[P3 after acoustic and somatosensory stimulation in patients with Huntington disease].

Sixteen Huntington patients (HD) (mean age 43.7 years) were studied and compared to 12 risk people for Huntington disease (HR) (mean age 31.2 years) and 25 normal people (mean age 33.2 years). A simple auditory or somatosensory paradigm was used requiring counting of the rare target stimulus. For the normal subjects, most of the recordings showed a slightly earlier latency for the P3 component of the ERPs with the auditory paradigm (P3A). For the HD, a clear P3 was observed in both modalities in 8 patients, in 5 cases no P3 for both stimuli and in 3 cases no P3 for the somatosensory paradigm (P3S) only. The mean value of the P3A latencies was increased compared to the normal control group and after the age effect correction. The mean value of the P3S is significantly more increased compared to the normal group and the "expected" value, according the P3A latencies. This dissociation is constant in all HD when the P3S is recorded and could be due to the fact that the endogenous component is also related to the stimulus modality (increased difficulty and/or subclinical abnormality in the somatosensory modality).