Voice range in superior laryngealnerve paresis and paralysis

Evaluation of Physiologic Frequency Range (PFR) and Musical FrequencyRange (MRP) of Phonation was performed on 56 adults (singers and nonsingers) presenting with superior laryngeal nerve (SLN) paresis or paralysis confirmed by laryngeal electromyography. The most common etiology was neuritis (69.7%), followed by iatrogenic and unlcnown causes,each accounting for 10.2 % of cases, and finally trauma (8.9%). Both female and male singers with SLN paresis or paralysis had significantly higher PFR and MPR than nonsingers. Female classical singers presented PFR and MPR of up to 10 semitones (ST) higher than nonclassical singers and nonsingers. The lowest PFR and musical ranges were found in patients with SLN paresis associated with recurrent laryngeal nerve paresis or paralysis. The authors suggest that voice range measurement is a useful parameter for analyzing the effects of SLN paresis or paralysis on voice and that it may also assist in measuring outcome following voice therapy.     

Objective Voice Measures in Nonsinging Patients With Unilateral Superior Laryngeal Nerve Paresis

The clinical value of objective voice measures in nonsinging patients with superior laryngeal nerve dysfunction is unknown. In this study, patients with symptomatic unilateral superior nerve paresis were evaluated for maximum phonation time, frequency range of phonation, and mean flow rate. Patients with coexisting pathology, bilateral superior nerve paresis, and those with recurrent laryngeal nerve paresis were excluded from this analysis. A total of 35 nonsinging patients, 14 men and 21 women, with unilateral superior laryngeal nerve paresis were examined between 1999 and 2002. The severity of superior laryngeal nerve paresis ranged from 25% to 85% of normal recruitment with a mean of 70% superior laryngeal nerve recruitment in men and 65% in women by electromyography. In both men and women with superior laryngeal nerve paresis, the maximum phonation time and frequency range of phonation were decreased and the mean air flow rate was increased when compared with normal population values. The jitter percent, shimmer percent, and noise-to-harmonic ratio were also increased in patients when compared with normative data. Selected objective voice measures are abnormal in voice patients with superior laryngeal nerve paresis, which suggests that the measures may be useful as outcomes measures after therapy. More research is encouraged.     

Repetitive Phonatory Tasks for Identifying Vocal Fold Paresis

Vocal fold paresis may be present in patients with voice complaints. Identification of paresis is important so that appropriate neurolaryngologic evaluation can be ordered and the appropriate treatment can be offered. Repetitive phonatory tasks (RPTs) fatigue patients vocally and may elicit signs of subtle paresis. In this study, four laryngologists independently reviewed the RPT portions of routine fiberoptic voice examinations of 100 patients in a blinded fashion. All patients had presented with voice complaints, were suspected of having a movement disorder of the larynx, and had been referred for laryngeal electromyography (LEMG). Predictions were compared with LEMG results and with predictions made at the time of each initial evaluation. Although RPTs are useful to laryngologists, predictions based on the entire examination are more accurate. LEMG can confirm clinical suspicions or identify paresis missed on fiberoptic laryngeal examination.     

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.     

Determining the etiology of mild vocal fold hypomobility

The prevalence of mild vocal fold hypomobility is unknown. In a study by Heman-Ackah et al, vocal fold hypomobility in a population of singing teachers was found to be associated more frequently with vocal complaints than was the presence of vocal fold masses.¹ The etiology of mild vocal fold hypomobility has not been previously explored. In the present study, a retrospective chart review was performed of 134 patients who presented to a tertiary laryngology referral center over a 6-month period for evaluation of vocal complaints. Of the 134 patients, 61 (46%) were found to have mild vocal fold hypomobility previously undiagnosed by the referring otolaryngologist. Imaging studies and laboratory tests to evaluate for structural, metabolic, and infectious causes of the decreased mobility had been ordered. Forty-nine patients completed the work-up. Of these, 41 out of 49 (84%) were found to have imaging or laboratory findings that could explain the hypomobility. Thyroid abnormalities were found to be associated with vocal fold hypomobility in 21 out of 49 (43%) of those with a complete evaluation. Other causes of vocal fold hypomobility included idiopathic (8 of 49, 16%), viral neuritis (5 of 49, 10%), central nervous system abnormality (4 of 49, 8%), neural tumor (3 of 49, 6%), joint dysfunction (3 of 49, 6%), iatrogenic nerve injury (2 of 49, 4%), myopathy (2 of 49, 4%), and noniatrogenic traumatic nerve injury (1 of 49, 2%), This study shows that unilateral vocal fold hypomobility often is associated with a physiologic process, and a complete investigation to determine the etiology is warranted in all cases.     

