Somatosensory and brainstem auditory evoked potentials in neurodegenerative system disorders.

Brainstem auditory (BAEP) and somatosensory (SEP) evoked potentials to median and peroneal nerve stimulation were investigated in 25 patients with neurodegenerative system disorders: 9 Friedreich's ataxia, 7 hereditary motor sensory neuropathies, 3 familial spastic paraplegia, 3 olivopontocerebellar atrophy, 1 ataxia telangiectasia and 1 abetalipoproteinemia. BAEPs were abnormal in 39%, SEPs to both upper- and lower-limb stimulation were abnormal in 63%. Serial evoked potential testing paralleled the clinical progression. SEPs were more frequently and severely altered than BAEPs suggesting that SEP testing may be a more sensitive indicator of early involvement of afferent pathways in these disorders.