Data strongly suggest that acute induced hyperinsulinism suppresses cochlear function. Results may be attributed to loss of Na+K+ATPase activity in the stria vascularis, leading to loss of endocochlear potential and subsequent depolarization of cochlear hair cells as well as of neural cells in the auditory portion of cranial nerve VIII.

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Hyperi nsulinism secondary to peripheral insulin resistance has been described as the most frequent etiologic factor in cochlear and vestibular syndromes. Aim: This experimental study recorded and analyzed evoked auditory potential changes using transtympanic electrocochleography (EcochG) during induced acute hyperinsulinism in an animal model. Materials and Methods: Six adult male sheep were randomly divided into 2 groups. The animals were submitted to EcochG under general anesthesia, and a peripheral blood sample was collected to measure glycemia and insulinemia. Animals in the intervention group (n=3) received regular human insulin IV (0.1 U/kg). The control group (n=3) received saline solution. Glycemia and insulinemia were measured simultaneously with the recording of evoked potentials at 10-minute intervals during 90 minutes. Results: The intervention group experienced a progressive suppression in action potential amplitude when compared to the control group (p=0.001). Conclusion: Data strongly suggest that acute induced hyperinsulinism suppresses cochlear function. Results may be attributed to loss of Na+K+ATPase activity in the stria vascularis, leading to loss of endocochlear potential and subsequent depolarization of cochlear hair cells as well as of neural cells in the auditory portion of cranial nerve VIII.

Ut riculostomy is a new surgical alternative for Ménière's disease. The basis of this procedure is that the outcome of an electrocautery-induced utricular trauma does not affect cochlear function. However, a demonstration of the hypothesis that this approach to the utricle would preserve hearing is still pending.Objective: To determine whether any changes would occur in the electrical potentials evoked in the cochlea and auditory nerve before, during, and 1 month after a surgical procedure in the utricule in an animal model. Materials and Methods:An experimental study. Eight sheep underwent electrocautery-induced utricular trauma, and their cochlear function was assessed by electrocochleography -recording of electrical evoked potentials, in the preoperative, immediate postoperative and medium-term postoperative periods. The results were analyzed statistically.Results: There were no statistically significant variations in amplitude (p = 0.099) and latency (p = 0.591) before and 1 month after the surgical procedure. There was a statistically significant change in the summation of the potential/action potential area ratio (p = 0.0122), a calculated loss of 11.8 dB. Conclusion:The intervention performed in this study enabled us to conclude that, taking into account the impaired electrophysiological responses observed during and 1 month after the surgical procedure, hearing was preserved in the operated sheep. ORIGINAL ARTICLEBraz J Otorhinolaryngol. 2012;78(2):52-8.

RESUMOIntrodução: As cirurgias dos shunts endolinfáticos empregadas para o tratamento da vertigem na doença de Ménière incapacitante permanece um tópico controverso. Portmann, em 1926, foi o primeiro a executar a cirurgia, incisando o saco endolinfático com o objetivo de diminuir a pressão endolinfática da orelha interna. Planejadas para criar uma fístula que conecte o espaço endo e perilinfático, as saculotomias foram descritas por FICK em 1964, por CODY em 1969 e por SCHUKNECHT (cocleossaculotomia) em 1982, entretanto foram paulatinamente abandonadas devido à alta incidência de perda auditiva. Uma nova e promissora opção cirúrgica dos shunts, em caráter experimental, é a utriculostomia, realizada por LAVINSKY em 1999. Objetivo: Realizar uma revisão da literatura sobre as principais técnicas cirúrgicas dos shunts endolinfáticos empregados no tratamento da doença de Ménière, seus resultados e o que há de avanços no entendimento desses procedimentos. Método: Com base nos dados da literatura, são discutidas as principais técnicas cirúrgicas dos shunts endolinfáticos e sua racionalidade no tratamento da doença de Ménière incapacitante. Conclusão: Existe muita controvérsia sobre a efetividade dos procedimentos cirúrgicos dos shunts endolinfáticos para o tratamento da doença de Ménière incapacitante, e muitos deles causam danos à orelha interna. A cirurgia experimental utriculostomia, portanto, parece-nos uma opção promissora. Futuras pesquisas poderão fornecer a resposta para essa questão. Palavras-chave: doença de Ménière, vertigem, saco endolinfático.