Author Topic: Transient global amnesia  (Read 6963 times)

DeeFoster

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Transient global amnesia
« on: February 17, 2010, 17:14:31 UTC »
 This one is pretty much for Doc Vikengo---I just experienced a bout of TGA.  I'm fine, fully recovered after 24 hours, and the event itself was about six hours.  It was pretty much text-book.  I"m learning more about it( now that I can remember what I learn...) and one of the common triggers is "immersion in hot or cold water".  That was not the trigger in my case, it was exercise, and I have a mild history of migraines.  But that got me curious about diving.  Have you ever heard of any dive induced TGA?  I realize my risk of a second attack is practically nil, it's more just curiosity?

DocV

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Re: Transient global amnesia
« Reply #1 on: February 18, 2010, 11:59:54 UTC »
Hi Dee,

Interesting topic.

SCUBA can present a number of events that may be possible triggers of TGA, including exercise, cold water immersion, Valsalva-like activities used in equalizing the ears and breathing 02 enriched gases such an nitrox.  Also, be aware there is some evidence suggesting that right-to-left cardiac shunts, such as PFOs ("PFO and SCUBA" -- http://www.awoosh.com/DocVikingo/PFO_2.htm ) which clearly have been implicated in DCI, can precipitate TGA.

As regards the risk of a second attack, recurrence indeed is very low, but not nonexistent.  It appears that recurrence is between 2-3% per year, with time intervals between attacks being as recent as the same day to as long as 19 years.

In answer to your specific question, I have heard of two cases of TGA while diving.  I would venture that SCUBA-induced TGA is exceptionally rare.

Regards,

DocVikingo

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual, and should not be construed as such.

DeeFoster

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Re: Transient global amnesia
« Reply #2 on: February 18, 2010, 20:19:42 UTC »
Thanks for the quick answer!  Strangely enough, I know I don't have PFO, as I had an echocardiogram a few years ago, for premature ventricular contractions (as it turned out).  While they were doing the test I asked them to check, and they said I looked fine.  By the way, is that ear test readily available in America?  It would be nice for my husband to know too.

I guess I won't worry about two known incidents....

DocV

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Re: Transient global amnesia
« Reply #3 on: February 19, 2010, 11:18:06 UTC »
By the way, is that ear test readily available in America?  It would be nice for my husband to know too....I guess I won't worry about two known incidents....

LOL--more accurately, not "two known incidents," but rather "two incidents that I know of directly."

And, to which "ear test" are you referring?

Regards,

DocV

DeeFoster

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Re: Transient global amnesia
« Reply #4 on: February 27, 2010, 16:55:42 UTC »
The ear test for PFO?  Ear oximetry, I think it's called?

DocV

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Re: Transient global amnesia
« Reply #5 on: March 01, 2010, 10:25:16 UTC »
Hi Dee,

Ear oximetry measures the oxygen saturation of circulating blood. The oximeter transmits a beam of light through the earlobe or pinna to a receiver on the other side. By analyzing the amount of light received relative to the amount of light transmitted, the percentage of oxygen saturation of the blood can be calculated.  A positive finding involves transient drops in oxygen saturation following techniques that provoke right-to-left cardiac shunting, such as the Valslava maneuver.

The technique is both a sensitive and specific method for the detection of PFO. It's noninvasive, inexpensive and causes no discomfort for the patient, unlike the current gold standard for the detection of PFO, transesophageal echocardiography (TEE) with bubble contrast.  And, yes, it generally is readily available in the USA.

Helpful?

Regards,

DocVikingo

 

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