Bilateral Functional Electrical Stimulation for the Treatment of Presbyphonia in a Sheep Model.

OBJECTIVES: The aim of the study was to increase muscle volume and improve phonation characteristics of the aged ovine larynx by functional electrical stimulation (FES) using a minimally invasive surgical procedure. METHODS: Stimulation electrodes were placed bilaterally near the terminal adduction branch of the recurrent laryngeal nerves (RLN). The electrodes were connected to battery powered pulse generators implanted subcutaneously at the neck region. Training patterns were programmed by an external programmer using a bidirectional radio frequency link. Training sessions were repeated automatically by the implant every other day for 1 week followed by every day for 8 weeks in the awake animal. Another group of animals were used as sham, with electrodes positioned but not connected to an implant. Outcome parameters included gene expression analysis, histological assessment of muscle fiber size, functional analysis, and volumetric measurements based on three-dimensional reconstructions of the entire thyroarytenoid muscle (TAM). RESULTS: Increase in minimal muscle fiber diameter and an improvement in vocal efficiency were observed following FES, compared with sham animals. CONCLUSION: This is the first study to demonstrate beneficial effects in the TAM of FES at molecular, histological, and functional levels. FES of the terminal branches of the RLN reversed the effects of age-related changes and improved vocal efficiency. LEVEL OF EVIDENCE: NA Laryngoscope, 134:848-854, 2024.

The effects of transcutaneous electrical nerve stimulation on muscle activity pattern in professional voice users with muscle tension dysphonia using surface electromyography data: A pilot study.

OBJECTIVES: Muscle Tension Dysphonia is a voice disorder, which results in stiffness in the laryngeal extrinsic muscles, intense collision, painful contractions, and vibrations of the vocal cords. Due to the multifactorial identity of Muscle Tension Dysphonia, its therapeutic approach must be multidisciplinary. METHODS: The participants were divided into two groups: a control group (5participants) that received Circumlaryngeal Manual Therapy (CMT) + Placebo Transcutaneous Electrical Nerve Stimulation and an experimental group (5participants) that received Transcutaneous Electrical Nerve Stimulation + CMT. Both groups received 10 sessions of treatment, twice a week, for 40 min each. Before and after treatment, participants were assessed using the Dysphonia Severity Index (DSI) and surface electromyography for their ability to sustain the vowels /e& u/and count from 20 to30. RESULT: After therapy, there were substantial improvements in the DSI (2.72 ± 0.55, P < 0.05) and muscle electrical activity in the control group. The DSI (3.66 ± 0.63, P < 0.05) and muscle electrical activity were also significantly improved in the experimental group after treatment. The findings of the between-group comparison after treatment revealed a significantly greater increase in the Dysphonia Severity Index in the experimental group compared with the control group (P = 0.037). Although there was no significant difference between the two groups in terms of muscle electrical activity, clinically significant changes were more noticeable in the experimental group when compared with the control group. CONCLUSIONS: Positive results were seen in both groups. The results demonstrate that both approaches relax vocal tract muscles. As a result, Transcutaneous Electrical Nerve Stimulation was recommended as a complementary treatment for clients with Muscle Tension Dysphonia.

Transoral radiofrequency of the terminal branches of the recurrent nerve in the treatment of adductor spasmodic dysphonia: our experience over 11 patients.

