Clinical Reasoning: A 67-Year-Old Man With Exercise Intolerance and Progressive Weakness

Area of Science:

• Neurology
• Clinical Medicine
• Biochemistry

Background:

• Presents a complex case of a 67-year-old male with long-standing Human Immunodeficiency Virus (HIV) on antiretroviral therapy.
• Co-morbidities include type 2 diabetes with polyneuropathy and hyperlipidemia, managed with statin and fibrate therapy.

Purpose of the Study:

• To review the diagnostic approach to adult-onset myopathy.
• To explore challenges in diagnosing myopathy when clinical presentation and diagnostic tests appear discordant.
• To emphasize a structured, stepwise methodology for localization, differential diagnosis, and targeted testing.

Main Methods:

• Case presentation of a patient with new-onset hamstring weakness and exercise intolerance.
• Review of diagnostic strategies for adult-onset myopathy.
• Discussion of discordant findings between clinical examination and laboratory tests (elevated creatine kinase).

Main Results:

• The patient exhibited new hamstring weakness alongside chronic distal weakness and sensory loss.
• Elevated creatine kinase levels persisted even after statin and fibrate therapy discontinuation, suggesting non-statin/fibrate related myopathy.
• The case underscores the complexity of myopathy diagnosis in patients with multiple comorbidities.

Conclusions:

• Adult-onset myopathy requires a systematic diagnostic approach, especially when initial tests are inconclusive.
• Challenges in myopathy diagnosis can arise from polypharmacy and co-existing conditions like HIV and diabetes.
• A stepwise strategy involving localization, differential diagnosis, and targeted testing is crucial for accurate diagnosis and management.