Measurement of pharyngeal sensory cortical processing: technique and physiologic implications

<p>Abstract</p> <p>Background</p> <p>Dysphagia is a major complication of different diseases affecting both the central and peripheral nervous system. Pharyngeal sensory impairment is one of the main features of neurogenic dysphagia. Therefore an objective technique to examine the cortical processing of pharyngeal sensory input would be a helpful diagnostic tool in this context. We developed a simple paradigm to perform pneumatic stimulation to both sides of the pharyngeal wall. Whole-head MEG was employed to study changes in cortical activation during this pharyngeal stimulation in nine healthy subjects. Data were analyzed by means of synthetic aperture magnetometry (SAM) and the group analysis of individual SAM data was performed using a permutation test.</p> <p>Results</p> <p>Our results revealed bilateral activation of the caudolateral primary somatosensory cortex following sensory pharyngeal stimulation with a slight lateralization to the side of stimulation.</p> <p>Conclusion</p> <p>The method introduced here is simple and easy to perform and might be applicable in the clinical setting. The results are in keeping with previous findings showing bihemispheric involvement in the complex task of sensory pharyngeal processing. They might also explain changes in deglutition after hemispheric strokes. The ipsilaterally lateralized processing is surprising and needs further investigation.</p

Effects of Therapy in Oropharyngeal Dysphagia by Speech and Language Therapists: A Systematic Review

Medical and paramedical treatments should be evaluated according to current standards of evidence-based medicine. Evaluation of therapy in oropharyngeal dysphagia fits into this growing interest. A systematic review is given of the literature on the effects of therapy in oropharyngeal dysphagia carried out by speech therapists. Thus, the review excludes reports of surgical or pharmacological treatments. The literature search was performed using the electronic databases PubMed and Embase. All available inclusion dates up to November 2008 were used. The search was limited to English, German, French, Spanish, and Dutch publications. MESH terms were supplemented by using free-text words (for the period after January 2005). Fifty-nine studies were included. In general, statistically significant positive therapy effects were found. However, the number of papers was rather small. Moreover, diverse methodological problems were found in many of these studies. For most studies, the conclusions could not be generalized; comparison was hindered by the range of diagnoses, types of therapies, and evaluation techniques. Many questions remain about the effects of therapy in oropharyngeal dysphagia as performed by speech and language therapists. Although some positive significant outcome studies have been published, further research based on randomized controlled trials is needed

Electrical Bioimpedance Measurement as a Tool for Dysphagia Visualization

A non-invasive and portable bioimpedance method and a device for detecting superior to inferior closure of the pharynx during swallowing have been developed. The 2-channel device measures electric impedance across the neck at two levels of the pharynx via injected currents at 40 and 70 kHz. The device has been trialled on both healthy and dysphagic subjects. Results from these trials revealed a relationship (r = 0.59) between the temporal separation of the second peaks in the bioimpedance waveforms and descending pressure sequence in the pharynx as measured by pharyngeal manometry. However, these features were only clearly visible in the bioimpedance waveforms for 64% of swallows. Further research is underway to improve the bioimpedance measurement reliability and validate waveform feature correlation to swallowing to maximise the device's efficacy in dysphagia rehabilitation

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

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.Sebastian H. Doeltgen, John Dalrymple-Alford, Michael C. Ridding and Maggie-Lee Huckabe