Respiratory Laryngeal Dystonia: Characterization and Diagnosis of a Rare Neurogenic Disorder

Abstract

Objectives/Hypothesis: Respiratory laryngeal dystonia (RLD) is poorly understood and rarely reported in the literature. Patients have atypical laryngeal movement resulting in airway obstruction. This motion is neurogenic in nature, is constant while awake, nonepisodic, and non-trigger dependent. Given its rarity, it is often misdiagnosed for inducible laryngeal obstruction; however, it is refractory to medical and behavioral management. Although this condition has been addressed in the literature, this report is the largest case series characterizing presenting symptomology, multimodal treatment outcomes, and longitudinal course of these patients, and proposes a set of diagnostic criteria to aid in clinical identification of RLD patients. Our objectives were to characterize RLD clinically and offer diagnostic guidelines to clinicians. Study Design: A prospective case series with a retrospective analysis at a tertiary referral center. Methods: A review of clinical records and videostroboscopic analysis of 16 patients treated for respiratory laryngeal dystonia from October 2005 to October 2018 was performed. Results: Sixteen patients with respiratory laryngeal dystonia were included. The common features of this group were persistent, nonepisodic dyspnea and stridor with laryngoscopic evidence of paradoxical vocal fold motion. Our patients had no structural neurologic abnormalities. These patients typically failed respiratory retraining therapy and medical management of laryngeal irritants. In our series, 100% of patients underwent respiratory retraining therapy, 68.8% received laryngeal botulinum toxin injection, and 31.3% required tracheostomy. Conclusions: RLD is a rare and challenging condition. The disorder can be severely disabling, and treatment options appear limited. A multidisciplinary approach may be helpful. Some patients responded to laryngeal botulinum injection and medical management, whereas others required tracheostomy for symptom control.

Treatment of Dystonia: Medications, Neurotoxins, Neuromodulation, and Rehabilitation

“…A much rarer subtype of laryngeal dystonia affects respiratory function and has been labeled alternately adductor laryngeal breathing dystonia, respiratory type focal laryngeal dystonia, spasmodic laryngeal dyspnea, or respiratory laryngeal dystonia (RLD) [121]. Diagnosis typically relies on endoscopic visualization of the larynx revealing adduction of the true vocal folds during inspiration.…”

“…However, laryngeal dyspnea related to dystonic activity in adjacent laryngeal regions but with normal opening of the glottis can occur [122]. Several series report improvement in RLD symptoms with botulinum toxin injections [117,118,121], though no controlled studies have been performed. Injections have been described primarily in the adductor compartment, including the lateral cricothyroid and thyroarytenoid muscles, but ventricular fold injections are also reported [121].…”

“…Several series report improvement in RLD symptoms with botulinum toxin injections [117,118,121], though no controlled studies have been performed. Injections have been described primarily in the adductor compartment, including the lateral cricothyroid and thyroarytenoid muscles, but ventricular fold injections are also reported [121]. In one series, 12 patients received onabotulinumtoxinA injections with an average dose of 0.6-3.75 units bilaterally and experienced 55% average improvement over multiple injection sessions with a mean duration of benefit of 14 weeks [117].…”

“…In a more recent series, 11 patients received BoNT injections directed at bilateral thyroarytenoid muscles, of which 54% experienced adequate symptom relief. Among those achieving inadequate symptom relief, however, two (18.2%) ultimately required tracheostomy [121].…”

The impact of identifying laryngeal obstruction syndromes on reducing treatment of pediatric asthma: A systematic review

“…10 Inhaled anticholinergic (ipratropium bromide) is used to treat EILO, based on the premise that vagus nerve stimulation and a dysautonomic response to respiratory irritants may trigger symptoms. 13,14 Local botulinum toxin injection can lead to improvement in selected adult patients, 15 but has not been demonstrated in children. This systematic review evaluated the scientific evidence on the effects of diagnosing and treating ILO on asthma medication use and respiratory symptoms among pediatric patients.…”