Leg Muscle Pain

Clinical History

35-year-old previously healthy woman presented with dark urine, severe pain & swelling in bilateral lower extremity 1 day post marathon training. She has a history of muscle aches following exercise. Her CPK was around 14,000.

What is a likely underlying cause of this patient’s disorder?

A. PHKA2 mutation

B. MMA deficiency

C. IDH1 deficiency

D. PYGM mutation

Correct Answer: PYGM mutation

Spontaneous compartment syndrome is a rare complication of McArdle’s disease. The clinical history is that of compartment syndrome; however a prior history of muscle aches following exercise along with loss of myophosphorylase activity suggest McArdle disease. Although phosphorylase reactivity may be artifactually lost in muscle biopsies, other labile enzymes (e.g. MAD) remained positive. In this case, the diagnosis was confirmed by a mutation in PYGM.

McArdle disease

• PYGM mutation
  • 1:100,000 persons
  • Autosomal recessive
• Symptoms:
  • Exercise intolerance
  • Cramping
  • Myoglobinemia
• Mechanism: muscle phosphorylase deficiency

References/Additional Readings:

• Triplet JJ, Goss DA Jr, Taylor B. Spontaneous Compartment Syndrome in a Patient with McArdle Disease. JBJS Case Connect. 2017;7:e49
• Pollock AB, Huggins JC, Harrell KN. Atraumatic Acute Paraspinal Compartment Syndrome in a Patient With McArdle’s Disease. Am Surg. 2023;89:3545-6
• Famili DT, et al. Recurrent atraumatic compartment syndrome as a manifestation of genetic neuromuscular disease. Neuromuscul Disord. 2023;33:866-72