Fibre composition of the feline trochlear and abducens nerves

Cat trochlear and abducens nerves were studied by electron microscopy at two different levels. Five mm peripheral to the exit from the brainstem, the average number of myelinated axons is 965 in the trochlear nerve and 1901 in the abducens nerve. The size spectrum is unimodal and small myelinated axons predominate. Both nerves contain 16% unmyelinated axons at this level. At the PNS/CNS transition, the nerve fascicles contain few unmyelinated axons, but bundles of such axons are present in the adjacent pia mater. We suggest that the trochlear and abducens nerves may channel unmyelinated sensory and/or autonomic axons to the leptomeningeal blood vessels and the pia mater of the brainstem.     

迟发型外伤性双侧展神经麻痹一例

患者男性,41岁。因摔伤后头痛、头晕2h,于2011年3月21日入院。患者于入院当日晚饭后骑摩托车时不慎摔倒,头部着地,当即意识丧失,约30min清醒后自觉头痛,恶心、呕吐2次,呕吐物为胃内容物。被他人送入我院。诊断与治疗经过入院时查体:体温37.1℃,脉搏84次/min,呼吸21次/min,血压151/87mmHg     

Cellular schwannoma of the abducens nerve: Case report and review of the literature

Schwannomas of the abducens nerve are extremely uncommon tumors. Here, we report the case of a 26-year-old woman who presented with a 6th nerve palsy and was found to have a large tumor at the right side of her pons. Neuropathologic exam revealed a cellular schwannoma with a high proliferation index. The case is presented in its clinical, neurosurgical and neuropathologic aspects and the literature on 6th nerve schwannomas is reviewed.     

大鼠面神经缺血后面神经核磷酸化CREB水平的变化

目的探讨大鼠面神经缺血损伤后面神经元内环磷腺苷反应元件结合蛋白（CREB）磷酸化水平的变化及其与氧化应激的关系。方法 55只成年雄性SD大鼠随机分为正常组（5只）、假手术组（25只）和面神经缺血组（25只）,后两组又根据时间分为术后1、3、7、14、21 d 5个亚组,每亚组5只大鼠。显微手术阻断大鼠鼓室段岩动脉建立大鼠面神经缺血损伤模型。采用分光光度法测定面神经核丙二醛（MDA）含量;利用免疫印迹法测定面神经元内锰超氧化物歧化酶（Mn SOD）和磷酸化CREB（p-CREB）表达水平。结果面神经缺血后,面神经核MDA含量先增高,7 d达峰值,随后降低;而面神经元Mn SOD和p-CREB表达水平先降低,7 d达最低值,随后逐渐增高。面神经缺血组每个时间点MDA水平、Mn SOD和p-CREB表达水平均与正常组和假手术组差异显著（P〈0.05）,而假手术组与正常组之间无显著差异（P〉0.05）。结论面神经缺血损伤后造成面神经元氧化应激损伤,导致p-CREB水平先降低后增高,p-CREB水平的增高可降低ROS对面神经元的氧化损伤能力。     

The superior cervical ganglion: Origin of sympathetic fibers in the facial and hypoglossal nerves in the cat

Location of superior cervical ganglion (SCG) neurons, sending axons into the facial and hypoglossal nerves, was investigated in the cat by means of retrograde axonal transport of horseradish peroxidase (HRP). After wheat germ agglutinin conjugated HRP (WGA-HRP) was injected into these nerves, many retrogradely labeled neurons were found widely in the ipsilateral SCG, particularly around the caudal half of the SCG. These neurons were round or oval in shape and 70-80% of these were medium in size. In fluorescent experiments, fast blue (FB) was used in combination with diamidino yellow (DY). After injections of FB into the facial nerve and DY into the hypoglossal nerve, a few FB-DY double-labeled neurons occurred in the SCG ipsilaterally.     

