Observational Evaluation of Muscle Echointensity and EMG Insertional Activity in Poststroke Spasticity

Area of Science:

• Neurology
• Rehabilitation Medicine
• Musculoskeletal Ultrasound

Background:

• Post-stroke spasticity can lead to peripheral muscle architectural changes.
• Muscle echointensity (EI) assessed via the Modified Heckmatt Scale (MHS) is a non-invasive measure of muscle tissue composition.
• Electromyography (EMG) detects electrical activity in muscles, including insertional activity, which can reflect muscle health.

Purpose of the Study:

• To investigate the association between spastic muscle echointensity (EI) and electromyography (EMG) insertional activity in post-stroke patients.
• To determine if botulinum neurotoxin (BoNT) exposure influences the relationship between EI and EMG findings.

Main Methods:

• Fifty-five patients with post-stroke spasticity were evaluated.
• Muscle EI (MHS) and needle EMG insertional activity were assessed in eight muscles per patient.
• Statistical analyses (Chi-square/Fisher's exact tests) were used to correlate EI and EMG findings and assess BoNT effects.

Main Results:

• Muscles with higher MHS grades (3-4) showed significantly more abnormal EMG insertional activity (53.6%) compared to lower grades (1-2) (8.3%) (p < 0.001).
• Abnormal insertional activity in higher-grade muscles was often reduced/absent, while in lower-grade muscles, it was more frequently increased.
• Botulinum neurotoxin (BoNT) exposure did not alter the association between MHS grade and abnormal EMG insertional activity.

Conclusions:

• Elevated muscle echointensity in post-stroke spasticity is linked to abnormal EMG insertional activity.
• The observed EI and EMG changes are not explained by BoNT treatment.
• Further research is required to understand the mechanisms behind muscle architectural and electromyographical alterations in post-stroke spasticity.