单侧感音神经性耳聋病人听觉中枢的fMRI研究

目的探讨单侧感音神经性耳聋病人与正常听力者的听皮质频率敏感性排列结构的差异;双侧听皮质中枢半球优势的变化;单侧感音神经性耳聋病人皮层下区听觉传导通路的变化.方法20例正常志愿者和20例单侧感音神经性耳聋病人,分别采集T1WI、GRE-EPI及3D GRE T1WI影像.采用组块式方法分别随机给予500 Hz,4000 Hz两种纯音刺激,每种刺激重复2次.所有图像均经AFNI进行后处理,统计阈值概率设定为P＜10-5,激活范围阈值设定为半径5 mm,体积300 mm3的连续激活区域考虑为有意义激活区.结果正常听力者和单侧耳聋病人给予单耳500 Hz,4000 Hz刺激时,二者对于听皮质激活容积存在统计学差异(P＜0.05).正常听力者给予单耳刺激表现为对侧半球优势,半球激活容积比分别为7.56,6.02(右耳刺激);2.56,5.11(左耳刺激).而单侧耳聋病人则表现为同侧半球优势,半球激活容积比分别为0.62,0.69(左侧耳聋,右耳刺激);0.96,0.83(右侧耳聋,左耳刺激).结论正常听力者对500 Hz和4000 Hz的频率刺激激活区的位置存在差别.单侧感音神经性耳聋失去了听觉中枢的频率敏感性空间排列结构.单侧耳聋病人表现为同侧半球优势.500 Hz对正常听力者和单侧感音神经性耳聋病人的听皮质激活范围明显大于4000 Hz者.

Functional MRI study of auditory cortex in patientswith unilateral sensorineural hearing loss

Objective To study the difference of tonotopicity between hearing and unilateram hearing loss patients, and to reveal the lateralization of functional auditory cortex between hearing and hearing-loss patients. Methods Twenty hearing subjects and 20 unilateral (10 left, 10 right) hearing-loss patients received anatomical T1WI, GRE-EPI fMRI with a 1.5 T whole body MRI scanner and high-resolution 3D GRE T1WI. Experimental tasks included randomly pure-sound of 500 Hz, 4000 Hz stimulating. Following block design, 4 trial blocks and 5 contrast blocks were performed alternatively. Realigning, normalizing and smoothing were performed using AFNI for fMRI data, activation foci were superposed on high-resolution T1WI. Numbers of activative volumes were included when statistical threshold P<10 -5, 5 mm radius and 300 mm3 continuous stimulating areas. Results There was statistically difference between 500 Hz and 4000 Hz (P<0.05) in both hearing and unilateral hearing-loss patients. The latter was smaller that the former. It showed contralateralization in hearing subjects when given single ear stimulation of 500 Hz and 4000 Hz. The ratio of hemisphere stimulating volume was 7.56, 6.02 (right stimulation); 2.56, 5.11 (left stimulation). But the unilateral hearing-loss patients showed ipsilateralization when given single ear stimulation of 500Hz and 4000Hz .The ratio of hemisphere stimulating volume was 0.62, 0.69 (right stimulation); 0.96, 0.83 (left stimulation). Conclusion It showed tonotopicity in hearing subjects and the stimulating area of 500 Hz located in the anterior part of the Heschl's gyrus, the stimulating area of 4000 Hz were in the posterior-lateral part. But the unilateral hearing-loss patients lost their tonotopicity when given different frequency stimulation. The hearing subjects showed contralateralization and the unilateral hearing-loss patients showed ipsilateralization. The extent of stimulating area of 500 Hz is obviously larger than that of 4000 Hz.