Vasodilator responses following intracranial stimulation of the trigeminal, facial and glossopharyngeal nerves in the cat gingiva

The effects of electrical stimulation of the trigeminal, facial and glossopharyngeal nerves on gingival blood flow in the cat were studied. The intracranial part of these nerves was stimulated electrically, and gingival blood flow was measured by the laser Doppler technique. Electrical stimulation of the trigeminal, facial and glossopharyngeal nerves caused blood flow to increase in the ipsilateral gingiva both with the cranial nerve intact and after cutting it to the medulla. Stimulation of the distal cut ends of the facial and glossopharyngeal nerves elicited an increase in blood flow but no increase in systemic blood pressure. Pretreatment with hexamethonium reduced the increase in blood flow elicited by electrical stimulation of the facial and glossopharyngeal nerves, but had no effect on that elicited by stimulation of the trigeminal nerve. In contrast, pretreatment with tripelennamine attenuated the trigeminal nerve-stimulated blood flow increase, but not that elicited by stimulation of the facial and glossopharyngeal nerves. Atropine, propranolol and phentolamine had no effect on these responses. These results suggest that the autonomic nervous system, particularly the parasympathetic nervous system, is responsible for the blood flow increase elicited by facial and glossopharyngeal nerve stimulation, and that the trigeminal nerve-stimulated blood flow increase is induced by antidromic vasodilatation of the trigeminal sensory nerve.     

大型听神经瘤的显微手术治疗与面神经保护

目的探讨大型听神经瘤的显微手术治疗及面神经的保护。方法54例大型听神经瘤（直径＞3cm）患者,均在面神经及脑干电生理监测下采用枕下乙状窦后入路显微手术切除,术中采用长＂S＂形或直形切口,开枕骨骨瓣直径约4cm,显露横窦和乙状窦,放出枕大池脑脊液,再行显微镜下分离及切除肿瘤,术后对其面神经功能进行随防。结果全切49例（91%）,近全切5例,面神经保留51例,保留率为94%,无死亡病例。结论显微手术与面神经的电生理监测是大型听神经瘤得以全切并保留面神经的关键,扎实的显微解剖知识、娴熟的显微手术技巧及完善的手术中监测是手术成功的保障。     

大中型听神经瘤的显微手术治疗及面神经的保护

目的 探讨显微手术治疗大中型听神经瘤的疗效及保护面神经的方法。方法 23例大中型听神经瘤（直径>2 cm）患者均在电生理监测下采用枕下乙状窦后入路显微手术切除,术后对其面神经功能进行随防。结果 肿瘤全切除15例,近全切除8例;面神经保留22例,保留率为95.7%;术后面神经功能House-Brackmann分级:1级3例,2级10例,3级6例,4级2例,5级1例,6级1例。术后所有病人随访3~24月,发生脑脊液漏者1例,长期昏迷1例,无死亡病例。结论 显微手术与面神经的电生理监测为全切除大中型听神经瘤并保留面神经提供了保障。     

Intracranial stimulation of the facial nerve: normative values with magnetic coil in 240 nerves

This study was aimed at defining normative values of latency and amplitude of the compound muscle action potential (CMAP) from the orbicularis oculi muscle, obtained by transcranial magnetic stimulation. We evaluated the dependence of latency and amplitude on the age of the subjects, in order to calculate cut-off values for each age decade. A total of 120 healthy normal subjects, aged 15–78 years, were studied. CMAP from the orbicularis oculi muscle, pars inferior, was excited by means of transcranial magnetic stimulation of the homolateral scalp. A suitable mathematical model was developed to evaluate the mean variation of the latency and amplitude of CMAP for each age decade in the studied population. Mean values were, respectively, 4.62±0.40 ms for latency and 4.17±0.72 mV for amplitude. We found an increase in latency of about 0.12 ms for every ten years, that became 0.15 ms if referring only to subjects over 20 years, and a decrease in amplitude of 0.18 mV each ten years. Normality interval values for the latency and amplitude were calculated for each age decade. Our data, obtained in a representative population for range of age of evaluated subjects, provide normality values and variability coefficients useful for future confronting works. Received: 20 September 2002 / Accepted in revised form: 6 December 2002 Correspondence to D. Cocito     

Cardiovascular and respiratory consequences of bilateral involvement of the medullary intermediate reticular formation in syringobulbia

