 7 months. 85% of the 61 patients showed neurogenic findings, indicating neural lesion; 13% showed normal electromyography, indicating cricoarytenoid joint ankylosis; and 1 patient showed a myogenic pattern. Neurogenic cases were usually secondary to cervical surgery. Thirty-eight patients were followed up. In total, 75% of patients showing reinnervation potentials recovered. The positive predictive value of laryngeal electromyography was 69.2%.

CONCLUSION

Laryngeal electromyography is effective in specifying the origin of unilateral vocal-fold immobility in adults. It also has a prognostic role, lack of reinnervation potentials being a possible indication for early medialization surgery.

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.

Laryngeal electromyography findings of vocal fold immobility in patients after radiotherapy for nasopharyngeal carcinoma

BACKGROUND

The clinical features of vocal fold immobility (VFI) after radiotherapy for nasopharyngeal carcinoma (NPC) have seldom been reported.

METHODS

We retrospectively reviewed laryngeal electromyography (LEMG) and tumor study findings to elucidate the common clinical features of patients who presented with VFI after radiotherapy for NPC. The LEMG signals obtained from the cricothyroid and thyroarytenoid muscles were used to confirm superior laryngeal nerve (SLN) and recurrent laryngeal nerve (RLN) injury.

RESULTS

The medical records of 13 patients were reviewed and 11 of them had evidence of RLN injury. Six of the 11 patients also had SLN injury, indicating possible vagus nerve (VN) injury. Two patients had cricoarytenoid joint fixation without evidence of nerve injury. None of the nerve injuries were caused by skull base recurrence or tumor metastasis.

CONCLUSION

VFI is usually caused by nerve injury, but it is not a malignant sign of tumor recurrence or metastasis.

Differentiating arytenoid dislocation and recurrent laryngeal nerve paralysis by arytenoid movement in laryngoscopic video

OBJECTIVE

To present a new method of quantifying arytenoid movement during inspiration and determine if it can be used to distinguish arytenoid dislocation from vocal fold paralysis.

STUDY DESIGN

Case series with chart review.

SETTING

Retrospective study conducted in a university laboratory based on university hospital data.

SUBJECTS AND METHODS

Endoscopic videos from 8 patients with dislocation and 5 patients with vocal fold paralysis diagnosed by electromyography were included. Vector analysis measured cuneiform movement, an indirect measurement of arytenoid movement, during 1 inspiration. Measurements normalized and not normalized to vocal fold length were evaluated. Interrater reliability (2 raters) and intrarater reliability (1 rater performing the analysis twice) were evaluated using intraclass correlation coefficient (ICC) analysis. Raters were blinded to subject group during analysis.

RESULTS

Pixel-valued cuneiform movement was 81.16 ± 25.62 for dislocation and 30.22 ± 23.60 for paralysis (P = .019). Unitless cuneiform movement was 0.58 ± 0.17 for dislocation and 0.24 ± 0.18 for paralysis (P = .030). Interrater ICC was 0.942 for pixel-valued measurements and 0.962 for unitless measurements. Intrarater ICC was 0.909 for pixel-valued measurements and 0.881 for unitless measurements.

CONCLUSIONS

Both pixel-valued and unitless measures of arytenoid movement were significantly greater in arytenoid dislocation than vocal fold paralysis. Pixel-valued measurements were included to demonstrate the ability to make quantitative comparisons across subjects without precise knowledge of camera precision, provided position is approximately stable, as each measurement is inherently normalized by vocal tract length. Future studies will apply this new method of evaluating vocal fold immobility disorders on a larger scale and incorporate a more diverse group of etiologies.

Laryngeal electromyography in dysphonic patients with incomplete glottic closure

The lack of specificity in laryngoscopical examination requires that the diagnosis of superior laryngeal and recurrent laryngeal nerve involvement be carried out with the aid of electromyography.

Objective

This study aims to assess the electrophysiological function of the superior and inferior laryngeal nerves by measuring the electrical activity of the muscles they innervate in dysphonic patients with incomplete closure of the vocal folds during phonation.

