Pruritus: do Aδ fibers play a role?

Neuropathological and molecular basis of pruritus has not been clarified and the presence of certain specific neural circuits have been proposed. Our aim in this study was to evaluate the role of Aδ fibers in the neural circuits of pruritus by cutaneous silent period (CSP). Thirty-six patients with chronic idiopathic generalized pruritus and 32 healthy controls were enrolled in the study. CSP and nerve conduction studies of upper and lower extremities were performed in both groups. Latencies of CSP in the upper and lower extremities were observed to be prolonged in the patient group compared with the controls while durations were shortened (all P < 0.001). However, these values were not correlated with sex, age, duration or severity of the disease (all P > 0.05). Our data suggest that pruritus may be developed by a nerve conduction abnormality in the afferent fibers of Aδ, or cortical hypersensitivity, abnormality of the cortical inhibitory mechanisms or lack of inhibition in the intermediate spinal inhibitory neurons generating CSP. This topic needs to be evaluated thoroughly in larger series with more detailed studies.