A Study of the Frontal Components of P22 and N30 of Somatosensory Evoked Potentials Following Median Nerve

正中神経刺激による体性感覚誘発電位の基礎的・臨床的研究 : とくにP22, およびN30を中心として

A Study of the Frontal Components of P22 and N30 of Somatosensory Evoked Potentials Following Median Nerve

Creators Hirata Ikuo

Frontal components of P22 and N30 of somatosensory evoked potentials following median nerve stimulation were studied in 25 normal young adults and 15 patients with a unilateral focal cerebral lesion. Somatosensory evoked potentials were recorded from the 8 places over the scalp with the reference to the ipsilateral ear, following the stimulation of the right and left median nerve, respectively. In normal subjects, following left median nerve stimulation, mean peak latencies of P22 and N30 were 18.9 msec and 27.5 msec on the contralateral frontal area and those of the postrolandic components of N2^^-0^^- and P2^^-3^^- were 18.1 msec and 22.8 msec on the contralateral hand sensory area. There were no significant right to left difference. The scalp distribution of each potential was as follows : P22 was restricted to the contralateral frontal region and, simultaneously, N2^^-0^^- was found in the cotralateral posterior quadrant. N30 was more widely distributed in the bilateral frontal area. In patients with a capsular lesion, the amplitude of P22 decreased significantly and the degree of its decrease correlated to the decrease in the amplitude of N2^^-0^^-. And the amplitude of P22 also decreased in patients with sensory disturbance. Meanwhile, N30 did not decrease significantly in the patient group, except for the cases in which N30 was absent. Those findings suggest that P22 arises from a dipole generator in the sensory cortex with postrolandic negative component, N2^^-0^^-. It is thought that two dipole generators correlate to the production of both N30 and P2^^-3^^- components : the majority of the N30 is subcortical origin and P2^^-3^^-, for the most part, arises from the sensory cortex.

[ISSN]0513-1731

[NCID]AN00243156