EEG Simulator
Waveform Simulator
Normal Features:
Slowing Patterns:
Epileptiform Patterns:
Pattern Information
Normal EEG Patterns
| Rhythm | Frequency | Location | Clinical Significance |
|---|---|---|---|
| Alpha | 8-13 Hz | Posterior dominant (occipital) | Normal awake rhythm with eyes closed; attenuates with eye opening or mental activity |
| Beta | 13-30 Hz | Frontal predominant | Normal during alertness, cognitive activity; enhanced by benzodiazepines and barbiturates |
| Theta | 4-8 Hz | Diffuse, temporal | Normal in drowsiness and young adults; excessive in awake adults may indicate abnormality |
| Delta | 0.5-4 Hz | Diffuse | Normal in deep sleep (N3) and infants; abnormal when awake except in anterior head regions |
Common Artifacts
| Artifact | Appearance | Location | Identification Tips |
|---|---|---|---|
| Eye Blinks | Large amplitude downward deflections | Frontal (Fp1/Fp2), attenuating posteriorly | Occurs at 0.5-2Hz when awake; synchronous with visible eye movements; maximal at frontal polar leads |
| Chewing | Rhythmic EMG bursts at ~1Hz with high-frequency spikes | Temporal leads (T3/T4) | Distinguished by muscle artifact clusters, rhythmic appearance at 1Hz; disrupts normal activity |
| Sweat | Slow, undulating baseline shifts (0.1-0.7 Hz) | Often frontal/temporal | Appears as slow baseline wander; often in anxious patients or warm environments |
| 60Hz | Regular, fast oscillations superimposed on EEG | Often one electrode or side | Perfect 60Hz rhythm; indicates electrical interference or poor electrode contact |
| ECG | Regular QRS complexes seen as sharp upward deflections across channels | All channels; strongest in temporal leads (T3/T4) closest to neck/heart | Precisely synchronous with heartbeat; most prominent in patients with short/thick necks, low BMI, or when using non-cephalic references (e.g., ear/mastoid) |
Abnormal EEG Patterns
| Pattern | Morphology | Clinical Association | Key Features |
|---|---|---|---|
| Spikes | Brief (<70ms) pointed transients | Epilepsy, irritative zone | Fast upstroke, pointy peak, slow downstroke; isolated or grouped; usually pathological |
| Sharp Waves | 70-200ms pointed transients | Epilepsy, cerebral injury | Longer duration than spikes but similar morphology; often with slow wave following |
| LRDA | Lateralized rhythmic delta (1-4Hz) | Focal cerebral dysfunction | Continuous rhythmic slowing in localized regions; indicates underlying structural or functional pathology |
| GRDA | Generalized rhythmic delta (1-4Hz) | Diffuse cerebral dysfunction | Continuous rhythmic slowing across all regions; indicates global encephalopathy or metabolic disturbance |