[wineeg] Re: Drop in amplitude right hemisphere?

  • From: Joe Siri Ekgren <joesiri@xxxxxxxx>
  • To: wineeg@xxxxxxxxxxxxx
  • Date: Sun, 24 Aug 2003 17:02:44 +0200


Thank you so much for your valuable comments.

At 12:35 -0800 21.08.03, Jay Gunkelman wrote:
>You are reporting focal low amplitude across the frequencies for a specific
>region. The EEG can be seen with areas of decreased amplitude, not just a
>beta deficit, but an area of general amplitude minima. This phenomenon is
>seen well in topographic EEG mapping and has been reported in areas of
>cortical dysfunction (Brownback and Mason, 1998).  The area is effectively
>shut down and is not functioning.  These areas have been observed frontally
>in attentional and affective disorders (Gunkelman, 1997).
>The functional areas you describe would suggest hyperactive/impulsive
>behavior (fight frontal) with poor social environment awareness (right
>temporal)... is this seen clinically... if not, the effect is likely an

The behaviour does reflect some impulsivity, but aside from an 
element of immaturity ("life has been unfair to me") one would find 
the client normal at first glance.

The artefact behind this effect, is electrical activity picked up at 
the right earlobe?
And if so, could the culprit be:
        10-20 paste on the outside of the A2 electrode,
        residual nu-prep
        earring (or nu prep in the pierced lobe)

What other sources could generate this artefact?

>You are right about the subdural doing this attenuation pattern... a chronic
>subdural attenuates the EEG... but a tumor would generally show as a slow
>focus in addition to this attenuation.


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