Idiopathic lumbosacral plexitis

Idiopathic lumbosacral plexitis (LSP) or non-diabetic lumbosacral radiculoplexus neuropathy (LRPN) is a rare monophasic immune-mediated disorder. The disease is characterized by multiple lumbosacral root and nerve involvement in the absence of trauma, mass lesion or elevated blood sugar. We report a 60-year-old man presenting with a 4-day history of acute-onset sharp left hip pain radiating down his leg associated with numbness over the lateral dorsum of his left foot. MRI of the lumbosacral plexus revealed gadolinium enhance¬ment of mainly L5 on the left. A dramatic response to oral steroids was observed.