361 - A Case of Atypical Low Back Pain in a Warfarin-dependent Male

Case Diagnosis: Left lumbosacral plexopathy in a 78-year-old male.

Case Description: A 78-year-old, warfarin-dependent male was walking his dog. The dog suddenly pulled the leash as the patient pulled back without falling. The following day he awakened with low back pain radiating to his left lower extremity, and difficulty walking. At the emergency room (ER), the patient received symptomatic management with intramuscular pain medication. Throughout the following 3 weeks the patient developed progressive left lower extremity weakness and numbness. He was re-evaluated at a different ER, warranting admission. Pain radiated from lower back towards left flank, anterior thigh and medial leg, with associated paresthesia. Examination found weakness in left hip flexion, hip adduction, and knee extension, patellar hyporeflexia, thigh fasciculations, and a visible left flank hematoma. Findings were concerning for lumbosacral plexopathy. Abdomen and pelvis CT found a left retroperitoneal hemorrhage within the quadratus lumborum and iliopsoas. Electrodiagnostic studies (EDX) confirmed a left lumbosacral plexopathy.

Discussions: The patient's initial presentation was acute low back pain after a sudden pulling injury. However, this case presented with several red flags eventually leading to further evaluation and intervention. Past medical history included warfarin-dependence due to a bioprosthetic mitral valve replacement. The patient presented focal weakness, numbness and paresthesia, fasciculations, and hyporeflexia. After CT found retroperitoneal hemorrhage, EDX confirmed our suspicion of a left lumbosacral plexopathy, affecting mostly the lumbar plexus. The patient received fresh frozen plasma and underwent embolization of the left internal iliac artery. After rehabilitation, he recovered strength and was able to ambulate with a rolling walker.

Conclusions: This case highlights the importance of assessing for red flags in low back pain. EDX continues to be a crucial tool in evaluation of suspected lumbosacral plexopathy, providing information of chronicity, activity and distribution of injury.