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.     

Combination thyroplasty and the “twisted larynx:” combined type IV and type I thyroplasty for superior laryngeal nerve weakness

Vocal cord medialization through Isshiki type I thyroplasty is part of the standard approach for patients with unilateral vocal cord immobility secondary to recurrent laryngeal nerve paralysis. However, several other modalities have been used to treat the symptomatic “twisted” larynx caused by unilateral superior laryngeal nerve weakness. The Isshiki type IV thyroplasty (cricothyroid approximation) specifically addresses cricothyroid muscle weakness, but, canine studies at the Mayo Clinic demonstrated a trend toward decreased acoustic power and sound intensity with simulated cricothyroid activity. Thus it is reasoned that addition of an ipsilateral type I thyroplasty should help compensate for this power loss.Using videostroboscopic and acoustic analysis, 9 patients with unilateral superor laryngeal nerve weakness were treated with combination type IV and type I thyroplasty. Subjective dysphonia and objective visual and acoustic measurements revealed postoperative improvement in most patients. The combination type IV and type I thyroplasty is recommended for surgical treatment of patients with superior laryngeal nerve weakness, because it addresses cricothyroid muscle weakness without compromising vocal power.     

A study on the mechanism of functional dysphonia

A total of 333 patients with a diagnosis of functional dysphonia were studied by both laryngeal electromyography (EMG) and spectral analysis. EMG and acoustic analysis revealed that some patients with so-called functional dysphonia diagnosed by physical examination alone in fact suffered from a variable degree of laryngeal nerve paralysis. Laryngeal EMG plays an important role in determining whether patients with a diagnosis of functional dysphonia have organic disease of the laryngeal nerves.     

Unilateral cricothyroid contraction and glottic configuration

It is frequently stated that unilateral cricothyroid muscle (CT) paralysis can be diagnosed by physical examination, noting rotation of the glottis, and shortening and vertical displacement of the ipsilateral vocal fold. These signs, however, are inconsistently observed, and there is considerable controversy regarding the direction of glottic rotation. To determine the effects of CT contraction on three-dimensional glottic configuration, we performed computerized tomography on cadaver larynges before and after simulated CT contraction. Radiopaque makers were used to compute distances. Unilateral CT contraction equally increased the length of both membranous vocal folds, and rotated the posterior glottis less than 1 mm. CT contraction neither adducted the vocal processes, nor significantly their altered vertical level. These results suggest that unilateral CT paralysis cannot be diagnosed on the basis of any clinically apparent change in glottal configuration.     

Comparing the Long-Term Outcome of Immediate Postoperative Facial Nerve Dysfunction and Vocal Fold Immobility After Parotid and Thyroid Surgery

