What are the contraindications for quantitative electroencephalography (qEEG) in various patient populations, including those with implanted medical devices, history of seizures, metal implants, acute head injury, increased intracranial pressure, or pregnancy?

Contraindications for Quantitative EEG (qEEG)

There are no absolute contraindications to performing qEEG or standard EEG in any patient population, including those with implanted medical devices, metal implants, history of seizures, acute head injury, increased intracranial pressure, or pregnancy.

Key Evidence on Safety Across Patient Populations

Implanted Cardiac Devices

• Cardiac pacemakers do not contraindicate EEG, despite manufacturer warnings—observational data demonstrates no interference between EEG and pacemaker function, and no loss of EEG image quality with pacemaker use 1
• Less data exists for implantable cardioverter defibrillators and left ventricular assist devices, though available evidence suggests safety 1

Metallic Implants and Skull Defects

• Metallic skull plates and cranial implants are not contraindications to EEG—the procedure involves only recording electrical activity, not delivering electrical current 2
• EEG has been safely performed in patients with skull defects, metallic plates, and cranial prostheses following traumatic brain injury 2
• Subdural electrode grids can be safely implanted even in patients with previous cranial surgery, though this invasive monitoring carries separate surgical risks 3, 4

History of Seizures

• Seizure history is actually an indication for EEG, not a contraindication—EEG is strongly recommended for all patients with altered consciousness and unexplained neurological deficits 1, 5
• Patients with known epilepsy routinely undergo EEG monitoring, including continuous monitoring for days to weeks 6

Acute Head Injury and Increased Intracranial Pressure

• EEG can be safely performed in patients with acute brain injury—it is recommended for all patients with acute brain injury and unexplained persistent altered consciousness 1
• The only relevant contraindication relates to lumbar puncture (for CSF analysis), not EEG, when increased intracranial pressure is present 1
• EEG is non-invasive and does not affect intracranial pressure 1

Pregnancy

• Pregnancy is not a contraindication to EEG—the procedure involves no radiation, no contrast agents, and no electrical stimulation
• Standard EEG monitoring is purely passive recording of brain electrical activity 5

Important Distinctions

EEG vs. Other Procedures

• Do not confuse diagnostic EEG (surface scalp electrodes) with invasive intracranial monitoring (subdural grids/depth electrodes), which requires craniotomy and carries surgical risks including infection (3-13%), hemorrhage, and transient neurological deficits 3, 4, 7
• Do not confuse EEG with electroconvulsive therapy (ECT), which does deliver electrical current and has different contraindications 2

Practical Limitations (Not Contraindications)

• Electromagnetic interference from strong electromagnetic fields can degrade EEG quality—maintain distance from electric motors (30-60 cm), mobile phones (15 cm), and high-voltage lines 8
• Environmental electrical noise in ICU settings may obscure recordings but does not contraindicate the procedure 8
• Patient cooperation affects recording quality, but inability to cooperate is not a contraindication—EEG can be performed on comatose, sedated, or paralyzed patients 1, 5

Clinical Pitfalls to Avoid

• Do not delay EEG in critically ill patients due to concerns about contraindications—the average response time is already 3 hours, and early EEG (within 24 hours) is crucial for detecting nonconvulsive seizures 5
• Do not confuse relative contraindications to brain imaging (CT/MRI with metal implants) with EEG—these are entirely different modalities 1
• Do not withhold EEG from patients with skull defects or previous neurosurgery—these patients often have the highest yield for detecting seizures 2, 3