Experimental Autoimmune Inner Ear Disease: An Electrocochleographic and Histophysiologic Study

Abstract

Systemic immunization with swine inner ear antigens in complete Freund's adjuvant induces functional disturbances in the cochlea. Morphometric data indicate that an endolymphatic hydrops develops within 2 weeks. It diminishes 6 weeks after immunization. A progressive decrease in the compound action potential amplitude is observed from 2 to 6 weeks after immunization. Enhancement of the amplitude of the summating potential is present without a clear overall correlation to the presence of endolymphatic hydrops. The amplitude of the cochlear microphonics shows no significant changes after immunization. Western blot analysis of the sera performed 2 and 6 weeks after immunization shows enhanced reactivity at 68, 50, 45, and 27 kd molecular weights, as compared to controls. The same spectrum of cross-reacting antibodies is believed to be instrumental in immune-mediated sensorineural hearing loss in patients. Apparently, cross-reacting antibodies and released mediators disturb cochlear homeostasis, resulting in the observed changes in the electrophysiological responses. However, these changes are not clearly related to structural changes at the light and electron microscopic levels.

Diameter of the Cochlear Nerve in Endolymphatic Hydrops: Implications for the Etiology of Hearing Loss in Ménière's Disease

“…The results of the present study demonstrated no correlation between hearing deterioration and nerve deterioration, nor did the severity of hydrops predict nerve deterioration. Although hydrops did correlate with overall hearing loss, as shown by studies using ABR, 48,49 other reports using more near‐field physiological measures have shown no such correlation in the animal model 50,51 . This implies that hydrops itself may be an epiphenomenon of Meniere's disease.…”

“…Although hydrops did correlate with overall hearing loss, as shown by studies using ABR, 48,49 other reports using more near-field physiological measures have shown no such correlation in the animal model. 50,51 This implies that hydrops itself may be an epiphenomenon of Meniere's disease. This is supported by human temporal bone studies in which ELH was found in patients who did not exhibit symptoms of Meniere's disease in their medical history and therefore had "asymptomatic endolymphatic hydrops."…”

The Quantification of Endolymphatic Hydrops in an Experimental Animal Model with Guinea Pigs

“…From then on, the animal model has been widely used in experimental research on Ménière's disease. Other procedures such as cauterization of the distal portion of the endolymphatic sac with silver nitrate, introduction of cholera toxin into the inner ear and various techniques for the induction of inner ear autoimmune disease also produce both histologic hydrops and hearing loss [3][4][5].…”

Emerging options in immune‐mediated hearing loss

“…Patients with Meniere's symptoms also have a higher rate of systemic autoimmune disease compared to what is expected in normal population . In animal models, antigen challenge either in the inner ear or with inner ear antigens consistently results in endolymphatic hydrops …”

“…28 In animal models, antigen challenge either in the inner ear or with inner ear antigens consistently results in endolymphatic hydrops. [29][30][31] The autoimmune process can result in direct destruction of inner ear structures. In Wegener's granulomatosis, vasculitis is observed in the cochlea, vestibule, and facial nerve.…”