1. Muscle Artifacts:
o Description: Caused by
electromyographic (EMG) activity from muscle contractions.
o Characteristics: Higher
amplitude, confluence of activity, and frequency overlap with EEG signals.
o Appearance: Diphasic and
triphasic potentials with varying durations and locations.
o Distribution: Commonly
observed in regions with underlying muscles, such as the frontalis and masseter
muscles.
2. Cardiac Artifacts:
o Description: Result from
electrical and mechanical effects of cardiac activity.
o Characteristics: Time-locked to
cardiac contractions, co-occurring with ECG complexes.
o Types:
§Pacemaker
Artifact:
Broad field, high-frequency polyphasic potentials with shorter duration than
ECG artifact.
§Pulse Artifact: Periodic slow
wave following ECG artifact's peak, commonly over frontal and temporal regions.
§ Ballistocardiographic
Artifact:
Waveform similar to pulse artifact but more widespread, associated with body
movements during cardiac contractions.
3. Environmental
Artifacts:
oDescription: Result from
devices in the patient's surroundings during EEG recording.
o Causes: Electrical
fields surrounding devices or mechanical effects on the patient or the
patient's bed.
o Common Artifact: Alternating
current (AC) noise at 60 Hz in some regions and 50 Hz in others, affecting some
or all EEG channels.
4. Technical
Artifacts:
oElectrode
Artifacts:
Arise from issues with electrode placement, impedance mismatches, or movement
artifacts during recording.
o Amplifier
Artifacts:
Result from problems with the EEG amplifier, such as saturation, noise, or
incorrect settings.
5. Artifact Mimics:
oBenign
Epileptiform Transients of Sleep (BETS): Resemble ECG artifacts but can be distinguished based
on waveform characteristics and temporal correspondence to ECG signals.
o Focal Ictal and
Interictal Epileptiform Discharges: Differentiated from ECG artifacts based on waveform
features, location, and occurrence patterns.
Understanding the
types of EEG artifacts and their distinguishing features is crucial for
accurate EEG interpretation and diagnosis, as it helps in differentiating
genuine brain activity from unwanted signals that can affect the quality of EEG
recordings.
Comments
Post a Comment