EEG artifacts
EEG artifacts can arise from various physiological and extraphysiological sources other than brain activity. Physiological artifacts originate from the patient's own generator sources like eye movements, muscle activity, movement, and cardiac activity. Extraphysiological artifacts are externally generated, such as from medical devices, electrical equipment, or the environment. Common EEG artifacts include cardiac artifacts like ECG signals, ballistocardiographic artifacts from head or body movement, pacemaker signals, and pulse artifacts. Electrode artifacts can be transient pops or low frequency rhythms across electrodes from poor contact or movement. External artifacts include 50/60 Hz ambient noise, intravenous drips, and signals from devices like pumps and ventilators. Muscle and ocular artifacts
EEG artifacts
- 1. EEG ARTIFACTS DR SRIRAMA ANJANEYULU RESIDENT,NEUROLOGY KING GEORGE HOSPITAL,VIZAG
- 2. 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.
- 3. 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
- 4. 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.
- 9. 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.
- 10. Electrode pop
- 12. Lead movement
- 13. Sweat artifact
- 15. EXTERNAL DEVICE ARTIFACT • 50/60 HZ ambient electrical noise • Intravenous drip • Electrical devices-intravenous pumps, telephone • Mechanical artifacts-ventilators,circulator pumps
- 16. 60 Hz artifact
- 17. IV drip
- 18. Electrical motor
- 20. Circulatory pump
- 21. MUSCLE ARTIFACT • Glossokinetic • Photomyogenic • Surface EMG
- 22. Muscle artifact
- 23. Muscle and movement artifact
- 24. EMG artifact
- 26. OCULAR ARTIFACT • Blink • Eye flutter • Lateral gaze • Slow/rowing eye movements • Lateral rectus spike
- 27. Blink artifact
- 31. Slow roving eye movement
- 33. Thank you