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Introduction: Unilateral vocal fold paralysis (UVFP) without an identifiable cause is termed idiopathic unilateral vocal fold paralysis (IUVFP). Some authors have postulated that select cases of IUVFP have a viral etiology, but the causality has not been established. We set out to review institutional cases of IUVFP and determine if there is a correlation between upper respiratory infection symptoms and presentation of IUVFP. Methods: Cases of IUVFP were reviewed over a 10-year period (2002-2012). The history was investigated to review presenting symptoms. We specifically reviewed for symptoms of upper respiratory infection at the onset of UVFP and tallied the frequency. Symptoms included sore throat, laryngitis, cough, influenza, bronchitis, pneumonia, otalgia, and sinusitis. The seasonal onset (if possible) was determined based on the history provided from the initial consultation. Study Design: Case series. Results: Overall, 107 patients presented with IUVFP; 35.5% of patients reported symptoms of upper respiratory infection at the onset of UVFP. Among these individuals, pharyngitis/laryngitis was the most common presenting symptom; 34.2% reported cough. In total, 40.0% of patients with IUVFP reported an onset of symptoms between December and February. Conclusions: This study suggests that symptoms of upper respiratory infection frequently occur with the presentation of IUVFP. The onset of symptoms tended to occur between December and February. The mechanism of viral-mediated UVFP has not been established. Future studies to explore this pathophysiology are needed. [ABSTRACT FROM AUTHOR]

Objective: Vocal fold paralysis is caused by injury to the recurrent laryngeal nerve (RLN). Current clinical measures of laryngeal innervation are often nonquantitative. Compound motor action potentials (CMAP) measure motor innervation. The goal of this study was to determine whether CMAP can quantify laryngeal innervation following acute nerve injury. Study Design: Animal study. Methods: Twelve canine hemilaryngeal preparations were used. The RLN was serially stimulated with increasing intensities until the nerve was maximally stimulated. The CMAP amplitude was measured for each intensity stimulation and correlated. Next, the RLN was incompletely transected, and the reduction in CMAP amplitude was correlated to the percentage of transected axons. The percentage of transected axons was determined using horseradish peroxidase (HRP) staining. Results: Combining all hemilaryngeal preparations, the submaximal stimulation of the RLN linearly correlated with the resultant CMAP amplitude (r = 0.83; 95% CI, 0.76-0.88). Following partial RLN transection, the percentage of remaining axons linearly correlated with the CMAP amplitude (r = 0.87; 95% CI, 0.34-0.98). Conclusions: CMAP amplitude is a quantitative measure that may correlate with the degree of vocal fold innervation in canines. Following RLN injury, CMAP may help clinicians quantify the number of intact axons, assess the likelihood of recovery, and counsel patients on their prognosis. [ABSTRACT FROM AUTHOR]

Introduction: The strength of glottic closure with recurrent laryngeal nerve (RLN) stimulation has been indirectly measured experimentally by determining the squeezing pressure on a balloon inserted between the vocal folds, termed laryngeal adductory pressure (LAP). In this study, we sought to measure glottic closing force (GCF) directly and compare these results to LAP measures obtained with identical stimulation parameters. Methods: In canines, a method for measuring GCF was developed in which a suture was looped through a lateral thyrotomy hole, around the vocal process and back, then attached to a force gauge. The RLN was maximally stimulated and GCF recorded. The LAP was then measured as previously described, using the same stimuli. This process was repeated at 9 stimulation frequencies in 10-Hz intervals from 20 to 100 Hz. The GCF and LAP were compared using Pearson's correlation coefficient (PCC). Results: Both sides were measured in 16 dogs, resulting in 32 data sets. The LAP measures were obtained at all frequencies, while GCF was obtained in 246 of 288 (85.4%) attempts. The maximum GCF for each dog typically occurred at 80 to 100 Hz and averaged 0.287 ± 0.106 newtons. Plotting GCF versus LAP for each hemilaryngeal preparation, the mean PCC was 0.932 ± .042 (range, 0.802-0.987). The mean PCC did not differ between control (n = 26) and postoperative (n = 6) hemilarynges. Conclusion: This method for measuring GCF appears valid. The high Pearson's correlation coefficient indicates strong covariance between GCF and LAP, demonstrating that they are both measures of the same physical property. The LAP is easier to perform and more consistently obtained. [ABSTRACT FROM AUTHOR]

