Maggie-Lee Huckabee

Outcomes of swallowing rehabilitation in chronic brainstem dysphagia: A retrospective evaluation.

Abstract. This study examines the functional and physiologic outcomes of treatment in a group of 10 patients with chronic dysphagia subsequent to a single brainstem injury. All patients participated in a structured swallowing treatment program at a metropolitan teaching hospital. This program differs from more traditional swallowing treatment by the inclusion of surface electromyography biofeedback as a treatment modality and the completion of 10 hr of direct treatment in the first week of intervention. A retrospective analysis of medical records and patient questionnaires was used to gain information regarding medical history, site of lesion, prior interventions, and patient perception of swallowing recovery. Physiologic change in swallowing treatment, as measured by severity ratings of videofluoroscopic swallowing studies, was demonstrated in nine of 10 patients after 1 week or 10 sessions of treatment. Functional change was measured by diet level tolerance after 1 week of treatment, at 6 months, and again at 1 year posttreatment. Eight of the 10 patients were able to return to full oral intake with termination of gastrostomy tube feedings, whereas two demonstrated no long-term change in functional swallowing. Of the eight who returned to full oral intake, the average duration of tube feedings following treatment until discontinuation was 5.3 months, with a range of 1–12 months. Six patients who returned to oral intake maintained gains in swallowing function, and two patients returned to nonoral nutrition as the result of a new unrelated medical condition.

A Pilot Study of Respiration and Swallowing Integration in Parkinson's Disease: ''On'' and ''Off'' Levodopa

Parkinson’s disease is associated with both swallowing and respiratory dysfunction, increasing the risk of aspiration and pneumonia. Previous studies have shown improvements in measurements of swallowing and respiration with levodopa; however, the studies are small and some studies show conflicting reports. The aim of this study was to further investigate the effect of levodopa on respiration. Ten patients with Parkinson’s disease were tested “On” and “Off” levodopa. Assessments included Unified Parkinson’s Disease Rating Scale (UPDRS), coordination of swallowing and respiration, timed-test of swallowing, lung function testing, and, qualitative assessment of swallowing. There was a nonsignificant trend to lower volume per swallow when “On” levodopa, significant reduction in lung function when “On” levodopa, but no difference in coordination of swallowing and respiration or qualitative assessment of swallowing. There was a significant increase in motor examination score of the UPDRS when “Off” levodopa compared to “On.” There may be a reduction in efficiency of swallowing with levodopa medication without any apparent increase in risk of aspiration. These pilot data suggest that further evaluation with larger numbers of participants is justified.

The Influence of Orolingual Pressure on the Timing of Pharyngeal Pressure Events

This study explored the influence of two methods of effortful swallow execution on the timing of pharyngeal pressure events. Participants were asked to either emphasize or minimize tongue-to-palate contact during performance of the maneuver. Twenty healthy participants were evaluated using concurrent submental surface electromyography (sEMG), orolingual manometry, and pharyngeal manometry. Each subject performed three repetitions of three counterbalanced tasks (noneffortful dry swallows, effortful dry swallows with tongue-to-palate emphasis, and effortful dry swallows with tongue-to-palate de-emphasis). Four variables were measured: Onset Lag vs. sEMG Peak, Peak Lag vs. sEMG Peak, Total Duration, and Percent Rise Time to Peak. Compared to noneffortful swallows, the effortful swallow task elicited significantly earlier onsets and peaks of pharyngeal pressures relative to the submental sEMG peak. Total pressure event durations were greater and rise times were significantly shorter. When comparing the two methods of effortful swallow execution, a longer latency to peak proximal pharyngeal pressure was found in the tongue-to-palate emphasis condition. These results support the interpretation that the effortful swallow maneuver involves generation of higher velocity bolus driving forces that propel the bolus into and through the pharynx with greater efficiency and that pressure is then sustained to facilitate more complete bolus clearance.

