Need to be careful what you define as useful: cure? Decrease in severity of symptoms? Decrease in frequency of symptoms? Etc
Research in the area is poor. The article you referenced notes: “MAIN RESULTS: We did not identify any studies that met the inclusion criteria for the review.“
Clinically, we have seen some patients do significantly better (less severe, less frequent attacks) with low salt and diuretics. Likewise, other similarly presenting patients don’t benefit nearly as much. Compliance on something so difficult in America (low salt) is also a major issue in determining efficacy. I can, however, speak from personal experience. I had major hearing loss in 2011 in my left ear after a bad ear infection, in addition to my congenital progressive loss. It left major damage to my inner ear. I would have fluctuating loss. My doc put me on a diuretic and I limited to less than 2g of salt a day, and I noticed a direct correlation with my fluctuating loss with my salt intake (ie, my compliance). After 6 months of a diuretic for solely this purpose, the hearing loss stabilized to what it is today.
Salt and the ear is not a fully understood relationship. However, I would be hard pressed to find any ENT with years experience who would say a high salt diet is beneficial for the inner ear. Take from this what you want.