Preliminary approach for the surface electromyographical evaluation of the oral phase of swallowing

Abstract

Swallowing is a muscular activity that occurs both after mastication and spontaneously as a result of saliva accumulation. Spontaneous saliva swallowing occurs about every 2 minutes. Comprehension of its functional mechanisms is relevant to assess their modification in clinical situations. A standardised surface electromyographical (ssEMG) protocol for the evaluation of this muscle activity is lacking. Aims of the present study are: (i) to determine the reproducibility of a ssEMG protocol for the evaluation of the oral phase of saliva swallowing and (ii) to evaluate the activity of masseter (MM), anterior temporalis (TA), submental muscles (SM) to draw a reference model of swallowing. Standardised surface electromyographical activity of MM, TA and SM during swallowing of saliva spontaneously accumulated was recorded in 20 healthy participants. Functional indexes including symmetry (POC), recruitment (Impact), duration of activation of each couple of muscles and of the whole exercise, position, intensity of the spike were computed. Inter- and intra-appointment reliabilities were assessed and method errors calculated. Descriptive statistics, sex- and muscles-related comparisons were carried out. Standardised surface electromyographical assessment of MM, TA and SM muscles was reliable. A high inter-individual variability was found. Percentage overlapping coefficient (POC) values were close to 80% for TA and SM, higher than for MM (P < .001). Impact values ranged between 16.4% and 30.7%, and differences were found between muscles (P < .001). The global muscle activity during swallowing lasted between 1.5 and 1.8 seconds. For each couple of muscles, the duration of activation ranged between 0.7 and 1.6 seconds and muscles-related differences were found (P < .001). The spike of activation for each couple of muscle ranged between 35.7% and 44.2% of the duration. The protocol was reliable and intra-participants repeatable measures can be carried out. Due to the high inter-participants variability, further analyses are needed to draw a model of muscular activity.

Electromyographic analysis of the oral phase of swallowing in subjects with and without atypical swallowing: A case‐control study

“…The aim of this work was to compare the muscular activation pattern during swallowing in dysfunctional and normal patients and to detect whether significant differences emerged. To do so, we focused on the muscular activity during swallowing by asking the patient to keep the teeth in contact while swallowing saliva as it can be considered as the most common physiological activity and it has been demonstrated a reliable test in healthy subjects …”

“…Surface EMG activity was recorded in order to analyse the activation pattern of the MM, TA and SM, using a standardised method with a computerised instrument (Easymyo; 3 Technology Srl), whose electrode type and procedure of analysis have been described previously The bipolar surface electrodes (21 × 41 mm, 20 mm inter‐electrode distance; F3010; Fiab) were positioned on the muscular bellies parallel to the muscular fibres for the bilateral recording as follows : MM—The electrodes were fixed parallel to the exocanthion‐gonion line and with the upper pole of the electrode under the tragus‐labial commissural line. TA—The electrodes were fixed vertically along the anterior margin of the muscle (corresponding to the frontoparietal suture). SM—The electrodes were placed in the submental area, paramedian to the midline and lightly diverging, 1 cm posterior to the mental symphysis …”

“…">3.Duration of activation of each couple of muscles (MM, TA, SM): considered as the interval in which muscle activity was higher than 10% of its standardisation procedure. Values below this threshold were considered muscular basal activity as reported previously …”

“…Although some authors have suggested that the electromyographical signal has technical and biological limits that could make a comparative and longitudinal analysis difficult, the standardised sEMG (ssEMG) procedure excludes these features and permits data evaluation . Recently, a standardised protocol on muscular activity of MM, TA and SM during saliva swallowing has been defined in healthy adult subjects, with preliminary normalised data being available . According to this proposed muscular model, during swallowing, there is a first activation of the masticatory muscles (MM and TA) with moderate intensity followed by a longer activation of SM with a higher intensity …”

“…Recently, a standardised protocol on muscular activity of MM, TA and SM during saliva swallowing has been defined in healthy adult subjects, with preliminary normalised data being available . According to this proposed muscular model, during swallowing, there is a first activation of the masticatory muscles (MM and TA) with moderate intensity followed by a longer activation of SM with a higher intensity …”