Rapid Increase in Neural Conduction Time in the Adult Human Auditory Brainstem Following Sudden Unilateral Deafness

Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.     

听神经瘤术中耳蜗电图监测与听力保护

目的：评价耳蜗神经电位活动直接监护在听神经瘤手术中对保护听力的作用。方法：听神经瘤手术中施行耳蜗电图监护。结果：１６例听神经瘤手术中施行耳蜗电图监护者，术后听力保留５例（３１％），其中４例为有效听力保留。肿瘤在２厘米以下者听力保留为３８％（５／１３）。结论：听神经瘤手术过程中采用耳蜗电图监护，能敏感地反应即时的听神经功能状况，给术者及时的反馈信息，有助于听力保护     

近端/远端复合肌肉动作电位振幅比率在术后面神经功能评估上的价值

目的 探讨近端/远端复合肌肉动作电位振幅比率在术后面神经肿瘤侵犯段功能评估上的价值和对早期面神经修复的指导意义。方法 比较术末面神经近端/远端复合肌肉动作电位振幅比率和术后2周、6个月患侧面神经功能的H-B分级之间的关系。结果 术后6个月面神经H-B分级恢复到Ⅰ-Ⅱ级者,术末近端/远端复合肌肉动作电位振幅比率均>0.3。结论 术末面神经近端/远端复合肌肉动作电位振幅比率是判断术后面神经远期功能,特别是肿瘤侵犯段功能的重要指标,为术中直接修复面神经提供了指导依据。     

两种MRI序列对听神经瘤成象的比较与评价

为选择中等场强的ＭＲＩ听神经瘤成像最佳序列。收集手术和病理证实的听神经瘤１３５例，分析序列Ⅰ、Ⅱ对内听道中心层面、三叉神经显示率及ＭＲ征象的显示情况。结果：序列Ｉ择内听道中心层面及三叉神经的显示均优于序列Ⅱ，序列Ⅱ在显示肿瘤内囊变、出血、不肿优于序列Ｉ；对肿瘤钙化、肿瘤血管、脑干移位的观察，两者相仿。结果显示：序列Ｉ在中等场经下作为听神经瘤成像的首选序列，并中运用到小脑角区ＭＲＩ成像。     

脑干听觉诱发电位诊断听神经瘤的假阳性分析

综合分析ＢＡＥＰ各项指标，应用ＣＰＡ病变的ＢＡＥＰ４型诊断标准，从６００例可疑听神经瘤患者中，诊断出ＣＰＡ肿瘤５４例，同时发现４例假阳性。本文的假阳性率为７％（４／５８），较多数文献报道为低。在诊断听神经瘤中，ＢＡＥＰ的峰间期比波的绝对潜伏期准确，只有Ⅰ～Ⅲ峰间期增大所导致的Ⅰ～Ⅴ峰间期增大，才有诊断价值，ＢＡＥＰ只有定位作用，无定性价值，故ＢＡＥＰ诊断听神经瘤必须结合临床表现才有意义。在临床上即使已有明确的长束征时，但ＢＡＥＰ无健侧Ⅳ～Ⅴ波的改变，仍可排除肿瘤的诊断。在ＢＡＥＰ的Ⅳ型中，当健侧Ⅳ～Ⅴ波正常时，应参考复合检查，若其阴性则可排除肿瘤的诊断。     

Ring chromosome 22 and neurofibromatosis

Variable constitutional mosaicism, mos45,XY,-22/46,XY,-22,+mar/46,XY,-22,+r(22)/47,XY,-22,+r(22)+mar/ 47, XY,-22,+r(22)*2, was found in PHA-stimulated peripheral blood, in a lymphoblastoid cell line and in cultured skin fibroblasts from a mentally retarded patient with neurofibromatosis. Both the ring chromosome and the small extra marker chromosome stained positively by in situ hybridization with a chromosome 14/22-specific alphoid repeat probe. DNA dosage analysis showed constitutional loss of one copy of the arylsulfatase A gene (ARSA), consistent with its terminal location on 22q. There was no evidence of constitutional loss of D22S1 or D22S28 which flank the neurofibromatosis type 2 (NF2) locus. Analysis of two DNA samples from a skin neurofibroma indicated retainment of two copies of D22S1, whereas the results were ambiguous with respect to tumor-specific loss of one copy of D22S28. It is suggested that the development of neurofibromatosis of unclear type in two r(22) carriers might be associated with somatic mutation of the NF2 locus due to instability of the ring chromosome(s), and in analogy, that somatic mutation of either NF1 or NF2 may account for some cases of neurofibromatosis which do not meet the criteria of either NF1 or NF2. The occurrence of seminoma in the proband may be fortuitous, but could also be due to the presence of a seminoma-associated locus on chromosome 22.     