We studied five patients with clinical and radiological evidence of syringobulbia (SB) to determine whether the distribution of lesions in relationship to the cardiorespiratory control networks in the medullary intermediate reticular zone (IRt) correlates with the presence of abnormalities in autonomic cardiovascular and respiratory control in these patients. All patients underwent high resolution MRI to characterize the size, volume and distribution of the SB lesions, cardiovascular autonomic function testing and polysomnography. One patient with bilateral IRt involvement at both the rostral and caudal medulla had orthostatic hypotension (OH), absent HR_DB, abnormal Valsalva ratio, exaggerated fall of BP during phase II and absent phase IV during VM, and a dramatic fall of BP during head up tilt; this patient also had severe obstructive sleep apnea (OSA) and exhibited BP drops during each respiratory effort. A second patient, with bilateral IRt involvement restricted to the caudal medulla, had less severe cardiovascular autonomic dysfunction but also exhibited severe OSA. The other three patients had small SB cavities sparing the IRt and had sleep apnea but no autonomic dysfunction. Autonomic dysfunction could not be related to the size of the syrinx or the degree of atrophy in the cervical spinal cord in any of the five patients. Bilateral involvement of the IRt by SB produces cardiovascular autonomic failure and sleep apnea. In patients with more restricted lesions, autonomic and respiratory dysfunction may be dissociated. Clinico-radiological correlations using high resolution MRI assessment of medullary lesions can provide insight into the central organization of cardiovascular and respiratory control in humans. Received: 6 August 2002, Accepted: 26 September 2002 Correspondence to Dr. Martín Nogués     

A comparison of thyroxine- and polyamine-mediated enhancement of rat facial nerve regeneration

Thyroid hormones and spermidine, a motor neuron trophic polyamine (PA), have been shown to enhance peripheral motor nerve regeneration; however, the mechanism by which these treatment modalities exert their effect is unknown. Similarities in treatment outcome suggest that these molecules may be working via a common mechanism. Such an explanation is plausible since thyroid hormone is a potent inducer of ornithine decarboxylase (ODC), which is the rate-limiting enzyme involved in polyamine synthesis. This study was designed to morphologically evaluate the effects of exogenous thyroxine and spermidine on the regeneration of the rat facial nerve. Myelinated fiber density, axonal size, and degree of myelination were assayed by light and electron microscopy 21 days following facial nerve crush. Strikingly, the two treatment modalities had identical effects on all parameters tested. Each significantly enhanced the density of myelinated axons in regenerating nerves relative to the vehicle control. In addition, relative to the control treatment, both thyroxine and spermidine significantly increased the cross-sectional area of regenerating axons (P < 0.05). Interestingly, neither of the drug treatments had any effect on remyelination at the position where this parameter was analyzed. The concurrent administration of both thyroxine and spermidine did not synergistically enhance motor neuron regeneration. These data support the hypothesis that thyroxine and spermidine enhance neural regeneration by a common mechanism.     

大型听神经瘤的显微手术治疗及术中面神经保护

目的 探讨显微手术切除大型（肿瘤最大径>3 cm）听神经瘤的疗效及术中面神经保护的方法。方法 回顾性分析2014年1月至2018年2月手术治疗的86例大型听神经瘤的临床资料,均在电生理监测下采用枕下乙状窦后入路显微手术。结果 肿瘤全切除83例,近全切除3例。面神经保留78例（91%）;术后1周面神经功能House-Backmann分级:1级11例,2级37例,3级22例,4级16例。术后门诊随访3~30个月,术区皮下积液4例,口唇疱疹9例,无死亡病例。结论 术前多模态肿瘤-神经评估,术中实时电生理监测,精细显微手术对大型听神经瘤全切和保留面神经功能可提供保障。     

