Nah, tests can't disprove a middle ear issue. Current doctor knowledge of the middle ear is pitiful. It's rumored Silverstein recently came up with a device to measure stapes velocity. Silverstein after a lifetime in this in one of his seminars says maybe the inner ear and the brain causes the stapes hypermobility, or maybe it's the other way around, we don't know. So that's pretty much the state of otology. Sismanis is rumored to have gone in without any objective tests, just like Harold Kim. MRI is mentioned by the benzobuddies girl I linked to in the botox thread I posted here, where she gets cured of H by botox on the eustachian tubes she says, but she didn't want to explain further. So none of that is even close to a few theoretical fibers deep inside the cochlea. Some more obvious etiologies are observable though, on tympanogram or eardrum inspection while the event takes place, but a lot of angles and stories come up of no objective provable method.
I have been reading about otosclerosis and apparently it can affect the middle ear bone chain, including the stapes. The surgical approach has certain risks (like sensorineural hearing loss) and once the surgery is planned, the bones are pretty much checked and evaluated more closely at the moment of the surgery, as the surgery is progressing (and in some cases surgeons find out on that moment that due to complications they cannot actually perform the surgery). Before considering surgical treatment, the tests are just aimed at getting a diagnosis of possible otosclerosis, having a look at audiogram, tympanometry, CT scan maybe..
https://en.wikipedia.org/wiki/Otosclerosis#Amplification
The more I read about hearing issues that may be (even remotely) linked to causes of H, the more I realise that there aren't any real treatments. It seems some surgeries or treatments work only partially and pretty much by chance.