Vagal nerve stimulator-associated sleep disordered breathing secondary to vagal-induced laryngospasm in pediatric populations: Case presentation and systematic review

OBJECTIVES

Sleep disordered breathing (SDB) is a well-documented complication of vagus nerve stimulation (VNS) in the literature. Yet, a formal consensus on its management has not been established, particularly in the pediatric population. This study aims to evaluate the current literature on VNS-associated SDB in order to further characterize its presentation, pathogenesis, diagnosis, and treatment.

METHODS

A literature review from 2001 to November 8, 2021 was conducted to search for studies on SDB during vagal nerve stimulation in pediatric populations.

RESULTS

Of 277 studies screened, seven studies reported on pediatric patients with VNS-associated SDB. Several investigators found on polysomnogram that periods of apnea/hypopnea correlated with VNS activity. When VNS settings were lowered or turned off, symptoms would either improve or completely resolve.

CONCLUSION

VNS-associated SDB is a well described complication of VNS implantation, occurring due to an obstructive process from vagal stimulation and laryngeal contraction. Diagnosis can be made via polysomnogram. Recommended treatment is through adjustment of VNS settings. However, those who are unable to tolerate this, or who have had pre-existing obstructive issues prior to VNS, should pursue other treatment options such as non-invasive positive pressure or surgery directed by DISE findings.

Negative Pressure Pulmonary Edema: A Case Report

Negative pressure pulmonary edema is an uncommon complication of the extubation of theendotracheal tube. An increase in intrathoracic pressure and negative pressure of the lung causedby acute laryngeal spasm results from acute upper respiratory obstruction causing life-threateningpulmonary edema by alveolar-capillary damage is called negative pressure pulmonary edema. Wehere describe 28-years old female case the preoperative diagnosis of pelvic inflammatory diseaseundergoing exploratory laporoscopy caused negative pressure pulmonary edema while extubation.With the immediate treatment, the patient was discharged without any abnormalities.

Guideline for Monitoring and Management of Pediatric Patients Before, During, and After Sedation for Diagnostic and Therapeutic Procedures: Update 2016

The safe sedation of children for procedures requires a systematic approach that includes the following: no administration of sedating medication without the safety net of medical/dental supervision, careful presedation evaluation for underlying medical or surgical conditions that would place the child at increased risk from sedating medications, appropriate fasting for elective procedures and a balance between the depth of sedation and risk for those who are unable to fast because of the urgent nature of the procedure, a focused airway examination for large (kissing) tonsils or anatomic airway abnormalities that might increase thepotential for airway obstruction, a clear understanding of the medication's pharmacokinetic and pharmacodynamic effects and drug interactions, appropriate training and skills in airway management to allow rescue of the patient, age- and size-appropriate equipment for airway management and venous access, appropriate medications and reversal agents, sufficient numbers of staff to both carry out the procedure and monitor the patient, appropriate physiologic monitoring during and after the procedure, a properly equipped and staffed recovery area, recovery to the presedation level of consciousness before discharge from medical/dental supervision, and appropriate discharge instructions. This report was developed through a collaborative effort of the American Academy of Pediatrics and the American Academy of Pediatric Dentistry to offer pediatric providers updated information and guidance in delivering safe sedation to children.

Management of Aerodigestive Tract Foreign Bodies: Innovative Teaching Concepts

Objectives:

We discuss a method to provide medical education in bronchoesophagology by using high-fidelity patient simulation manikins.

Methods:

A sophisticated, life-sized infant manikin with realistic anatomic, physiologic, and hemodynamic responses to interventions was programmed to simulate endobronchial foreign body lodgment by blocking ventilation of one lung and manifesting audible stridor, asymmetric chest wall motion, and decreased oxygen saturation.

