A unique presentation and etiology of neonatal paradoxical vocal fold motion

Clinical presentation of paradoxical vocal fold motion or laryngeal dyskinesia in infants

OBJECTIVES

Paradoxical vocal fold motion (PVFM) is not well-characterized in infants. Sex- and race/ethnicity-based differences have been described in older children with PVFM. This study's objectives are to characterize demographic and clinical characteristics of infants diagnosed with PVFM and investigate sex- and race-specific differences in presentation.

METHODS

We retrospectively reviewed infants ≤1 year of age diagnosed with PVFM at our institution from 2009 to 2019. Patient demographics, symptoms, and findings on flexible laryngoscopy are described. Sex- and race/ethnicity-based differences were assessed using Fisher's exact test analyses.

RESULTS

We identified 22 infants who were diagnosed with PVFM. The average age (range) at diagnosis was 5.7 (0.25-12.0) months, and 45.5% were male. The majority (54.6%) of patients identified as non-Hispanic White. Common comorbidities included GERD (45.5%) and chronic rhinitis (13.6%). Stridor was the only presenting symptom in the majority of patients (95.4%). The most common episode triggers were crying (45.5%), feeding (27.3%), and gastric reflux (9.1%). On flexible laryngoscopy, PVFM was observed in 95.5% of patients. A third of patients (31.8%) were misdiagnosed as having reactive airway disease or laryngomalacia prior to evaluation by otolaryngology. No sex- and race/ethnicity-based differences in presentation were identified.

CONCLUSION

We present the largest case series of PVFM in infants. We found sparse clinical signs/symptoms other than stridor and a high incidence of misdiagnosis, which supports the importance of objective flexible laryngoscopy for the evaluation of stridor in this age group. Previously reported sex- and race/ethnicity-based differences in presentation of PVFM were not observed in this cohort of infants.

Obstructive Sleep Apnea with Paradoxical Vocal Cord Movement in Children during Sleep Endoscopy: Case Series

Objective

To describe a series of pediatric cases of obstructive sleep apnea (OSA) with paradoxical vocal cord movement noted on drug-induced sleep endoscopy (DISE).

Materials and Methods

Case series and chart review of children who had undergone DISE for OSA that showed PVCM.

Results

Three cases where paradoxical vocal cord motion (PVCM) was noted during DISE are described. Two had an enlarged adenoid, and one had no other site of obstruction. Two were treated with adenoidectomy and antireflux medications. One received proton pump inhibitors alone. In all 3 cases, OSA symptoms resolved.

Conclusion

This case series of documented obstructive sleep apnea related to paradoxical vocal cord movement suggests that this entity occurs during sleep with airway obstruction. Further clarification of etiology of PVCM during OSA and its management is needed.

An Up-to-Date Overview of the Complexity of Genotype-Phenotype Relationships in Myotonic Channelopathies

Myotonic disorders are inherited neuromuscular diseases divided into dystrophic myotonias and non-dystrophic myotonias (NDM). The latter is a group of dominant or recessive diseases caused by mutations in genes encoding ion channels that participate in the generation and control of the skeletal muscle action potential. Their altered function causes hyperexcitability of the muscle membrane, thereby triggering myotonia, the main sign in NDM. Mutations in the genes encoding voltage-gated Cl⁻ and Na⁺ channels (respectively, CLCN1 and SCN4A) produce a wide spectrum of phenotypes, which differ in age of onset, affected muscles, severity of myotonia, degree of hypertrophy, and muscle weakness, disease progression, among others. More than 200 CLCN1 and 65 SCN4A mutations have been identified and described, but just about half of them have been functionally characterized, an approach that is likely extremely helpful to contribute to improving the so-far rather poor clinical correlations present in NDM. The observed poor correlations may be due to: (1) the wide spectrum of symptoms and overlapping phenotypes present in both groups (Cl⁻ and Na⁺ myotonic channelopathies) and (2) both genes present high genotypic variability. On the one hand, several mutations cause a unique and reproducible phenotype in most patients. On the other hand, some mutations can have different inheritance pattern and clinical phenotypes in different families. Conversely, different mutations can be translated into very similar phenotypes. For these reasons, the genotype-phenotype relationships in myotonic channelopathies are considered complex. Although the molecular bases for the clinical variability present in myotonic channelopathies remain obscure, several hypotheses have been put forward to explain the variability, which include: (a) differential allelic expression; (b) trans-acting genetic modifiers; (c) epigenetic, hormonal, or environmental factors; and (d) dominance with low penetrance. Improvements in clinical tests, the recognition of the different phenotypes that result from particular mutations and the understanding of how a mutation affects the structure and function of the ion channel, together with genetic screening, is expected to improve clinical correlation in NDMs.