Predictive values of motor unit potential analysis in limb muscles

Area of Science:

• Neurology
• Clinical Electrophysiology

Background:

• Accurate interpretation of diagnostic findings relies on positive and negative predictive values.
• Published data on predictive values for motor unit potential (MUP) analysis is lacking.

Purpose of the Study:

• To determine the predictive values of template-operated MUP analysis for diagnosing facioscapulohumeral muscular dystrophy (FSHD).

Main Methods:

• Concentric needle electromyography (EMG) was used to examine biceps brachii and vastus lateralis muscles in 31 FSHD patients and 34 controls.
• Template-operated MUP analysis was employed.
• Results were compared to non-parametric reference data from additional control groups.

Main Results:

• For biceps brachii, sensitivity was 59%, specificity 91%, positive predictive value 85%, and negative predictive value 72% using at least two abnormal MUP criteria.
• All subjects with three abnormal EMG criteria were FSHD patients.
• 90% of subjects with normal EMG findings were controls.

Conclusions:

• Template-operated MUP analysis demonstrates reasonable predictive value for diagnosing and excluding myopathy.
• Quantitative MUP analysis is useful for the preliminary diagnosis of FSHD in clinically suspected cases.