David Link, PGY-1
Article: Rapid Diagnosis of Rhabdomyolysis with Point-of-Care Ultrasound
Background: Rhabdomyolysis can rapidly progress to acute renal failure, arrhythmia, and potentially death if not treated in a timely manner. Early identification of Rhabdomyolysis is therefore paramount in preventing morbidity and mortality. In cases of isolated muscle pain, point of care ultrasound in the emergency department can quickly provide important diagnostic information to expediate treatment and decrease sequelae of rhabdomyolysis.
Study Type: University of South Florida Case Report
Study: Case report of a 24 y.o. male with 2 days of constant, bilateral, bicep pain after lifting weights, and recent use of cocaine, marijuana, and “spice”. The patient was hypertensive and tachycardic with bilateral biceps swelling and tenderness, and no evidence of trauma. Physical exam was otherwise unremarkable, and the patient was neurovascularly intact. Point of care ultrasound was performed to evaluate for bicep tendon tear, but instead found areas of both increased and decreased echogenicity, disorganized muscle fibers, and surrounding fluid, consistent with rhabdomyolysis, and patient was started on IV fluids prior to lab results. CPK returned at 83,000, and patient was admitted for fluid resuscitation with progressive improvement and discharge several days later.
Ultrasound evaluation of rhabdomyolysis
On ultrasound normal skeletal muscle has a relatively hypoechoic echotexture with clearly demarcated linear hyperechoic strands. In rhabdomyolysis the findings are variable but may include hyperechoic areas of muscle (hypercontractile muscle fibers in the acute phase of muscle injury) hypoechoic areas of muscle (edema and inflammation of the muscle), increased muscle thickness, and fluid within the surrounding the muscles.
Partial tears, strains, and contusions have similar hypoechoic areas within the muscle fibers themselves, representing localized edema and hemorrhagic changes. Unlike in rhabdomyolysis, the sonographic findings seen with tears, strain injuries, and contusions are limited to a focal area of injury and are not diffusely present throughout the involved muscle.
Takeaway: Point of care ultrasound may be a useful tool in evaluation of rhabdomyolysis, especially in cases of isolated muscle pain. When utilized appropriately, ultrasound can expedite care in patients with rhabdomyolysis, or decrease time to discharge in patients with isolated muscle pain found to be free of acute muscular changes on ultrasound.
However, further characterization of consistent ultrasound findings in rhabdomyolysis is needed to accurately assess for and diagnose it. Furthermore, ultrasound would be less useful in both patients with more generalized presentations (such as those found down for an unknown amount of time) or those where the index of suspicion is high (such as crush injuries) where treatment will be started immediately.