Sandra,
Ray's description of dripping a topical anesthetic like lidocaine on the sphenopalatine ganglion is spot on with respect to method of application and efficacy in aborting cluster headaches. My doctors at NIH agreed to let me try this method of treatment as an abortive for my cluster headache attacks and gave me a 4% solution of lidocaine.
The sphenopalatine ganglion (also called pterygopalatine, nasal, or Meckel’s ganglion), is that thing in the back of your nasal passage that stings just before you sneeze. It's also connected to the center (maxillary) branch of the trigeminal nerve ganglion as shown in the following photo from the University of Pittsburgh web site.
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The theory behind the sphenopalatine ganglion block as a cluster headache abortive is not too well understood, but appears to be based on its direct link to the trigeminal nerve and that it plays a role as a relay center of the autonomic nervous system. Some think there's a cascade effect in anesthetizing the sphenopalatine ganglion that spreads to the trigeminal nerve bundle and that this brings a measure of relief from the pain of a cluster headache attack and other chronic pain disorders of the head, neck, and upper back.
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I've found that using my NRB mask configured with a mouthpiece and free-cycling oxygen at 15 to 24 liters/minute in my mouth and out my nose creates enough evaporative cooling in the area around the sphenopalatine ganglion to shorten my abort times.
If you try this, you'll notice your mouth will cool and dry as the oxygen evaporates moisture in your mouth. I try to let this happen as the next sensation is a cooling effect in the back of the nasal passage as the oxygen evaporates moisture in the area of the sphenopalatine ganglion on the hit side. I also press on the side of my nose opposite the hit side to direct most of the flow out the hit side of my nose.
I've found that free-cycling oxygen like this is much easier to do than dripping lidocaine in my nose while nearly inverted. It's also more effective for me with a noticeable reduction of pain in less than a minute or two. Hope this helps.
Take care,
V/R, Batch