面神经管裂缺处面神经组织学观察

目的探讨先天性面神经管裂处神经外膜缺陷可能引起的病理学改变。方法采用光学显微镜对美国明尼苏达大学颞骨病理实验室１５２６具颞骨连续切片的面神经颞骨全程进行组织病理学观察。结果发现先天性面神经管裂者８８５耳，其中４８耳在管裂处神经外膜缺损，其中４０耳面神经从管裂处疝出，有１３耳在管裂处形成外生性面神经鞘瘤。３耳在管裂处面神经受炎性细胞浸润。而管裂处有神经外膜覆盖的８３７耳均未见此类病变。结论面神经管裂处神经外膜的缺损是此处面神经疝出、外生性神经鞘瘤形成和面神经易于受炎症浸润的组织解剖学原因。     

Reversed palmaris longus muscle on MRI: report of four cases

Muscle anomalies around the wrist, in particular the palmaris longus muscle, may cause effort-related median nerve compression. A search of the medical records at our university hospital between 1994 and 1999 revealed four patients with an effort-related median nerve compression due to a reversed palmaris longus muscle. Magnetic resonance imaging was used in the patient work-up and showed an anomalous muscle in each case that had been missed initially. All four patients were free of pain after simple excision of the anomalous muscle. Awareness of muscle anomalies at the wrist on MR imaging is essential in evaluating patients with nerve compressions at the wrist. The purpose of this article is to heighten this awareness in radiologists. Received: 23 June 1999; Revised: 30 September 1999; Accepted: 24 December 1999     

Early and selective pathology of light chain neurofilament in the spinal cord and sciatic nerve of G86R mutant superoxide dismutase transgenic mice

Pathologic accumulation of neurofilament protein (NF), both within spheroids of the proximal axon and within inclusions of motor neuron somata, is a hallmark of neurodegeneration in amyotrophic lateral sclerosis (ALS). Transgenic mice that express mutations in superoxide dismutase (SOD-1), which were genetically linked to familial ALS, develop symptomatology and pathology that strongly resemble ALS and therefore provide a useful model for studying the disease. Examining NF in the G86R mutant SOD-1 transgenic mice, we previously demonstrated that phosphorylated NF accumulates in motor neuron somata of symptomatic transgenic mice. In the present study, we expand these results by examining the immunocytochemical distribution of the three subunits of NF (i.e., light, medium, and heavy chains) as well as tubulin in presymptomatic and symptomatic SOD-1 transgenic mice. Although all NF subunits, but not tubulin, accumulate along with phosphorylated NF in the spinal cord inclusions of symptomatic mice, numerous inclusions containing only light chain NF are found in the spinal cord of presymptomatic SOD-1 transgenic mice. In addition to these results in the spinal cord, intensely immunoreactive aggregates of NF-L, but not the other NF subunits or tubulin, were observed in the sciatic nerve of both symptomatic and presymptomatic mutant SOD-1 transgenic mice. These results suggest that the mechanism of NF alteration in SOD-1 transgenic mice, and also perhaps in ALS patients, originates with the disruption of NF-L, only later involving the other subunits.     

兔蜗神经直接动作电位的特征

目的　探讨新西兰大白兔蜗神经直接动作电位 (directcochlearnerveactionpotential,DCNAP)的记录方法和特征 ,建立术中听觉监护动物模型。方法　纯种新西兰大白兔 6只 (12耳 ) ,乙状窦后进路暴露小脑、脑干及双侧桥脑小脑角区 ,插入针状电极于蜗神经 ,记录DCNAP ,并按常规方法记录听性脑干反应 (auditorybrainstemresponse ,ABR)。结果　用本方法记录的DCNAP具有振幅大、波形稳定、重复性好、记录时间短的特点 ,但个体差异较大。结论　在蜗神经桥脑小脑角区用针状电极可以可靠记录到DCNAP ,是术中听觉监护的可行方法     

A ventral approach to stereotaxy of the guinea pig brain

For skeletal muscles, a well-known match exists between the properties of motoneurones and those of their muscle fibres. Hence, the intramuscular distribution of different kinds of motoneuronal nerve endings (e.g. ‘slow’ versus ‘fast’) can be mapped by determining the distribution of the corresponding types of muscle fibre. As a background for further studies of motoneuronal plasticity, we needed precise measures of such distributions. Simple quantitative methods were developed for defining the position and extent of sub-populations of cells within a structure (e.g. the regional distribution of slow versus fast muscle fibres within a muscle cross-section): (a) The ‘mass vector method’ defined the relative position of the target cell cloud. A line was drawn between the calculated centre of mass for the target cells and that for the whole structure. The direction (a1) and length (a2) of this line gave a measure of the direction and degree of target cell eccentricity within the structure. (b) The ‘sector method’ delineated the region containing the target fibres. A circle around the centre of mass for the target fibres was subdivided into a number of equal sectors (standard setting: 20). The most remote point was found within each sector and a line joining these points defined the region of the target fibres. When applied to the ‘slow’ type I fibres of cross-sections from rat hindlimb muscles, the regional area estimates obtained by the sector method were highly correlated with, but 10% lower than those achieved by the well-established ‘convex hull’ method. Highly significant inter-muscular differences were observed for each one of the three new parameters described in this paper (a1, a2, b).     

