P985: Diabetic small fibre neuropathy diagnosis: a comparison between the diagnostic accuracy of skin biopsy and laser evoked potentials

Abstract

Small fibre neuropathy related to diabetes is a condition characterized by a selective involvement of nociceptive fibres. The currently recommended method for assessing diabetic small neuropathy is the skin biopsy, that assess cutaneous C-fibres. Laser evoked potentials mediated by A δ -fibres is a widely accepted neurophysiological method for assessing nociceptive pathways. We aimed at comparing the diagnostic accuracy of LEPs and skin biopsy in the diagnosis of diabetic small fibre neuropathy. We screened 93 diabetic patients with distal sensory disturbances that, on the basis of clinical examination and standard nerve conduction study, were divided into three subgroups: pure small fibre neuropathy (15 patients), pure large fibre neuropathy (28 patients) and mixed fibre neuropathy (50 patients). Patients with small-neuropathy and pure large fibre neuropathy underwent LEP recordings and skin biopsy. Using the skin biopsy as the gold standard for assessing the small fibre neuropathy LEPs showed a sensitivity of 100% and a specificity of 91%. Our data suggest that LEPs have a diagnostic accuracy comparable to that of the skin biopsy in the diagnosis of diabetic small fibre neuropathy.