Reliability study on quantitative detection of extensor digitorum brevis strength with needle electromyography and...

Area of Science:

• Neuroscience
• Clinical Electrophysiology

Background:

• Accurate muscle strength assessment is crucial for forensic and clinical evaluations.
• Needle electromyography (EMG) and nerve conduction studies (NCS) are common electrodiagnostic tools.

Purpose of the Study:

• To evaluate the objectivity and reliability of EMG and NCS for detecting musculus extensor digitorum brevis strength.
• To establish a basis for quantitative muscle strength detection in forensic clinical studies.

Main Methods:

• Forty-four healthy subjects underwent simultaneous EMG and NCS during toe dorsiflexion.
• Measurements included motor unit potential (MUP) amplitude and count, recruitment reaction type, compound muscle action potential (CMAP) amplitude, CMAP latent period, and motor nerve conduction velocity (MNCV).
• Testing was conducted under both cooperation and disguise conditions.

Main Results:

• Good test-retest reliability was observed for MUP amplitude, CMAP amplitude, CMAP latent period, and MNCV under cooperation and disguise.
• Normal reliability was found for MUP count and recruitment reaction type, with slightly better repeatability between the same operator.
• Under disguise, MUP count and recruitment reaction type showed low reliability.

Conclusions:

• MUP amplitude, CMAP amplitude, CMAP latent period, and MNCV demonstrate good reliability for consistent muscle strength assessment.
• MUP count and recruitment reaction type can help identify examinee deception but are subject to operator and examinee influence.
• Further research is needed to identify objective measures for muscle strength evaluation.