Results:

Otolaryngology residents participated in simulation exercises incorporating the cognitive and technical skills necessary for successful airway endoscopy, including technical proficiency and teamwork, to learn to coordinate endoscopy and ventilation and manage laryngospasm. Rather than relying on instructor description, the participants responded directly to the manikin. This sense of realism stimulated participants to rehearse to improve provider performance and patient safety. Simulation provided an agenda determined by the needs of the learners, exploration without direct risk to patients, immediate feedback, and objective documentation.

Conclusions:

Rapidly evolving medical simulation technologies support activated, effective adult learning; they will play an increasing role in medical education.

A medical crisis management simulation activity for pediatric dental residents and assistants

Dentists are expected to deliver safe and pain-free dental procedures after they graduate from dental school. This includes using local anesthetics and sedative drugs that may be associated with side effects and complications that can lead to crisis situations. This study postulated that teaching medical crisis management to dental residents and assistants using human patient simulation (HPS) would improve their confidence in managing crisis situations in the real world. Four medical crisis scenarios were designed and programmed into a pediatric simulator. The scenarios included anaphylaxis, laryngospasm during procedural sedation, sedative medication overdose, and multiple drug interaction with cardiac arrhythmia. The simulation room was outfitted with an authentic dental operatory and emergency equipment to enhance the realism. One first-or second-year pediatric dentistry resident and a staff dental assistant were assigned as a team to participate in each ten-minute scenario followed by a debriefing session. At the end of the sessions, the participants completed an anonymous survey regarding the simulation experience. There were a total of twenty-four participants, 91.7 percent of whom felt that HPS was a good tool for learning medical crisis and that they will be more confident in managing a similar situation in the dental office after this experience. A majority of the participants felt that using HPS as a tool to teach crisis management is an acceptable and valuable technique to help improve their confidence in managing crisis situations that may occur in dental offices.

[The use of "laryngospasm notch" in a patient who was unable to breathe during general anesthesia with a ProSeal laryngeal mask airway--the effect of Kino's approach]

We report a case where "laryngospasm notch" technique was used in a patient to initiate spontaneous respiration during general anesthesia. The patient was a 43-year-old woman who underwent conization. A Pro-Seal laryngeal mask airway was inserted after induction of general anesthesia. General anesthesia was maintained with sevoflurane (1.7-2%) and fentanyl. Surgical course was uneventful until the patient became unable to breathe towards the end of surgery. Positive-pressure ventilation was applied, but the patient could not be ventilated. "Laryngospasm notch" technique was performed by applying digital pressure in front of the tragus of the ears, and the patient began to breathe spontaneously. We describe our experience with the "laryngospasm notch" technique applied to the front of the tragus of the ears to treat laryngospasm.

[The use of "laryngospasm notch" in two patients whose oxygen saturations dropped after tracheal extubation]

In 1998, Dr. Larson described the technique of applying pressure to the "laryngospasm notch" as the best treatment for laryngospasm. Yet, there are no case reports of using this technique in the literature. We report 2 cases of using this technique in patients whose oxygen saturation levels dropped after tracheal extubation. The first patient was a 48-year-old man who underwent laparoscopic cholecystectomy and the second patient was a 67-year-old man who underwent lumbar laminectomy. In both cases, induction of general anesthesia and surgery were uneventful. After surgery, we confirmed spontaneous respiration and the patients were able to respond and shake hands. However, immediately after extubation, the patients could not breathe and their oxygen saturation levels decreased to 76% and 84%, respectively. In the first patient, mask ventilation was easy and we used the "laryngospasm notch" technique during ventilation. However, in the second patient, mask ventilation was difficult and we used this technique prepared for re-intubation. In both cases, the patients began to breathe spontaneously shortly after using this technique and oxygen saturation increased to 100%. The incidence of laryngospasm is higher after tracheal extubation. The "laryngospasm notch" method is a good technique to treat this condition.

Management of complications during moderate and deep sedation: respiratory and cardiovascular considerations

The risk for complications while providing moderate and deep sedation is greatest when caring for patients already medically compromised. It is reassuring that significant untoward events can generally be prevented by careful preoperative assessment, along with attentive intraoperative monitoring and support. Nevertheless, we must be prepared to manage untoward events should they arise. This continuing education article will review critical aspects of patient management of respiratory and cardiovascular complications.

