INTRA-OPERATIVE NEUROPHYSIOLOGICAL MONITORING (IONM):
INOMED IONM system was used in this patient (Figure 3 ).
Modalities consisting of Free-run EMG and Triggered EMG for identifying
and mapping vital nervous tissue were planned. The disposable needle
electrodes (27 gauge) were positioned in the quadriceps (L2-4), anterior
tibialis (L4-5), abductor hallucis (S1-2), and external anal sphincters
(S2-4), groups of muscles that are innervated by the nerve roots and are
at the highest risk of injury during the release of the tethered cord.
Filters between 20 Hz (High Pass) and 2000 Hz (Low Pass), 50 Hz (Notch),
gain 100 V/division, and time base five m/div were used to create the
recording conditions for free-run and triggered EMG [8].