Secondary cochlear hydrops
Secondary cochlear hydrops is a pathological event resulting from external insults, capable of inducing a clinical condition comparable to idiopathic cochlear hydrops, capable of inducing Ménière’s syndrome, or syndromes and variants that we can define as meniere-like in general.
Cochlear hydrops arises from an increase in endolymph which exerts an abnormal pressure force on the Reissner membrane, which separates the cochlear duct and the vestibular duct in the cochlea, and on the basilar membrane with repercussions on the stereocilia. In practice, it can be defined as the pathological distension of the endolymphatic spaces of the inner ear.
Secondary cochlear hydrops is scientifically proven to be present in patients with apparently idiopathic, severe, or even disabling forms of tinnitus.
Among the secondary events that may be responsible for this condition are surgical interventions, stapedectomy in otosclerosis surgery, and endolymphatic sac surgery. Cochlear implant surgery may also present a minimal risk in the induction of secondary cochlear hydrops. In this context, we must take into consideration neuromas / meningiomas (acoustic), acoustic and mechanical traumas, ototoxicity from drugs, systemic and non-systemic vascular pathologies, inflammatory / infectious processes not exclusively of the auditory system but also systemic.
Within the pathophysiological field, the direct metabolic mechanism of endolymph does not seem to be the only factor involved, there are in fact, pathological conditions that may alter the pressure values of the cerebrospinal fluid. The latter is in direct continuity with perilymph; therefore, it would secondarily alter the endolymphatic / perilymphatic homeostasis.
A further important factor is that of damage from chronic noise exposure, such as that which may occur in a workplace. More than direct cochlear damage, long-term noise exposure provokes a series of damage from metabolic stress on the membranous labyrinth.
Among the systemic inflammatory processes inducing secondary cochlear hydrops, rheumatic or autoimmune diseases in general also seem to have a certain effect.
An important chapter of scientific research which we wish to consider attentively is secondary cochlear hydrops following head trauma, whereby for head trauma it is not meant exclusively an extremely serious form, but also, if not more importantly, those traumas only apparently of slight to medium entity, also referred to as microtraumas. A typical example of such traumas related to the area of sports, particularly team sports, even if not exclusively. Specifically, cases where there is a continuity of apparently irrelevant microtraumas, which we arbitrarily define as “ghost” microtraumas. An extremely simple example to convey and comprehend can be football, where the many head shots and contacts are repeated not only during a match, but also during practice. Such repeated microtraumas can induce secondary cochlear hydrops with repercussions on auditory functions and balance and consequently, on the effectiveness of the competitive activity. Therefore, vestibular rehabilitation in athletes is of fundamental importance.