I16 Pain Stimuli Processing In Pre-symptomatic And Early Huntington's Disease

Abstract

Huntington’s disease is a neurodegenerative genetical autosomal dominant disorder, caused by an abnormal expansion of CAG on the IT-15 gene which results in movement, cognitive and psychiatric disorders. Data suggest that the basal ganglia may be involved in the sensory-discriminative, affective and cognitive dimension of pain, as well as modulation of nociceptive information and sensory gating of nociceptive information to higher motor area. A delay in nociceptive input processing emerged in HD patients, concurring with the main features of the disease, in absence of clinical evidence of abnormalities in pain perception. Recent theories about Laser Evoked Potentials (LEPs) outlined that they reflect cortical–not pain specific activation through salient stimuli, probably preparing to motor action. In this sense HD patients seem to be affected by a slowing in detecting salient stimuli, potentially related to a motor activation. This may be relevant for sensory-motor integration. The aim of the present study was to evaluate evoked responses by laser stimuli (LEPs) and auditory event related potentials (Auditory ERPs) in pre-symptomatic and early Huntington’s disease (HD) patients. Ten HD patients, 10 pre-symptomatic subjects (pre-HD) and 20 controls subjects were selected. LEPs were obtained by 62 scalp electrodes, stimulating the dorsum of right hand. All patients were also evaluated by Auditory ERPs. Preliminary results confirm LEPs N2 latency increase in HD patients in respect to controls, while no difference was detected in comparison with pre-HD. An amplitude decrease of LEPs late P2 component emerged, concurring with Auditory ERPs reduction in both HD patients and pre-HD in respect of controls. HD patients and pre-HD may be characterised by a disturbance in salient stimuli processing, with a reduced activation of cortical zones devoted to stimuli processing and motor response planning (cingulate). This may explain a normal pain perception, with a probable deterioration of voluntary and involuntary motor reaction and pain syntoms expression.