[Comparative investigation of somatosensory spinal and cortical evoked potentials in children (author's transl)]

Somatosensory spinal (spinEP) and primary cortical evoked responses (ssEP) to median and tibial nerve stimulation (at forefinger, wrist, and ankle respectively) were investigated by means of summation techniques in 23 normal children aged 6 to 14 years. Amplitude recovery functions of cervical spinEP were tested by paired stimuli and short tetanic stimulation at the wrist; spinEP amplitudes were unchanged for stimulus intervals down to 5 ms. The amplitudes of the cervical spinEP after strong stimuli to the finger were only a quarter as great as those obtained by stimulation of the wrist at motor threshold strength. In one patient with the Brown-Séquard syndrome cervical spinEP were absent for stimuli on the side of position sense impairment, but were unaffected for stimuli on the side of dissociated sensory loss. The normal latencies of spinEP (to the onset of the negative potential) and ssEP (to first negative peak) are presented as functions of body height. The difference between these two latencies yielded a central latency from the lower cervical spinal cord of about 9--10 ms. The spinal afferent conduction velocity, calculated from the difference between the lumbar and cervical latencies after tibial nerve stimulation at the ankle, was found to be 74m/s.