Crisis management during anaesthesia: laryngospasm

BACKGROUND

Laryngospasm is usually easily detected and managed, but may present atypically and/or be precipitated by factors which are not immediately recognised. If poorly managed, it has the potential to cause morbidity and mortality such as severe hypoxaemia, pulmonary aspiration, and post-obstructive pulmonary oedema.

OBJECTIVES

To examine the role of a previously described core algorithm "COVER ABCD-A SWIFT CHECK", supplemented by a specific sub-algorithm for laryngospasm, in the management of laryngospasm occurring in association with anaesthesia.

METHODS

The potential performance of this structured approach for the relevant incidents amongst the first 4000 reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual management as reported by the anaesthetists involved.

RESULTS

There were 189 reports of laryngospasm among the first 4000 incidents reported to AIMS. These were extracted and analysed. In 77% of cases laryngospasm was clinically obvious, but 14% presented as airway obstruction, 5% as regurgitation or vomiting, and 4% as desaturation. Most were precipitated by direct airway stimulation (airway manipulation, regurgitation, vomiting, or blood or secretions in the pharynx), but patient movement, surgical stimulus, irritant volatile agents, and failure to deliver the anaesthetic were also precipitating factors. Desaturation occurred in over 60% of cases, bradycardia in 6% (23% in patients aged <1 year), pulmonary oedema in 4%, and pulmonary aspiration in 3%. It was considered that, correctly applied, the combined core algorithm and sub-algorithm recommended for the diagnosis and management of laryngospasm would have led to earlier recognition of the problem and/or better management in 16% of cases.

CONCLUSION

Laryngospasm may present atypically and, if not promptly managed effectively, may lead to morbidity and mortality. Although usually promptly recognised and appropriately managed, the use of a structured approach is recommended. If such an approach had been used in the 189 reported incidents, earlier recognition and/or better management may have occurred in 16% of cases.

Pulmonary edema and lung injury after severe laryngospasm

A young male with no pre-operative medical illness underwent corrective surgery for a deviated nasal septum under general anesthesia. At the end of surgery, patient was extubated but went into severe laryngospasm that did not improve with gentle Intermittent Positive Pressure Ventilation (IPPV) and small dose of Suxamethonium. As the situation worsened and patient developed severe bradycardia and de-saturation, re-intubation was done that revealed pink froth in the endotracheal tube. His portable chest X-ray was suggestive of non-cardiogenic pulmonary edema. With an overnight supportive treatment, using mechanical ventilation with Positive End-Expiratory Pressure (PEEP), morphine infusion and frusemide, patient improved and was subsequently weaned off from ventilator.

Postobstructive pulmonary edema after laryngospasm in the otolaryngology patient

CONTEXT

Post-obstructive pulmonary edema (PPE) is an uncommon complication which develops immediately after the onset of acute airway obstruction such as laryngospasm or epiglottitis (type I) or after the relief of chronic upper airway obstruction such as adenotonsillar hypertrophy (type II).

OBJECTIVE

To describe the development of type I PPE following laryngospasm in pediatric and adult patients undergoing otolaryngologic surgical procedures other than those for treatment of obstructive sleep apnea.

DESIGN

Retrospective case series of 13 otolaryngology patients from 1996 to 2003.

SETTING

Tertiary care teaching hospital and its affiliates.

PATIENTS

13 patients (4 children, 9 adults, 5 males, 8 females) ranging in age from 9 months to 48 years.

RESULTS

Operative procedures included adenoidectomy, tonsillectomy, removal of an esophageal foreign body, microlaryngoscopy with papilloma excision, endoscopic sinus surgery, septorhinoplasty, and thyroidectomy. Six patients required reintubation. Treatment included positive pressure ventilation, oxygen therapy, and diuretics. Seven patients were discharged within 24 hours and the others were discharged between 2 and 8 days postoperatively. There were no mortalities.