PURPOSE: Spasmodic dysphonia (SD) or laryngeal dystonia is as a rare vocal disorder characterized by involuntary action-induced endolaryngeal contraction. In the last decade, botulin toxin injection has become the standard treatment in adductor spasmodic dysphonia necessitating repetitive injections. The purpose of this study is to analyze retrospectively data from patients treated with the minimal-invasive transoral radiofrequency-induced thermotherapy (RFITT) of the terminal branches of the recurrent nerve. METHODS: Between 2009 and 2015, 11 patients (six females and five males aged from 32 to 91 years) with adductor SD were treated with RFITT. Pre-operative and post-operative vocal assessments (VHI-30, GRBASI, and acoustic-aerodynamics measurements), number of surgical revisions, delay between procedures, and post-operative complications were recorded. Statistical analyses were carried out on the first vocal assessment performed 2-8 weeks after the first procedure. RESULTS: Based on available data from ten patients, voice handicap index (VHI) showed improvement with a mean value of -17.7 points (p-value (pval) = 0.014, adjusted p-value (adj pval) = 0.21); instability has also revealed improvement in six patients (pval = 0.05, adj pval = 0.31). Four patients underwent only one procedure including one patient showing still long-term beneficial results after 5 years of follow-up. Other patients required one to three new procedures with an average time between procedures of 15.3 months. Over 24 surgeries performed on a total of 11 patients, one definitive treatment-related severe adverse event was reported. CONCLUSION: Thanks to long-lasting effect, repetitive treatments are less frequent compared to botulin toxin therapy. In our opinion, RFITT is a promising alternative to botulin toxin as a second-step procedure in case of toxin resistance or patient's lack of compliance.

Functional Evaluation of Larynx Nerve Stimulator With EMG Acquisition Capability and Wireless Connectivity.

Recently, an electrical stimulation of the paralyzed muscle, as a potential therapy for restoring function of a denervated muscle system, has been debated as an innovative treatment in the management of patients with laryngeal paralysis. Numerous studies in acute and chronic animal models have demonstrated that electrical stimulation of the paralyzed posterior cricoarytenoideus muscle (PCA) offers an approach to induce vocal fold abduction and restore ventilation through the glottis. The study aims to test applicability of the controlled opening of the rima glottides via direct electrical stimulation of the posterior cricoarytenoideus muscle. We developed for this purpose a novel instrument system for the controlled larynx nerve stimulation. An acute experiment on the 4 years old pig showed effectiveness of the engineered stimulator. The controlled opening of rima glottidis of both posterior cricoarytenoid muscles and afterwards of both PCA muscle contraction were observed as a result of the electrical stimulation with the applied current in the range of 0.1-3 mA and pulse width of 1 ms and 10 ms. Performed research indicates a large potential of the novel nerve stimulator for the human larynx stimulation.

[Neurolaryngology]. / Neurolaryngologie.

Neurological and neurophysiological knowledge of neuromuscular diseases is combined in neurolaryngology with experience from laryngology. Laryngeal electromyography (LEMG) is the most important diagnostic and prognostic tool in neurolaryngology. It can be combined with diagnostic electrostimulation. Interest in LEMG today extends beyond the thyroarytenoid muscle to all accessible laryngeal muscles. LEMG should be performed and interpreted according to a standardized protocol. Main applications of LEMG are confirmation, topodiagnostic and prognostic assessment of vocal fold paralysis. It is possible to differentiate fresh from old recurrent laryngeal nerve lesions as well as mechanical vocal fold fixations from paralysis. Needle guidance for botulinum toxin injections in spasmodic dysphonia and for augmentation laryngoplasty can be supported by LEMG, but also by laryngeal ultrasound. The timing of therapy for temporary and permanent augmentations, thyroplasty and reinnervation surgery may be better defined with experience from neurolaryngology. The use of diagnostic neurostimulation can reveal any remaining active movement potential of a vocal fold and thus help identify candidates for future laryngeal pacemaker treatments. Other topics in neurolaryngology include spasmodic dysphonia and underlying neurological diseases such as stroke, central vocal fold paralysis, essential tremor and Parkinson's disease. Laryngoscopic, clinical and LEMG characteristics of these diseases are presented.

Subcutaneous Ports for Chronic Nerve Cuff and Intramuscular Electrode Stimulation in Animal Models.

