DR SRIRAMA ANJANEYULU
KING GEORGE HOSPITAL,VIZAG
• 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
Physiological : from patient’s own,generator sources
other than the brain.
– Eye movement
– Muscle ( EMG )
• Extraphysiological : Externally generated e.g.
instrumental & environmental.
- IV drip,
• ECG artifact-poorly formed QRS complex , left
• Ballistocardiographic-movement of head or
body with cardiac contractions.
• Pacemaker-generalized across scalp , shorter
• Pulse-electrode resting on vessel , frontal and
temporal leads , follows ECG artifact.