CONCLUSION

Laryngospasm resulting in PPE may occur in both children and adults after various otolaryngologic procedures. Among the subgroup of children, our study is the first to report its occurrence in healthy children without sleep apnea undergoing elective surgery.

Idiopathic laryngeal spasm: management and long-term outcome

Idiopathic laryngeal spasm (ILS) is an uncommon disorder characterised by brief episodes of stridor, occurring at any time. Subsequent outpatient ENT examination is normal. These episodes cause considerable anxiety for both patient and physician. Little is known about the initiating event(s) in this condition or the long-term outcome. Using a combination of telephone and postal questionnaires with case note review, we have reviewed a cohort of 21 patients with this diagnosis managed by the senior author over the last 15 years. None of the 19 patients who responded were worse; 13 (68%) described improvement or complete resolution of symptoms. ILS is difficult to classify in the spectrum of vocal cord disorders, but appears distinct to those previously described. The condition responds well to a conservative management approach of reassurance and counselling.

Laryngospasm in neurological diseases

Laryngospasm is a clinical symptom characterized by involuntary spasms of the laryngeal muscles, which leads to paroxysms of coughing, inspiratory stridor, and sometimes to episodes of complete upper-airway occlusion. Although laryngospasm is a symptom mainly seen in otolaryngeal diseases and in the context of anesthesiological complications, it also occurs in neurological disorders. In this review of the occurrence of laryngospasms in neurological diseases, the clinical symptomatology, additional circumstances, possible underlying causes, and therapeutic options are presented.

Vagal nerve stimulator implantation: an otolaryngologist's perspective

OBJECTIVE

This study was conducted to compare an otolaryngologist's experience with a cohort of epilepsy patients implanted with a vagal nerve stimulator (VNS) to previously published data.

METHODS

Demographics, preoperative seizure frequency, medications, and complications were retrospectively collected from patients implanted by the senior author. Postoperative medications and seizure frequency were obtained from referring neurologists.

RESULTS

Seventeen patients were implanted over a 24-month period. Average age was 28.3 years. Patients presented with petit mal (n = 3), tonic-clonic (n = 6), complex partial (n = 5), and grand mal (n = 8) seizures. Mean follow-up postimplantation was 13.5 months. Most patients had at least a 50% reduction of seizure frequency, with 3 patients being seizure free. There were no postoperative infections. One patient had left vocal cord immobility. The most common side effect was voice disturbance during device activation.

CONCLUSION

Otolaryngologists are well equipped to perform VNS implantation and to diagnose and treat possible laryngeal side effects.

EBM RATING

C-4.

Recurrent episodes of intractable laryngospasm during dissociative sedation with intramuscular ketamine

We report 2 cases of dissociative sedation with intramuscular ketamine with recurrent episodes of laryngospasm that we were unable to ventilate with bag-mask ventilation, in 1 case leading to endotracheal intubation to protect the airway. Supplemental oxygen was given throughout the sedations, and ventilatory status was noninvasively monitored on a continuous basis, providing detailed and objective documentation of the patients' clinical status throughout the sedations. We were, therefore, able to rapidly assess and confirm apnea, laryngospasm, and airway dysfunction.

[Laryngospasm associated with anesthesia: diagnosis and management]

Securing the airway is the most important part of anesthesia safety. In clinical practice there is always the risk of encountering laryngospasm, which is defined as the occlusion of the glottis by the action of the intrinsic laryngeal muscles. Once laryngospasm occurs, it leads to acute desaturation and subsequent organ dysfunction. In spite of such a dramatic deterioration, however, there are no systematic reviews that include pathophysiology, clinical incidence, prevention and its treatment. In this paper, we have reviewed laryngospasm, according to the induction of anesthesia and emergence from it, methods for securing the airway using a tracheal tube or a laryngeal mask airway, and the timing of tracheal extubation. In addition, we have summarized a prompt diagnosis and adequate prevention and management of laryngospasm associated with anesthesia.