OBJECTIVE: Tracking recovery after nerve injury may require many intermittent assessments over long periods, preferably with non- or minimally invasive methods. We developed subcutaneous electrical connection ports (ECPs) for repeated connection to nerve cuff or intramuscular electrodes via transdermal needles and evaluated them during studies of laryngeal reinnervation. STUDY DESIGN: Animal experiment. SETTING: Laboratory. METHODS: ECPs were designed and 3-dimensionally printed for connection to bipolar electrodes with biocompatible polymers. Dual compartments filled with conductive silicone capped with nonconductive silicone were used to make the connections between electrode leads and transdermally inserted needles. Ten dogs (19-29 kg) were implanted with 22 ECPs. In 7 dogs, 11 electrodes were placed on recurrent laryngeal nerves proximal to transection and suture repair to track laryngeal reinnervation. In 6 dogs, 8 spinal accessory nerve cuff electrodes were used to stimulate neck muscle contraction. In 2 dogs, 3 electrodes were implanted in the thyroarytenoid muscle. Stimulation thresholds, electromyography, and videolaryngoscopic imaging were obtained in 156 tests over survival periods up to 32 months. Stimulation data provided information about ECP performance. RESULTS: ECPs added negligible resistance to electrodes (mean ± SD, 2.14 ± 0.9 Ω). Despite some electrode leads breaking distally, ECPs were reliable and well tolerated at implant sites and enabled periodic assessment of nerve and muscle function over the time course of laryngeal reinnervation. Histology showed ECP encapsulation as thin layers of connective tissue and minimal acute inflammation. CONCLUSION: Custom ECPs are easily fabricated and cause little tissue reaction over months to years of subcutaneous implantation, facilitating long-term physiologic studies.

Spasmodic Dysphonia.

Spasmodic dysphonia (SD) is a rare focal laryngeal dystonia. It is characterized by task-specific voice dysfluency resulting from selective intrinsic laryngeal musculature hyperfunction. Symptoms may be attenuated by a sensory trick. Although SD can be seen at times in generalized dystonia syndromes, it is typically a sporadic phenomenon. Involvement of the laryngeal adductor muscles is more common than abductor muscles. The standard treatment of this disorder is with botulinum toxin injection, usually electromyography-guided, which must be repeated periodically as the toxin wears off. A number of non-reversible surgical procedures have also been described to mitigate the symptoms. Other treatment modalities are under investigation, including implantable electrical stimulation devices and deep brain stimulation.

Laryngeal Electromyography.

Laryngeal electromyography (LEMG) is an important diagnostic and prognostic tool in neurolaryngology. This chapter presents the advances in LEMG in the last 5 years based on clinical trials. LEMG is in most cases an office-based procedure for decision making in neurolaryngology. When performed in a standardized way, LEMG helps to differentiate abnormal function of the vocal folds from nonorganic disorders. It is mainly used to confirm the diagnosis of vocal fold paralysis (VFP) and is less frequently used for the diagnosis of myopathies and motor neuron disorders. Also, the value of LEMG for other diseases than VFP is presented. First consensus recommendations for standard performance of LEMG have been published. This will facilitate the comparison of results from different researchers in the future. For many years, LEMG focused on the thyroarytenoid muscle. Data are presented showing that now more and more studies are performed including other laryngeal muscles, most importantly the posterior cricoarytenoid muscle and cricothyroid muscle. Diagnostics and estimating the prognosis for patients with VFP remains the most important issue for LEMG. First meta-analyses are now available analyzing which LEMG parameters are the best prognosticators for recovery or persistent palsy. Due to the advances in multichannel LEMG, laryngeal nerve monitoring can now control the recurrent laryngeal nerve and the external branch of the superior laryngeal nerve during thyroid surgery. Finally, also the advances of LEMG for laryngeal pacing, guided laryngeal injections, laryngeal electrostimulation, and other indications beyond otolaryngology are discussed.

Bilateral Posterior Cricoarytenoid Myoneurectomy for Abductor Spasmodic Dysphonia.

