Download - EEG Artifacts
Introduction
• Unwanted electrical activity arising from different sources, other than cerebral activity.
• EEG -highly sensitive recording device, easilyinterrupted by other electrical activity of veryhigh voltages .
• Some readily distinguished, others closelyresemble cerebral activity that theirinterpretation is taxing even to the mostexperienced eletroencephalographer.
CLASSIFICATION
Physiological : 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.
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.
EXTERNAL DEVICE ARTIFACT
• 50/60 HZ ambient electrical noise
• Intravenous drip
• Electrical devices-intravenous pumps, telephone
• Mechanical artifacts-ventilators,circulatorpumps
OCULAR ARTIFACT
• Blink
• Eye flutter
• Lateral gaze
• Slow/rowing eye movements
• Lateral rectus spike