Traumatic endolymphatic hydrops is an accumulation of endolymph – the fluid in the membranous labyrinth of the ear – in the cochlear duct caused by traumatic insult. This is caused by fistulization of the bony labyrinth, direct injury to the membranous labyrinth, and injury to the endolymphatic fluid drainage system. The diagnosis of traumatic endolymphatic hydrops is made by a history of trauma, such as barotrauma, a blow to the head, or perhaps a previous ear operation, such as stapedectomy.
Shea Clinic, Traumatic Endolymphatic Hydrops, Pub Med, https://www.ncbi.nlm.nih.gov/pubmed/8572126