Bedside and laboratory diagnostic testing in myasthenia

Area of Science:

• Neurology
• Clinical Neurophysiology
• Immunology

Background:

• Myasthenia gravis (MG) and congenital myasthenic syndromes (CMS) are distinct neuromuscular junction disorders.
• These conditions have well-defined autoimmune or genetic etiologies and neurophysiological underpinnings.
• Accurate diagnosis is crucial for effective patient management.

Purpose of the Study:

• To review and assess the diagnostic utility of neurophysiological, immunological, provocative, and genetic tests for MG and CMS over the past 20 years.
• To compare the sensitivity and specificity of established diagnostic methods.
• To explore emerging diagnostic strategies.

Main Methods:

• Literature review of studies published in the last two decades.
• Analysis of diagnostic performance metrics (sensitivity and specificity) for various tests.
• Identification and evaluation of novel diagnostic approaches.

Main Results:

• Repetitive nerve stimulation sensitivity: 14–94%, specificity: 73–100%.
• Single-fiber EMG (SFEMG) sensitivity: 64–100%, specificity: 22–100%.
• Anti-acetylcholine receptor (AChR) antibody sensitivity: 13–97%, specificity: 95–100%.
• SFEMG demonstrated the highest sensitivity; anti-AChR antibodies showed the highest specificity.
• Emerging tests include ocular vestibular-evoked myogenic potentials, otoacoustic emissions, serum miRNAs, and next-generation sequencing for CMS.

Conclusions:

• Established tests like SFEMG and anti-AChR antibody assays are vital for diagnosing MG and CMS.
• While newer diagnostic tools show promise, further research is necessary to validate their sensitivity and specificity.
• Continued advancement in diagnostic strategies is essential for improving the detection of these complex neuromuscular disorders.