Method

Thirty-nine patients with incomplete glottic closure were enrolled in a prospective study and had their cricothyroid, thyroarytenoid, and lateral cricoarytenoid muscles examined bilaterally through electromyography. Insertion activity, electrical activity at rest (fibrillation, positive wave and fasciculation) and during muscle voluntary contraction (recruitment, amplitude, potential length and latency between electrical activity and phonation) were measured.

Results

No altered test results were observed for parameters insertion activity and electrical activity at rest. None of the patients had recruitment dysfunction. The mean electrical potential amplitude values were within normal range for the tested muscles, as were potential durations and latency times between the onset of electrical activity and phonation.

Conclusion

No signs of denervation were seen in the thyroarytenoid, cricothyroid, and lateral cricoarytenoid muscles of the studied patients.

A promising new technique for closed reduction of arytenoid dislocation

Objectives:

To study the effect of a new technique for closed reduction of dislocated arytenoids.

Methods:

The study included 21 females (72.4 per cent) and eight males (27.6 per cent) with a diagnosis of arytenoid dislocation. There were 18 cases of left arytenoid dislocation and 11 of right arytenoid dislocation.Twenty-eight cases had anteromedial dislocation and one had posterolateral dislocation. All patients were treated with closed reduction using custom-made metal rods and an operating microscope, under general anaesthesia.

Results:

Post-operatively, 21 patients’ voices returned completely to normal (including full vocal fold mobility), five had an improved voice and three failed to show any improvement. There were no post-operative complications.

Conclusion:

This new closed reduction technique is a safe procedure for patients with dislocated arytenoids. It is repeatable and the outcome is reliable and effective. Closed reduction can be a useful treatment for arytenoid dislocation.

Office-Based Arytenoid Palpation for Diagnosis of Disorders of Bilateral Vocal Fold Immobility

Bilateral vocal fold immobility is an uncommon but serious condition with many causes. Accordingly, accurate diagnosis is essential in order to treat patients promptly and avoid long-term sequelae. Historically, diagnosis has been performed in the operating room with the patient under general anesthesia. We present the case of a patient who was diagnosed with bilateral vocal fold immobility by in-office arytenoid palpation that required only topical anesthesia of the larynx. The patient subsequently underwent appropriate treatment. In our opinion, office-based arytenoid palpation is a simple, safe, and accurate procedure for diagnosing bilateral vocal fold immobility.

Diagnosis of Unilateral Recurrent Laryngeal Nerve Paralysis: Laryngeal Electromyography, Subjective Rating Scales, Acoustic and Aerodynamic Measures

OBJECTIVE/HYPOTHESIS

To determine whether specific laryngeal electromyography (LEMG) patterns in patients with unilateral vocal fold paralysis/paresis (UVFP) are related to etiology of injury, time from onset of injury, patient perception of symptom severity, acoustic measures, and laryngeal aerodynamic measures.

STUDY DESIGN

This is a retrospective review of 75 patients.

METHODS

Each patient received LEMG, acoustic and aerodynamic testing, and a subjective rating scale assessment (the Glottal Closure Index). Statistical analysis by groups were performed using both chi and single-factor analysis of variance testing.

RESULTS

An iatrogenic etiology was associated with poor tone on LEMG (P = .05). Those individuals evaluated after 3 months after onset demonstrated more nascent units, a sign of reinnervation, compared with individuals evaluated before 3 months (P < .02). Individuals with fewer normal motor units on LEMG had significantly higher mean translaryngeal air flows (P = .044). Individuals with poor recruitment had significantly shorter maximum phonation times (P = .034) and higher mean flows (P = .044). Individuals with better laryngeal tone as noted on LEMG had significantly lower mean flows (P = .06).

CONCLUSIONS

Specific LEMG patterns are related to the etiology of the UVFP and time course since recurrent laryngeal nerve injury. LEMG appears to reflect vocal fold muscle tone as seen on laryngeal function studies. In combination, these studies provide a cohesive assessment of laryngeal function in patients with UVFP.

