Diabetic Neuropathy--A Review

Gérard Said


Nat Clin Pract Neurol. 2007;3(6):331-340. 

In This Article

Diagnosis of Diabetic Neuropathy: Nerve Conduction Studies

In symptomatic diabetic neuropathy, there is slowing of nerve conduction velocity owing to demyelination and loss of large myelinated fibers, and a decrease in nerve action potentials owing to loss of axons.[39,56,57] Purely demyelinative neuropathy is rare in patients with diabetes, and is more suggestive of a demyelinative neuropathy of inflammatory or dysglobulinemic origin.[58] Systematic electrophysiological testing is not necessary in diabetic patients with typical peripheral neuropathy. Changes in conduction velocity can be detected in asymptomatic patients, but their presence is not predictive of the onset of symptomatic neuropathy.

Nerve conduction studies (NCS) are the most objective noninvasive measures of nerve function. They represent a valuable tool of evaluation of neuropathy in large clinical and epidemiological studies.[59] In clinical practice, however, NCS should not be considered a substitute for careful clinical examination, because NCS have many pitfalls and their results must be interpreted in the context of clinical data. In the case of LDDP, as in all small-fiber polyneuropathies, the main drawback of NCS is that small myelinated and unmyelinated nerve fibers, which are affected early in the disease course of diabetic neuropathy, do not contribute to the sensory action potential detected by routine NCS. The sensory action potential is altered only after involvement of larger myelinated fibers, which is often a late event in patients with diabetes. Electrophysiological data must, therefore, always be evaluated in a clinical context.


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