Abnormal spinal cord pain processing in Huntington's disease. The role of the diffuse noxious inhibitory control

Objectives: Our study is aimed to evaluate the spinal cord pain processing in Huntington's disease (HD) by testing both the temporal summation threshold (TST) of the nociceptive withdrawal reflex (NWR) and the functional activity of the diffuse noxious inhibitory control (DNIC) as form of supraspinal control of pain. Methods: We enrolled 19 HD patients and 17 healthy controls. We measured threshold (Th), Area, TST and related psychophysical pain sensations of the NWR, at baseline and during and after activation of the DNIC by means of cold pressor test (CPT) as heterotopic noxious conditioning stimulation. Results: In HD patients we found a significantly higher Th and TST as well as a lower Area when compared to controls. During the CPT, a significant inhibition of reflex and psychophysical pain responses were found in both HD patients and controls when compared to baseline, without differences between the groups in CPT results. Conclusions: Our study demonstrated an abnormal spinal cord pain processing in HD patients. Abnormalities in pain processing are not apparently linked to a dysfunctional DNIC inhibitory projection system in HD patients. Significance: Our findings support the hypothesis that the striatum could play a role in pain modulation and that its atrophy could affect pain processing without change the DNIC efficiency. (C) 2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.