Electrical stimulation of hyoid muscles in post-stroke dysphagia

Post-stroke dysphagia manifests as a swallowing disorder. The incidence of dysphagia in patients after cerebrovascular accident is 20% - 65% (ref.1,2). A complex interdisciplinary approach is needed for diagnostics and therapy3 . Objective x-ray-based method - the videofluoroscopic swallowing study (VFSS) is used for evaluating a person's swallowing ability. During the VFSS video recordings of the swallowing act are evaluated and duration of different swallowing phases measured. The oral phase is determined by the so-called oral transit time (OTT). OTT is measured from the start of bolus passage from the mouth to the back of the tongue – entrance into the pharynx. Pharyngeal transit time (PTT) is measured from the time that the bolus enters the pharynx to the moment it reaches the cricopharyngeal area (beginning of the oesophagus).

Compensatory and therapeutic strategies are used in the management of swallowing disorders. Compensatory strategies ensure food intake by substitute nutrition (nasogastric intubation, percutaneous endoscopic gastrostomy or parenteral intravenous nutrition), by selection of suitable food and by modification of food consistency. Therapeutic strategies restore the oropharyngeal motor skills and swallowing maneuvers with the help of therapeutic exercise. This is orofacial rehabilitation (OFR). Our standard OFR therapy included 3 steps. Step 1 (Preparatory phase): postural therapy and respiratory rehabilitation with practise to close the laryngeal strait. Step 2 (Practise of “dry” swallowing): practising the oral phase (exercise of tongue, thermal touch therapy, exercising face and lip muscles) and pharyngeal phase (strenuous swallowing training with the pressure of tongue on palate and strengthening vocal cord closure). Step 3 Practise of swallowing with the use of foods and drinks of different consistency, activation of the propulsion force, training of the supraglotic swallowing and eventually practise of the compensation swallowing strategy with the help of controlled head position7 . OFR has impact not only on the restoration of the swallowing but also on the other orofacial functions (mimics, speech), overall health and life quality4,8. A newly recommended approach for the functional restoration of swallowing muscles is electrical stimulation (ES) of hyoid muscles. ES of hyoid muscles in post-stroke patients with dysphagia leads to improved elevation of the larynx and better closure of the airways and therefore it prevents food aspiration. The most clinically useful approach is to stimulate the suprahyoid muscles by means of TENS (transcutaneous electrical nerve stimulation) currents with a frequency of 60 Hz, a pulse length of 300 ms and intensity of the motor threshold9-12. ....

Texto completo en: http://biomed.papers.upol.cz/pdfs/bio/2018/01/07.pdf