Swallowing and speech production in Parkinson's disease

Abstract

Videofluoroscopy was used to examine movement patterns during swallowing and speech production in 6 parkinsonian subjects and 6 age-matched controls. Motility patterns for liquid and semisolid swallows were documented. We performed temporospatial analyses of oropharyngeal structures, particularly the velum, which is prominently involved in both motor speech production and swallowing. Differences were found between groups and conditions. All of the parkinsonian subjects exhibited abnormal oropharyngeal movement patterns and timing during the volitional oral as well as the pharyngeal stage of swallowing; only 50% of these subjects admitted to any swallowing difficulty upon questioning. Two of the subjects with Parkinson's disease aspirated liquids. Duration of velar movement during speech production significantly differentiated the groups (p less than 0.01), reflecting reduced range of velar motion. Our findings suggest that rigidity and bradykinesia underlie the volitional speech abnormality as well as the disordered oral and pharyngeal stages of swallowing. Findings indicate that parkinsonian patients may be "silent aspirators" with decreased cough reflexes and lack of awareness of aspiration. The clinical value of videofluoroscopic monitoring of swallowing is that aspiration may be detected and managed early.

Voluntary and reflex cough: Similarities and differences

“…Of note, such impairment was much more prominent during reflex than voluntary coughing. On one hand, the results demonstrate that Parkinson's disease features a generalised impairment of autonomic reflexes such as, for instance, the pharyngeal phase of swallowing [18] and the cough reflex. On the other hand, the findings also suggest that the evaluation of the cough motor pattern provides useful information on the central mechanisms subserving this crucial reflex response; in more details, it seems likely that impaired expiratory muscle recruitment during voluntary and, more markedly reflex cough reflect one of the most prominent functional disturbances of patients with Parkinson's diseases, i.e slowness of movement that is ongoing, or bradykinesia [7].…”

“…The importance of abdominal muscles in the production of the cough expulsive force is well known, and it has been confirmed by many electromyographic (EMG) studies [6][7][8][9][10] . For instance, several human investigations have shown activation of the rectus abdominis, internal oblique, external oblique, and transversus abdominis muscles during voluntary cough [16][17] Furthermore, abdominal muscle activation has been found to be proportional to cough flow rate, and a linear relationship has been demonstrated between increases in EMG activity and voluntary cough flow rates [18,19] In addition to abdominal muscles, EMG bursts over the latissimus dorsi and pectoralis major muscles have been demonstrated during voluntary cough efforts in healthy volunteers and tetraplegic subjects in whom corticospinal abdominal inputs were interrupted [20,21] At variance with the inspiratory and compressive phases, several comparisons of the motor features of the expulsive efforts of cough produced voluntarily and reflexly in the same subjects can be found in the literature. A recent study analysed motor activation patterns of voluntary and reflex cough adjusted for flow rates.…”

“…In this connection, Addington et al [18] evaluated the physiological characteristics of intra-abdominal pressure changes generated during voluntary cough and reflex cough of laryngeal origin, which provides efficient neurophysiological airway protection in humans [18 for Refs]. It was found that reflex cough generated significantly higher peak intrabdominal pressure and larger overtime intrabdominal pressure changes compared to maximum voluntary cough.…”

“…It was found that reflex cough generated significantly higher peak intrabdominal pressure and larger overtime intrabdominal pressure changes compared to maximum voluntary cough. The different motor behaviours of laryngeal vs voluntary cough may be due to the continual and simultaneous activation of cough-associated expiratory muscles with rapid and repeated glottal closure with laryngeal cough compared with voluntary cough, the latter being mainly characterized by brief and often single event of brief glottal closure [18]. The differences between the two types of cough provide a new perspective to study the neurophysiological differences between these two events.…”

Central nervous system control of the laryngeal muscles in humans

“…The recent tracing studies in monkey Jurgens, 2003, 2005) have demonstrated dense reciprocal connections between the laryngeal motor cortex and the putamen and thalamus, yet subcortical control systems and their modulation of cortical and the brain stem centers are virtually unexplored. Significant voice and swallowing deficits seen in Parkinson disease suggest that other regions besides the cortex and medulla are critical to normal laryngeal control for speech and swallowing (Logemann et al, 1977;Robbins et al, 1986). Improved knowledge of the basal ganglia control of the laryngeal musculature might allow for exploration of various neurotransmitter systems to improve laryngeal function in cough, swallow, voice, speech and respiration.…”