OBJECTIVE: To discuss the utility and outcomes of bilateral myoneurectomy for treatment of abductor spasmodic dysphonia. METHODS: Bilateral myoneurectomy is a known treatment option for patients with adductor spasmodic dysphonia. Its use for treatment of abductor spasmodic dysphonia, however, has not been documented previously. In this case report, treatment and long-term outcomes of abductor spasmodic dysphonia with bilateral myoneurectomy are discussed. RESULTS: A 50-year-old male presented with abductor spasmodic dysphonia. His initial Voice Handicap Index-10 (VHI-10) score was 29, and he had breathy breaks during 60 series. He had no improvement in vocal quality after 6 botulinum toxin injections over 21 months. He underwent staged bilateral posterior cricoarytenoid partial myoneurectomy, with the left posterior cricoarytenoid myoneurectomy performed 33 months after presentation and right posterior cricoarytenoid myectomy 11 months later. Eight years postoperatively, his VHI-10 score was 12. During postoperative 60 series, the patient demonstrated few breathy breaks. Overall, the patient reports improved quality of life and satisfaction with his voice. CONCLUSION: This is the first report of a long-term follow-up data for bilateral, endoscopic, partial posterior cricoarytenoid muscle myoneurectomy to treat refractory abductor spasmodic dysphonia. Long-term VHI-10 results suggest improvement of symptoms, despite mild difficulty with 60 series. While botulinum toxin therapy is the mainstay of management for abductor spasmodic dysphonia, surgical treatment is a potential alternative at least for refractory cases.

Transcutaneous Electrical Nerve Stimulation Combined With Voice Therapy in Women With Muscle Tension Dysphonia.

OBJECTIVES: The purpose of the present study was to investigate the effect of Voice Therapy (VT) with and without Transcutaneous Electrical Nerve Stimulation (TENS) in women with Muscle Tension Dysphonia (MTD). METHODS: A total of 20 women with MTD participated in the study. Participants underwent evaluation of auditory-perceptual assessment, acoustic voice analysis, Vocal Tract Discomfort (VTD), and musculoskeletal pain before and after the treatment. The participants were divided into two groups: (1) TENS + VT group (10 participants) and (2) VT group (10 participants). Both groups received 10 sessions of treatment, twice a week, each lasting 50 minutes. The statistical analysis was performed using Wilcoxon signed ranked and Mann-Whitney U tests (P < 0.05). RESULTS: After VT, significant improvements were observed in all auditory-perceptual parameters and all VTD items except for the tickling frequency and severity. The VT caused significant reduction in the frequency of pain in anterior neck, posterior neck, and the larynx. Also, VT resulted in a significant reduction in pain intensity only in the larynx. After VT + TENS, significant improvements were observed in all auditory-perceptual parameters, shimmer, and all VTD items. Moreover, the VT + TENS led to a significant decrease in the frequency and intensity of pain in anterior neck, posterior neck, the larynx, masseters, shoulders, and upper back. The findings of between-group comparison after treatment showed significantly more reduction in the frequency (dry and pain items) and severity (tight and pain items) of the VTD in VT + TENS group compared with VT group. Regarding the musculoskeletal pain, significantly more reduction in the frequency and intensity of pain in anterior neck and the larynx was observed in VT + TENS group compared with VT group. CONCLUSIONS: The VT and VT + TENS could lead to positive outcomes in auditory perceptual assessment, acoustic voice analysis, the VTD, and assessment of musculoskeletal pain. In some items of frequency and severity of VTD scale and assessment of musculoskeletal pain, VT + TENS also produced better results compared with VT. As a result, TENS was recommended as a complementary therapy for patients with MTD, especially when these patients had more complaints about VTD and musculoskeletal pain.

Recurrent Laryngeal Nerve Stimulator.

Electrical stimulation of the recurrent laryngeal nerve is a safe and promising therapeutic approach with the potentiality to overcome the shortcomings of conventional surgical glottal enlargement. Although aberrant or synkinetic reinnervation is commonly considered an unfavorable condition, particularly for recovery of vocal fold movement, its presence is essential to ensure the effective clinical performance of laryngeal pacemakers. Thus, the effective selection of patients who can profit from laryngeal pacemakers implantation demands the implementation of new diagnostic tools based on tests capable of reliably detecting the presence of viable reinnervation on at least one vocal fold.

The Nerve to Thyrohyoid Muscle as a Novel Donor Nerve for Laryngeal Reinnervation.