Use of acupuncture for the treatment of adductor spasmodic dysphonia: a preliminary investigation

Ten subjects with adductor spasmodic dysphonia participated in a study examining the effects of an acupuncture treatment protocol on their voice disorder. Treatment consisted of eight sessions, and it was designed and performed by two physicians certified in acupuncture. Voice characteristics were evaluated pretreatment and posttreatment using the CSL Motor Speech Profile (MSP), Unified Spasmodic Dysphonia Rating Scale, and Voice Handicap Index (VHI). Subjects also answered a posttreatment questionnaire regarding their experience. Significant pretreatment and posttreatment differences occurred for some MSP measures. Significant differences were found on all three subtests of the VHI, and the average total scores pretreatment and posttreatment differed by 17 points (considered significant according to VHI standardization). Seven of 10 subjects reported improvements in voice production, although expert raters did not detect perceptual changes in voice quality. Possible reasons for the discrepancies between objective measures and self ratings, and implications for further research, are discussed.

Acupuncture therapy for sleep-related laryngospasm

Sleep-related laryngospasm is a rare disorder that may cause severe disablement. It refers to episodic arousal from sleep with a sense of suffocation followed by stridor. This phenomenon, which is caused by laryngospasm, is probably secondary to gastroesophageal reflux. The reflux is the target for current treatment of this serious disorder. Treatment by acupuncture for sleep-related laryngospasm has not been previously reported in the English medical literature. We describe a previously healthy patient with sleep-related laryngospasm caused by gastroesophageal reflux refractory to current medical treatment who was treated successfully using acupuncture.

[Emergency from anesthesia in small children. From laryngospasm to prolonged apnea]

Postoperative laryngospasm during emergence from anaesthesia represents a potentially life-threatening complication. Even if this is successfully overcome using drug therapy, new, serious problems may develop. We report the case of a 3 1/2 -year-old boy of African descent weighing 15 kg who developed a laryngospasm during emergence from anaesthesia. Because the airway obstruction could not be controlled by deepening the anaesthesia again and administering anti-obstructive drugs, the boy was given 15 mg succinylcholine. Thereafter prolonged apnea developed such that the patient had to be admitted to the pediatric intensive care unit. The child was extubated 6 h later and the further course was normal so that he could be released from the hospital the following day. Further diagnostic study revealed a dibucaine-sensitive, fluoride-resistant pseudocholinesterase in the plasma, which is a rare form of atypical pseudocholinesterase, explaining the prolonged arousal phase after the administration of succinylcholine. Three significant aspects of this case are discussed: 1. risk factors and treatment of perioperative airway obstruction 2. factors and treatment of prolonged apnea, and 3. delayed arousal reactions and their management in an outpatient setting.

Is there a role of a small dose of propofol in the treatment of laryngeal spasm?

BACKGROUND

Propofol has been found to depress the laryngeal reflexes. We studied whether this property could be utilized to relieve laryngeal spasm.

METHODS

This study was conducted over a period of 3 years, and included children aged 3-10 years, ASA status I and II. Most of the children were undergoing minor surgical procedures, under general anaesthesia with Laryngeal Mask Airway (LMA trade mark ) and caudal epidural analgesia.

RESULTS

During this period, 20 patients developed laryngeal spasm on removal of the LMA at the end of surgery. Initially, they all were treated with 100% O2, with gentle positive pressure ventilation. Out of 20 patients, seven responded well with 100% O2 and gentle positive pressure ventilation. The remaining 13 were treated with a small dose of propofol (0.8 mg.kg-1 body weight). Laryngeal spasm was relieved successfully in 10 patients and three patients required intubation to improve their oxygenation.