Timing of Pharyngeal and Upper Esophageal Sphincter Pressures as a Function of Normal and Effortful Swallowing in Young Healthy Adults

The effect of effortful swallow on pharyngeal pressure and UES relaxation onsets and durations was examined. Eighteen adults, nine males and nine females (mean age = 27.9 yr), participated. Timing of pharyngeal pressure and onset and duration of UES relaxation were measured across ten trials of normal and ten trials of effortful swallows. Results revealed that manometric timing measurements are consistent across trials. The first and second statistical analyses investigated the pharyngeal pressure and UES relaxation onsets and durations, respectively. Both analyses identified a significant interaction of swallow type (i.e., effortful vs. normal) by manometric sensor location (p < 0.05). Across normal and effortful swallows, UES relaxation preceded pharyngeal pressure onsets, yet the rate of change (or degree of delay) varied across the sensors. Furthermore, the effortful swallow elicited longer pharyngeal pressure and UES relaxation durations, yet the pressure duration measured in the upper pharynx was significantly longer than that measured lower in the pharynx. These findings offer insight as to the potential positive and negative influence of the effortful swallow on pharyngeal timing.

Cortical Control Mechanisms in Volitional Swallowing: The Bereitschaftspotential

Objective: This research sought to identify a well-defined pre-motor potential, the Bereitschaftspotential (BP), as a manifestation of cortical contribution to the pre-motor planning of volitional swallowing. Methods: EEG data were collected from 20 research participants during volitional execution of swallowing and finger movement tasks. A 5 second pre-movement epoch for each task was triggered on EMG identification of movement onset. A grand average for each task representing approximately 2400 trials across all research participants was derived to compare and contrast morphological features of the derived waveform. Results: Volitional pharyngeal swallowing and finger movement generated similar waveform characteristics of duration and slope; however, statistically significant differences were identified in polarity and in amplitude at four points both early and late in the epoch. Additionally, swallowing produced a pre-motor waveform with a rapid declination of EEG activity in the final 500 msec prior to movement onset. Conclusions: This study demonstrates activation of the supplementary motor cortex preceding the onset of volitional swallowing. However, unlike purely voluntary movements, the volitional pharyngeal swallowing task, as assessed with this methodology, does not appear to recruit the primary motor cortex. Thus engagement of the swallowing response appears to rely on indirect parallel pathways between extrapyramidal cortical motor planning regions and lower motor neurons.

Cough Reflex Testing in Dysphagia Following Stroke: A Randomized Controlled Trial

Background Significant health issues and service delivery costs are associated with post-stroke pneumonia related to dysphagia. Silent aspiration is known to increase pneumonia and mortality in this population. The utility of cough reflex testing (CRT) for reducing pneumonia in acute stroke patients was the subject of this randomised, controlled trial. Methods Patients referred for swallowing evaluation (N = 311) were assigned to either 1) a control group receiving standard evaluation or 2) an experimental group receiving standard evaluation with CRT. Participants in the experimental group were administered nebulised citric acid with test results contributing to clinical decisions. Outcomes for both groups were measured by pneumonia rates at 3 months post evaluation and other clinical indices of swallowing management. Results Analysis of the data identified no significant differences between groups in pneumonia rate (P = 0.38) or mortality (P = 0.15). Results of CRT were shown to influence diet recommendations (P < 0.0001) and referrals for instrumental assessment (P < 0.0001). Conclusions Despite differences in clinical management between groups, the end goal of reducing pneumonia in post stroke dysphagia was not achieved.

Comparison of cough reflex test against instrumental assessment of aspiration

BACKGROUND Silent aspiration is associated with pneumonia and mortality, and is poorly identified by traditional clinical swallowing evaluation (CSE). The aim of this study was to validate cough reflex testing (CRT) for identification of silent aspiration against aspiration confirmed by instrumental assessment. METHODS Cough reflex threshold testing was completed on all patients using inhaled, nebulised citric acid. Within an hour, 80 patients underwent videofluoroscopic study of swallowing (VFSS) and 101 patients underwent fibreoptic endoscopic evaluation of swallowing (FEES). All tests were recorded and analysed by two researchers blinded to the result of the alternate test. RESULTS Significant associations between CRT result and cough response to aspiration on VFSS (X(2) (2)=11.046, p=.003) and FEES (X(2) (2)=34.079, p<.001) were identified. Sensitivity and specificity were optimised at 0.6mol/L in patients undergoing VFSS (71%, 60% respectively) and at 0.4mol/L in patients undergoing FEES (69%, 71% respectively). A concentration of 0.8mol/L had the highest odds ratio (OR) for detecting silent aspiration (8 based on VFSS; 7 based on FEES). CONCLUSION CRT results are significantly associated with aspiration response on instrumental assessment. Lower concentrations of citric acid provide a better predictive measure of silent aspiration.

