A1, A2, and Neurolines disposable electrodes

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A1, A2, and Neurolines disposable electrodes

Postby nightworker » Fri Oct 20, 2006 12:57 am

Does anyone consider the best locations of A1 and A2 to be the earlobe, then the mastoid bone ? If mastoid, do you consider the large boney part behind the earlobe or at the top of the ear on the skull to be the mastoid ?

Does anyone use Neurolines disposable electrodes ? If you do, then do you use them for A1,A2, Left Outer Canthus and Right Outer Canthus, Ground, and System Reference and emg-chins ?

If you do not use disposble electrodes what is the reason (s) ?

Tanks, :)
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Postby somnonaut » Fri Oct 20, 2006 1:41 am

The "reference" is supposedly electrically neutral, and the ear lobe was the most "non-skull" location the EEG field could find. After sleep studies entered the fray, it was uncomfortable to use ear lobe electrodes which usually required a spring basec clip on electrode, and the reference moved to the Mastoid bone or "Mastoid process"

http://en.wikipedia.org/wiki/Mastoid_po ... poral_bone
Image

It was felt that since we are already recording large swaths of EEG (Central to contra-lateral reference,) then the amount of "contaminating EEG" would be neglegible in realtion to the actual signal we are studying. The lower the application of the electrode on the mastoid process, the further away from the majority of the brain, therefore EEG activity, to possibly contribute to contaminate the "reference site," BUT, the more likely ECG contamination from the huge Carotid artery running somewhat under the mastoid process.

Image

So it is a happy medium one must find for the refence application on the mastoid process between NOT being an EEG site vs. NOT being an ECG site.

We do not use disposable electrodes on the head because they usually are of lesser quality than gold cups, and lesser quality wires. Our infection control dept says that since it is surface application, no need to get crazy with worry of sterile needs.
Make sure you use same electrode types for a channel derivation, otherwise there is a chance of build up electricty between dissimilar electrodes (ie, disposable Central/Gold cup reference.)
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re: disposable electrodes

Postby nightworker » Fri Oct 20, 2006 4:58 am

Is there proof that disposable electrodes produce an inferior signal on the A1A2, chins, loc/roc, ground, system ref ?

Also, why would a manufacturer make disposable electrodes for use on let's say loc/roc and chins knowing that gold cup metal electrodes are used for c4,c3,o1,o2 if they were not safe ?

These disposables have a self adhesive backing so cannot be used for EEG scalp locations.
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Postby somnonaut » Fri Oct 20, 2006 12:31 pm

Never said the signal was inferior, just the quality of the electrode and wire. As for how to use, I am pretty sure ALL electrode manufacturers state something about the use of their electrode in a dissimilar configuration. It is an electronic thing. It has been talked about on Binarysleep many a time. Do a search.

Oh OK here.
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Postby RPSGT88 » Sat Oct 21, 2006 12:08 am

Is there proof?

sigh

You could start by reading about EEG in papers and books by John Knott and Gibbs & Gibbs from the 1950s. These facts were well established over 50 years ago.
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Neurolines disposables and gold cups

Postby nightworker » Sat Oct 21, 2006 1:43 pm

Thanks for your answers. I have read your links except http://www.brainquiry.nl/file.php?fId=68 This page cannot be found.

Your statements and reference material infer that disposable electrodes should not be used for all the reasons given. I wonder how the mfg came up with the product obviously knowing what you have stated....how could they not know :?:

Thanks again.
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Postby somnonaut » Sat Oct 21, 2006 2:49 pm

Try this link.
http://www.brainquiry.com/default.aspx? ... &MenuID=19
[no affiliation]

An interesting question raised by this link
is if in the grand scheme of 10-20 placement:
"The smaller the number, the closer the position to the mid line. ‘Fp’ stands for Front polar."

Then why is T3 FURTHER from the midline than T5? As in the picture of 10-20 placements int he document. Hmmm.
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Postby Mairi2 » Mon Oct 23, 2006 7:38 pm

Actually, T3 and T5 have been renamed (as well as T4 and T6)- they are now T7 and T8, (forerly T3 and T4,) and P7 and P8 (formerly T5 and T6.
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Postby Mairi2 » Mon Oct 23, 2006 7:46 pm

Actually, T3 and T5 have been renamed (as well as T4 and T6)- they are now T7 and T8, (forerly T3 and T4,) and P7 and P8 (formerly T5 and T6.
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Postby somnonaut » Mon Oct 23, 2006 8:30 pm

But still the lower number is FARTHER from midline?
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Postby strawberri » Mon Oct 23, 2006 10:17 pm

Thanks somnonaut for the detailed explanation PLUS the images.

The contributions to this site are fantastic! Keep them coming everyone, us "newbies" need all the help we can get.

KUDOS to binary sleep forum!
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Postby RPSGT88 » Tue Oct 24, 2006 11:02 am

Information for newbies regarding EEG wires:

Experiment if you desire but the best electrodes produced today (and the most cost efficient) are made by Grass technologies:

They are the selection of "Hand-crafted SAFELEAD" and "Extended-Width SAFELEAD (also Hand-crafted) Precious Metal Recording Electrodes using "Traditional Grass Light-Weight Teflon wires.

The wire is composed of 7 strands of silver-plated Cadmium bronze with Kevlar members insulated with Teflon.

The plug is not molded. (Molded plugs permit sharp angle wire strain at the plug which is the cause of most wire failures. So stay away from molded plugs.) The Handcrafted plugs are fashioned with a soft, extra long, highly effective strain relief that will not permit sharp angle strain at the plug. That is the key to long life.

Always buy the gold cup type of electrode.

I have used whole sets of these types of wires (gold cup Handcrafted/Extended-Width SAFELEAD) for several years at a time without experiencing any bad wires. That is with daily use, collodion and disinfection.

When molded wires are subjected to the same stressors they typically last 1 year or less.

Lessor brands of wires tend to have artifact and "pop." Then you have to throw them away and buy new wires which often give the same problems.

These Grass Hand-crafted/Extended Width SAFELEAD wires are $108-113 per box of ten. Its slightly more expensive than other gold wires. The cost of using disposable electrodes over the same period of time (several years) is much greater. Don't forget to add the cost of snap-leads if that is what you use.
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Postby steves » Tue Oct 24, 2006 5:51 pm

Comments:
"Actually, T3 and T5 have been renamed (as well as T4 and T6)- they are now T7 and T8, (forerly T3 and T4,) and P7 and P8 (formerly T5 and T6."

"But still the lower number is FARTHER from midline?"

I recently read in the 2nd edition of sleep medicine pearls about this.

They renamed them so that the numbers are in a straight line.

Instead of a line of:

f7
t3
t5
it is now
f7
t7
p7.
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update on new 10-20 terms

Postby steves » Sat Nov 11, 2006 4:57 pm

I made this up so it could be more easily visualized...
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10-20 system.doc
10-20
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Postby oldsleeper » Sat Nov 11, 2006 5:21 pm

I have used whole sets of these types of wires (gold cup Handcrafted/Extended-Width SAFELEAD) for several years at a time without experiencing any bad wires. That is with daily use, collodion and disinfection.

Me too, they are the best I have found.
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