Vocal Fold "Paralysis": An Early Sign in Multiple System Atrophy

Asymmetric triangular body-cover model of the vocal folds with bilateral intrinsic muscle activation

Many voice disorders are linked to imbalanced muscle activity and known to exhibit asymmetric vocal fold vibration. However, the relation between imbalanced muscle activation and asymmetric vocal fold vibration is not well understood. This study introduces an asymmetric triangular body-cover model of the vocal folds, controlled by the activation of bilateral intrinsic laryngeal muscles, to investigate the effects of muscle imbalance on vocal fold oscillation. Various scenarios were considered, encompassing imbalance in individual muscles and muscle pairs, as well as accounting for asymmetry in lumped element parameters. Measurements of amplitude and phase asymmetries were employed to match the oscillatory behavior of two pathological cases: unilateral paralysis and muscle tension dysphonia. The resulting simulations exhibit muscle imbalance consistent with expectations in the composition of these voice disorders, yielding asymmetries exceeding 30% for paralysis and below 5% for dysphonia. This underscores the relevance of muscle imbalance in representing phonatory scenarios and its potential for characterizing asymmetry in vocal fold vibration.

Asymmetric triangular body-cover model of the VFs with bilateral intrinsic muscle activation

Many voice disorders are linked to imbalanced muscle activity and known to exhibit asymmetric vocal fold vibration. However, the relation between imbalanced muscle activation and asymmetric vocal fold vibration is not well understood. This study introduces an asymmetric triangular body-cover model of the vocal folds, controlled by the activation of intrinsic laryngeal muscles, to investigate the effects of muscle imbalance on vocal fold oscillation. Various scenarios were considered, encompassing imbalance in individual muscles and muscle pairs, as well as accounting for asymmetry in lumped element parameters. The results highlight the antagonistic effect between the thyroarytenoid and cricothyroid muscles on the elastic and mass components of the vocal folds, as well as the impact on the vocal process from the imbalance in the lateral cricoarytenoid and interarytenoid adductor muscles. Measurements of amplitude and phase asymmetry were employed to emulate the oscillatory behavior of two pathological cases: unilateral paralysis and muscle tension dysphonia. The resulting simulations exhibit muscle imbalance consistent with expectations in the composition of these voice disorders, yielding asymmetries exceeding 30% for paralysis and below 5% for dysphonia. This underscores the versatility of muscle imbalance in representing phonatory scenarios and its potential for characterizing asymmetry in vocal fold vibration.

Subacute Horizontal Diplopia, Jaw Dystonia, and Laryngospasm

Jaw dystonia and laryngospasm in the context of subacute brainstem dysfunction have been described in a small number of diseases, including antineuronal nuclear antibody type 2 (ANNA-2, also known as anti-Ri) paraneoplastic neurologic syndrome. Severe episodes of laryngospasms causing cyanosis are potentially fatal. Jaw dystonia can also cause eating difficulty, resulting in severe weight loss and malnutrition. In this report, we highlight the multidisciplinary management of this syndrome associated with ANNA-2/anti-Ri paraneoplastic neurologic syndrome and discuss its pathogenesis.

Pharyngolaryngeal semiology and prognostic factors in multiple system atrophy

Introduction

Multiple system atrophy (MSA) is a rare degenerative neurological disorder in adults. It induces parkinsonian and/or cerebellar syndrome associated with dysautonomia. Pharyngolaryngeal symptoms are common. Our aim is to describe the Pharyngolaryngeal semiology on one hand, and to ascertain whether the presence of these symptoms represents a prognostic factor for MSA on the other.

Methods

Thus, we carried out a retrospective, single-centre study, on a cohort receiving care at the centre of reference for MSA. The patients were referred for otorhinolaryngology assessment. The data was collected over the year 2020 with the help of computer software from the university hospital centre (UHC). Firstly, we described the Pharyngolaryngeal semiology specific to MSA by questioning patients, and by the results of nasofibroscopic examinations and swallowing tests. We then used multivariate analysis of variance to describe the prognostic factors of MSA progression (in UMSARS I and II points per month of progression) and survival (number of years between the first symptoms and death).

Results

This study included a hundred and one patients and made it possible to define a Pharyngolaryngeal semiology profile of MSA, which is: a reduction in laryngeal mobility (primarily vocal cord abduction defects), abnormal movements (particularly at rest or when initiating a movement) and a defect in the protection mechanisms of the upper airways. The swallowing difficulties are moderate and the main mechanisms are delayed pharyngeal swallow and/or an oro-pharyngeal transport defect. In the multivariate analyses, the contributing factors are laryngeal anomalies, modification of solid food to fluid food and nutritional complication.

Conclusion

ENT specialists should pay close attention to problems in the Pharyngolaryngeal dynamic and then consider a neurological cause. They can also itemize the clinical factors that could have a negative effect on the prognosis of the patient with MSA. Indeed, early detection makes it possible to provide care for respiratory and nutritional complications.