Table 2 Stimulation and recording parameters for the MEP, SEP, and EMG monitoring

Stimulation point

Cz (anode)/Cz + 6 cm (cathode)

Posterior N. tibialis (bilaterally) cathode: proximally between Achilles tendon und Malleolus medialis anode: 2-3 cm distal

-/-

direct nerve root stimulation

Stimulation technique

transcranial, high frequency ("multipulse-technique) scalp-screw electrodes

adhesion electrodes

-/-

bipolar stimulation probe, monophasic square impulse

Stimulation frequency

500 Hz, "train of 5"

4.7 Hz

-/-

3.0 Hz

Impulse duration

0.3 ms

0.2 ms

-/-

0.1 ms

Stimulation intensity

max. 100 mA

max. 60 mA

-/-

max. 2 mA

Recording technique

bipolar, subdermal needle electrodes

scalp-screw electrodes

bipolar, subdermal needle electrodes

bipolar, subdermal needle electrodes

Recording location

M. vastus lateralis,

Cz'- Fpz

(L2)/L3/(L4) - M. vastus lateralis,

(L2)/L3/(L4) - M. vastus lateralis,

M. tibialis anterior,

M. peronaeus longus,

L4/(L5)/(S1) - M. tibialis anterior,

L4/(L5)/(S1) - M. tibialis anterior,

M. gastrocnemius,

L5/(S1) - M. peronaeus longus,

L5/(S1) - M. peronaeus longus,

M. sphincter ani QI/II,

M. sphincter ani QIII/IV

S1 - M. gastrocnemius,

S1 - M. gastrocnemius,

S2/3 - M. sphincter ani QI/II,

S2/3 - M. sphincter ani QI/II,

S4/5 - M. sphincter ani QIII/IV

S4/5 - M. sphincter ani QIII/IV

Recording potential

CMAP

P40/N50

multichannel EMG activity

multichannel EMG activity

(500-2000 signals averaged)

Filter settings

100-1500 Hz

30-1000 Hz

100-5000 Hz

100-5000 Hz

Presentation

visual

visual

auditory & visual

auditory & visual

100 msec, 200 μV/div

100 msec, 10 μV/div

200-500 msec, 10-200 μV/div

200-500 msec, 10-200 μV/div