Users Manual Part 1
16
Nerve Integrity Monitor
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1 Scale. Displays screen scale settings.
2 Settings button.
3 Save Prole button (only when settings have been
changed, but not saved into a prole).
4 Trace. Display stimulus nerve activity/inactivity.
5 Adjust view.
6 Snapshot button.
7 Freeze button (when activated).
8 Measure button (when activated).
9 Check Electrodes button.
10 Baseline button (only active if the user activates it
on the settings panel).
11 Channel label. Displays the channel number and
nerve being monitored.
12 Amplitude.
13 Stim panels.
14 Stim return value.
15 Threshold panel.
16 Show details button. Provides access to event
capture and adjust threshold.
17 Volume panel. Adjust the system volume.
EMG display area
The amplitude displays activity level in microvolts on each channel:
• A box encloses the activity level of the highest channel.
• If there are multiple channel events, the box encloses the largest.
• If the system detects a signal (response) outside the range of the system’s ability to measure (100,000 μV or higher), the system
displays the “Out of Measurement Range” message.
Recognizing stimulus artifacts
Stimulus artifact is a monitoring term for an artifact created by stimulus voltage delivered to the patient, which is picked up as
feedback either internally or externally to the monitoring equipment. It is normally small and does not impact monitoring but can,
under certain conditions, be displayed and sounded on the monitor. It is important to understand the NIM system’s visual and audio
feedback so as not to confuse the stimulus artifact with real EMG, or recognize if both the stimulus artifact and real EMG are present
at the same time.
The on-screen stimulus artifact, when it appears on the monitoring panel display, is seen as an event (above or below threshold)
which starts directly after the stimulus on the left side of the screen and proceeds for a duration into the EMG waveform detection
area. The level of the artifact is directly proportional to the stimulus delivery and cannot be EMG because nerve signals need time
propagate.
The stimulus artifact sound is the audio representation of stimulus artifact. It is a high frequency sound similar to cymbals and
sounds like “ti - - tchi.” It is unlike an EMG sound which is similar to a drum sound.
The stimulus rejection period enables you to lter the stimulus artifact (electric noise caused by stimulation) and all other signals in
this period.
FCC use only, not for Medical use