Frostbite is a focal tissue injury from exposure to extremely low temperatures, and most commonly involves the fingers and toes. It is most commonly encountered in radiology in a differential for acro-osteolysis.
Tissue injury from frostbite occurs in two ways 1:
- direct tissue necrosis from freezing
- indirect tissue injury from inflammatory changes and release of inflammatory mediators
Most common on exposed areas: hands, feet, face and ears. The skin changes texture ("waxy") and may develop bullae if the frostbite is severe.
May be useful to help determine the degree of injury or presence of secondary injury in patients who present clinically with frostbite.
- acro-osteolysis of the distal phalanx / phalangeal tuft
- swelling of affected soft tissues
- it has been reported that the thumb may be relatively spared (patient likely to wrap thumb in palm) 2
Tc-99m-MDP (bone scintigraphy)
- a two-phase scan may be useful to assess the viability of tissue 3
- a combination of the perfusional phase and soft tissue phase can help characterize areas of inflammation and areas of ischemia (increased or decreased radiotracer activity, respectively)
- limited data suggests that MRI may be a useful modality for demarcating ischemic tissue 4
Treatment and prognosis
Clinically, frostbite is classified similarly to burns: 1st-4th degree.
Incautious thawing of the tissue may lead to worsened injury (higher degree burn) from the ensuing inflammatory reaction.
Treatment of systemic hypothermia should be prioritized over frostbite.
- "frostnip": focal tissue injury without permanent damage
- "immersion foot": frostbite and immersion in water (a type of "trench foot")
- acro-osteolysis: imaging differential
- 1. Murphy JV, Banwell PE, Roberts AH et-al. Frostbite: pathogenesis and treatment. J Trauma. 2000;48 (1): 171-8. Pubmed citation
- 2. Kahn JE, Lidove O, Laredo JD et-al. Frostbite arthritis. Ann. Rheum. Dis. 2005;64 (6): 966-7. doi:10.1136/ard.2004.027961 - Free text at pubmed - Pubmed citation
- 3. Cauchy E, Marsigny B, Allamel G et-al. The value of technetium 99 scintigraphy in the prognosis of amputation in severe frostbite injuries of the extremities: A retrospective study of 92 severe frostbite injuries. J Hand Surg Am. 2000;25 (5): 969-78. Pubmed citation
- 4. Barker JR, Haws MJ, Brown RE et-al. Magnetic resonance imaging of severe frostbite injuries. Ann Plast Surg. 1997;38 (3): 275-9. Pubmed citation