Electromyography and the immobile vocal fold

Laryngeal EMG has become a useful tool for the otolaryngologist in the four decades since the pioneering work of Faaborg-Anderson and Buchtal. It is able to distinguish between mechanical limitation and denervation in an immobile vocal fold. In the paralyzed vocal fold, it can guide workup by pointing to the site of the lesion. In the hands of a circumspect clinician, it can provide clinically valuable information regarding prognosis. Useful application of laryngeal EMG must rest on the basic fact that it isa qualitative test. Because of factors like sampling error, interfering signal from neighboring muscles, difficulties in needle placement, and our in-complete understanding of reinnervation physiology, the boundary between sophisticated, subtle interpretation and overreading is particularly difficult to distinguish. EMG diagnosis is based on patterns of abnormalities over time and, like other tests, requires interpretation in a clinical context. As in any such undertaking, there is no substitute for good judgment and experience. The most important benefit of clinical use of laryngeal EMG may be that it has catalyzed and broadened interest in laryngeal neurophysiology in the same way that stroboscopy has focused attention on the structure and function of the vocal fold lamina propria. The continuing refinement of electrodiagnostic approaches to the larynx that has resulted, including quantitative, single-fiber. and vector laryngeal EMG, and evolving methods of nerve conduction testing will continue to yield important insights into mechanisms of neural control that are likely to drive developments in the treatment of vocal fold paralysis in the future.

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.

Inspiratory Activation of the Vocal Cord Adductor, Part I: Human Study in Patients With Restricted Abduction of the Vocal Cords

OBJECTIVES/HYPOTHESIS

In patients with restricted abduction of the vocal cords, it has generally been accepted that glottis narrowing with laryngeal stridor during inspiration is attributed to static and passive obstruction of the glottis. However, active glottis narrowing can also be contributory. We tested the hypothesis that the vocal cord adductor is activated during inspiration in patients with restricted abduction of the vocal cords.

STUDY DESIGN

Electromyographic evaluation of vocal cord adductor activity in patients with restricted abduction of the vocal cords.

METHODS

Five patients with restricted abduction of the vocal cords who had stridor with mild to severe dyspnea during wakefulness were anesthetized with propofol. We recorded the adductor muscle electromyogram during breathing through a laryngeal mask airway while observing the vocal cord movement endoscopically. In three patients who had undergone tracheostomy, we also recorded adductor firing patterns not only while closing but also while opening the tracheostoma.

RESULTS

The adductor was activated during inspiration, and the glottis was narrowed in accordance with inspiratory stridor. This adductor inspiratory activity was abolished by opening the tracheostoma in the tracheostomized patients.

CONCLUSION

Not only static or passive glottis narrowing but also active narrowing may contribute to inspiratory flow limitation in patients with restricted abduction of the vocal cords. This active glottis narrowing is probably induced by an airway reflex.

Permanent medialization of the paralyzed vocal fold utilizing botulinum toxin and Gelfoam

The clinical picture of a paralyzed vocal fold often has the same appearance as a subluxated arytenoid, with anterior and medial displacement of the arytenoid and a foreshortened and lax vocal fold. Previous work by the authors has shown that a subluxated arytenoid may be permanently repositioned by reduction and selective injection of the intrinsic laryngeal musculature with botulinum toxin. The injection changes the forces within the larynx, allowing the arytenoid to be brought back to proper position on the cricoid cartilage. This concept has been extended to the paralyzed vocal fold. It has been noted that even a clinically paralyzed vocal fold has voluntary motor units that may still act on the arytenoid through residual action from the interarytenoid and synkinesis. These forces are significant enough to manipulate the arytenoid and, thus, the vocal fold, into its correct, adducted position. In this paper, the arytenoid is mobilized to free any fibrosis. The thyroarytenoid and lateral cricoarytenoid muscles are then injected to prevent any forward synkinetic pull on the arytenoid. Next, a Gelfoam injection medializes the vocal fold to create glottic closure. This rebalancing sufficiently positions the arytenoid, so that valvular function is permanently restored. In the ten patients studied for over 1 year, there was a 90% success rate as measured by videostroboscopy, phonation time, and V-RQOL analysis. There were no untoward complications. All the materials used are nonpermanent. The procedure does not limit other techniques from being performed at a later time.

