耳鸣的防治培训课件.ppt

主观性耳鸣的病因及机制 耳鸣起源于中枢而非耳蜗： MRI has revealed differences in sound-evoked responses between tinnitus and nontinnitus groups in cortical [12] and subcortical auditory nuclei [13] and found evidence for structural differences in the thalamus [14], the auditory brainstem[15] and the auditory cortex [16]. 听觉中枢异常电活动：认为耳呜的产生可能由神经元的自发放电率(spontaneous firing rates)增加、簇状放电(burst-firing activity)的形成及神经元同步放电(neural synchrony)引起 伴与不伴有耳聋的耳鸣，其机制不同。 * 主观性耳鸣的病因及机制 Adjamian P, et al. The mechanisms of tinnitus: Perspectives from human functional neuroimaging. Hearing Research 253 (2009) 15–31 伴有耳聋的耳鸣 图： 耳鸣与耳聋的联系 (Konig et al., 2006). The mean function represents the data from 24 patients who matched the dominant pitch of their tinnitus to a single-frequency tone. Tinnitus pitch is represented by the vertical bars. The arrow points to the mean audiogram edge of the hearing loss. Note that most patients matched their sensation to the region of hearing loss. 85%的耳鸣患者伴有听力减退 耳聋的频率与耳鸣频率匹配 * 主观性耳鸣的病因及机制 外周听力损害所致耳鸣的机制 耳聋所致传入冲动减少，对听觉中枢的抑制性减弱，使得听觉中枢自放电增强。 The prevailing opinion is that tinnitus is a perceptual consequence of altered patterns of intrinsic neural activity generated along the central auditory pathway following damage to peripheral auditory structures (Eggermont and Roberts, 2004). While the loss of afferent input to the central auditory system can initiate tinnitus, thereafter, central mechanisms play an important role in maintaining it. The primary hypothesis of cellular mechanisms underlying tinnitus development is that hearing loss leads to a down-regulation of inhibition and reorganization of the central auditory system . 为什么要放电增强？The central auditory system appears to increase its gain to compensate for the reduced sensorineural input from the cochlea. As a result, hyperactivity often develops in the cochlear nucleus [29,30], the inferior colliculus [23,24,25,31] and the auditory cortex [32]. Tinnitus and underlying brain mechanisms.Curr Opin Otolaryngol Head Neck Surg 2012,