SUMMARY: Hypothesis: The long-term recovery rate of immediate postoperative facial nerve dysfunction with an electrophysiologically and anatomically intact facial nerve is higher than the long-term recovery rate of immediate postoperative vocal fold immobility with an electrophysiologically and anatomically intact recurrent laryngeal nerve. Methods: A retrospective review of parotid and thyroid surgery with electrophysiologic monitoring of the facial and recurrent laryngeal nerves, respectively. Results: Forty-five consecutive patients had electrophysiologic and anatomic integrity of the facial nerve at the conclusion of the parotidectomy. Eight of 45 (18%) patients developed a postoperative facial nerve dysfunction. All eight patients with facial nerve dysfunction had complete return of facial nerve function within 3 months. A total of 102 consecutive patients underwent dissection of the recurrent laryngeal nerve during thyroid surgery. Seven of 102 (7%) had immediate unilateral vocal fold dysfunction. All 102 had electrophysiologic and anatomic integrity of the recurrent laryngeal nerve at the conclusion of the procedure. Two of 102 (2%) have clinically complete permanent vocal fold dysfunction. Five of seven (71%) with immediate complete vocal fold immobility had complete return of mobility. Conclusions: A higher immediate postoperative rate of transient facial nerve dysfunction is reported compared with vocal fold immobility in parotid and thyroid surgery, respectively (P < 0.05). Immediate postoperative facial nerve dysfunction with an electrophysiologically response at 1 mA and an anatomically intact facial nerve during parotid surgery resulted in a complete return of function in all cases in this series. Immediate postoperative vocal fold immobility with an electrophysiological response at 1 mA and an anatomically intact recurrent laryngeal nerve had a 30% rate of being permanent in this series.     

Unilateral recurrent laryngeal nerve paralysis:The importance of “preoperative” voice therapy

This preliminary retrospective study of 19 female patients and 22male patients with unilateral recurrent nerve lesions demonstrated the promise of objective measurements in predicting the need for surgery, the efficacy of voice therapy in ameliorating vocal symptoms, and the effects of therapy in conjunction with surgery. Sixty-eight percent (68%) of the female patients and 64% of the male patients did not elect to have surgery. Outcome satisfaction of nonsurgical and surgical patients appeared to be similar. The data from this study support the importance of preoperative therapy for patients with unilateral vocal fold paralysis.     

Relationship among glottal area, static supraglottic compression, and laryngeal function studies in unilateral vocal fold paresis and paralysis

In this study, we evaluated the relationship between laryngeal function measures and glottal gap ratio and normalized measures of supraglottic behaviors in patients with unilateral vocal fold paresis (UVFP). Thirty-one patients were found to have unilateral vocal fold paresis by videoendoscopy and laryngeal electromyography, and 13 controls participated in this study. Patients with UVFP demonstrated significantly larger glottal gap ratios (p = 0.016) than control subjects. The nonparalyzed or contralateral vocal fold was associated with significantly more static false vocal fold compression (p = 0.03) compared with the paralyzed vocal fold or with the controls. Patients with unilateral vocal fold paresis were divided into subgroups: those with normal or abnormal maximum phonation time, flow, or pressure measures. Smaller glottal gap ratios were identified in patients with normal maximum phonation times and flow measures. Greater false vocal fold activity was identified in unilateral vocal fold paresis patients with normal laryngeal function measures than in unilateral vocal fold paresis patients with abnormal measures. These findings suggest that some patients with documented unilateral paresis and glottal incompetence can compensate for vocal fold weakness such that their acoustic and aerodynamic measures are normal.     

Arytenoid Cartilage Dislocation: A 20-year Experience

SUMMARY: Arytenoid cartilage dislocation is an infrequently diagnosed cause of vocal fold immobility. Seventy-four cases have been reported in the literature to date. Intubation is the most common origin, followed by external laryngeal trauma. Decreased volume and breathiness are the most common presenting symptoms. We report on 63 patients with arytenoid cartilage dislocation treated by the senior author (RTS) since 1983. Significantly more posterior than anterior dislocations were represented. Although reestablishing joint mobility is difficult, endoscopic reduction should be considered to align the heights of the vocal processes. This process may result in significant voice improvement even long after the dislocation. Strobovideolaryngoscopy, laryngeal electromyography, and laryngeal computed tomography (CT) imaging are helpful in the evaluation of patients with vocal fold immobility to help distinguish arytenoid cartilage dislocation from vocal fold paralysis. Familiarity with signs and symptoms of arytenoid cartilage dislocation and current treatment techniques improves the chances for optimal therapeutic results.     

