Atypical Wounds - Myonecrosis

Myonecrosis is an aggressive, fast-spreading soft tissue infection caused by the Clostridium bacteria that requires immediate diagnosis and treatment in order to prevent death and to preserve limb function.

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Myonecrosis, also known as gas gangrene, is a rare skin and soft tissue infection with high morbidity and mortality.[1]  It frequently occurs after a deep penetrating injury that compromises blood supply;[2] however, it has also been associated with colorectal carcinoma, hematologic malignancies, and diabetes.1 Patients with acquired neutropenia who are immunocompromised can also develop myonecrosis without trauma, and will present with the acute onset of limb pain.[3]  The majority of the infections are caused by Clostridium perfringens, although other strains of Clostridium have been implicated.  The bacteria produce multiple toxins (including proteases, phospholipases, and cytotoxins) that cause aggressive necrosis of the skin and muscles.  The condition can become calcific myonecrosis which occurs most frequently in the lower extremity, but has been reported in the upper extremity as well.[4]

Clinical presentation of myonecrosis involves severe pain, usually with skin color changes of pale to bronze to purplish-red with bullae formation.2 Gas in the tissue is evident from physical examination as crepitus upon palpation, and is visible in radiographs as fluid collections in the affected soft tissue.  Diabetic necrosis may reveal swollen and tender muscle, much like the presence of a DVT.  The skin will be intact but bulging, and there is an indurated feel upon palpation as a result of subcutaneous fluid and edema.[5]  In addition, renal failure may occur as a result of hemoglobinuria and myoglobinuria, as well as bacteremia and hemolysis, and may rapidly progress to shock and multiorgan failure with toxic psychosis.2

The following table presents a synopsis of the signs and symptoms associated with myonecrosis:

Early signs and symptoms

Skin changes

Late signs and symptoms

Other findings

 

Incubation period of about 48 hours

Fever

Pain out of

proportion to injury

Tachycardia

Diaphoresis

Gray Pallor

Anoxemia

Apprehension

D isorientation

Obtundation

                

 

Shiny & tense skin

Tense, bronzed and tender skin

Blue-black bullae

Gas & crepitation

Odor of gas when debrided

 

 

Myonecrosis

Hemolytic anemia

Hematuria

Myoglobinuria

Acute Renal Failure

Metabolic Acidosis

Consumptive coagulopathy

Seizures and death

 

 

Ischemia & inoculation

Bacterial proliferation

Exotoxin production

Tissue destruction

Edema & necrosis

Decreased redox potential

Gangrene

Hemorrhagic bullae

Gas in muscles

 

 

Medical management of myonecrosis is predicated on debridement of all devitalized, infected tissue and aggressive appropriate antibiotics.  In the case of diabetic myonecrosis without skin changes, conservative therapy comprised of bed rest, analgesics to control pain, and aggressive control of the diabetes is advised.In addition, it is recommended to avoid anticoagulation therapy that can worsen the condition, as well as muscle biopsies (in the case of diabetic myonecrosis).

After debridement, initial local wound care consists of covering the open area with antimicrobial dressings.  When healthy tissue is visible, the principles of moist wound healing are followed and may include the use of negative pressure wound therapy to help decrease the size of the tissue defect created by surgical debridement.  In some cases, surgical closure with a skin graft or flap may be required. 

In summary, myonecrosis is an aggressive, fast-spreading soft tissue infection caused by the Clostridium bacteria that requires immediate diagnosis and treatment in order to prevent death and to preserve limb function.

[1] Sright WF.  Clostridium septicum myonecrosis presenting as an acute painful foot.  Am J Emerg Med. 2012;30(1):253.e3-5.

[2] Hamm RL, Shah JB.  Atypical Wounds.  In Hamm R. (Ed) Text and Atlas of Wound Diagnosis and Treatment.  New York: McGraw-Hill Education.  2019;235-268.

[3] Thompson KM, Kruse BT, Hedges MAS.  Atraumatic clostridial myonecrosis in an immunocompromised host.  J Emerg Med.  2018;54(6):e121-e123.

[4] Ryndres SD, Boachie-Adjei YD, Gaskin CM, Chhabra B.  Calcific myonecrosis of the upper extremity: Case report.  J Hand Surg. 2012;37(1):130-133.

[5] Gupta S, Goyal P, Sharma P, Soin P, Kochar P.  Recurrent diabetic myonecrosis – an under-diagnosed cause of acute painful swollen limb in long standing diabetics.  Annals of Medicine and Surgery. 2018;35(9):141-145.

Rose Hamm

Physical Therapy, University of Southern California

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