I am not familiar with the Electrocochleaography test although it may well go by another name on this side of the Atlantic
Tests performed so far:
Cat scan of the sinuses.
Mri of the Brain
Mri of the inner ear
Mri of the spine and upper neck
Nystagmus testing for eye tracking, numerous balance tests, including wearing what looks like a snorkelers mask with individual eye covers that are alternately closed and opened and also with both covers closed, moving ones head with left and right, up and down with eyes stationary then moving from side to side.
Blowing hot and cold air into each ear separately to induce dizziness while connected to electrodes, measuring recovery time ?
Standing on one foot/ both feet eyes open/ closed looking at balance.
Standing on a wobbly pillow, eyes / open closed, measuring balance.
Numerous hearing tests in soundproof booth with beeps / words to repeat as they get softer.
Listening through deliberately induced static to hear sounds.
Blood test to investigate possibility of infection from Herpes 1 virus.
I do not have the names for all of these tests and may have forgotten some that were done.
Incidentally, all were negative and balance / hearing was 'normal'