Objective: To investigate the efficacy of a novel adductor muscle-releasing technique designed to decrease the force of vocal fold adduction, as a potential surgical therapy for patients with adductor spasmodic dysphonia (ADSD). Study Design: Experimental animal study. Methods: A canine laryngeal model was used to assess the acute and sustained efficacy of a lateral cricoarytenoid (LCA) muscle release. A total of 34 canine hemilaryngeal preparations were divided among 7 experimental groups. The LCA muscle was separated from its cricoid cartilage origin via an open, anterior, submucosal approach. The laryngeal adductory pressures (LAP) were assessed pre- and post-muscle release via direct recurrent laryngeal nerve stimulation. Measurements were repeated at 1.5, 3, or 6 months postoperatively. Another study evaluated release of the thyroarytenoid (TA) muscle from its thyroid cartilage origin. Results: Releasing the LCA muscle demonstrated a significant decrease in LAP acutely and was maintained at all 3 time points with the aid of a barrier (P < .05). Without the barrier, the LCA muscle reattached to the cricoid. Acute release of the TA muscle did not significantly decrease the LAP. Conclusions: The proposed LCA release procedure may provide patients with a permanent treatment option for ADSD. However, longer-term studies and human trials are needed. [ABSTRACT FROM AUTHOR]

Objective: The compound motor action potential (CMAP) is the summated action potential from multiple muscle fibers activated by a single nerve impulse. The utility of laryngeal muscle CMAP for quantifying innervation following recurrent laryngeal nerve (RLN) injury was investigated. Method: In a series of 21 canine hemi-laryngeal preparations, RLNs were exposed and a stimulating electrode placed. Maximum CMAP amplitudes and area under the curve from the thyroarytenoid (TA) muscles were obtained at baseline and at 6 months following injury to the RLN. Injury mechanisms included crush, stretch, cautery, and complete transection with microsuture repair. Results: Prior to injury, baseline CMAP amplitudes and area under the curve were 15.81 mV and 15.49mVms, respectively. Six months following injury, CMAP amplitude and area under curve were 105.1% and 102.1% of baseline for stretch, 98.7% and 112.7% for crush, 93.3% and 114.3% for cautery. The CMAP amplitude and area under the curve in the transection/repair group had a 54.3% and 69.4% recovery, respectively, which were significantly different than baseline (P < .01, P < .05). These values were correlated with vocal fold motion. Conclusion: The CMAP is a measure of vocal fold innervation. The technique could be further developed for clinical and experimental applications. [ABSTRACT FROM AUTHOR]

The article presents a study which determines the effects of vincristine on the laryngeal adductor function of posterior cricoarytenoid (PCA) muscle following a recurrent laryngeal nerve (RLN) injury. The study uses canine animal as subject of the experiment. The study reveals that vincristine injection in PCA muscle blocks the antagonist muscle against synkinetic reinnervation.

We performed a retrospective chart review to examine and describe our clinical experience of use of the Lichtenberger technique to place silicone elastomer keels after lysis of existing webs or for prevention of webs following anterior commissure surgery in adults. Twenty-two patients were identified for inclusion, ranging in age from 24 to 80 years. For 18 patients with existing glottic webs, the surgical procedure involved laryngoscopy with complete lysis of the anterior glottic web by laser or sharp technique, followed by placement of a square of silicone elastomer that is sutured in place with the Lichtenberger needle holder and left in place for 3 to 5 weeks. The procedure was well tolerated, and successfully corrected the web in all but 2 cases. For 4 patients, the procedure was performed prophylactically at the time of anterior commissure surgery considered high-risk for web formation. The procedure does not require a tracheotomy, and patients can maintain a normal diet and have functional phonation while the keel is in place. This approach to treating anterior glottic webs offers several advantages over traditional open thyrotomy with keel placement and should be considered to treat or prevent anterior glottic webs. [ABSTRACT FROM AUTHOR]

Objectives: The intensity of muscle activity immediately following intramuscular botulinum toxin injection may affect the clinical efficacy of the injection. We tested this effect in patients w ho underwent botulinum toxin injections for adductor spasmodic dysphonia. Methods: Patients were studied over 3 to 5 injection cycles. Cycle 1 was the baseline control, cycle 2 was randomized between a 1-hour reading aloud task ("exercise") and a 24-hour period of complete voice rest. For cycle 3, the patient completed the task not performed in cycle 2. Patients who were willing to continue for cycles 4 and 5 repeated the experiment at one half the injection dosage. Efficacy was determined with a battery of voice recordings and clinical outcomes instruments administered via telephone at 2- to 4-week intervals. The primary outcome measure was the result of the Voice-Related Quality of Life (VRQOL) instrument. Results: Nine patients (8 women, 1 man) with a mean age of 60.8 years (range, 42 to 76 years) completed at least 3 injection cycles. The VRQOL results were significantly higher for cycles that followed the exercise task. The patients reported subjectively that these were some of the best injection cycles they had ever experienced. Some achieved equivalent results with the half-dose injection plus exercise. The VRQOL results after voice rest cycles were not significantly different from the patients' baseline cycles. Conclusions: These results support the conclusion that a period of intense vocalization immediately following laryngeal botulinum toxin injections improves the efficacy of the injection. Possible mechanisms are proposed. [ABSTRACT FROM AUTHOR]