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.

Vocal cord paralysis, synkinesis and vocal fold motion impairment

Felix Semon's 'laws' of vocal cord paralysis were conceived over a century ago, based on the simple concept that abductor function of the recurrent laryngeal nerve was more vulnerable than adductor function. It is now clear that the neuromuscular pathology of laryngeal innervation is much more complex. Whether the nerve has been cut, crushed, stretched, cauterized or otherwise injured, it is seldom completely transected. There might be no detectable vocal cord movement at laryngoscopy, yet, electromyography usually shows at least some activity because of incomplete denervation and/or developing synkinesis. Electrical silence hardly ever persists forever. Disordered vocal fold movement following nerve injury appears to depend on laryngeal synkinesis with disorganized neuromuscular function caused by misdirected regeneration and aberrant reinnervation, sometimes by adjacent nerves. The severity of the injury, abnormal random reinnervation, scar tissue formation and nerve growth-stimulating and inhibiting factors influence the final position of the vocal fold. For a better understanding of neurolaryngological disorders it is no longer sufficient to think merely in terms of 'vocal cord paralysis'.

The evolving etiology of bilateral vocal fold immobility

In the past, bilateral vocal fold immobility (BVFI) occurred most commonly after thyroidectomy. However, no large series documenting the etiology of adult BVFI has been published within the past fifteen years. This study reviews the etiologic patterns of BVFI at our institutions. We compare BVFI from before and after 1980. We also review combined studies of unilateral vocal fold immobility (UVFI) to compare and unilateral versus bilateral etiologic trends. In comparison with previously published series, fewer cases of BVFI present today as a complication of thyroid surgery and more as the result of malignancies and nonsurgical trauma. Unfortunately, BVFI caused by malignancy is not usually an initial sign of local disease, but an ominous sign of recurrence or metastases. In comparing UVFI and BVFI we found that thyroidectomy causes a higher percentage of BVFI than of UVFI. Over one-third of UVFI cases were caused by neoplasm which further underscores the potential seriousness of immobile vocal folds and the need for careful investigation.

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.

Laryngeal electromyography in the management of vocal cord mobility problems in children

OBJECTIVES

To evaluate the efficacy and clinical usefulness of laryngeal electromyography (EMG) in the evaluation and management of vocal cord mobility problems in children; and to determine the ability of laryngeal EMG to differentiate vocal fold fixation versus paralysis.

STUDY DESIGN

Case-series review of 8 children with vocal cord immobility who underwent laryngeal EMG.

METHODS

Eight children with bilateral vocal fold immobility underwent microlaryngoscopy and electromyography. Bipolar concentric needle electrodes were used and implanted separately into both posterior cricoarytenoid (PCA) and both thyroarytenoid (TA) muscles. EMG activity was recorded during spontaneous ventilation under a light plane of anesthesia with propofol. EMG activity was correlated with the phases of the respiratory cycle.

RESULTS

Three patients had evidence of normal EMG activity with PCA activity peaking during early inspiration. Maximal TA activity occurred expiration. These patients were assumed to have vocal fold fixation. Two of these 3 patients underwent laryngotracheoplasty (LTP) with posterior glottic expansion with costal cartilage. One is being considered for LTP in the future. Five patients had abnormal EMG activity and remain tracheotomy-dependent. Four patients exhibited synkinetic activity with peak PCA activity during expiration and peak TA activity during expiration. Two patients had both fixation and unilateral vocal cord paralysis. One was successfully decannulated after posterior graft LTP and the other is planned for the future.

CONCLUSIONS

Electromyography, which differentiates paralysis from fixation, is a useful diagnostic tool in the evaluation of children with vocal cord immobility.

