**4. Histopathology**

It has also been reported in the literature that there is a relation between systemic lupus erythematosus (SLE) and SHL. It was reported that circulating autoantibodies might enter into the reaction directly with the inner ear antigens in SLE patients and the activated T cells might increase the levels of intracellular interferon gamma and some other cytokines and thus cause cellular damage [51]. Additionally, it is well known that in SLE, circulation antibodies such as anticardiolipin antibody, lupus anticoagulant, and anti-β2 GP1, antiphospholipid antibodies cause emboli and microinfarcts in the systemic circulation. As these antibodies may cause the same problems in the cochlear microcirculation, they may also cause SHL with the mechanism explained in the vascular hypothesis of SHL. Meanwhile, it was also stated in the literature that the SHL, which is believed to be developed due to SLE, might improve with a proper

Hearing losses, which are believed that they develop in relationship with autoimmunity and manifest themselves with progressive, recurrent, and fluctuating clinical picture, are also called autoimmune hearing loss or autoimmune inner ear disease [54]. Yoo [41] created hearing loss in rats with Type 2 collagen immunization and showed the monoclonal antibodies, which were formed against the antigen related to the otic capsule, with radioimmunoassay. Harris [55] identified five antibodies formed against the inner ear antigens and suggested that the inner ear might have its own immunoreactive mechanism apart from the systemic immune response, but this was not supported by studies conducted after this hypothesis was introduced. Lymphocyte transformation and Western-blot tests are recommended for the diagnosis of the autoimmune hearing loss. Heywood [56] used infliximab in the treatment of fluctuating and progressive high-frequency recurrent hearing loss and reported that the patients benefited from this anti-TNF-alpha agent. Although all these findings might show the place of the autoimmunity in the etiology of SHL, there is still a need for further studies with larger samples size, as the sample sizes in the available studies are

Round- and oval-window membranes are two anatomical structures that separate the inner and middle ear from each other. These structures are responsible for restricting the endolymph to the inner ear and for preventing its penetration to the middle ear. There are other additional membranes in the inner ear that prevent the endolymph from interfering with the perilymph, and it is well known that their rupture will cause hearing loss. Goodhill [57] detected a perilymph fistula in three patients with SHL. Simmons [58] was one of the earliest authors, who suggested that the labyrinthine membrane damages might play a role in the etiology of SHL. Gussen [59] has identified healed Reissner membrane in the temporal bone dissections and succeeded to reveal membrane ruptures in the SHL etiology. Similarly, Kamerer [60] demonstrated microfissures between the posterior canal ampulla and the roundwindow niche during his temporal bone studies. Although there are other studies with small patient sizes, the main question is whether the hearing losses depending on membrane ruptures should be classified as SHL. Because, in that case, we have to assume that SHL arises from a mechanical problem and the treatment procedure should be based mainly on surgical

anticoagulant treatment [52, 53].

76 An Excursus into Hearing Loss

relatively small.

**3.4. Intracochlear membrane rupture**

The histopathology of SHL is quite diverse because of the several factors blamed regarding its etiology. In the temporal bone studies, as mentioned above, along with the membrane ruptures, degenerative findings such as atrophy in the corti organ, loss of cochlear neurons, and neuron fibrils might be encountered in the viral etiology. On the other hand, histopathological findings such as labyrinthine fibrosis and new bone formation are the predominant histopathological findings in vascular events. Yood [61] observed certain changes in 7 of 11 temporal bones in his histopathological study. These changes include especially damage to the corti organ or loss of total corti organ; even it may differ according to the etiology. On the other hand, Vasama [62] determined in his study on 12 temporal bones degeneration and loss in the spiral ligament and stria vascularis. He also observed cochlear ossification in one patient. Since SHL's etiology is multifactorial, multiple histopathological findings are expected and it can be suggested that majority of these findings might be reversible regarding the spontaneous healing rates of SHL.
