Botulinum toxin treatment for adductor spasmodic dysphonia with EMG and endoscopic guidance

Background & Objective: Spasmodic dysphonia is idiopathic focal dystonia characterized by irregular contractions or postural disorders of the laryngeal muscles, resulting in abnormal speech. Progress in laryngoscopy has resulted in development of a precise technique of botulinum toxin (BTX) injection into the thyroarytenoid muscle under visual control. Methods: We used EMG and endoscopic guidance for BTX injection in adductor spasmodic dysphonia (AdSD). Results: Thirty eight patients with AdSD were injected with BTX in 84 treatment sessions. The voice handicap index (VHI) level of the patients were: severe (73.8%), moderate (26.2%) and mild (none). The average VHI score was 74.6 points. After 8 weeks of BTX treatment, the VHI level was: Severe (3.6%), moderate (10.8%), and mild (85.7%). The average VHI score was 27.7 points. The average values of jitter, shimmer and harmonic to noice ratio (HNR) improved statistically (p < 0.05). The incidence of side effects were: breathiness (17.9%), choking (15.5%); hoarseness (8.5%), and dysphagia (4.7%). Conclusions: Injection of BTX under both EMG and laryngoscopy guidance for treatment of adductor spasmodic dysphonia is an effective and safe treatment.

Surface Electromyography for Identification of Pre-Phonatory Activity

Surface electrode EMG is an established method for studying biomechanical activity. It has not been well studied in detecting laryngeal biomechanical activity of pre-phonatory onset. Our aims were to compare the sensitivity of surface EMG in identifying pre-phonatory laryngeal activity to needle electrode laryngeal EMG and to compare the pre-phonatory period in patients with adductor laryngeal dystonia (ADLD) with that in controls. ADLD patients (n = 10) undergoing needle LEMG prior to Botox injection and participants with normal voices (n = 6) were recruited. Surface EMG electrodes were placed over the cricoid ring and thyrohyoid membrane. Needle EMG electrodes were inserted into the thyroarytenoid muscle. EMG and auditory output samples were collected during phonation onset. Tracings were de-identified and evaluated. Measurements of time from onset in change of the amplitude and motor unit frequency on the interference pattern to onset of phonation were calculated by two blinded raters. 42 of 71 patient and 40 of 50 control tracings were available for analysis. Correlation for pre-phonatory time between electrode configuration was 0.70 for patients, 0.64 for controls and 0.79 for all the data combined. Inter-rater correlation was 0.97 for needle and 0.96 for surface electrodes. ADLD patients had a longer pre-phonatory time than control subjects by 169.48ms with surface electrode and 140.23ms with needle electrode (p < 0.001). Surface EMG demonstrates equal reliability as Needle EMG in detecting pre-phonatory activity in controls and subjects. Patients with ADLD have a significantly prolonged pre-phonatory period when compared with controls.

Voice Characteristics in Smith–Magenis Syndrome: An Acoustic Study of Laryngeal Biomechanics

Smith–Magenis syndrome (SMS) is a rare genetic disease characterized by intellectual disability, serious behavior disorders, neurodevelopment delay, and speech and language disorders. An acoustic and biomechanical analysis of the voice of SMS young adults was carried out due to (a) the close relationship between the laryngeal biomechanics and the clinical and emotional state of a person; (b) the fact that no research on the voice in this syndrome has been conducted previously. The vocal timbre of most people diagnosed with SMS does not seem to be according to the complexion of diagnosed individuals, nor to their gender and age, so it could be interesting to attend the analysis of phonation of people with a rare genetic syndrome such as SMS. We used BioMetPhon, a specific piece of software to analyze the glottal source and biomechanics of vocals folds. Nineteen features related to dysphonia, physiology, and biomechanics of the vocal folds were considered. The adult phonation of 9 individuals with SMS was analyzed and compared to 100 normative male and female adult voices. Results showed that the phonation of the SMS group significantly deviates from the adult normophonic profile in more than one of the 19 features examined, such as stiffness of the thyroarytenoid muscle and dynamic mass of the vocal fold cover, among others.

Effects of Vocal Training on Thyroarytenoid Muscle Neuromuscular Junctions and Myofibers in Young and Older Rats

The purpose of this investigation was to determine the effects of vocal training on neuromuscular junction (NMJ) morphology and muscle fiber size and composition in the thyroarytenoid muscle, the primary muscle in the vocal fold, in younger (9-month) and older (24-month) Fischer 344 × Brown Norway male rats. Over 4 or 8 weeks of vocal training, rats of both ages progressively increased their daily number of ultrasonic vocalizations (USVs) through operant conditioning and were then compared to an untrained control group. Neuromuscular junction morphology and myofiber size and composition were measured from the thyroarytenoid muscle. Acoustic analysis of USVs before and after training quantified the functional effect of training. Both 4- and 8-week training resulted in less NMJ motor endplate dispersion in the lateral portion of the thyroarytenoid muscle in rats of both ages. Vocal training and age had no significant effects on laryngeal myofiber size or type. Vocal training resulted in a greater number of USVs with longer duration and increased intensity. This study demonstrated that vocal training induces laryngeal NMJ morphology and acoustic changes. The lack of significant effects of vocal training on muscle fiber type and size suggests vocal training significantly improves neuromuscular efficiency but does not significantly influence muscle strength changes.

Hemi-laryngopharyngeal Spasm (HeLPS): Defining a New Clinical Entity

Objective: Hemi-laryngopharyngeal spasm (HeLPS) has recently been described in the neurosurgical literature as a cause of intermittent laryngopharyngeal spasm and cough due to vascular compression of the vagus nerve at the cerebellopontine angle. We present the diagnostic criteria for this syndrome. Methods: A retrospective chart review of six patients with HeLPS and three patients misdiagnosed with this condition are presented. All patients were diagnosed and treated at a tertiary care academic centre from July 2013 to July 2017. Results: Patients with HeLPS had five defining characteristics: 1) All patients had symptoms of episodic laryngopharyngeal spasm and coughing. Patients were asymptomatic between episodes and were refractory to speech therapy and reflux management. 2) Laryngoscopy showed hyperactive twitching of the ipsilateral vocal fold in two of the six patients. No other inter-episodic abnormalities were seen. 3) Botulinum toxin A injections into the thyroarytenoid muscle on the affected ipsilateral side reduced laryngopharyngeal spasms. Botulinum toxin injection in the contralateral thyroarytenoid muscle did not improve laryngopharyngeal spasm. 4) Magnetic resonance imaging revealed ipsilateral neurovascular compression of the vagus nerve rootlets by the posterior inferior cerebellar artery. 5) Microvascular decompression (MVD) surgery of the ipsilateral vagus nerve resolved all symptoms (follow-up 2-4 years). Conclusion: The diagnostic criteria for hemi-laryngopharyngeal spasm (HeLPS) are proposed. Otolaryngology recognition of this new clinical entity may lead to a surgical cure and avoid the unnecessary therapies associated with misdiagnosis. Level of Evidence: 4