Good question. We don't know either. Most of the people on the Wim Hof thread have had similar symptoms (ETD issues and tinnitus, high pitched, mostly hissing); however, there is a large number of sufferers that don't get the ETD symptoms, just the tinnitus. We are divided between ETD, hypoxia causing neuropathy, shock to the ANS, CSF leak, intracranial pressure and/or a mixture of all the above.
I am less inclined to believe it is a perilymph fistula, CSF leak or intracranial pressure since many of us have had MRIs and they do not show those conditions. I know that they can be hard to diagnose by MRI but our neurologists have dismissed the idea. I am still a little skeptical and believe it could be one of these conditions.
Many of the Wim Hof sufferers seem to have mostly recovered from the ETD symptoms. I am 3 months in and still fighting some form of glue ear and occasional fullness. The tinnitus has gotten worse but only slightly. Seems to be holding steady over the last month.
@FGG, do you believe it could be cochlear hydrops? None of us have been able to get a definitive answer but I know I have additional sinus pressure, headaches (that are getting better) and eye floaters. I feel like the symptoms match a stroke of sorts but the neurologists don't believe that is the case.