Has anybody heard of this?
Here is some info about their stage 2 clinical trials:
http://globenewswire.com/news-release/2016/02/25/814088/0/en/Capnia-Enrolls-First-Patient-in-Phase-2-Clinical-Trial-Evaluating-Nasal-CO2-for-the-Symptomatic-Treatment-of-Trigeminal-Neuralgia.html?f=22&fvtc=7
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