A Waves in Diabetic Neuropathy: Pathophysiology and Neurographic Images

To evaluate the presence of A waves in diabetic neuropathy, we designed a retrospective observational study recruiting patients with type II diabetes and chronic diabetic distal sensorimotor polyneuropathy.

We recruited 238 patients of both sexes aged between 41 and 89 years. Neurography was undertaken on two bilateral upper (median and ulnar) and lower (peroneal and tibial) limb nerves. As controls, we considered that neurographs performed bilaterally on the same nerves of 40 healthy subjects.

In addition to neurographic changes typical of chronic distal sensorimotor neuropathy, patients had a 32.77% incidence of A waves, mostly found in the tibial (16.38%) and peroneal (8.8%) nerves. Among controls, A waves were found only in the tibial nerve of a single subject (2.5%). Chi-square test with Yates correction to compare the two percentages (32.77% of patients and 2.5% of healthy subjects): 13.98, P = 0.0002, highly significant.

We postulate that demyelination may be the site of backfiring or slowing of nerve conduction velocity, explaining the appearance of A waves in their different varieties. Implementing the search for A waves in routine neurographic examination can be a useful option for the diagnosis of neuropathy and the prediction of possible latent neuropathic processes.