面神经保留程度对神经再生及重建眼轮匝肌功能影响的实验研究

目的探讨保留不同程度的再生面神经对面神经-舌下神经侧-侧吻合术后大鼠眼轮匝肌功能重建的作用。方法采用随机抽样分组的方法,将40只大鼠分为4组(每组10只),4组大鼠均行面神经钳夹线拴损伤及面神经-舌下神经侧-侧吻合术(简称吻合术)。术后3个月,A组(对照组):模型建立后不做任何处理;B组:横截断结扎线近头端面神经1/3部分;C组:横截断结扎线近头端面神经2/3部分;D组:于面神经结扎线近头端全部离断面神经。分别于吻合术后1、2、3个月和横截断面神经1周后采用瞬目反应评分评估大鼠患侧眼睑的闭合程度;行运动诱发电位(MAPs)检测大鼠患侧眼轮匝肌的动作电位幅度及波幅下面积;神经元逆行示踪检测面神经核及舌下神经核内阳性神经元的数量;面神经及移植神经半薄切片计数髓鞘数目。结果4组大鼠吻合术后1、2、3个月的瞬目反应评分比较差异均有统计学意义(F值分别为12.47、11.00、10.61、19.13,均P<0.05);横截断面神经1周后4组瞬目反应评分的差异有统计学意义(F=29.06,P<0.05),其中D组分别低于A组和B组(均P<0.01);横截断面神经1周后,刺激面神经吻合口近头端及移植神经中点,4组的MAPs波幅及波幅下面积的差异均有统计学意义(F值分别为27.56、11.86、6.33、4.65,均P<0.05),其中D组的MAPs波幅及波幅下面积均低于A组(均P<0.05)。神经元逆行示踪显示,4组的面神经核内阳性神经元计数的差异有统计学意义(F=6.52,P<0.05),其中D组的阳性神经元数量分别低于A组和B组(均P<0.05)。4组的面神经干及移植神经中段髓鞘计数差异均有统计学意义(F值分别为8.33、6.35,均P<0.05),其中A组分别高于C组和D组(均P<0.05)。结论面-舌吻合术中保留面神经结构完整性具有积极意义,至少保留2/3再生面神经对眼轮匝肌恢复有利。     

Selective blockade of muscarinic receptor subtypes in the brain stem reticular formation in rats: effects on anesthetic requirements

Muscarinic involvement in the modulation of general anesthesia was examined in the rat with a cannula implanted in the pontine reticular formation. Atropine microinjected into the reticular formation reversed the minimum alveolar concentration (MAC) reducing effect of carbachol on halothane anesthesia, but M(1) or M(3) antagonist had no effect. An M(2) antagonist reduced the MAC of halothane following saline and carbachol. The results suggest that any of the muscarinic receptor subtypes in this region do not independently mediate the cholinomimetic effect on halothane anesthesia.     

Morphometric study of hypoglossal nerve and facial nerve on the submandibular region in korean

Objective

This study was performed to determine the anatomical landmarks and optimal dissection points of the facial nerve (FN) and the hypoglossal nerve (HGN) in the submandibular region to provide guidance for hypoglossal-facial nerve anastomosis (HFNA).

Methods

Twenty-nine specimens were obtained from 15 formalin-fixed adult cadavers. Distances were measured based on the mastoid process tip (MPT), common carotid artery bifurcation (CCAB), and the digastric muscle posterior belly (DMPB).

Results

The shortest distance from the MPT to the stylomastoid foramen was 14.1±2.9 mm. The distance from the MPT to the FN origin was 8.6±2.8 mm anteriorly and 5.9±2.8 mm superiorly. The distance from the CCAB to the crossing point of the HGN and the internal carotid artery was 18.5±6.7 mm, and that to the crossing point of the HGN and the external carotid artery was 15.1±5.7 mm. The distance from the CCAB to the HGN bifurcation was 26.6±7.5 mm. The distance from the digastric groove to the HGN, which was found under the DMPB, was about 35.8±5.7 mm. The distance from the digastric groove to the HGN, which was found under the DMPB, corresponded to about 65.5% of the whole length of the DMPB.

Conclusion

This study provides useful information regarding the morphometric anatomy of the submandibular region, and the presented morphological data on the nerves and surrounding structures will aid in understanding the anatomical structures more accurately to prevent complications of HFNA.     

面中下部除皱术中面神经的解剖与保护

目的根据面神经的解剖特点探讨面中下部除皱术中面神经的保护。方法对16例行面中下部除皱患者,采用合适的分离平面及范围,且在术中对面神经进行主动保护。结果2例出现一过性面瘫后逐渐恢复,其余恢复顺利,随访6个月～2年效果满意。结论了解面神经各分支的分布及走行,同时在术中进行主动保护,这是除皱手术成功的基础。     

Changes in glycosaminoglycans during regeneration of post-crush sciatic nerves of adult guinea pigs

