Neurostimulation Improves Swallowing After Stroke

Paired associative stimulation of the pharyngeal motor cortex improves swallowing after stroke

WEDNESDAY, Jan. 4 (HealthDay News) -- A new neurostimulation technique called paired associated stimulation (PAS), which combines peripheral stimulation of the targeted muscle with cortical stimulation of the targeted muscle's representational area, may be useful in the rehabilitation of patients with dysphagia due to stroke, according to a study published in the January issue of Gastroenterology.

Emilia Michou, M.D., of the University of Manchester in the United Kingdom, and colleagues first investigated the effects on swallowing function of a 10-minute application of PAS applied to the unlesioned pharyngeal motor cortex of 12 healthy patients who had been given a virtual lesion as an experimental model of stroke. The virtual lesion was created using a 1-Hz repetitive transcranial magnetic stimulation over the pharyngeal cortex. Results were compared with that observed after a sham technique was performed. Once the technique was refined, it was applied to six patients with chronic dysphagia due to stroke (mean time post-stroke, 38.8 ± 24.4 weeks). Five of these patients were tube fed. Swallowing reaction time tasks, excitability, penetration-aspiration scores, and swallowing biomechanics (measured using videofluoroscopy) were used to measure results.

The researchers found that, in healthy patients, the cortical suppression induced by the virtual lesion was bilaterally reversed with only a 10-minute application of PAS. In patients with dysphagia due to stroke, PAS yielded short-term bilateral changes in the brain; increased excitability in the unaffected pharyngeal cortex; decreased penetration-aspiration scores; and changes in swallowing biomechanics, such as improved swallowing accuracy when performing complex tasks.

"Even though the study was not controlled and the patients were not severely dysphagic, immediate behavioral effects were observed. Thus, the fact that in the current protocol a single application of PAS showed immediate behavioral and neurophysiological effects in patients with chronic dysphagic stroke is of interest and provides additional information to support the role of carefully designed interventions even after long-term swallowing disability," the authors write.

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