MRI scan

[seawitch]

Hi guys,

Just wondering how you are and if you're still diving.

Not yet!
Still waiting for the appointement with a specialist BSAC approved medical referee. This is nto his fault - i had to go to New Zealand to visit family for July. Am just back so will make the appointment asap.



We are 2 divers
who are going in for MRI's next week to check for lesions after getting
positive PFO diagnosis. We had each been getting skin/torso symptoms post
diving for years without getting a "proper" diagnosis.


I can hardly BELIEVE what you say!
Surely you knew that ANY odd symptoms should be noted and possible DCI causes blamed.


Then one day the
skin symptoms progressed to recognizable Type II symptoms... We would
certainly call all of our "hits" non deserved as far as table limits and
ascent rates are concerned (we are instructors with over 10,000 logged
dives between us).

THAT is the prob!
One thinks wee dives to <10m are *safe* whereas they are most definitely NOT!


Was your MRI helpful - or did it just scare you? Our physicians here
told us not to bother getting them since there is nothing that can be
done now about any damage we've received, so it would just "freak" us
out!

The brain MRI scan was certainly NOT for someone who is likely to be freaked out by possible claustrophobia (but divers are usually not)


Fortunately, we don't believe there's nothing that can be done about it
(Chinese medicine, meditation, even cross word puzzles could help improve
brain function).

Any info you could share would be helpful.

My scan apparantly showed no sign of any damage
(was "entirely normal" )so _I_ have concluded that my bend was NOT a neurological one but possibly a spinal one caused by an old neck injury - this has still to be discussed with the Medical referee.
AND I'm still not diving <sob>

Good luck with your own result - I'll let you know how I get on.
Thanks for your interest.
Carol

 

[sky50960]

Is it possible to open (more than it used to be ) a foramen ovale by performing many valsalva's for exapmle during body building?
I mean can a " almost closed foramen ovale " be forced open by valsa during those heavy body building efforts??????

Hy seawitch how are you?
If going on diving you should use NITROX ( the feel good gas ) on air table, but do not forget deph restriction using NITROX.

Don't be worried about MRI it is a very noisy machine but not dangerous a all...

CIAO CIAO

Fa

 

[John Reinertson]

MRI 's that are negative are not wholly convincing as to absence of CNS damage. Small areas between the slices can easily be missed.
The result of that tidbit is that a negative MRI does not mean there was no CNS DCS, and a positive one for a small area or several small UBOs (unidentified bright objects) is only suggestive and far from certain.

If you have an abnormal MRI showing a large area of injury and had a known DCS hit, then diving again is a major risk. If you have residual spinal or CNS symptoms after DCS, that is a significant risk.

Small white areas (UBOs)are of uncertain significance. They are known to occur in both non-divers and in commercial divers with no known DCS. It is true that commercial divers show more of them than nondivers and that active recreational divers may show more unidentified bright objects "UBOs" on an MRI, but the evidence is very incomplete at this point.

That's the real reason we don't push for MRI's in all cases like this. If we get an abnormal result, we don't know with any certainty what to make of it. If we get a normal MRI we can't be reassured. Since the MRI doesn't give us any decisive info, we don't recommend them routinely in persons with no known CNS hits. The field is evolving and we may get a major new study some year that clears the air, but for now, the answers aren't clear and each doc has to go on educated guesses and judgment..

We know that no dive is 100% safe. We know that the closer one is to the limits, the more frequently people will develop bubbles in their blood, and beyond the limits, the rates of bubbling and DCS go up substantially.
Physiologically it would make sense that dives with shallow max depths and very slow ascents and shorter bottom times would have less chance of bubbling than a more aggressive profile.
I would not quarrel with a diver that had a PFO and a previous hit who chose to do forty minute dives to forty feet with EAN 32 or some other highly conservative profile. We each take some risk daily and I might choose to take that risk, knowing that the odds were in my favor.
That is not to say I am a reckless person.. I would keep my profiles exceptionally conservative and do multiple safety stops, and accept the small amount of residual risk.

The risk of DCS is partially individual and partially profile dependent. If the individual is at higher risk, you can probably balance the risk somewhat with much more conservative profiles.

Dive safe and bubble-free,
John Reinertson

 

[sky50960]

MRI detects cerebral damage in AGE but has low sensitivity in DCS.

A negative MRI investigation cannot rule out AGE or DCS.

MRI is useful in the examination of patients with decompression illness to detect large infarcted areas ( hyperintense on T2, FLAIR, Proton sequences). MRI may also reveale subcortical white matter lesions in the brain. But what does they mean...

Subcortical white matter lesions in the brain or UBO's might be pressent in older people just refleting bad vascular status ( atherisclerosis ).
But i can also occure in multiple sclerosis, lupus...

BUT : MRI is certainly reliable in the detection of pathologic changes of spinal cord decompression sickness that are not detected by other neuroimaging methods.

 

[sky50960]

A study, of the British Medical Journal, reported MRI brain scanning in 87 recreational divers with a minimum of 160 dives each and free of DCS symptoms.
There investigation showed multiple brain lesions or hepersignals on MRI within white matter ( UBO’s ) when there was a large PFO.
Size of the PFO was defined by the degree of blood shunting through the atrial opening .
Large PFO in divers seemed to be related to many more MRI bright spots or hyperintesities comparing to divers with small or no PFO.
Notice this group had no history of DCS and no symptoms, so the clinical significance of the bright spots is unknown.
However, the implication of the MRI findings is clear: venous bubbles at some point did pass through the PFO shunt to directly enter the arterial circulation.

 

[Dr Deco]

Dear Readers:

This PFO situation is always a difficult question.

One should recognize that Valsalva or Valsalva-like maneuvers are an important aspect of gas bubble arterialization. When pressure is released, there is a rebound flow and an increase in preload which can lead to a reversal of the normal left-to-right atrial gradient.

Thus when one holds their breathe on the surface , as for example, holds their breathe while they strain on ascending the boat ladder, this is assisting bubble passage in the presence of a PFO. Other activities in this category are coughing.

More information is in Balestra C, Germonpre P, Marroni A. Intrathoracic pressure changes after Valsalva strain and other maneuvers: implications for divers with patent foramen ovale. Undersea Hyperb Med 1998 Fall; 25(3): 171-4

Dr Deco

 

[sky50960]

Dear DrDeco

To me brain and /or spinal MRI is necessary only if persistent symptoms post -DCS occur or for evaluation of stroke like events .
The best way to deal with undeserved DCS seems to be ruling out PFO.
-----------------------------------------------------------
But the question begins here: Some pulmonary problems might also cause off-gassing problems (for example air trapping…)
So if PFO negative why not performing high resolution CT SCAN. with both inspiratory and expiratory maneuvers to rule out any pulmonary problems?

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Just a quetion

Fa

 

[diverjohnz]

does any one think its funny that 99% of the people that get DCS dive with computers and they wonder why.

 

[seawitch]

Hi Diverjohn,
This is now off-topic!
But what is the point you are making?
That computers CAUSE DCI?
That divers are less careful because they rely on computers?
I suppose *you* use tables! Do you really think they are safer? Dives have to be planned (with the help of either computers or tables) by means of the best computer - your own brain!

 

[sky50960]

99%…I don’t like to ask this, but what are your references????
Fa