Differential Diagnosis for 72 YO Indian Male with Subacute BLE Paresthesia and Weakness with CK 650

• Single most likely diagnosis:
  • Inflammatory Myopathy (e.g., Polymyositis): Elevated CK levels and subacute onset of bilateral lower extremity (BLE) paresthesia and weakness are consistent with an inflammatory myopathy. The age and presentation are typical for this condition.
• Other Likely diagnoses:
  • Dermatomyositis: Similar to polymyositis but with additional skin manifestations. The absence of mentioned skin findings does not rule out this diagnosis entirely, as skin involvement can be subtle or develop later.
  • Toxic Myopathy: Certain medications and toxins can cause myopathy with elevated CK levels. The patient's age and potential for polypharmacy increase the likelihood of this diagnosis.
  • Muscular Dystrophy: Though less common in this age group, certain types of muscular dystrophy can present later in life and cause significant weakness and elevated CK levels.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
  • Guillain-Barré Syndrome: An autoimmune disorder that can cause rapid onset of muscle weakness. Although CK levels are not typically elevated, some variants can present with mild elevations, and the diagnosis is critical due to the potential for respiratory failure.
  • Spinal Cord Compression: Can cause bilateral lower extremity weakness and paresthesia. Elevated CK levels might not be directly related but could be seen in cases of significant muscle injury from immobility or trauma.
  • Vasculitis (e.g., Giant Cell Arteritis or Polyarteritis Nodosa): Systemic vasculitis can cause a wide range of symptoms, including muscle weakness and elevated CK levels, especially if there is involvement of the blood vessels supplying the muscles.
• Rare diagnoses:
  • Mitochondrial Myopathies: A group of disorders caused by mutations in the mitochondrial DNA affecting muscle tissue. These can present at any age and may cause weakness and elevated CK levels.
  • Inclusion Body Myositis: The most common acquired myopathy in adults older than 50 years, characterized by slowly progressive muscle weakness and wasting, especially of the distal muscles. CK levels can be elevated, but the diagnosis is often made based on muscle biopsy findings.
  • Lyme Disease: Caused by Borrelia burgdorferi, can lead to neurological manifestations, including radiculopathy or meningitis, and very rarely, a myopathic presentation with elevated CK levels.