神经移植端侧缝合颈5/7神经根与上干桥接治疗产瘫

目的：探讨一种不影响残存神经自行恢复的产瘫臂丛神经修复新方法。方法：将上干损伤部位行松解,不切除神经瘤,将其近端的颈5或颈7神经根和神经瘤远端的臂丛上干的神经束膜切开窗口,取颈丛皮支或前臂外侧皮神经前成多段（一般每段长约2．0－2．5cm）,两端分别与颈5神经根和上干的神经束膜行端侧缝合,结果：8例患儿经术后1－11年（平均3年）的随访,4例的三角肌和肱二头肌骨力达4级和4^-级,4例达3例。3例后期进行了肩关节松解和旋前圆肌肌腱切断,结论：该方法既提供了可使损伤近端颈5神经根的新生纤维生长至上干的神经通道,又未阻断神经瘤内残存神经纤维的自行恢复,是治疗产瘫特别是Tassin2型的新术式。     

听神经瘤手术保留面神经的显微外科解剖

目的 :观察面神经在脑桥小脑角、内耳道的显微外科解剖 ,为听神经瘤手术保留面神经提供解剖依据。方法 :采用头颅标本 2 0例 ,对 4 0侧脑桥小脑角部位的面神经进行显微外科解剖观察。结果 :在桥延沟 ,面神经运动根在前庭蜗神经根内侧稍上方 ( 1 .98± 0 .1 0 ) mm,展神经根外侧 ( 8.76± 1 .4 2 ) mm,在舌咽神经根出脑干处的上方约 ( 8.1 5± 2 .1 8) mm。在脑桥小脑池 ,4 0侧面神经共有 62支营养血管 ,主要来自小脑前下动脉及其分支 ;在内耳道有营养动脉 1 7支 ,主要来自迷路动脉。 结论 :熟悉面神经在脑桥小脑角及内耳道的显微解剖 ,有助于听神经瘤术中定位面神经 ,提高面神经保留率。     

岩骨后壁的显微外科解剖对听神经瘤手术中骨迷路保护的意义

目的 观察岩骨后壁表面标志与骨迷路的空间位置关系，为外科手术听力保护提供解剖学基础。方法 20例甲醛固定的成人头颅标本，在手术显微镜下磨除岩骨后壁，充分暴露骨迷路，游标卡尺进行测量。结果 乙状窦前缘与岩嵴相交点前1．24cm、岩嵴下0．34cm，岩骨后壁0．2cm以内磨除骨质，可不破坏骨迷路结构。结论 掌握岩骨后壁表面标志与岩骨内部结构的空间位置关系，是术中定位岩骨内部结构、充分磨除岩骨、扩大手术视野及减少手术并发症的关键。     

经迷路进路听神经瘤术后脑脊液漏的预防及处理

目的　探讨经迷路进路听神经瘤切除术后脑脊液漏发生的影响因素及处理方法。方法1999年以来采用迷路进路或扩大迷路进路听神经瘤切除术 85例 ,前 4 1例采用传统关闭术腔技术 ,后4 4例对关闭技术进行改良 ,分析其脑脊液漏的发生率。发生脑脊液漏者行保守或手术治疗。结果传统关闭技术组中脑脊液漏的发生率为 19 5 % ( 8 4 1) ,改良关闭技术组中脑脊液漏的发生率为 2 3%( 1 4 4 ) ,两组差异有显著性意义 (P =0 0 13)。传统关闭技术组中脑脊液漏多数发生在大型听神经瘤中 ,其发生率随肿瘤增大有上升的趋势。 9例脑脊液漏的患者中 ,3例经保守治疗 ;6例经手术修补成功 ,其中 5例 1次修补成功。结论　改良关闭术腔技术可显著降低经迷路进路听神经瘤切除术后脑脊液漏的发生率 ,手术修补为终止脑脊液漏的有效措施