OBJECTIVES: Recurrent laryngeal nerve (RLN) injury may be a consequence of surgical procedures of the skull base, neck, and chest, with adverse consequences to function and quality of life. Laryngeal reinnervation offers a potentially stable improvement in vocal fold position and tone. The classic donor nerve is the ansa cervicalis, but is not always available due to damage or sacrifice during previous neck surgeries. Our objective was to introduce the nerve to the thyrohyoid (TH) muscle as an alternate donor nerve for reinnervation, which has not previously been described. METHODS: Case series of two patients using the TH nerve for laryngeal reinnervation after RLN injury, with description of surgical harvest. RESULTS: Follow-up results are available for 10 months (one patient) and 3 years (one patient) demonstrating both subjective and objective improvement in function. GRBAS scores were reduced. Maximal phonation time was improved. Patient rating of voice was stable or improved postoperatively. One patient described significant preoperative dyspnea which was significantly improved postoperatively, from a score of 24 to 10 out of 40 on the dyspnea handicap index. VHI was improved in one patient, but scores elevated in the other, despite a change from "moderately severe impairment" to "normal voice" subjectively. Neither patient experienced significant complications from the procedure. CONCLUSION: Laryngeal reinnervation procedures provide good outcomes in pediatric patients. When ansa cervicalis is not available as a donor nerve, the nerve to TH provides a reasonable alternative.

Exploring stimulation patterns for electrical stimulation of the larynx using surface electrodes.

PURPOSE: Functional electrical stimulation (FES) is considered an upcoming treatment modality for a number of laryngeal diseases. However, sound data are scarce when it comes to surface FES to treat voice disorders. Aim of the present study was to identify and differentiate suitable surface FES patterns to activate internal laryngeal muscles. METHODS: Non-invasive FES was performed in a cohort of 17 elderly woman. Our user-customized electrical stimulation setup allowed us to deliver ten different stimulation patterns (rectangular and sawtooth shaped) with variation of frequency and amplitude. Stimulation outcome, i.e., vocal fold (VF) reaction, was continuously verified by transnasal endoscopy. RESULTS: Responses to FES using ten different stimulation patterns varied inter-individually. None of the stimulation parameter sets could elicit a VF reaction in all participants. CONCLUSION: Based on our findings we conclude that individual fitting is necessary when defining surface stimulation parameters. To overcome limitations of previous studies, devices with freely programmable patterns are required as shown here. Endoscopic control of VF reaction is absolutely essential to ensure effectiveness of the delivered patterns.

Functional electrical stimulation following nerve injury in a large animal model.

INTRODUCTION: Controversy exists over the effects of functional electrical stimulation (FES) on reinnervation. We hypothesized that intramuscular FES would not delay reinnervation after recurrent laryngeal nerve (RLn) axonotmesis. METHODS: RLn cryo-injury and electrode implantation in ipsilateral posterior cricoarytenoid muscle (PCA) were performed in horses. PCA was stimulated for 20 weeks in eight animals; seven served as controls. Reinnervation was monitored through muscle response to hypercapnia, electrical stimulation and exercise. Ultimately, muscle fiber type proportions and minimum fiber diameters, and RLn axon number and degree of myelination were determined. RESULTS: Laryngeal function returned to normal in both groups within 22 weeks. FES improved muscle strength and geometry, and induced increased type I:II fiber proportion (p = 0.038) in the stimulated PCA. FES showed no deleterious effects on reinnervation. DISCUSSION: Intramuscular electrical stimulation did not delay PCA reinnervation after axonotmesis. FES can represent a supportive treatment to promote laryngeal functional recovery after RLn injury. Muscle Nerve 59:717-725, 2019.

Development of a Closed-Loop Stimulator for Laryngeal Reanimation: Part 2. Device Testing in the Canine Model of Laryngeal Paralysis.

