BACKGROUND: Peripheral nerve injuries can occur perioperatively and postoperatively. While ultrasound cannot determine etiology, it helps evaluate suspected peripheral nerve injury. This paper describes sonographic findings in 2 patients who developed peripheral nerve injuries and subsequent complex regional pain syndrome type II following lower extremity surgery with popliteal catheter placement.

CASE REPORT: Case 1: A 53-year-old woman developed neuropathic pain after lower extremity surgery with popliteal catheter placement. Ultrasound performed at 6 weeks revealed disrupted fascicular architecture, altered echogenicity, and enlargement of the right fibular and tibial nerves, each more than twice the cross-sectional area of the corresponding contralateral nerve. She was subsequently diagnosed with complex regional pain syndrome type II.

Case 2: A 27-year-old man developed neuropathic pain and paresthesia following lower extremity fixation with popliteal catheter placement. Ultrasound performed at 9 weeks demonstrated distorted fascicular architecture, altered echogenicity, and enlargement of the right sciatic, tibial, and fibular nerves compared with the corresponding contralateral nerves. He was subsequently diagnosed with complex regional pain syndrome type II.

CONCLUSIONS: Ultrasound serves as a valuable adjunct to electrodiagnostic testing for comprehensive peripheral nerve injury evaluation.

KEYWORDS: Ultrasonography; peripheral nerve injury; electrodiagnostic testing; complex regional pain syndrome; sciatic nerve; case series