Posted by drummer (18.104.22.168) on April 06, 2000 at 07:10:58:
I'm not sure how scientific my mind is, but I went searching for some information on Dennis O'Connor's question about Oxygen and why it may stop working for some people.
Here's what I came up with. I think. :-)
Yes, Oxygen is a medicine. In fact, Oxygen has not yet been determined if or how damaging it is to lung tissue. That's why it is important to not use Oxygen for more than 15-20 minutes at a high flow rate (5-10L/min.)
See the [ask Doc Greg] link to the left: "Oxygen is a medication controlled by the FDA. So, can use of oxygen cause harm? Yes it can." -- Doc Greg
I'm going to try and explain the 'mechanism of action' of Oxygen as it relates to aborting a cluster attack and why Oxygen may no longer work as an abortive medicine. (Again, I don't know how scientific my mind is).
As you know, Doc Goadsby 'triggered' cluster attacks with Nitroglycerine. I always thought that it was the vaso-dilator properties of the Nitro that caused Goadsby's patients to have an attack.
I was wrong.
It's actually the ipsilateral anteroventral hypothalamus that is activated by the Nitro, thereby causing the Cluster attack.
Ipsilateral simply means 'one-sided'. Anteroventral simply means the 'back part'.
Goadsby then aborted each patient's attack with an injection of Imitrex/Imigran.
Now, more about Oxygen and Cluster attacks. Doc Greg says this: "Why does it (Oxygen) work? Well, remember that cluster headaches are considered a vascular headache (actually much more involved than just vascular, but there is a definite vascular component to it)." -- Doc Greg
The much more involved is what YOU (Dennis) found located in the medical info page at CH.com. This:
"Sakai and Meyer (1979) have shown that marked cerebral vasoconstriction results from the administration of 100 percent oxygen during cluster headache attacks. Whether this effect is direct or is mediated centrally has not been studied. Oxygen also stimulates the synthesis of serotonin in the central nervous system (CNS) (Costa and Meek, 1974)."
Also, Oxygen boosts the hypothalamic activity involving melatonin-serotonin generation and thus stimulates exactly the same receptor areas that most of the current research is indicating in rethinking CH as a primarily neurological event, usually leading to accompanying vascular inflammation.
Now, if you also look at the [ask Doc Greg] link, you'll see that he talks about Triptans. Doc Greg uses the analogy of a squirt gun and a cat to describe how Serotonin is a chemical neurotransmitter in the brain.
He goes on to use the analogy of doors in a building. Oxygen works in much the same way. Oxygen doesn't open all the doors, but only certain doors.
Why does Oxygen stop working all of a sudden? Perhaps the Serotonin receptors (doors) are not responding to the Oxygen (keys) any longer. Perhaps the 'teeth' on the keys have grown dull. Perhaps it's time for a new key.
Oxygen doesn't work for me anymore, but yet, Imitrex does.
Well, that's my 'scientific explanation'. You can take it for what it's worth. I could be wrong.
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