Stretch of mammalian nerve in vitro: effect on compound action potentials

Stretch of nerve has been reported to decrease the amplitude of the compound action potential (CAP) with a complete block appearing in approximately 30 minutes. But for the most part, those experiments were carried out in vivo, and it is generally accepted that the failure of responses was due to a closure of vessels supplying the nerve with a resulting ischemia and anoxia. These studies were undertaken to determine if stretch of nerve has effects that are independent of interference with its vascular supply. In the studies, lengths of rat sciatic and dog peroneal nerves were removed and placed in a chamber supplied with oxygen in which their CAPs were continuously elicited and recorded. This in vitro preparation obviated interference with the nerve's metabolism on stretching. We have previously shown that the form change termed 'beading,' appearing within 10 seconds and reversing as quickly on relaxation, can be elicited with tensions of only several grams. We wished to determine if stretch adequate to produce beading could alter CAPs with the same rapidity. Tensions below 2 g had little effect. On applying tensions of 10-100 g, levels well above those needed to bead the fibers, both increases and decreases of CAP amplitude were seen. The changes occurred within 10 seconds of stretch application, the time at which beading arises with stretch. Although the decreases of CAP amplitudes could be accounted for by beading, the degree of CAP change did not correspond to the amount of tension applied. We hypothesize that the constrictions in the beaded fibers increase axial resistivity and diminish local currents so as to block conduction. The lack of an increasing degree of decreased CAP amplitude with increases in tension is ascribed to the inhibition of elongation offered by the collagen fibrils present in nerve. Collagenase applied to nerves allowed a further increase in length, producing a 'hyperbeading,' showing much longer lengths of beading constrictions on stretch. This would further increase axial resistance and is taken to account for the greater decreases of CAP amplitudes seen following collagenase treatment. To account for those cases where increases of CAP amplitude were seen on stretch, we hypothesize that stretch can also cause an increase in the excitability of the nodes. The outcome of stretch in any given nerve would be the resultant of two opposing actions; beading of the internodes causes a decrease of local currents leading to block of CAPs, while an increased excitability of the nodes acts to augment the responses.     

局部浸润和神经阻滞麻醉在会阴切开中的应用分析

目的 探讨会阴切开时不同麻醉方式对产妇的影响.方法 将100例产妇随机分为左侧阴部神经阻滞麻醉组(阻滞组)和局部组织浸润麻醉组(浸润组),每组50例,比较两组产妇镇痛效果、缝合时间、第四产程出血量及产后72h活动的情况.结果 浸润组在镇痛效果、缝合时间、出血量及产后的活动方面均优于阻滞组.结论 在会阴切开缝合术中应用小剂量利多卡因作阴部浸润麻醉有效减轻了产妇的切口疼痛,缩短缝合时间,减少第四产程出血量.     

桡神经损伤62例治疗体会

目的回顾桡神经损伤62例的治疗,探讨其最佳治疗方案。方法闭合性肱骨骨折并桡神经损伤38例,先手法复位小夹板或石膏托外固定,观察2周,有20例改手术治疗;开放性、刀砍伤22例,行急诊手术;陈旧性骨折、桡神经扭曲成瘤2例,择期手术神经吻合。结果62例桡神经损伤的治疗随访8个月至12年,非手术治疗18例,均4个月后功能恢复;手术治疗44例,神经吻合15例,松解29例,大部分术后4～6个月开始恢复功能,其中1例手术时间较晚,神经外膜挫伤严重,1年后才稍有恢复。结论合理选择治疗方案,提高手术技巧,有利于桡神经功能早恢复,保证治疗效果。     

上颌骨前牵引对犬眶下神经的影响

目的:观察犬双侧上颌骨前牵引的不同时期眶下神经组织学结构的改变,探讨其对眶下神经的影响。方法:选12周龄杂种犬13只为实验对象,实验组12只,用特制牵引器进行上颌骨前牵引;对照组1只,未配戴牵引器。牵引过程包括15d牵引期和20d固定期,牵引力为800g。于术后不同时间点分组处死动物,取双侧眶下神经,制成常规切片,光镜下观察不同时期的神经组织形态。结果:随着牵引的进行,上颌骨明显前移,眶下神经出现明显病理变化,牵引结束时神经损伤最严重;固定期神经出现修复性变化。结论:双侧上颌骨前牵引对眶下神经可产生一定的损伤,但这种损伤是暂时的、可逆的,随着时间的延长,神经的形态结构可恢复正常。     

大鼠视神经钳伤后外侧膝状体细胞损伤的研究

目的　探讨大鼠视神经钳伤后 ,外侧膝状体 (lateralgeniculatebody,LGB)细胞的损伤情况。方法　用 4 0g视神经损伤钳 ,压迫Sprague Dawley(SD)大鼠双侧视神经 30s,制成视神经部分定量损伤的动物模型。对LGB连续梯度切片 ,7d后用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法 (teriminaldeoxynucleotidyltransferase mediateddUTPnickend labeling ,TUNEL)对LGB细胞进行凋亡检测。 1个月后通过免疫组化染色技术 ,用兔抗鼠神经丝 (neurofilament,NF)单克隆抗体对LGB的神经元进行检测。同时经视觉中枢注入荧光染料颗粒蓝 ,对LGB细胞进行逆行荧光标记 ,在 70 0nm波长荧光显微镜下对连续切片的LGB标记细胞进行平均密度计数 ,并与对照组比较。结果　TUNEL法染色证实LGB细胞发生凋亡。对照组神经丝免疫组化染色呈清晰的条索状 ,而实验组明显减少。对照组LGB细胞密度均值为 (5 172± 2 4 8)个 /mm2 ,而损伤组LGB细胞密度均值为 (414 4± 6 1)个 /mm2 ,两组比较差异有非常显著意义 (t=8 995 ,P <0 0 1)。结论　在大鼠视神经钳伤后 ,LGB细胞受损 ,其损伤机制与凋亡有关