Rhabdomyolyse

Rhabdomyolysis describes the breakdown of striated muscles with the release of intracellular contents and represents a severe muscle injury. MRI is the imaging modality of choice. Rhabdomyolysis is potentially life-threatening although recovery is excellent with early treatment.

Clinical presentation

Symptoms and signs are varied, but a classic triad of muscle pain, weakness, and dark urine are described.

Pathology

Etiology

Most common causes reported in Western adult populations is trauma/crush injury, exercise, cocaine and immobilization. The range of causes is wide:

  • non-traumatic
    • infection, e.g. infectious myositis
    • electrolyte abnormalities, e.g. hypokalemia, hypocalcemia
    • immune-mediate, e.g. dermatomyositis, polymyositis
    • drugs, e.g. alcohol, cocaine, statins, anesthetic agents, heparin
    • hyperthermia/hypothermia
    • metabolic disease, e.g. myophosphorylase deficiency
    • ischemia
    • immobilization
  • traumatic
Markers
  • serum creatinine kinase (CK) will be markedly raised (at least five times normal)
  • elevated serum potassium
  • positive urine myoglobin

Radiographic features

CT

Rhabdomyolysis has a heterogeneously hypodense appearance on CT. There may be rim-enhancement on post-contrast images .

MRI

Edema throughout affected muscles with signal intensity reflecting the severity of an injury is seen in mild-moderate cases. When severe, features of myonecrosis will be demonstrated. Two types of MRI findings have been described :

  • type 1
    • T1: homogeneously iso to hyperintense
    • T2/STIR: homogeneously hyperintense
    • T1 C+ (Gd): homogeneously enhancing
  • type 2
    • T1: homogeneously/heterogeneously hyperintense
    • T2: heterogeneously hyperintense
    • T1 C+ (Gd): rim-enhancing

Treatment and prognosis

The release of intracellular contents (e.g. myoglobin) can result in the development of cardiac arrhythmias, acute renal failure (~30%) and tetanus. Muscle edema may lead to compartment syndrome. Full recovery with early treatment.

Differential diagnosis

For MRI appearances consider:

Siehe auch: