Key Insights On Diagnosing And Treating Cold Injuries To The Lower Extremity

This winter has so far been particularly harsh to the Northeast and to the rest of the United States as even Las Vegas got snow recently. Accordingly, I thought it would be fitting to review the most common cold weather injuries that manifest on the lower extremities. As I call it, this is a cursory list of things that make toes blue.

Let us start with chilblains, also known as pernio. It is a non-freezing injury that occurs in response to repeated cold exposure with humid conditions and manifests itself as erythematous to violaceous papules, nodules or plaques that may burn, be pruritic or become vesicles.1 This typically happens on toes and fingers, and occurs more often in women. The lesions may occur 24 hours after exposure and last from one to three weeks.

When I think of pernio, I think of equestrians developing it on the upper thighs but I also think of the systemic disorders — such as lupus, leukemia, celiac disease, cryofibrogenemia, etc. — that can cause a more long-lasting presentation. Of course, warming the affected part, cessation of smoking (case dependent) and wearing appropriate clothing during future cold exposure is helpful in treatment and prevention.1

Frostnip is a milder form of cold injury in comparison to pernio. It generally occurs on the most distal aspects: toes, fingers, nose and ears. Think of skiers being exposed to very cold and fast moving air. Frostnip represents a superficial injury to the skin and manifests itself as blanching of the skin and numbness. It is reversible upon re-warming of the affected part and preventing further cold exposure.

Due to the similarity of the injury to burns, frostbite injuries are classified as first-, second-, third- and fourth-degree injuries. However, most of us like to consider frostbite as either superficial (includes first and second degrees) or deep (third and fourth degrees). Upon initial presentation, it is difficult to tell which degree of frostbite is present. Only after re-warming can the clinician tell how deeply the layers of the skin and subcutaneous tissue have been affected.

The skin and subcutaneous tissue are affected in superficial frostbite, which may manifest as non-blanching, anesthetic white waxy skin. The skin will become painful upon thawing as well as edematous with serous vesicles and bullae. Deep frostbite goes beyond the skin and subcutaneous tissues into the muscles, neurovascular structures and bone. The frozen part may look wooden and have a lack of sensation that may look ashen upon re-warming. Hemorrhagic bullae may form eventually.

In cases of frostbite, after removing the patient from the environment, rapid re-warming in a bath of 39ºC to 42ºC is indicated.2 One should verify tetanus status as these injuries can be tetanus-prone.3 Unfortunately, in our line of work, we see many of these deep injuries go on to amputation.4 However, revascularization of the affected area and use of tissue plasminogen activator has decreased the rate of amputation.5

I have not gone into detail here about Raynaud’s phenomenon or disease, cryofibrinogenemia, hypothermia or trench foot. Perhaps I will discuss these conditions in a future blog.

References

1. Almahameed A, Pinto DS. Pernio (chilblains). Curr Treat Options Cardiovasc Med 2008; 10(2):128-35.

2. Golant A, Nord RM, Paksima N, Posner MA. Cold exposure injuries to the extremities. J Am Acad Ortho Surg 2008; 16(12):704-715.

3. Edlich RF, Hill LG, Mahler CA, et al. Management and prevention of tetanus. J Long Term Eff Med Implants. 2003;13(3):139-54.

4. Heggers JP, Robson MC, Manavalen K, et al. Experimental and clinical observations on frostbite. Ann Emerg Med. 1987;16(9):1056-62.

5. Bruen KJ, Ballard JR, Morris SE, Cochran A, Edelman LS, Saffle JR. Reduction of the incidence of amputation in frostbite injury with thrombolytic therapy. Arch Surg. 2007; 142(6):546-51; discussion 551-3.