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What This Guide Helps With
Loss of EEG signal, excessive artifact, or poor waveform quality caused by electrode issues, connections, or setup errors.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Do not troubleshoot while electrodes are connected to an active patient study unless clinically appropriate
- Pause or stop the recording if needed
Expected: Patient is safe and monitoring can be resumed later
Why it matters: Prevents disruption of clinical care and ensures safe handling of leads
Verify the Reported Signal Issue
- Observe the EEG display for flat lines (no signal)
- Check for excessive noise or artifact
- Look for intermittent or drifting signals
Expected: Issue is clearly visible and reproducible
Why it matters: Confirms whether this is a global issue or isolated to specific channels
Check Electrode Placement and Skin Preparation (Most Common Cause)
- Ensure proper placement per montage
- Verify skin prep (clean, dry, lightly abraded if required)
- Confirm conductive paste/gel is applied
Expected: Improved signal quality after proper prep
Why it matters: Poor skin contact is the most common cause of high impedance and bad signals
Check Electrode Impedance Values
- Use the system’s impedance check function
- Verify impedance is within acceptable range (typically <5–10 kΩ depending on protocol)
- Re-prep or reapply electrodes with high impedance
Expected: Balanced and acceptable impedance across channels
Why it matters: High or uneven impedance leads to noise and unstable signals
Inspect Lead Wires and Headbox Connections
- Ensure electrodes are securely connected to lead wires
- Verify lead wires are fully seated in the headbox/amplifier
- Look for damaged or frayed cables
Expected: Stable signal when connections are secure
Why it matters: Loose or damaged leads cause intermittent or absent signals
Check for Environmental or Electrical Interference
- Move cables away from power cords or other equipment
- Ensure proper grounding of the system
- Turn off nearby non-essential electrical devices
Expected: Reduction in noise/artifact
Why it matters: External interference can mimic poor electrode quality
Verify Amplifier/Headbox Detection
- Confirm the amplifier/headbox is recognized by the system
- Ensure all cables between amplifier and acquisition computer are connected
- Restart acquisition software if needed
Expected: System detects hardware and channels respond
Why it matters: Hardware communication issues can appear as no signal
Perform a System Restart
- Close acquisition software
- Power cycle the amplifier and computer
- Reopen software and test signals
Expected: Normal signal returns if issue was software-related
Why it matters: Resolves temporary software or communication faults
Swap Components to Isolate the Issue
- Try a known-good electrode
- Swap lead wires or headbox
- Test another input channel
Expected: Identification of faulty component
Why it matters: Confirms whether the issue is accessory-related or system-related
If the Problem Persists
If electrode placement, impedance, connections, and environmental factors have been ruled out, the issue is likely internal (amplifier or acquisition system).
Remove the device from service, label it Out of Service, and send for repair or bench evaluation.
Knowing when to stop prevents unnecessary downtime and protects patient care.
Clinical Use Tip
Always ensure the patient is disconnected or monitoring is safely paused before adjusting electrodes or leads. Never troubleshoot during active critical monitoring unless clinically approved.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"EEG system showing no signal on multiple channels during patient setup."
Cause
What was observed during troubleshooting.
Example:
"Poor electrode contact and high impedance due to inadequate skin preparation."
Resolution
What action was taken.
Example:
"Re-prepped skin, reapplied electrodes, and verified impedance within acceptable range; normal signal restored."
Helpful Details to Include (If Known)
- Electrode impedance readings
- Specific channels affected
- Cables or electrodes swapped
- Presence of artifact or flatline
- Amplifier detection status
- Environmental interference observed
- Final system status (working or removed from service)
Final Thought
EEG signal issues are most often caused by electrode preparation, impedance imbalance, or connection problems. A structured, external-first approach ensures quick resolution while maintaining patient safety. Proper documentation and escalation when needed are key to effective Clinical Engineering support.
That is successful troubleshooting.