Magnetic resonance neurography-supported L3-L4 radiculitis presenting as refractory peripatellar neuropathic pain in a patient with diabetes: A case report.
Xue Huang, Dan Yang, Jie Wang et al.
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Case in brief
A 75-year-old man with longstanding type 2 diabetes developed severe burning, stabbing pain around the left kneecap, with numbness and touch-evoked allodynia but no back pain, typical radicular symptoms, weakness, or reflex changes. Knee MRI showed degenerative findings that did not account for the neuropathic features; lumbar MRI showed no definite L3 or L4 root compression, and electrodiagnostic testing did not localize the lesion. Magnetic resonance neurography demonstrated asymmetric signal abnormality in left proximal L3-L4 neural structures, supporting radiculitis. After medication adjustment and glycemic optimization, symptoms improved; at 3 months, pain and allodynia were markedly reduced or resolved.
What made this case unusual
The radiculitis presented predominantly as peripatellar neuropathic pain, without typical radicular symptoms, and was supported by neurography despite no definite root compression on conventional lumbar MRI.
Diagnostic / clinical pearl
When neuropathic pain around the knee is unexplained by local findings, consider a proximal neural source even without back pain or classic radicular symptoms; magnetic resonance neurography may help when conventional imaging is nondiagnostic.