OBJECTIVE:: Laryngeal paralysis of central or peripheral origin can potentially be treated using functional electrical stimulation (FES) of laryngeal muscles. Experiments in canines (dogs) were performed using implant prototypes capable of closed-loop FES to refine engineering designs and specifications, test surgical approaches for implantation, and better understand the in vivo effects of laryngeal muscle stimulation on short- and long-term glottic function. STUDY DESIGN:: Prospective, laboratory. METHODS:: We designed and tested a series of microprocessor-based implantable devices that can stimulate glottic opening or closing based on input from physiological control signals (real-time processing of electromyographic [EMG] signals). After acute device testing experiments, 2 dogs were implanted for 8 and 24 months, with periodic testing of closed-loop laryngeal muscle stimulation triggered from EMG signals. In total, 5 dogs were tested for the effects of laryngeal muscle stimulation on vocal fold (VF) posturing in larynges with nerve supplies that were intact (7 VFs), synkinetically reinnervated (2 VFs), or chronically denervated (1 VF). In 3 cases, the stimulation was combined with airflow-driven phonation to study the consequent modulation of phonatory parameters. RESULTS:: Initial device prototypes used inductive coupling for power and communication, while later iterations used battery power and infrared light communication (detailed descriptions are provided in the Part 1 companion paper). Two animals were successfully implanted with the inductively powered units, which operated until removed at 8 months in 1 animal or for more than 16 months in the second animal. Surgically, the encapsulated implants were well tolerated, and procedures for placing, attaching, and connecting the devices were developed. To simulate EMG control signals in anesthetized animals, we created 2 types of nerve/muscle signal sources. In one approach, a neck muscle had a cuff electrode placed on its motor nerve that was connected to transdermal electrical connection ports for periodic testing. In the second approach, the recurrent laryngeal nerve on one side of the larynx was stimulated to generate a VF EMG signal, which was then used to trigger FES of the paralyzed contralateral side (eg, restoring VF movement symmetry). Implant testing identified effective stimulation parameters and closed-loop stimulation artifact rejection techniques for FES of both healthy and paralyzed VFs. Stimulation levels effective for VF adduction did not cause signs of discomfort during awake testing. CONCLUSION:: Our inductive and battery-powered prototypes performed effectively during in vivo testing, and the 2 units that were implanted for long-term evaluation held up well. As a proof of concept, we demonstrated that elicited neck strap muscle or laryngeal EMG potentials could be used as a control signal for closed-loop stimulation of laryngeal adduction and vocal pitch modulation, depending on electrode positioning, and that VFs were stimulable in the presence of synkinetic reinnervation or chronic denervation.

Positive Effects of Manual Circumlaryngeal Therapy in the Treatment of Muscle Tension Dysphonia (MTD): Long Term Treatment Outcomes.

INTRODUCTION: Manual circumlaryngeal therapy (MCT) aims to correct laryngeal position and relax (para) laryngeal and cervical muscles resulting in improved voice quality. The goal of the current study was to further verify long-term effects of MCT in the treatment of Muscle Tension Dysphonia (MTD) patients based on acoustic findings and perceptual judgments. METHOD: Twenty-eight adult female patients who had been referred to the speech therapy clinic of Khatam Hospital, Zahedan city, participated in this study. Manual circumlaryngeal therapy was undertaken. There were 15 therapy sessions, three sessions per week, each with duration of 30 minutes. Pre- and post-treatment audio recordings of sustained vowels, selected sentences, and connected speech samples were submitted to auditory-perceptual and acoustical analysis to assess the long-term (6-months) effects of the 15 treatment program. RESULTS: Acoustically, Harmonic to Noise Ratio (HNR) increased and perturbation (Jitter and Shimmer) measures decreased, and perceptually, the subjective CAPE-V ratings improved in all patients. CONCLUSION: These results suggest that MCT can be an effective method for voice rehabilitation in patients with MTD and the changes due to the therapy were persistent over a 6-month duration following the termination of treatment sessions.

Selective recurrent laryngeal nerve stimulation using a penetrating electrode array in the feline model.