Objectives: Anterior cervical spine procedures carry an inherent risk of recurrent laryngeal nerve (RLN) injury. Patients with persistent RLN paresis may be asymptomatic because of compensation from the opposite side. If such patients undergo an opposite-side anterior approach for revision surgery, they are at risk for a second RLN injury, creating the potential for bilateral vocal fold paresis and possible need for tracheotomy. A program of routine screening for laryngeal paresis was implemented for these patients. This retrospective study reviews the results of this screening process. Methods: Patients referred for preoperative laryngeal nerve screening were identified. Their charts were reviewed for the results of the videolaryngoscopic examination, and for any recommendations made based on the findings. Relevant history and other physical findings were recorded. Results: Fifty screening laryngeal examinations were performed in 47 patients, of whom 31(66%) had previously under- gone a single anterior cervical approach procedure, and 16 (34%) had undergone more than one. Thirteen of the examinations (26%) revealed abnormal laryngeal findings, including paresis or paralysis in 11 cases (22%), of which 5 were asymptomatic. The findings resulted in a recommendation of a cervical approach from the already-involved side. None of the revision procedures resulted in bilateral vocal fold paralysis. The risk of laryngeal nerve injury appears to increase as higher cervical levels are approached. Conclusions: Minimally symptomatic injuries of the laryngeal nerves from prior neck surgery create a potential serious risk of bilateral vocal fold paralysis with subsequent procedures. Preoperative laryngeal screening is a simple and effective method for reducing this risk. [ABSTRACT FROM AUTHOR]

Objectives: Endoscopic approaches for submucosal vocal fold surgery may limit the surgeon's ability to release scars or to precisely implant filler material such as fat. In 1999, Gray et al described the "minithyrotomy" approach to this region. Technical aspects of this important new technique, clinical indications, and early results are reviewed. Methods: We performed a retrospective review and compiled the data of the office records, clinical notes, and videostroboscopic examinations of all of the four authors' patients who underwent this procedure. Results: Twenty-one patients underwent 22 minithyrotomy procedures for vocal fold scarring (6), lateralizing scar following polytetrafluoroethylene removal or trauma (5), scar with radiation fibrosis (2), sulcus vocalis (2), or presbylarynx or bowing (6) — bilaterally in 14 operations and unilaterally in 8. There were 13 male patients and 8 female patients, with a mean age of 58.3 years (range, 22 to 87 years). The mean follow-up was 9.1 months (range, 1 to 46 months). After submucosal vocal fold exploration, autologous fat was implanted in 20 of the 21 patients. Postoperative videostroboscopy demonstrated improved mucosal pliability in 19 cases and improved glottal closure in 20 cases. Most patients noted voice improvement. Complications were minimal. Conclusions: Gray's minithyrotomy is a highly effective approach for treating vocal fold scar processes, bowing, sulcus vocalis, and, potentially, other conditions. [ABSTRACT FROM AUTHOR]

Objectives: This study was performed to investigate the muscle-nerve-muscle reinnervation technique in the larynx, in which a nerve conduit implanted into an innervated muscle conducts axonal sprouting into a denervated muscle while maintaining function of the donor muscle. Methods: In this study, the muscle-nerve-muscle technique was used to direct superior laryngeal nerve axons to reinnervate intrinsic laryngeal muscles by implanting the recurrent laryngeal nerve stump into the cricothyroid muscle in 8 dogs. In 4 of the dogs, the recurrent laryngeal nerve trunk to the adductor muscles was divided so that all axonal sprouting was directed to the posterior cricoarytenoid muscle. Six-month electromyography data were obtained from 6 of the 8 dogs. Results: All 6 dogs showed evidence of successful reinnervation of the thyroarytenoid or posterior cricoarytenoid muscles with action potentials that corresponded to spontaneous respiratory efforts, while the donor cricothyroid muscles retained their phasic contraction. These responses were obliterated when the recurrent laryngeal nerve conduit was divided. Histologic examination of the intrinsic laryngeal muscles demonstrated successful reinnervation. Conclusions: The results confirm that intrinsic laryngeal muscles may be successfully reinnervated by the superior laryngeal nerve with the muscle-nerve-muscle technique, without sacrifice of function of the cricothyroid muscle. This method offers an alternative source of appropriately firing axons for laryngeal reinnervation procedures. [ABSTRACT FROM AUTHOR]