Clinical Reasoning: A Woman With Subacute Progression of Distal Upper Extremity Weakness

Area of Science:

• Neurology
• Immunology
• Pathology

Background:

• Progressive hand weakness can indicate various neuromuscular disorders.
• Differentiating inflammatory myopathies from other neuropathies is clinically important.

Purpose of the Study:

• To present a case of a 65-year-old woman with progressive hand weakness.
• To discuss the diagnostic approach for localizing motor pathway lesions.
• To illustrate the utility of serologic, imaging, and electrodiagnostic tests.

Main Methods:

• Electromyography (EMG) to assess nerve and muscle function.
• Serologic studies for specific antibodies (anti-acetylcholine receptor, antistriated muscle).
• Muscle biopsy to evaluate for inflammation and fibrosis.

Main Results:

• EMG showed diminished radial nerve amplitudes without conduction block; sensory potentials were normal.
• Positive anti-acetylcholine receptor and antistriated muscle antibodies were noted.
• Muscle biopsy revealed extensive inflammatory infiltrates and significant fibrosis.

Conclusions:

• A comprehensive diagnostic strategy is essential for neuromuscular disorders.
• Inflammatory myopathy can present with distal-predominant weakness and specific electrodiagnostic findings.
• Muscle biopsy remains critical for definitive diagnosis in suspected inflammatory myopathies.