Surface EMG Activity of the Supra-hyoid Muscles in the Patients with Post-stroke Dysphagia

Research Objectives: To investigate the changes in surface electromyograph (sEMG) signals in the patients who were diagnosed as post-stroke dysphagia.

Design: Cross sectional study

Setting: Dysphagia research laboratory in a university affiliated general hospital .

Participants: Seven healthy subjects and twenty patients who were diagnosed as post-stroke dysphagia after unilateral cerebral infarction or hemorrhage, based on the findings of VFSS (videofluoroscopic swallow study).

Interventions: The sEMG signals were recorded from the supra-hyoid muscles of both sides, using a wireless sEMG analysis system. Frequency band-pass was set to 50- 500Hz and every effort was made to remove noise from movements or other sources. Collected data was compared among the groups of 1) healthy subjects, 2) patients without aspiration and 3) patients with aspiration.

Main Outcome Measures: Maximum, mean and minimum amplitudes of root mean square (RMS)
Median and mean frequencies

Results: When swallowing thick liquid, the maximum RMS amplitude in intact side was significantly larger in the aspiration group (233.8 ± 40.7 uV) than in the healthy group (140.0 ± 52.5 uV)(p < 0.05). The patient groups (both aspiration and non-aspiration) showed significantly larger mean RMS amplitude in both sides (43.3 ± 15.1 uV in intact side and 35.5 ± 13.2 uV in hemiplegic side of the non-aspiration patient group, 37.1 ± 6.5 uV in intact side and 38.1 ± 25.3 uV in hemiplegic side of the aspiration group) than the healthy group (20.9 ± 6.4 uV)(p < 0.05). The mean frequencies of both sides were significantly larger in the aspiration group than in the healthy group (p < 0.05). When swallowing thin liquid, only mean RMS amplitude was significantly larger in patient groups (both aspiration and non-aspiration) than in the healthy group (p < 0.05).

Conclusions: The results suggest that the suprahyoid muscles can be more activated in the post-stroke dysphagia patients than in the healthy subjects when swallowing thick and thin liquids. Further studies may be required to reveal the significance of hyperactivity of the suprahyoid muscles.

Author(s) Disclosures: The authors have nothing to declare regarding the conflicts of interest.