The glycosaminoglycans of sciatic nerves recovering from crush-injury were studied in adult guinea pigs and compared with those of non-injured mature neural tissues. The glycosaminoglycans were recovered from the 1,900 g supernatant and pellet of the tissue homogenates and assayed for hexuronate contents and susceptibilities to hyaluronidase, chondroitinase ABC, and nitrous acid. In the normal brain and central nerve tracts, the glycosoaminoglycans were distributed both in the supernatant and pellet fractions; the brain showed a predominance of chondroitin sulphates but the tracts showed a predominance of heparan sulphates. Twice as much glycosaminoglycans were found in normal sciatic nerves, only in the pellet fraction and with heparan sulphate predominant. In the 2 weeks post-crush, progressive increase in hexuronate was observed, due mainly to additional chondroitin sulphate forms in the supernatant; the pellet fraction in the same period was however similar to the untreated controls in relative abundance of glycosaminoglycan classes and hexuronate content. At 4 weeks post-crush, although the total hexuronate returned to the control level, a significant proportion of glycosaminoglycans remained in the supernatant fraction. Evidence is thus provided for the need to modulate the glycosaminoglycan expression pattern in adult neural tissue to allow post-traumatic tissue remodelling and axonal regrowth. © 1996 Wiley-Liss, Inc.     

Phenytoin administration reveals a differential role of pontine reticular formation and periaqueductal gray neurons in generation of the convulsive behaviors of audiogenic seizures

The ventrolateral periaqueductal gray (PAG) and pontine reticular formation (PRF) are implicated in the neuronal network for audiogenic seizures (AGS). The AGS of genetically epilepsy-prone rats (GEPR-9s) culminate in tonic hindlimb extension (TE), and elevated acoustically evoked neuronal firing and burst firing, immediately preceding TE, have been observed in PAG and PRF. This study examined changes in PAG and PRF neuronal firing and behavior in GEPR-9s, following phenytoin administration. Recordings involved 16 PAG and nine PRF neurons in GEPR-9s. Phenytoin in doses (mean, 6. 3 mg/kg) that suppressed TE selectively did not consistently alter PAG neuronal firing. However, these doses of phenytoin resulted in significant (51.6% of control) suppression of PRF neuronal firing. Doses of phenytoin (mean, 8.3 mg/kg), which completely blocked AGS, significantly reduced PAG neuronal firing (64.6% of control), and more greatly suppressed PRF firing (25.8% of control). These results are consistent with a critical role for PRF neurons in generation of TE not evident for PAG. The suppression of PAG and PRF neuronal firing induced by phenytoin with complete seizure blockade is consistent with vital roles for both structures in the seizure network. The differential effects of phenytoin on structures requisite to the seizure network indicate that this experimental approach may be able to identify the most sensitive therapeutic target for anticonvulsant drugs, which could be critical to pharmacological suppression of specific seizure behaviors manifest in various types of convulsions, potentially including human epilepsy.     

Electrophysiological properties and cholinergic responses of rat ventral oral pontine reticular neurons in vitro

In order to characterize the electrophysiological properties of morphologically identified neurons of the ventral part of the oral pontine reticular (vRPO) nucleus and the effects of cholinergic agonists on them, intracellular recordings were obtained from 45 cells in a rat brain-slice preparation. Intracellular staining was performed with 2% biocytin in potassium acetate (1 M)-filled micropipettes. Results demonstrated the presence of two types of vRPO neurons. Type I cells (n=12, 24%) were characterized by a break with a decrease of the depolarizing slope following hyperpolarizing pulses which delayed the return to the resting V_m and subsequent spike-firing. The delay was antagonized by 4-AP (200–500 μM) which specifically blocks the transient outward K⁺-mediated current I_A. Type II neurons (n=38, 76%) displayed a typical depolarizing sag during hyperpolarizing current pulses which was blocked by Cs⁺. This behavior is characteristic of the hyperpolarization-activated current I_Q. These two neuronal types displayed different morphological features. Most type I and II cells (100 and 73.7%, respectively) were depolarized by acetylcholine (1–15 μM), carbachol (0.5–1 μM) and muscarine (1–10 μM) through the activation of post-synaptic muscarinic receptors. The remaining type II cells (26.3%) were hyperpolarized (1–10 min, 3–15 mV) through the activation of post-synaptic muscarinic receptors. Results are consistent with the hypothesis that the vRPO could be a neuronal target of Cch in eliciting paradoxical sleep because most of its neurons are activated by muscarinic agonists. © 1979 Elsevier Science B.V. All rights reserved.