[Glottic immobility: retrospective study of 229 cases]

A retrospective study of the unilateral and bilateral vocal fold immobility cases diagnosed at our hospital between 1985 and 1998 was carried out. Of the 229 cases studied, vocal fold immobility was bilateral in 58 patients (25%), unilateral right in 60 (26%), and unilateral left 111 (49%). The most frequent etiologies in the bilateral cases were thyroid surgery (38%) and prolonged intubation (31%); idiopathic cases (32%) and thyroid surgery (23%) in the unilateral right cases; and idiopathic cases (28%) and extralaryngeal tumors (22%) in the unilateral left cases. Clinical compensation was achieved in more than 85% of cases of unilateral immobility when the etiology was idiopathic or due to surgical damage to the recurrent or vagus nerves, 70% when it was a prolonged intubation, 56% in neurological patients and 38% in extralaryngeal tumors. In patients with bilateral vocal fold immobility, 14% did not require any treatment, 34% had a permanent tracheostomy, and 52% recovered adequate naso-oral ventilation after surgery (tracheostomy only in 12 patients and arytenoidectomy in 18 patients).

Intraoperative pediatric laryngeal electromyography: experience and caveats with monopolar electrodes

We report our experience with intraoperative laryngeal electromyography (L-EMG) using direct laryngoscopy and placement of monopolar electrodes under general anesthesia in the evaluation and management of laryngeal dysfunction in pediatric patients. In this series of case studies, we present clinical data on 30 pediatric patients with known or suspected anatomic or neurologic laryngotracheal disorders evaluated with placement of shielded monopolar electrodes into the thyroarytenoid muscles during direct laryngoscopy under general anesthesia. Diagnoses included congenital vocal fold paralysis (VFP), laryngotracheal stenosis, cerebral palsy, laryngeal tumors, traumatic vocal fold dysfunction, and postsurgical VFP. The impact of L-EMG on patient management was assessed. We found that L-EMG objectively supported clinical findings, but provided new objective data relevant toward management recommendations in only a few selected pediatric patients with new-onset vocal fold paralysis or paresis or infiltrative laryngeal tumors, and in selected postsurgical cases involving decannulation decisions. The prognostic utility of L-EMG in newborns with congenital VFP has not been established. A normal L-EMG recording indicates an intact neuromuscular axis, but does not guarantee vocal fold mobility or guarantee muscle function in a partially denervated or deconditioned muscle. The potential for false-negative recordings is the major limitation of this technique.

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.

Aging effects on motor units in the human thyroarytenoid muscle

OBJECTIVES

To determine whether age differences are present in the human laryngeal thyroarytenoid muscle that would indicate that different normative values would be needed for identifying motor unit abnormalities.

STUDY DESIGN

Twenty-six consecutively recruited healthy subjects between the ages of 21 and 72 years participated in a laryngeal electromyography study.

METHODS

Bipolar needle electrodes were used to record motor unit action potentials from several locations in the right and left thyroarytenoid muscles of each subject. The duration of a motor unit was measured when at least 10 firings of the same motor unit could be identified. On the average, four units were measured per muscle.

RESULTS

In the subjects less than 60 years of age, motor unit duration did not increase significantly with age. However, motor units from subjects greater than 60 years of age had longer durations than those from subjects less than 60 years of age (P < .00005), and 25% of the units measured in subjects greater than 60 years of age had longer durations than any of the units measured in subjects less than 60 years of age. Further, the older subjects differed from each other in their mean unit durations (P < .0001). In subjects less than 60 years of age, significantly longer durations were found for units innervated by the longer, left-side recurrent laryngeal nerve in comparison with the right-side nerve (P = .005).

CONCLUSIONS

Different mean and SD values should be used for patients less than and greater than 60 years of age and for the right and left sides, when evaluating motor units in the thyroarytenoid muscles.

Evaluation and management of bilateral vocal cord immobility

Bilateral vocal cord immobility can be life threatening for some patients. Others, who have an open glottic chink, may have a breathy dysphonia, intermittent dyspnea, and stridor. These signs and symptoms may also be found in a number of other conditions that cause weakness or paradoxical motion of the vocal cords that mimics paralysis. These other conditions include central nervous system diseases, neuromuscular disorders, laryngospasm, and psychogenic disorders. In addition, patients with cricoarytenoid joint immobility or interarytenoid scar can also have similar symptoms at presentation. It is critical to consider the differential diagnosis of an assumed bilateral vocal cord paralysis and understand the management of paradoxical movement, weakness, joint fixation, interarytenoid scar, laryngospasm, and psychogenic disorders. The treatment for bilateral immobility should proceed only after a thorough evaluation, which might include electromyography and/or examination during general anesthesia under dense anesthetic paralysis. Reconstructive procedures are the treatments of choice, and destructive procedures should be chosen only as a last resort.

