Pain-related and electrically stimulated somatosensory evoked potentials in patients with Machado-Joseph disease and multiple system atrophy.

We investigated the ascending somatosensory pathway for pain in 8 patients with Machado-Joseph disease (MJD) and multiple system atrophy (MSA). Pain-related somatosensory evoked potentials (pain SEPs) by CO2 laser stimulation were examined together with conventional electrically stimulated somatosensory evoked potentials (electric SEPs). The sporadic cerebellar ataxia of patients with MSA showed a normal pattern of pain SEPs as well as electric SEPs. However, pain and electric SEPs were abnormal for the central and/or peripheral ascending pathway in MJD. These abnormalities of pain and electric SEPs in MJD were not related to the clinical severity of sensory impairment, but they indicate that MJD presents a subclinical abnormality for the ascending somatosensory pathways not only for vibratory sense but also for pain sense.