听力损害时脑皮层的正电子发射断层成像

Hearing Loss Related Brain Areas: A Positron Emission Tomography Study

目的 探讨听力损失对脑葡萄糖代谢活动的影响。方法 对12例有听力损失但无耳鸣患者进行正电子发射断层成像(PET)研究,其中2例双耳全聋,10例双耳中度聋。分别在静息(视听封闭)和声刺激(2kHz短纯音130dBSPL)条件下进行PET成像。与13例听力正常者在静息条件下和4例听力正常者在声刺激条件下的PET作对照。PET示踪剂为^(18)F标记的去氧葡萄糖(^(18)F-FDG)。用专门统计分析软件(SPM)以及感兴趣区技术(ROI)进行统计分析。结果 2例全聋患者的听皮层葡萄糖代谢活动显著低于正常人(P<0.001),而视皮层及体感皮层的代谢活动显著高于正常人(P<0.001)。另10例听力下降患者的听皮层代谢活动低于正常人(P<0.05),声刺激后听皮层兴奋区域显著大于正常人(P<0.001)。提示听力下降引起听皮层神经元葡萄糖代谢活动的相应下降,但与听力下降相邻频率的声刺激却引起相应听皮层的代谢活动的显著增加,而且兴奋区域扩大。表明听皮层发生了功能重组。全聋患者的结果提示,视觉功能显著增强了,这是系统间功能重组的重要证据。结论 PET作为新型脑功能成像仪器,为研究听觉与脑功能提供了新方法,为听系功能重组和中枢神经系统的可塑性提供了有力证据。

Objective To investigate the effects of hearing loss on cerebral metabolic rate for glucose (CMRgl). Methods CMRgl was studied with positron emission tomography (PET) using 18F - FDG as the radiotracer. Ten patients with hearing loss and thirteen control subjects with normal hearing participated in this study. Two patients with total hearing loss in both ears and 10 patients with middle hearing loss in both ears. Thirteen control subjects were scanned without acoustic stimuli and 4 control subjects with acoustic stimuli. The special software SPM (statistical parameter mapping) and region of interest (ROI) were used to analyze the data. Results The mechanical activities of auditory cortex in patients with total deafness were significantly lower than those in control subjects with normal hearing (p<0. 001). However their activities of visual cortex and somatical cortex were significantly higher than those in control subjects (p<0. 001) . The activities of auditory cortex in 10 patients with haring loss were lower than that in normal subjects (p<0. 05). The auditory cortex areas activated by acoustic stimuli in 10 patients were much larger than those in normal subjects (p <0. 001). It was suggested that hearing loss could decrease the activities of auditory cortex. However acoustic stimulation with frequency adjacent to hearing loss part induced activities and enlarged activated area of corresponding auditory cortex. Conclusion It indicated that functional reorganization or plasticity happened in auditory cortex after hearing loss. The results got from total deaf patients provided a clear evidence for functional reorganization among different systems (auditory cortex, visual cortex and somatical cortex).