Inflammatory Diabetic Neuropathy: Helpful Diagnostic Parameters.

Objectives: Mild inflammatory diabetic neuropathies (IDNs) overlap with diabetic sensorimotor neuropathy (DPN) in clinical presentation and electrophysiological and laboratory tests. This study is to determine whether IDN can be differentiated from DPN by clinical features, electrophysiological, pathological, or laboratory tests.

Methods: Suspected IDN cases were identified by a subacute onset and progressive sensory or motor neuropathy in patients with diabetes.

Results: IDN occurred earlier in the course of diabetes mellitus and had higher prevalence of limb weakness, walking difficulty, and more severe electrophysiological abnormalities suggesting both demyelination and axonal loss. Sensory nerve biopsies in IDN showed perivascular inflammatory infiltrates, decreased fiber density, increased demyelination, and axonal degeneration. Most patients with IDN improved with immunotherapy.

Conclusions: Features that favor IDN over DPN are limb weakness, more severe nerve conduction abnormalities, inflammatory infiltrates on nerve biopsy, and a favorable response to immunotherapy. A nerve biopsy can help establish an inflammatory cause.