822 - Lumbosacral Plexopathy following Neuroblastoma Resection in a 2-year-old

A previously healthy 2-year-old male underwent large neuroblastoma resection on June 18, 2025. Postoperatively, he demonstrated reduced movement of the left lower extremity with inability to bear weight secondary to swelling and pain. Initial duplex ultrasound and radiographs were negative. PMR recommended MRI of the lumbar plexus, which demonstrated edema and enhancement of the left L3–L5 and sacral nerve roots, concerning for traction or inflammatory injury.  Neurology was consulted, he was treated with high-dose intravenous steroids followed by an oral taper, and discharged with improvement.

About a week after discharge, physical therapy and family noticed increasing pain and decline in weight bearing. He was re-hospitalized with electromyography showing severe patchy lumbosacral plexopathy with active denervation affecting L5, obturator, and sciatic distributions. Lumbar plexus MRI again showed edema with possible evolving neuroma. Robust improvement occurred only after repeat steroids and intravenous immunoglobulin (IVIG) with multimodal neuropathic pain management and physical therapy.

Discussions: This case underscores the difficulties in diagnosing and treating postoperative plexopathies in children, especially in the very young.  While corticosteroids are standard, IVIG is not a routine treatment in this context. Adult literature supports IVIG use in idiopathic (non-immune mediated) plexopathies, though pediatric evidence remains sparse. This case suggests IVIG may warrant consideration in refractory, presumed inflammatory plexopathies even with negative autoimmune testing, particularly when functional recovery is at risk or response to corticosteroids is not sustained.

Conclusions: Postoperative plexopathies in pediatric oncology are rare but can cause profound functional impairment. Early recognition and multidisciplinary rehabilitation are critical to optimizing outcomes.