Effects of divided attention on swallowing in healthy participants.

Swallowing impairments are treated mostly behaviorally. It is requisite to understand the relationship of cognition, specifically attention, with swallowing since so many swallowing impairments occur concomitantly with cognitive disorders. This study examined the hypothesis that attentional resources are required during swallowing. The approach involved a dual-task, reaction time (RT) paradigm in ten healthy, nonimpaired participants. Baseline measures were obtained of the duration of the anticipatory phase and of the oropharyngeal phase of swallowing and the RTs to nonword auditory stimuli. A dual-task then required participants to swallow 5 ml of water from an 8-oz. cup while listening for a target nonword presented auditorily during the anticipatory or the oropharyngeal phase. Target stimuli were randomized across baseline and dual-task trials. Duration of the anticipatory phase and of the oropharyngeal phase of swallowing and duration of the RT baseline trial and of the dual-task trial were determined. Results showed a statistically significant increase in speed of the anticipatory phase, relative to the oropharyngeal phase, for swallowing during the dual-task. RTs were slowed for both the anticipatory and the oropharyngeal phase during the dual-task, although neither of these was statistically significant. Clinical implications of these data suggest that disruptive stimuli in the environment to nonimpaired individuals may alter feeding but have little effect on the oropharyngeal swallow.

Effects of divided attention on swallowing in persons with idiopathic Parkinson's disease.

The purpose of this study was to determine whether attentional resources are involved in swallowing in persons with idiopathic Parkinson's disease, and if so, in which phase(s) of swallowing. The approach involved a dual-task, reaction time (RT) paradigm using ten participants with Parkinson's disease. Single-task baseline measures were obtained for durations of the anticipatory phase and oropharyngeal phase of swallowing and RTs were obtained for nonword auditory stimuli. A dual-task then required participants to swallow 5 ml of water from an 8-oz. cup while listening for a target nonword presented auditorily during the anticipatory or oropharyngeal phase. Target stimuli were randomized across baseline and dual-task trials. Durations of the anticipatory and oropharyngeal phases of swallowing and RTs during baseline and dual-task trials were determined. Results showed a nonsignificant change in speed of completion for both the anticipatory phase and the oropharyngeal phase of swallowing during dual-task trials. However, there was a statistically significant increase in RT during the anticipatory phase during the dual-task condition. RT during the oropharyngeal phase remained unaffected. Given a need for additional research using more complex competing tasks, these data on attention are consistent with earlier claims of an automatic, nonresource-demanding, oropharyngeal swallowing mechanism that is preserved for persons with early-to-mid-stage Parkinson's disease. Clinical implications of these data suggest that disruptive environmental stimuli to individuals with early-to-mid-stage Parkinson's disease may alter feeding but have little effect on the oropharyngeal swallow.

The impact of listening with directional microphone technology on self-perceived localization disabilities and handicaps.

The chief complaint of individuals with hearing impairment is difficulty hearing in noise, with directional microphones emerging as the most capable remediation. Our purpose was to determine the impact of directional microphones on localization disability and concurrent handicap. Fifty-seven individuals participated unaided and then in groups of 19, using omni-directional microphones, directional-microphones, or toggle-switch equipped amplification. The outcome measure was a localization disabilities and handicaps questionnaire. Comparisons between the unaided group versus the aided groups, and the directional-microphone groups versus the other two aided groups revealed no significant differences. None of the microphone schemes either increased or decreased self-perceived localization disability or handicap. Objective measures of localization ability are warranted and if significance is noted, clinicians should caution patients when moving in their environment. If no significant objective differences exist, in light of the subjective findings in this investigation concern over decreases in quality of life and safety with directional microphones need not be considered.

Validity, internal consistency, and test/retest reliability of a localization disabilities and handicaps questionnaire.

Psychometric evaluations were performed on a self-perceived localization disabilities and handicaps questionnaire. Twenty individuals with normal hearing bilaterally, twenty with profound unilateral hearing impairment (UHI), and ten with any degree of bilateral hearing impairment participated. Each subject completed the questionnaire. Comparisons of the responses of the subjects with normal hearing and those with UHI revealed significant differences among the groups for both disabilities and handicaps, establishing construct validity. Cronbach's Alpha correlational analyses of the responses of all subjects with hearing impairment revealed correlations of .900 (disabilities) and .800 (handicaps), establishing internal consistency. Each participant with hearing impairment was asked to complete the questionnaire again after three weeks. Pearson's correlational analyses of the responses at time one versus time two revealed correlations of .900 (disabilities) and .700 (handicaps), establishing test/retest reliability. This questionnaire is an appropriate tool for investigating the self-perceived localization disabilities and handicaps of individuals with hearing impairment.

The relationship among voice onset, voice quality, and fundamental frequency: a dynamical perspective.

In dynamical motor theory, skill acquisition occurs as a modification of preexisting coordination patterns or attractor states. The purpose of this study was to assess how different levels of voice onset, voice quality, and fundamental frequency (F(0)) combine to form the attractor states common to voice motor control. Three levels of voice onset (glottal, simultaneous, and breathy), voice quality (modal speech, mixed, and falsetto), and fundamental frequency (low, mid, and high) were manipulated by vocally untrained, female subjects. Percent correct of acquisition trials and self-report of effort were used as measures of stable phonations indicative of an attractor state. Using intensity as a covariate, the results provided support for two of the three predicted triads representing attractor states in female speakers: (1) glottal onset/modal speech quality/low F(0); and (2) breathy onset/falsetto quality/high F(0). The results of this study suggest that certain parameters of voice motor control, such as onset, quality, and F(0), exist as part of a dynamical system that can be identified and manipulated in voice motor acquisition and learning.

Lung volume effects on pharyngeal swallowing physiology.

The experiment was a prospective, repeated-measures design intended to determine how the variation of lung volume affects specific measures of swallowing physiology. Swallows were recorded in 28 healthy subjects, who ranged in age from 21 to 40 yr (mean age of 29 yr), by using simultaneous videofluoroscopy, bipolar intramuscular electromyography, and respiratory inductance plethysmography. Each subject swallowed three standardized pudding-like consistency boluses at three randomized lung volumes: total lung capacity, functional residual capacity, and residual volume. The results showed that pharyngeal activity duration of deglutition for swallows produced at residual volume was significantly longer than those occurring at total lung capacity or at functional residual capacity. No significant differences were found for bolus transit time or intramuscular electromyography of the superior constrictor. The results of this experiment lend support to the hypothesis that the respiratory system may have a regulatory function related to swallowing and that positive subglottic air pressure may be important for swallowing integrity. Eventually, new treatment paradigms for oropharyngeal dysphagia that are based on respiratory physiology may be developed.

Physiologic effects of open and closed tracheostomy tubes on the pharyngeal swallow.

Studies linking aspiration and dysphagia to an open tracheostomy tube exemplify the possibility that the larynx may have an influence on oropharyngeal swallow function. Experiments addressing the effects of tracheostomy tube occlusion during the swallow have looked at the presence and severity of aspiration, but few have included measurements that capture the changes in swallowing physiology. Also, hypotheses for the importance of near-normal subglottic air pressure during the swallow have not been offered to date. As such, the aim of this study was to compare the depth of laryngeal penetration, bolus speed, and duration of pharyngeal muscle contraction during the swallow in individuals with tracheostomy tubes while their tubes were open and closed. The results of this series of experiments indicate that within the same tracheostomized patient, pharyngeal swallowing physiology is measurably different in the absence of subglottic air pressure (open tube) as compared to the closed tube condition.