Botulinum toxin injection in the treatment of vocal fold paralysis associated with multiple sclerosis: a case report

Botulinum toxin has been demonstrated clinically to be an effective treatment for a variety of laryngeal problems, most notably spasmodic dysphonia. As in other movement disorders, the theory behind the injection of this substance in the larynx has been a weakening of the vocal fold musculature to relieve uncoordinated and spasmodic movement of the vocal folds, presumably rebalancing the forces within the intralaryngeal musculature. Recently, this concept was applied to help reposition the arytenoid cartilage in acute and longstanding anteromedial cricoarytenoid dislocations. This same concept may apply to the paralyzed vocal fold. In support of this idea, a number of investigators have shown that immobile, clinically paralyzed vocal folds may still have partial voluntary motor unit activity. This voluntary activation may not produce clinically evident movement but may be sufficient to produce tone within the fold. If the voluntary motor units in the abductor musculature of the paralyzed fold are weakened with botulinum toxin, the continued pull of the functioning adductor musculature may be sufficient to medialize the paralyzed fold. This idea has been supported by animal experiments, which have shown that botulinum toxin may affect the ability of the fold to rebalance itself. With this evidence in mind, a patient with fold immobility secondary to multiple sclerosis was treated in an attempt at laryngeal rebalancing, using botulinum toxin to medialize the fold. However, instead of simply having the fold return fixed to the midline, the patient regained normal laryngeal mobility and voice. While it is unclear whether the botulinum toxin alone was responsible, the coincidence of this occurrence certainly requires reporting. This paper is a report of the first successful treatment of vocal fold paralysis using botulinum toxin to treat vocal fold fixation in a patient with multiple sclerosis.

Laryngeal rebalancing for the treatment of arytenoid dislocation

In almost every type of functional laryngeal operation a successful result hinges on the surgeon's ability to control the muscular and ligamentous forces that act upon the vocal folds. Most of the time these forces are small in relation to the manipulations and resections performed. Occasionally, the forces are significant relative to the problem encountered, resulting in a failed surgery. Of all the many conditions that fit in to this latter description, perhaps the best example in arytenoid dislocation. Dislocation of the arytenoid is usually secondary to trauma with the majority of reported cases resulting from some type of anesthetic misadventure. Two types of dislocation have been described, anteromedial and posterolateral, each with a different mechanism of causation. This paper concerns itself with the more common anteromedial variety and its treatment using botulinum toxin.

The evaluation of unilateral vocal fold immobility: is chest X-ray enough?

Unilateral vocal fold immobility (UVFI) is a sign of underlying disease. No consensus exists regarding the appropriate evaluation. This study was performed to determine the ability of a chest radiograph (CXR) to limit further costly testing. The charts of 169 patients with previously undiagnosed UVFI were reviewed. In 113 patients the etiology was identified during the history and physical examination (H&P), or the H&P led to a directed evaluation. There were nine patients in whom the evaluation was incomplete. There were 47 patients in whom the etiology was not identified during the H&P. In 28 patients, the CXR identified the etiology, and in 16 cases the CXR ruled out an intrathoracic cause. There were three patients whose H&P and CXR did not identify their cervical etiology No patients had a thoracic etiology that was not identified by CXR. An algorithm was developed: If H&P fail to determine the etiology or to direct the evaluation, CXR is performed and followed by appropriate evaluation if positive. A negative CXR is followed with computed tomography (CT) of the neck from the skull base to thoracic inlet for right-sided UVFI and to the aortic triangle for left-sided UVFI. Other diagnostic studies are directed by signs and symptoms. A chest CT is not recommended unless there is clinical suspicion of a pulmonary or thoracic process.