The Effect of Effortful Swallow on Pharyngeal Manometric Measurements During Saliva and Water Swallowing in Healthy Participants

OBJECTIVE To evaluate the effect of effortful swallow on pharyngeal manometric pressure measurements during saliva and water swallowing. DESIGN Comparative analysis of pharyngeal pressure generation under 2 bolus and 2 task conditions. SETTING Swallowing rehabilitation research laboratory. PARTICIPANTS Healthy participants (N=40), sex equally represented, with a mean age of 25.8 years. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Manometric peak and nadir amplitude and duration measures at 3 locations in the pharynx. RESULTS Significantly higher peak pressures were measured for saliva swallows compared with water swallows under both swallowing conditions at the proximal pharyngeal sensor only (P=.011). No significant differences were observed between the effortful versus noneffortful conditions at the proximal and midpharyngeal sensors; however, upper esophageal sphincter (UES) nadir pressures were significantly lower for effortful than noneffortful swallows (P=.034) with significantly lower pressure measurements in saliva effortful swallows (P=.008) compared with water effortful swallows. Saliva swallows resulted in significantly longer pressure durations than water swallows at the proximal (P=.003) and middle (P=.048) sensors. Pressure-generation duration was significantly longer in effortful versus noneffortful swallows for the middle sensor (P=.036) only. CONCLUSIONS The results indicate that the effect of effortful swallow on pharyngeal peak pressure measurement is not altered by bolus type (saliva vs water). However, this is not the case for nadir pressure measurements in the UES, which were significantly lower in effortful saliva swallows than in effortful water swallows.

Differential Effects of Neuromuscular Electrical Stimulation Parameters on Submental Motor-Evoked Potentials

Background. Neuromuscular electrical stimulation (NMES) of the muscles underlying the pharynx and faucial pillars affects the excitability of corticobulbar projections in a frequency- and duration-specific manner. The anterior hyomandibular (submental) muscles are primary targets for the clinical application of NMES to improve disordered swallowing, but the optimal NMES parameters for this application are unknown. Objective. To determine the influence of NMES parameters on the excitability of corticobulbar projections to the submental musculature. Methods. Transcranial magnetic stimulation (TMS) was used in event-related protocols, triggered by either volitional contraction of the submental muscles or pharyngeal swallowing, to assess corticobulbar excitability prior to, immediately following, and 30, 60, and 90 minutes post-NMES in 25 healthy volunteers. In the first 2 experiments, 4 stimulus frequencies (5, 20, 40, and 80 Hz) and 3 NMES dosages, manipulated through stimulus train durations or number of repetitions, were evaluated. The optimal excitatory NMES triggered by volitional swallowing (event-related NMES) was then replicated in a new sample and contrasted with non-event-related NMES (either discrete events or continuously for 1 hour). Results. It was found that 80Hz NMES increased motor-evoked potential (MEP) amplitude at 30 minutes and 60 minutes poststimulation only after 60 repetitions of 4-s event-related NMES trains. Non-event-related and continuous NMES did not affect MEP amplitudes. No changes in MEP onset latencies were observed. Conclusions. Changes in corticobulbar excitability induced by NMES of the submental muscle group are frequency and dose dependent and only occur after NMES triggered by volitional swallowing. Underlying neural mechanisms are discussed.

Test–retest reliability of motor evoked potentials (MEPs) at the submental muscle group during volitional swallowing

Motor evoked potentials (MEPs) recorded from pharyngeal and anterior hyo-mandibular (submental) muscles at rest have been used to evaluate treatment effects on neural pathways underlying swallowing. This study documents a novel methodological approach of recording reliable intra- and inter-session MEPs at the submental muscle group during task-related volitional swallowing. MEPs were elicited by single-pulse transcranial magnetic stimulation (TMS), triggered by a custom-made system when a pre-set level of surface electromyographic activity in the target muscles was breached. Fifteen MEPs were recorded during each of four sessions. Intraclass correlation coefficients (ICCs) were used to assess test-retest reliability within and across sessions for blocks of 3, 5, 10 and 15 trials. Highly reliable intra-session reliability was achieved, maximal for blocks of five trials (0.915). Inter-session reliability varied between 0.474 (three trials per block) and 0.909 (10 trials per block). Surface electromyography-triggered TMS allows reliable measurement of MEP amplitude at the submental muscle group within and across sessions when muscles are pre-activated during volitional swallowing. This methodology will be useful for future investigations on the effects of pathology and modulation of swallowing neural pathways.