Painful polyneuropathy in patients with and without diabetes: clinical, neurophysiologic, and quantitative sensory...

To study pain characteristics and peripheral nerve involvement in patients with painful diabetic and nondiabetic polyneuropathy in comparison with patients with non-painful polyneuropathy.

Fifty-five patients with polyneuropathy (37 with painful polyneuropathy, of whom 19 had diabetes and 18 had no diabetes; and 18 with painless polyneuropathy of different etiologies) were examined clinically using quantitative sensory tests and neurophysiology. Pain intensity and characteristics were analyzed by daily ratings on a 10-step verbal scale and by a questionnaire.

Most patients experienced pain of more than one character. There was no clear difference in character or duration of pain between patients with and without diabetes. The mean value of the daily rating of pain intensity showed that pain was more severe in the evenings than in the mornings and that diabetic patients reported worse pain than nondiabetic patients. Thirty-two of the 37 patients with pain had paresthesias and/or dysesthesias, whereas only 7 of 18 patients without pain had paresthesias. Pain was always located in the feet, and, in most patients, also in the lower part of the legs. Some patients also experienced pain in the hands. Tactile sensibility, measured by quantitative tests, was more affected in both diabetic and nondiabetic patients with painful polyneuropathy compared with patients without pain (p = 0.02). Temperature, pain, and vibratory sensibility were equally affected in all patient groups. Nerve conduction velocity, amplitudes, and distal latency were equally affected in the pain group as compared with the control group, indicating that both thin and thick nerve afferents are affected in patients with painful as well as non-painful polyneuropathy and that etiology has no clear impact on nerve involvement.

Neuropathy pain was always located in the feet and more severe in diabetic patients compared with patients with neuropathy pain of other etiologies. The authors also found evidence for a greater tactile sensibility involvement in patients with neuropathy pain, irrespective of etiology, whereas other quantitative sensibility and neurography parameters were equally affected in all patient groups.