Could this be due to thornwaldt cyst?
I read your question and I understand your concern. However, regarding what you are asking specifically about, Thorwald cyst, no, that shouldn't be the cause of the loss of consciousness. They are outside the brain, in the posterior part of your nasal-oral cavity and almost never cause symptoms. They could become symptomatic if they become infected with nasal discharge and bad breath. Another possibility is favoring middle ear infections, but that apart from being detectable on MRI would have presented other signs well before thinking of some brain involvement. I hope to have been of help.