1411 - Post-Cardiac Ablation Anterior Thigh Pain: Uncovering Femoral Neuropathy through Electrodiagnostics and Treatment with Ultrasound-Guided Injection

Iatrogenic femoral neuropathy following cardiac ablation with femoral artery access, suggested by electrodiagnostic findings and effectively treated with an ultrasound-guided fascia iliaca steroid injection.

Case Description:

A 78-year-old male with L5–S1 lumbar radiculopathy, end-stage right knee osteoarthritis, chronic kidney disease stage 3, and atrial fibrillation on rivaroxaban underwent right femoral artery access for cardiac ablation as preoperative clearance for total knee arthroplasty. Within 24 hours, he developed new severe groin pain, ecchymosis, and neuropathic pain radiating from the anterior thigh to the medial calf, distinct from prior radicular symptoms. Exam revealed antalgic gait, decreased anterior thigh sensation, depressed patellar reflex, and preserved quadriceps and iliopsoas strength.

Inguinal ultrasound, CT abdomen/pelvis, and vascular studies showed no vascular injuries. Electrodiagnostic findings in January 2025 demonstrated markedly reduced femoral motor amplitudes on the affected side and polyphasic units in the quadriceps, suggestive of femoral neuropathy but without active denervation. In April 2025, an ultrasound-guided fascia iliaca steroid injection produced rapid pain relief and durable resolution of neuropathic symptoms for over four months.

 

Discussions:

This case highlights diagnostic challenges of anterior thigh pain in patients with overlapping lumbar and musculoskeletal pathology. Despite negative imaging, electrodiagnostic testing provided supportive evidence for femoral neuropathy, though interpretation was limited by absence of contralateral saphenous responses and active denervation. Recognition of these limitations is important in clinical decision-making. Ultrasound-guided fascia iliaca injection provided diagnostic confirmation, and a minimally invasive, therapeutic benefit in an anticoagulated patient. Early recognition of iatrogenic femoral neuropathy after vascular access can prevent misdiagnosis, guide targeted interventions, and optimize patient function and outcomes.

Conclusions: Iatrogenic femoral neuropathy is a rare but significant complication of femoral access for cardiac ablation. When imaging is inconclusive, electrodiagnostics can provide supportive evidence. Ultrasound-guided steroid injection offers both diagnostic confirmation and therapeutic benefit, highlighting the essential role of physiatrists in managing post-procedural neuropathies.