Proximal monomelic amyotrophy of the upper limb

Area of Science:

• Neurology
• Clinical Case Study

Background:

• Monomelic amyotrophy (MMA) is a rare neuromuscular disorder characterized by unilateral muscle wasting and weakness.
• The etiology of MMA is often unclear, with theories suggesting anterior horn cell involvement.

Observation:

• A 30-year-old patient presented with progressive proximal weakness and atrophy in one upper limb, predominantly affecting the shoulder girdle.
• Clinical examination revealed significant muscle atrophy and weakness localized to the affected limb.

Findings:

• Electrodiagnostic studies demonstrated partial denervation in the affected limb.
• Motor and sensory nerve conduction studies were within normal limits, suggesting a focal process.
• The patient, of Central European origin, was diagnosed with a probable anterior horn cell disease.

Implications:

• This case underscores the generally benign course and favorable prognosis of monomelic amyotrophy.
• Long-term follow-up over eight years confirmed the stability and good outcome of the condition.
• The findings support the hypothesis of anterior horn cell involvement in MMA with a non-progressive nature.