In metabolic encephalopathy, EEG will most likely show:
Ans. d. Delta activity (Ref: Ganong 24/e p273; Guyton 11/741-743; Samson Wrights 13/e p315-318)In metabolic encephalopathy, EEG will most likely show delta activity."In metabolic encephalopathy, Delta waves are seen predominantly due to a decrease in the consciousness."EEG Patterns In Sleep Beta (b) WaveAlpha (a)WaveTheta WaveDelta WaveSeen in* Parietal and frontalQ region* Patients awake, at rest with eyes openQ* Recorded from parieto occipital regionQ.* Related to decreased level of attention* Seen in awake patient at rest with eyes closedQ and mind wandering* Seen in hippocampusQ in childrenQ and drowsiness* Found over parietal and temporal areas.* Seen in deep NREM sleepQ and infantQFrequency>14 Hz Q8-13 Hz4-7 Hz3-5 Hz (minimum)QAmplitudeLow amplitudeHigh amplitudeHigh amplitudeQLarge amplitude (Maximum)QCharacteristic Feature:* Low-voltage, high frequency desynchronized electrical activity* Can be produced by any form of sensory stimulation or mental concentration, such as solving arithmetic problems alpha rhythm gets replaced by beta, therefore beta rhythm known as alpha blockFrequency of alpha rhythm is decreased by:* Old age* Low blood glucose* Low body temperature* Low levels of adrenal glucocorticoids* High arterial PaCO2* SleepRecorded in:* Newborn infants* Stage 1 of NREM sleep* Emotional stress* in adults particularly disappointment and frustration* Many brain disorders* Accentuated in children when they are crying* High-voltage, low frequency synchronized electrical activity.* Evoked by overbreathing* Seen in pathological states in which thalamocortical transmission is blocked,such as coma. * Beta rhythm is also known as arousal or alerting response, because it is correlated with the aroused, alert state * Presence of intracranial tumor act as a source of delta wave activity.* In metabolic encephalopathy, Delta waves are seen predominantly due to a decrease in the consciousness.
Alpha activity
Beta activity
Gamma activity
Delta activity
Miscellaneous (C.N.S.)