Stimulation of denervated muscle promotes selective reinnervation, prevents synkinesis, and restores function.

Objectives/hypothesis: Previously, electrical stimulation of denervated canine laryngeal muscle was shown to promote reinnervation by native over foreign motoneurons. The goal of this study was to assess the effect of different stimulus paradigms on reinnervation quality and functional recovery.

Study Design: A prospective study of six canines over 8 to 20 months.

Comparison of ventilation and voice outcomes between unilateral laryngeal pacing and unilateral cordotomy for the treatment of bilateral vocal fold paralysis.

Background/aims: Rehabilitation of the bilaterally paralyzed human larynx remains a complex clinical problem. Conventional treatment generally involves surgical enlargement of the compromised airway, but often with resultant dysphonia and risk of aspiration. In this retrospective study, we compared one such treatment, posterior cordotomy, with unilateral laryngeal pacing: reanimation of vocal fold opening by functional electrical stimulation of the posterior cricoarytenoid muscle.

Bilateral motion restored to the paralyzed canine larynx with implantable stimulator.

Objectives/hypothesis: Bilateral stimulation of posterior cricoarytenoid (PCA) muscles offers a physiologic approach to restore ventilation to a normal level in case of bilateral laryngeal paralysis. The objective of this study was to evaluate the long-term efficacy and safety of a new generation stimulator in restoring ventilation and exercise tolerance.

Study Design: A prospective study of four canines over 8-20 months.

Botulinum toxin injections for new onset bilateral vocal fold motion impairment in adults.

Objectives/hypothesis: Review of clinical experience and results using botulinum toxin type A (BTX) for the management of adult patients with respiratory compromise due to new onset bilateral vocal fold motion impairment (BVFMI).

Study Design: Retrospective case series.

Methods: The records of 11 patients from two institutions with respiratory compromise due to bilateral vocal fold motion impairment were reviewed.

Rehabilitation of bilaterally paralyzed canine larynx with implantable stimulator.

Objectives/hypothesis: Bilateral stimulation of the posterior cricoarytenoid (PCA) muscles offers a physiologic approach to rehabilitate ventilation to a normal level in case of bilateral laryngeal paralysis. The objective was to evaluate the safety and efficacy of a new generation stimulator in restoring glottal opening, ventilation, and exercise tolerance.

Study Design: A prospective study in three canines over 6 to 17 months.

Evaluation of a deep brain stimulation electrode for laryngeal pacing.

Objectives: The purpose of the present study was to evaluate the suitability of a deep brain stimulation electrode for laryngeal pacing. Of interest was whether the smaller and more closely spaced channels could provide sufficient channel redundancy, controlled current distribution, and discrete activation of the posterior cricoarytenoid (PCA) muscle.

Methods: A study was conducted in dogs under differing states of PCA muscle innervation representing complete denervation to complete synkinetic reinnervation.

Evoked electromyographic technique for quantitative assessment of the innervation status of laryngeal muscles.

Objectives: The purpose of this study was to develop a minimally invasive, noninjurious evoked electromyographic technique that could accurately quantitate the level of innervation of laryngeal muscles with recurrent laryngeal nerve stimulation.

Methods: A four-phase study was conducted in 24 canines, including 1) identification of the best stimulation-recording configuration, 2) statistical analysis of sensitivity and accuracy, 3) evaluation of safety, and 4) identification of the laryngeal muscle(s) that contribute to the evoked response.

Results: The results demonstrated that an entirely noninvasive technique is not feasible.

Neurophysiology of vocal fold paralysis.

Although a tremendous volume of energy and literature has been devoted to laryngeal paralysis in the past decade, there are still substantial gaps in our understanding of fundamental issues. Oddly enough, controversy remains regarding the actual innervation pathways of the larynx and whether the paralyzed larynx is truly denervated or dysfunctionally reinnervated. An appreciation of these basic issues is prerequisite to making prudent decisions regarding the most appropriate type of intervention.

Reanimation of the paralyzed human larynx with an implantable electrical stimulation device.

Objectives/hypothesis: Electrical stimulation of the posterior cricoarytenoid muscle, when paced with inspiration, offers a physiological approach to restore ventilation in bilateral laryngeal paralysis without any of the disadvantages associated with conventional treatment.

Study Design: A prospective study of six patients.

Methods: The patients were successfully implanted with an Itrel II stimulator (Medtronic, Inc).

Voice outcome following thyroplasty in patients with longstanding vocal fold immobility.

Objective: Length of time elapsed between recurrent laryngeal nerve (RLN) injury and surgery may affect voice result. The purpose of this study was to compare voice outcome after thyroplasty in patients with short- and long-term vocal fold immobility.

Methods: Thirty-five patients with longstanding vocal fold immobility (8.

Comparison of neuromuscular blockade and recovery with botulinum toxins A and F.

Intramuscular injection of botulinum toxin A is used to treat focal dystonias. Because immunoresistance has been documented in some patients, other molecular forms of the toxin have been evaluated clinically. The present investigation compared the time course and extent of neuromuscular blockade and recovery of botulinum toxin types A and F using an electromyographic monitoring system implanted in the rat hindlimb.

Palatal adhesion: the treatment of unilateral palatal paralysis after high vagus nerve injury.

Background: Resection of skull base tumors commonly necessitates intraoperative sacrifice of lower cranial nerves at the level of the jugular foramen. Sequelae of unilateral vagus nerve loss include ipsilateral laryngeal paralysis, ipsilateral palatal and pharyngeal paralysis, and velopharyngeal incompetence (VPI) marked by hypernasal speech and nasopharyngeal reflux of liquids during swallowing.

Methods: Palatal adhesion (PA), a procedure whereby the unilaterally paralyzed palate is attached to the posterior pharyngeal wall, decreases the size of the velopharyngeal port and minimizes the symptoms.

Electrically stimulated glottal opening combined with adductor muscle botox blockade restores both ventilation and voice in a patient with bilateral laryngeal paralysis.

The purpose of this study was to determine whether paced electrical stimulation of the posterior cricoarytenoid muscle with an implantable device could restore ventilation in a patient with bilateral vocal fold paralysis without disturbing voice. In the first US case of a multi-institutional study, this patient was implanted with an Itrel II stimulator (Medtronic, Inc). In monthly postoperative sessions over an 18-month period, an effective stimulus paradigm was derived, the magnitude of stimulated vocal fold abduction and ventilation was measured, and perceptual judgments of voice quality were made.

Effect of chronic electrical stimulation of laryngeal muscle on voice.

Conventional surgical therapies for bilateral laryngeal paralysis sacrifice voice to enlarge the airway. Electrical pacing of the posterior cricoarytenoid (PCA) muscle to restore glottal opening and allow ventilation offers a new treatment approach. The purpose of this investigation was to determine whether long-term stimulation of the PCA muscle altered perceptual, acoustic, and aerodynamic parameters of voice.

Electrical stimulation of a denervated muscle promotes selective reinnervation by native over foreign motoneurons.

The effect of electrical stimulation of the denervated posterior cricoarytenoid (PCA) muscle on its subsequent reinnervation was explored in the canine. Eight animals were implanted with a planar array of 36 electrodes for chronic stimulation and recording of spontaneous and evoked electromyographic (EMG) potentials across the entire fan-shaped surface of a muscle pair. Normative EMG data were recorded from each electrode site before unilateral nerve section, and from the innervated partner after nerve section.