Case of the week Details

• Fig:1A (Axial T2), Fig:1B (Axial STIR) & Fig:1C (Coronal STIR) demonstrates extensive intramuscular edema involving muscles in all the compartments of leg with perifascial fluid and subcutaneous soft tissue edema. Note is made of fracture proximal Tibia.

• Fig:2 (Axial T1): Poorly circumscribed intramuscular T1 hyper intense areas suggestive of intramuscular hemorrhage.
• Fig:3 (Sagittal STIR): Zoomed image demonstrating on of the focal muscle herniation.

COMPARTMENT SYNDROME

• Elevated pressure within a relative non-compliant anatomical compartment resulting in ischemia and sequelae.
• Acute compartment syndrome is a surgical emergency, if not intervened early, may lead to:
  • Acute compartment syndrome  Neuromuscular injury, myonecrosis and rhabdomyolysis.
  • Chronic compartment syndrome Fibrosis and scarring: “Volkmann ischemic contracture”

ETIOLOGY

• Acute: Fractures.
• Chronic: Exercise, overuse, accessory muscles, SOL, infection.

CLINICAL FEATURES: 6 “P”s

• • Pain
  • Pallor
  • Paraesthesia
  • Paresis
  • Pulselessness
  • Poikilothermia

“ Distal pulse may be normal in early acute compartment syndrome”

MR IMAGING FEATURES

• Increased T2/STIR signal: Muscle edema (acute & chronic).
• Increased T1 signal: Hemorrhage (acute), fatty infiltration (chronic).
• Decreased T1 signal: Fibrosis, calcification (chronic).
• Increased muscle volume (acute) / decreased muscle volume (chronic).
• Bulging fascial outline (acute).
• Muscle herniations (acute).
• Fascial thickening (chronic).

CHRONIC EXERTIONAL COMPARTMENT SYNDROME

• Common in athletes, type of over-use injury
• Pain or sense of pressure in limbs typically after exertion.
• Increase in muscle bulk and edema post exertion.
• May co-exist with underlying bone stress features like periosteal edema or fatigue fractures.

DIFFERENTIAL DIAGNOSIS

1. Delayed onset muscle soreness (DOMS)
2. Muscle strain
3. Deep venous thrombosis.
4. Cellulitis and lymphedema.

Dr. Sushant Mittal
Senior resident & Cross sectional fellow
CARG

Dr. Dayanand Sagar G
Consultant Radiologist
CARG