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EEG Patterns 02

Topic: Physiology

Created on Saturday, April 28 2007 by jdmiles

Last modified on Saturday, April 28 2007.

A 65 year-old right-handed male had an episode of sudden loss of consciousness about 1 month ago. He is now having an EEG as part of his workup. The sharply contoured waves circled in red represent:


 
        A) Eye movements
 
        B) PLEDs
 
        C) EKG artifact
 
        D) The posterior dominant rhythm
 
        E) Epileptiform discharge
 

 


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This question was created on April 28, 2007 by jdmiles.
This question was last modified on April 28, 2007.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS AND EXPLANATIONS




A) eye movements

This answer is incorrect.


This patient does have eye movements which can be seen on this EEG (see FP2-F8 at the center of the picture). The sharply contoured waves circled in red are due to a separate process.  (See References)

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B) PLEDs

This answer is incorrect.


Although these waveforms are indeed periodic and are more prominent on the left, the fact that they are time-locked with the QRS complex on the EKG tracing suggests that they are EKG artifact, and not PLEDs.  (See References)

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C) EKG artifact

This answer is correct.


These sharply contoured waves are the result of EKG artifact. In addition to the ones circled in red, there are several more sharply contoured waves in this image, occurring at rhythmic intervals, and each occurring at the same time as the QRS complex on the EKG tracing. EKG artifact is common, especially if the sensitivity of the recording is high, as in this one (note the size of the 50uV calibration markers on the left).  (See References)

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D) the posterior dominant rhythm

This answer is incorrect.


This patient does have a posterior dominant rhythm, but the sharply contoured waves circled in red indicate a separate process. Unlike a typical posterior dominant rhythm, they are seen in the anterior leads as well as the posterior leads.  (See References)

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E) epileptiform discharge

This answer is incorrect.


These sharply contoured waves are not due to an epileptiform discharge.  (See References)

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References:

1. Levin, K.H., and Luders, H.O. (Eds.) (2000). Comprehensive Clinical Neurophysiology. W.B. Saunders Company, Philadelphia.
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physiology
EEG Patterns 02
Question ID: 042807125
Question written by J. Douglas Miles, (C) 2006-2009, all rights reserved.
Created: 04/28/2007
Modified: 04/28/2007
Estimated Permutations: 600

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