Sonographic extremity assessment of crotalinae envenomation

Abstract

The evaluation of a patient after Crotalinae envenomation requires assessment of local and systemic signs and symptoms in conjunction with laboratory data. Point-of-care ultrasound (POCUS) is an emerging modality used to evaluate soft tissue changes associated with snake envenomations around the world. However, more data are needed to characterize sonographic findings of snake envenomation. Our study used POCUS to evaluate the depth of soft tissue injury, involvement of the muscles/tendons, and the proximal edge of envenomation. This was a prospective observational study evaluating the sonographic characteristics of Crotalinae envenomation. The eight patients enrolled in the study included one envenomated by a Western diamondback (Crotalus atrox), and the others were envenomated by copperheads (Agkistrodon contortrix). All the patients demonstrated initial subcutaneous cobblestoning on POCUS at the bite site. All digit envenomations revealed edema in the tendon or tendon sheath. None of these cases required acute surgical intervention. There were no sonographic signs of envenomation found below fascia or muscle. Four of the eight patients had POCUS findings of cobblestoning proximal to the edge of envenomation palpated on the extremity. The clinical significance of this is unknown.