eeg artifacts
Post on 07-May-2015
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EEG ARTIFACTS
DR SRIRAMA ANJANEYULURESIDENT,NEUROLOGY
KING GEORGE HOSPITAL,VIZAG
Introduction
• Unwanted electrical activity arising from different sources, other than cerebral activity.
• EEG -highly sensitive recording device, easily interrupted by other electrical activity of very high voltages .
• Some readily distinguished, others closely resemble cerebral activity that their interpretation is taxing even to the most experienced eletroencephalographer.
CLASSIFICATIONPhysiological : from patient’s own,generator sources other
than the brain. – Eye movement
– Muscle ( EMG ) – Movement – Cardiogenic – Sweat
• Extraphysiological : Externally generated e.g. instrumental & environmental.
- IV drip, -ventilator
Cardiac artifacts
• ECG artifact-poorly formed QRS complex , left temporal leads.(BETS,IED,PLEDS)
• Ballistocardiographic-movement of head or body with cardiac contractions.
• Pacemaker-generalized across scalp , shorter duration.
• Pulse-electrode resting on vessel , frontal and temporal leads , follows ECG artifact.
Cardiac artifact
Cardiac artifact
Pacemaker artifact
Pulse artifact
ELECTRODE ARTIFACT-TYPES
• Two forms-brief transients limited to one electrode , low frequency rhythms across scalp region.
• Electrode pop-spontaneous discharges.• Electrode contact-poor contact.• Electrode/lead movement.• Perspiration-undulating waves >2 sec.• Salt bridge-lower amplitude.• Movement artifact.
Electrode pop
Electrode Movement artifact
Lead movement
Sweat artifact
Salt bridge artifact
EXTERNAL DEVICE ARTIFACT
• 50/60 HZ ambient electrical noise• Intravenous drip• Electrical devices-intravenous pumps,
telephone• Mechanical artifacts-ventilators,circulator
pumps
60 Hz artifact
IV drip
Electrical motor
Mechanical ventilator
Circulatory pump
MUSCLE ARTIFACT
• Glossokinetic• Photomyogenic• Surface EMG
Muscle artifact
Muscle and movement artifact
EMG artifact
Photomyogenic artifact
OCULAR ARTIFACT
• Blink• Eye flutter• Lateral gaze• Slow/rowing eye movements• Lateral rectus spike
Blink artifact
Eye flutter artifact
Eye flutter artifact
Lateral eye movement
Slow roving eye movement
Lateral rectus spike
Thank you
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