CONCLUSIONS

Propofol in a small dose (0.8 mg.kg-1 body weight) was a useful drug to relieve laryngeal spasm in most children (76.9%) following the removal of the LMA. Because it was not found to be effective in all patients, succinylcholine still has a role to play in critical conditions. However, we recommend propofol as a suitable alternative for relieving laryngeal spasm in situations where succinylcholine is contraindicated.

An overview of reflux-associated disorders in infants: apnea, laryngospasm, and aspiration

Problematic airway responses in infants are common. Reflux-induced apnea affects nearly 1% of infants and involves airway closure or laryngospasm. Recurrent or chronic stridor, caused by dynamic or structural airway abnormalities, occurs in up to 1 in 100 babies. It can be difficult to distinguish microaspiration, which may represent inadequate airway protection mechanisms, from reflexive responses to esophageal refluxate, which may represent overeffective airway protection mechanisms. The diagnosis of gastroesophageal reflux (GER) in babies can be facilitated by a careful history in conjunction with esophageal pH probe monitoring, laryngoscopic evaluation, bronchoalveolar lavage, or nuclear medicine scintigraphy. Conservative lifestyle measures for treating supraesophageal manifestations of infantile GER include prone positioning and thickened feedings. Prokinetic and acid-suppressing therapies are widely used, but their efficacy is incompletely established, and none is currently approved by the US Food and Drug Administration for this purpose. Fundoplication is not indicated if nonsurgical management can prevent serious problems during the child's maturation phase when many of these manifestations spontaneously resolve. Much remains to be learned about the developmental aspects of these supraesophageal manifestations of GER. This information not only will provide a greater understanding of developmental pathophysiology, but also will improve the clinical care of large numbers of infants.

Chemodenervation of the rat hemilarynx with phenol

In this study, the injection of phenol into the true vocal fold was evaluated on a rat model as a possible treatment for adductor spasmodic dysphonia. A 10% phenol solution was injected into the right true vocal fold. Quantitative measurement of vocal fold adductory force showed reduction to 35% of the preinjection value 3 months after injection (p < .05). Qualitative evaluation by videolaryngoscopy demonstrated maintenance of the normal vocal fold range of motion. Histologic studies showed a transient inflammatory infiltrate and myolysis, while the vocal fold mucosa and the cricoarytenoid joints remained undamaged. Further investigation into the potential use of phenol for treating spasmodic dysphonia is warranted.

Postlaryngospasm pulmonary edema in adults

Laryngospasm is a potential serious complication of intubation. Pulmonary edema can develop after laryngospasm and can affect any patient who has been intubated. Postlaryngospasm pulmonary edema is potentially life threatening and can result in reintubation, mechanical ventilation, admission to an intensive care unit, and a prolonged hospitalization for the patient. Perioperative nurses play a significant role in the prompt detection, diagnosis, and treatment of this syndrome.

The effect of acupuncture on the incidence of postextubation laryngospasm in children

Laryngospasm occurring after tracheal extubation in children is potentially dangerous. This study uses acupuncture with bloodletting at the Shao Shang (L 11) or Shang Yang (Li 1) acupoints to investigate whether this technique can prevent or treat laryngospasm. Seventy-six patients were randomly divided into two groups. Patients in the acupuncture group (n = 38) were treated with bilateral Shao Shang acupunctures at the end of the operation. Patients in the control group (n = 38) were not. The incidence of laryngospasm in the acupuncture group (5.3%) was less than that in the control group (23.7%) (p < 0.05). If laryngospasm developed, patients were immediately treated with acupuncture at either the Shao Shang or Shang Yang acupoints. As judged by an increase in peripheral oxygen saturation, the laryngospasm was relieved within 1 min of acupuncture in all patients. It is concluded that acupuncture with bloodletting at the Shao Shang acupoint may prevent and treat laryngospasm occurring after tracheal extubation in children.

[Postoperative laryngospasm may induce pulmonary edema. An unusual or overlooked complication?]

