The Role of Endolymphatic Hydrops in Patients with Pantonal Idiopathic Sudden Sensorineural Hearing Loss:A Cause or Secondary Reaction

The purpose of this study was to investigate the presence of endolymphatic hydrops(EH)in both affected and unaffected ears of patients with pantonal unilateral idiopathic sudden sensorineural hearing loss(ISSNHL)using three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging(3D-FLAIR MRI)and further evaluate the significance of EH in this disorder.Twenty-seven ISSHL patients were enrolled in this study.3D-FLAIR MRI was performed 24 h after intratympanic injection of gadolinium-diethylenetriaminepentaacetic acid(Gd-DPTA).The incidences of EH in the affected ears and contralateral unaffected ears were compared and the correlations of EH with vertigo or prognosis were analyzed using the Chi-square test.The results showed that the incidence of EH was 68.0%(17/25)in the affected ears and 34.8%(8/23)in the unaffected ears.There was a statistically significant difference between affected ears and unaffected ears in regard to the incidence of EH(P<0.05).There were no significant correlations of EH with vertigo(P=1.000)or with prognosis(P=0.359)in the affected ears.In conclusion,there is EH in the inner ear of patients with pantonal ISSNHL;EH is not related to vertigo,a concomitant symptom of ISSNHL,and the prognosis of this condition.The presence of EH may be a secondary reaction following the impairment of the inner ears with pantonal ISSNHL.

Assessment of Balance and Vestibular Functions in Patients with Idiopathic Sudden Sensorineural Hearing Loss

This study investigated the relationship among the severity of hearing impairment,vestibular function and balance function in patients with idiopathic sudden sensorineural hearing loss（ISSNHL）.A total of 35 ISSNHL patients（including 21 patients with vertigo） were enrolled.All of the patients underwent audiometry,sensory organization test（SOT）,caloric test,cervical vestibular-evoked myogenic potential（cV EMP） test and ocular vestibular-evoked myogenic potential（o VEMP） test.Significant relationship was found between vertigo and hearing loss grade（P=0.009）,and between SOT VEST grade and hearing loss grade（P=0.001）.The abnormal rate of o VEMP test was the highest,followed by the abnormal rates of caloric and c VEMP tests,not only in patients with vertigo but also in those without vertigo.The vestibular end organs were more susceptible to damage in patients with vertigo（compared with patients without vertigo）.Significant relationship was found between presence of vertigo and SOT VEST grade（P=0.010）.We demonstrated that vestibular end organs may be impaired not only in patients with vertigo but also in patients without vertigo.The cochlear and vestibular impairment could be more serious in patients with vertigo than in those without vertigo.Vertigo does not necessarily bear a causal relationship with the impairment of the vestibular end organs.SOT VEST grade could be used to reflect the presence of vertigo state in the ISSNHL patients.Apart from audiometry,the function of peripheral vestibular end organs and balance function should be evaluated to comprehensively understand ISSNHL.Better assessment of the condition will help us in clinical diagnosis,treatment and prognosis evaluation of ISSNHL.

Cause of idiopathic sudden sensorineural hearing loss:The stress response theory

The stress response theory is a relatively new concept about the cause of idiopathic sudden sensorineural hearing loss(ISHL). A number of possible etiologies have been proposed in the literature, as discussed in this paper, but each proposed etiology has been both supported and refuted in the literature. However, the stress response theory can integrate hypotheses that have been advocated so far. The word "stress" refers to a constellation of physical and psychological stimuli including systemic viral and bacterial illness, systemic inflammatory disorders, and physical, mental or metabolic stress. Numerous studies have demonstrated adverse effects of systemic stress on health. Stress causes changes in the immune system and cytokine network through activation of the hypothalamus-pituitary-adrenal axis and the sympathetic nervous system. Several types of catecholamine and cytokine receptors are in the cochlea cells other than capillary cells, and then they can respond to systemic stressors. However, there are few studies examining how systemic stress is associated with cochlear dysfunction. The stress response theory addresses this question. In the theory, a variety of stressors and risk factors contribute to the onset of ISHL in varying degrees. The lateral wall of the cochlea has very unique responses to systemic stressors. It plays a critical role in causing ISHL. Systemic stressors converge at the lateral wall and trigger pathological activation of nuclear factor κ-light-chain-enhancer of activated B cells, a transcriptional factor known as a stress sensor. This activation enhances local expression of genes associated with immune and inflammatory system, resulting in cochlear dysfunction. We review the original stress response theory advocated by Adams et al and the integrative stress response theory that integrates our knowledge about the etiologies of ISHL so far.