Somatosensory evoked potentials at rest and during movement in Parkinson's disease: evidence for a specific apomorphine effect on the frontal N30 wave

Sensory and motor evoked potentials in multiple system atrophy: A comparative study with Parkinson's disease

“…The latencies of the main cervical and cortical SEP components were normal, thus confirming indirectly the low incidence of peripheral nerve conduction abnormalities in MSA (2.5). Unlike previous reports (1)(2)(3), the average ratios between parietal N20 and frontal N30 components (P/F index) were not different in patients with parkinsonism (either MSA or PD) compared with normal controls, suggesting that the amplitude of the frontal N30 potential is depressed only in a small percentage (<15% in this series) of patients (5,7). The reason for the discrepancy of findings about N30 behavior in parkinsonian patients is uncertain and is most probably related to selection criteria, such as illness duration or previous medication, as has already been suggested (3,6).…”

“…However, later studies have reported conflicting results, some groups supporting the N30 depression (2,3) and others finding no SEP abnormalities ( 4 3 or SEP abnormalities without a clear clinical correlate (6,7).…”

Lateralization of the P22/N30 precentral cortical component of the median nerve somatosensory evoked potentials is different in patients with a tonic or tremulous form of cervical dystonia

“…Comparing parkinsonian patients with the healthy population, a relative decrease in N30 component was found, and the potentiation of this component was detected after administration of apomorphine, a dopaminergic agonist. 2,7,8 On the other hand, other investigators have failed to find the putative impairment of the N30 component in Parkinson's disease [9][10][11] or its potentiation by dopaminergic drugs, even in animal models. 12,13 In dystonic patients with either generalized or focal dystonic syndromes, a relative increase in the N30 and P22/N30 amplitudes was found.…”

Somatosensory input to non-primary motor areas is enhanced during preparation of cued contraterlateral finger sequence movements

“…N30 peak amplitudes are significantly depressed in individuals with Parkinson's disease [47][48][49][50][51][52][53] but are increased with apomorphine (dopamine-agonist) injection [52][53][54] and deep brain stimulation of internal globus pallidus or subthalamic nuclei [54]. As noted above, increased rCBF has been documented in bilateral globus pallidus and putamen with increased movement sequence complexity [16].…”