Vocal Process Avulsion

Vocal process avulsion is a rare condition in which laryngeal trauma causes a separation of the vocal process from the body of the arytenoid cartilage. Typically symptoms are dysphonia and shortness of breath during phonation. Strobovideolaryngoscopy, laryngeal electromyography, and laryngeal computed tomography are helpful in establishing this important and sometimes elusive diagnosis. Several treatment modalities have been reported with varying success. We report four new cases, review four cases reported previously by the senior author, and suggest approaches to diagnosis and optimal treatment of vocal process avulsion.     

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 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.     

Laryngeal Manifestations of Postpoliomyelitis Syndrome

Postpoliomyelitis syndrome (PPS) is a disease that may occur in survivors of acute poliomyelitis several decades after their initial infection. It can present as dysphonia, with vocal weakness and fatigue. Swallowing, respiratory, and other laryngopharyngeal symptoms may be manifestations of the disease or they may represent worsening of previously stable and compensated deficits. Three cases of laryngeal changes in PPS with videostroboscopic and laryngeal electromyography findings highlight the features of this disorder. We review possible etiologies of laryngeal PPS, diagnostic criteria, and treatment, as well as the current literature.     

Electrophysiologic monitoring of the recurrent laryngeal nerves may not predict bilateral vocal fold immobility after thyroid surgery

Two cases of bilateral vocal fold immobility (VFI) after identification and preservation of the recurrent laryngeal nerves (RLNs) required tracheotomy until vocal fold recovery. The first patient underwent thyroid surgery without preoperative or postoperative evaluation of the vocal folds, administration of postoperative intravenous steroids, or electrophysiologic monitoring of the RLNs, whereas the second patient underwent a thyroid procedure in which all of the aforementioned were executed. Preoperative and postoperative clinical evaluation of the RLNs is strongly suggested in patients undergoing thyroid surgery, especially revision surgery. Patients potentially undergoing total thyroidectomy should be counseled about the remote chance of airway obstruction and should be properly selected for this operation. Subclinical stretching of the RLNs or ischemia from the endotracheal tube cuff can result in unilateral VFI, and rarely bilateral VFI, requiring reintubation, tracheotomy, or vocal fold lateralization. Electrophysiologic monitoring may not always predict bilateral VFI.     

The Adjustable Laryngeal Implant

An adjustable laryngeal implant made of titanium has been developed for the treatment of unilateral vocal fold paralysis. The implant includes three parts: a plate that allows fixation to the thyroid cartilage, a block of titanium which includes the adjustable part, and a micrometric screw in the middle of the lateral side of the block, which moves the adjustable part. Precise medialization is accomplished by regulating the screw which also permits easy secondary adjustments, if needed in the future. This retrospective study assesses clinical outcomes of medialization laryngoplasty with the titanium adjustable implant, in patients with unilateral vocal fold paralysis. This study has the limitations of a retrospective study. However, preliminary results are encouraging. Analysis of subjective responses confirmed marked improvement in laryngeal function, speech, and swallowing. Objective voice analysis confirmed improvement in the aerodynamic measures. The adjustable laryngeal implant has many advantages including: precise medialization, ease of secondary adjustment, and preseveration of the mucosal wave. This implant is biocompatible, no migration is possible (it is fixed to the cartilage) and no extrusion of the implant has occurred. Titanium is magnetic resonance imaging (MRI)-safe.     

Pressure-flow relationships during phonation in the canine larynx

Measurements of air pressure and flow were made using an in vivo canine model of the larynx. Subglottic pressures at varying flow rates were taken during phonation induced by laryngeal nerve stimulation. Results showed that during constant vocal fold stiffness, subglottic pressure rose slightly with increased air flow. The larynx in the in vivo canine model exhibited a flow-dependent decrease in laryngeal airway resistance. Increasing flow rate was associated with an increase in frequency of phonation and open quotient, as measured glottographically. Results from this experiment were compared with a theoretical two-mass model of the larynx and other theoretical models of phonation. The influence of aerodynamic forces on glottal vibration is explained by increased lateral excursion of the vocal folds during the open interval and shortening of the closed interval during the glottal cycle.