Complex regional pain syndrome in a patient with an idiopathic lumbosacral radiculoplexus lesion: A Case Report

Introduction: Complex regional pain syndrome (CRPS) of the lower extremity can occasionally occur without an obvious precipitating cause.Case presentation: A 59-year-old female developed swelling, pain, and motor weakness in the left ankle without any trauma or systemic illness.Initial workup for musculoskeletal and infectious causes was unremarkable.The patient's symptoms fulfilled the Budapest criteria for CRPS, and she was treated conservatively with no improvement.Neurological examination revealed proximal weakness, prompting EMG, which showed neurogenic involvement from L4-S1.Subsequent contrast-enhanced lumbosacral MRI (neurography) demonstrated thickening and enhancement of the left L5 nerve root, consistent with plexitis.An idiopathic lumbosacral radiculoplexus lesion was diagnosed.The patient's symptoms gradually improved with gabapentin and a tramadol-paracetamol regimen.Conclusion: This case highlights a rare coexistence of CRPS with idiopathic lumbosacral radiculoplexopathy.In CRPS patients refractory to standard treatments, clinicians should consider proximal nerve lesions.EMG can localize such lesions, and targeted MRI can confirm inflammatory radiculoplexus neuropathy.