OBJECTIVES/HYPOTHESIS: Laryngeal muscles (LMs) are controlled by the recurrent laryngeal nerve (RLN), injury of which can result in vocal fold (VF) paralysis (VFP). We aimed to introduce a bioelectric approach to selective stimulation of LMs and graded muscle contraction responses. STUDY DESIGN: Acute experiments in cats. METHODS: The study included six anesthetized cats. In four cats, a multichannel penetrating microelectrode array (MEA) was placed into an uninjured RLN. For RLN injury experiments, one cat received a standardized hemostat-crush injury, and one cat received a transection-reapproximation injury 4 months prior to testing. In each experiment, three LMs (thyroarytenoid, posterior cricoarytenoid, and cricothyroid muscles) were monitored with an electromyographic (EMG) nerve integrity monitoring system. Electrical current pulses were delivered to each stimulating channel individually. Elicited EMG voltage outputs were recorded for each muscle. Direct videolaryngoscopy was performed for visualization of VF movement. RESULTS: Stimulation through individual channels led to selective activation of restricted nerve populations, resulting in selective contraction of individual LMs. Increasing current levels resulted in rising EMG voltage responses. Typically, activation of individual muscles was successfully achieved via single placement of the MEA by selection of appropriate stimulation channels. VF abduction was predominantly observed on videolaryngoscopy. Nerve histology confirmed injury in cases of RLN crush and transection experiments. CONCLUSIONS: We demonstrated the ability of a penetrating MEA to selectively stimulate restricted fiber populations within the feline RLN and selectively elicit contractions of discrete LMs in both acute and injury-model experiments, suggesting a potential role for intraneural MEA implantation in VFP management. LEVEL OF EVIDENCE: NA. Laryngoscope, 128:1606-1614, 2018.

Effects of laryngeal manual therapy (LMT) and transcutaneous electrical nerve stimulation (TENS) in vocal folds diadochokinesis of dysphonic women: a randomized clinical trial. / Efeitos da terapia manual laríngea e da estimulação elétrica nervosa transcutânea (TENS) na diadococinesia laríngea em mulheres disfônicas: estudo clínico randomizado.

PURPOSE: To verify and compare the effect of transcutaneous electrical nerve stimulation (TENS) and laryngeal manual therapy (LMT) on laryngeal diadochokinesis (DDK) of dysphonic women. METHODS: Twenty women with bilateral vocal nodules participated and were equally divided into: LMT Group - LMT application; TENS Group - TENS application; both groups received 12 sessions of treatment, twice a week, with a duration of 20 minutes each, applied by the same therapist. The women were evaluated as to laryngeal DDK at three moments: diagnostic, pre-treatment, and post-treatment, which produced three groups of measurements. The DDK recording was performed with intersected repetition of vowels /a/ and / i/. The analysis of vowels was performed by the program Motor Speech Profile Advanced (MSP)-KayPentax. The DDK parameters of the three evaluations were compared by means of the paired t-test (p≤0.05). RESULTS: The measurements of laryngeal DDK parameters were similar in the phase without treatment, indicating no individual variability over time. There was no change with respect to the speed of DDK after intervention, but after LMT, DDK of the vowel /i/ was more stable in terms of the duration of the emissions and intensity of emissions repeated. These results show improved coordination of vocal folds movement during phonation. There were no changes in the DDK parameters following TENS. CONCLUSION: LMT provides greater regularity of movement during laryngeal diadochokinesis in dysphonic women, which extends knowledge on the effect of rebalancing the larynx muscles during phonation, although TENS does not impact laryngeal diadochokinesis.

Effects of transcutaneous electrical stimulation on vocal folds adduction.

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

Unilateral Laryngeal Pacing System and Its Functional Evaluation.

Goal. To establish a reliable instrumental system for synchronized reactivation of a unilaterally paralyzed vocal fold and evaluate its functional feasibility. Methods. Unilateral vocal fold paralysis model was induced by destruction of the left recurrent laryngeal nerve (RLN) in anesthetized dogs. With a micro controller-based electronic system, electromyography (EMG) signals from cricothyroid (CT) muscle on the ipsilateral side were recorded and used to trigger pacing of paralyzed vocalis muscles. The dynamic movement of vocal folds was continuously monitored using an endoscope, and the opening and closing of the glottis were quantified with customized imaging processing software. Results. The recorded video images showed that left side vocal fold was obviously paralyzed after destructing the RLN. Using the pacing system with feedback triggering EMG signals from the ipsilateral CT muscle, the paralyzed vocal fold was successfully reactivated, and its movement was shown to be synchronized with the healthy side. Significance. The developed unilateral laryngeal pacing system triggered by EMG from the ipsilateral side CT muscle could be successfully used in unilateral vocal fold paralysis with the advantage of avoiding disturbance to the healthy side muscles.