Jim,
I'm likely one of the strongest and most vocal proponents of using oxygen therapy as an abortive for cluster headache. It is so effective for me that with the exception of an occasional snort of sumatriptan during airline travel or when trapped away from a source of oxygen, oxygen therapy at flow rates that support hyperventilation is all I use.
I take no preventatives, but I do take a regimen of calcium citrate tablets that also contain vitamin D3, magnesium and zinc washed down with a couple glasses of homemade sugar free lemonade, limeade, or Baja Bob's sugar free margarita mix when I start into a high cycle.
I find this regimen lowers the frequency and intensity of my cluster headaches better than 90% of the time. It also appears to work more effectively if taken just prior to a meal as it acts as a buffer on the stomach's gastric juices when the acid content is highest. This buffering mechanism helps to elevate the low arterial pH that usually accompanies my high cycles.
Now here's the kicker... As with nearly all methods of intervention for cluster headaches, there are exceptions. The high cycles I experience in the spring and fall tend to be more severe than at other times of the year. These cycles tend to last 10 days to two weeks and are characterized by an increase in the frequency of my cluster headaches with very fast onset and rise times to higher pain intensity levels... like two to three minutes from no pain to a 7 or 8 heavy hitter on the 10-Point Headache Pain Scale.
For what it's worth these two particular high cycle times coincide with the increase in frequency of cycle start times reported by episodic sufferers who took the cluster headache survey in December of 2008. A plot of this data is shown in the graph below:
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During these two periods, rapid aborts, even with oxygen therapy at flow rates that support hyperventilation, can become scarce a hen's teeth no matter how early I start. Under normal conditions I average of 3 to 4 minutes for an abort, but during these two time periods, my abort times jump up to an average of 8 minutes if I start early and 12 minutes if the cluster headache hits while sleeping and has a head start up the pain scale.
The only possible way I'm aware of where oxygen therapy might have any measurable efficacy as a preventative involves using this method as an abortive at oxygen flow rates that support hyperventilation on every attack no matter how minor. We saw this preventative effect during the analysis of abort data from a small informal pilot study of this method of oxygen therapy.
The exact mechanism or mechanisms involved are unclear, but it appears to involve a cumulative effect as the frequency, intensity and abort times experienced by all 7 participants, while using this method of oxygen therapy, all tended lower over the 8-week data collection period. One possible explanation other than improved lung functions from this aggressive method of oxygen therapy is a condition called vascular toning...
During the pilot study we collected data on 366 aborts with this method of oxygen therapy from seven cluster headache sufferers, 6 chronic and 1 episodic. When we analyzed the abort data, we found that all seven participants experienced a reduction in the frequency, intensity, and duration of their attacks with continued and repeated use of oxygen therapy at flow rates that support hyperventilation...
The following chart illustrates the weekly averages for frequency of attacks, pain intensity and abort times from the first week through Week-8 of the data collection period from one of the participants.
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It's also significant to note that the weekly average pain intensity and abort times dropped continuously from the first abort at the start of this data collection period to the last on Week-8. This same pattern was also consistent among the other participants.
The overall efficacy of this method of oxygen therapy was better than 99% with 365 successful aborts out of 366 attempts logged by the 7 participants and an overall average abort time of 7 minutes for attacks at pain levels 3 through 9.
As you can also see there was an initial spike in the weekly average frequency of attacks through week-4 then a rapid drop through week-8. Again, this pattern was consistent for all seven participants and it helped identify a phenomenon we now call re-attacks. Nearly all re-attacks occurred within a time period between 15 and 45 minutes following a successful abort.
What appears to be happening with re-attacks while using this method of oxygen therapy is the abort times are so fast, they abort the pain of the cluster headache, but the total time in hyperoxia is so short (<10 minutes), it's not sufficient to abort the triggering mechanism. When the effects of hyperoxia and respiratory alkalosis dissipate, this takes 15 to 20 minutes after completing this method of therapy, and the triggering mechanism is still present, the attack resumes.
After a further analysis of the abort data for all flow rates, we found there were very few instances of re-attacks when abort times were between 15 and 20 minutes and none if the abort times were 20 minutes or longer.
Based on this information we modified the therapy procedures to add additional time breathing 100% oxygen after the abort at a normal respiration rates (flow rates of 7 to 9 liters/minute) to bring the total time in hyperoxia up to 15 minutes.
The concept of vascular toning, also called cardiovascular toning, isn't new. Physicians and nutritionists recommend daily aerobic workouts to strengthen the cardiovascular system. Vascular toning involves strengthening and increasing the elasticity of the smooth muscles that line the arteries, arterioles and capillaries in and around the trigeminal nerve.
I'm of the opinion that if these vascular structures are physically toned up by repeated use of this aggressive method of oxygen therapy, they become more resistant to the triggering mechanism.
It's kind of like doing curls with a dumb bell weight to strengthen the biceps. Do reps for 5 minutes 4 to 5 times a day and your biceps will grow in size, strength and overall muscle tone.
The same thing happens to the muscles lining our arteries every time we hyperventilate long enough with oxygen therapy to push our circulatory and respiratory systems into respiratory alkalosis triggering the artery and capillary muscles to contract in vasoconstriction...
I've also found the reverse of vascular toning may be true as well... By sitting around doing nothing about low-level headaches for long periods of time, the arteries and capillaries in and around my trigeminal nerve may be in a state of complete dilation and losing muscle tone in the process...
Even if this method of oxygen therapy is not fully effective as a preventative in reducing the frequency and intensity of cluster headache, I think it works well enough to be worth a try as an abortive... Moreover, when coupled with the regimen of calcium citrate tablets taken with sugar free lemonade, limeade, or margarita mix, the results are encouraging.
Hope this helps.
Take care,
V/R, Batch