Young and healthy patients in whom laryngospasm secondary to postoperative extubation is encountered run a risk of developing pulmonary edema. The mechanism behind the edema is thought to be a strongly negative intrathoracic pressure generated by the patient's forced inspiration against a closed glottis. A net flow of fluid occurs to the interstitial space and further to the alveoli. Unusually the pulmonary edema can be noticed within a few minutes after relief of the obstruction, but occasionally it is delayed for several hours. The condition is potentially life-threatening, but usually responds favourably to positive pressure ventilation and diuretics. In anaesthesia and intensive care, it is important to be aware of the complication in order to be ready for adequate therapy when needed. We present three cases from the Central Hospital in Växjö, where pulmonary edema occurred directly following postoperative extubation.

Sleep-related laryngospasm

The term "sleep-related laryngospasm" refers to episodic, abrupt interruption of sleep accompanied by feelings of acute suffocation followed by stridor. The condition is included in the diagnostic and coding manual of the American Sleep Disorders Association (ASDA), but there are few references in the peer-reviewed literature. Our description of the distinct clinical picture associated with this condition is based on an analysis of the histories of a series of 10 patients. The patients and their families gave precise, uniform accounts of the dramatic attacks. Diagnostic work-up included pulmonary and gastroenterological assessment. All patients reported sudden awakening from sleep due to feelings of acute suffocation, accompanied by intense fear. Apnoea lasting 5-45 s was followed by stridor. Breathing returned to normal within minutes. Patients were left exhausted by the attacks. Nine of our 10 patients had evidence of gastro-oesophageal reflux and six responded to antireflux therapy. We conclude that the nocturnal choking attacks (and the occasional daytime attacks experienced by some of the patients) are caused by laryngospasm. The pathogenesis of the apparent underlying laryngeal irritability is unknown. The condition may be related to a gastro-oesophageal reflux.

Rupture of the stomach caused by manual ventilation during laryngospasm

We report a case, in which laryngospasm developed due to a failed intubation under sedation. During ventilation tension pneumoperitoneum developed resulting in cardiac and respiratory failure. Laparotomy revealed two tears on the lesser curvature of the stomach. Factors influencing stomach rupture are discussed.

Technique for injection of botulinum toxin through the flexible nasolaryngoscope

A new endoscopic method of injecting botulinum toxin into the thyroarytenoid muscles for treatment of adductor spasmodic dysphonia was evaluated. Twelve patients with adductor spasmodic dysphonia were given injections in the thyroarytenoid muscle under video visualization with a flexible catheter needle that was passed through the working channel of a flexible nasolaryngoscope. Six patients received unilateral injections, and six received bilateral injections. Preinjection and postinjection speech samples were compared by use of spectrographic analysis. Significant decreases in voice breaks and sentence duration were found after treatment with both unilateral and bilateral injections. Patient interviews and diaries documented the reported degree and duration of symptom reduction. All 12 patients reported that the injections were of significant benefit and that the endoscopic procedure was tolerable. We concluded that this is a safe and effective technique for injecting botulinium toxin into laryngeal muscles for treatment of spasmodic dysphonia.

A comparison of the efficacy of unilateral versus bilateral botulinum toxin injections in the treatment of adductor spasmodic dysphonia

The current treatment of choice of adductor spasmodic dysphonia due to focal dystonia is thyroarytenoid-vocalis injection of botulinum toxin type A (Botox). Botox exerts its effect by presynaptic motor endplate blockade, preventing the release of acetylcholine and causing muscle paresis. Botox treatment protocols vary. Some centres perform unilateral injections, whereas others treat both cords. Our hypothesis is that unilateral injections may reduce the severity of whisper voice and aspiration side effects in the early two to three weeks after treatment. The purpose of this study, therefore, is to compare the efficacy of unilateral versus bilateral Botox injections in the treatment of adductor spasmodic dysphonia in terms of duration of effect versus the side effects of breathing and swallowing difficulties. This study presents data from a retrospective chart review and a prospective telephone interview of all patients receiving bilateral and unilateral Botox injections.