Second-order vestibular neuron morphology of the extra-MLF anterior canal pathway in the cat

Second-order vestibular neurons form the central links of the vestibulo-oculomotor three-neuron arcs that mediate compensatory eye movements. Most of the axons that provide for vertical vestibulo-ocular reflexes ascend in the medial longitudinal fasciculus (MLF) toward target neurons in the oculomotor and trochlear nuclei. We have now determined the morphology of individual excitatory second-order neurons of the anterior semicircular canal system that course outside the MLF to the oculomotor nucleus. The data were obtained by the intracellular horseradish peroxidase method. Cell somata of the extra-MLF anterior canal neurons were located in the superior vestibular nucleus. The main axon ascended through the deep reticular formation beneath the brachium conjunctivum to the rostral extent of the nucleus reticularis tegmenti pontis, where it crossed the midline. The main axon continued its trajectory to the caudal edge of the red nucleus from where it coursed back toward the oculomotor nucleus. Within the oculomotor nucleus, collaterals reached superior rectus and inferior oblique motoneurons. Some axon branches recrossed the midline within the oculomotor nucleus and reached the superior rectus motoneuron subdivision on that side. Since these neurons did not give off a collateral toward the spinal cord, they were classified as being of the vestibulo-oculomotor type and are thought to be involved exclusively in eye movement control. The signal content and spatial tuning characteristics of this anterior canal vestibulo-oculomotor neuron class remain to be determined.     

良性阵发性位置性眩晕患者发病特点及手法复位疗效分析

目的 探讨良性阵发性位置性眩晕(benign paroxysmal positional vertigo,BPPV)患者的发病特点及手法复位治疗的疗效.方法 回顾性分析2008年1月～2013年12月广西右江民族医学院附属医院耳鼻咽喉一头颈外科确诊并治疗的968例BPPV患者的临床资料,分析该病发病特点及手法复位疗效.结果 ①968例BP-PV患者中男577例(59.61％),女391例(40.39％),男女比例为1.48:1,发病平均年龄51.36±10.63岁(23～96岁);后半规管BBPV 921例(95.14％,921/968),其中管结石症877例(95.22％,877/921),嵴顶结石症44例(约4.78％,44/921);水平半规管BBPV 39例(4.03％,39/968),其中管结石症35例(89.74％,35/39),嵴顶结石症4例(10.26％,4/39);上半规管BBPV 5例(0.52％,5/968),混合型BBPV 3例(0.31％,3/968).②921例后半规管BBPV行传统Epley法复位治疗,首次有效率为91.64％,远期(半年)有效率92.73％;水平半规管BBPV行Barbecue法复位治疗,首次有效率92.31％,远期(半年)有效率94.87％;上半规管BBPV行前翻法复位治疗,首次有效率60.00％,远期(半年)有效率80.00％;混合型半规管BBPV行联合复位治疗,首次有效率66.67％,远期(半年)有效率66.67％;③968例患者中半年内复发92例,复发率9.50％(92/968).结论 本组BPPV患者发病以男性患者和后半规管BPPV多见,手法复位能有效治疗BPPV,尤以后半规管BPPV及水平半规管BPPV疗效显著.     

水平半规管良性阵发性位置性眩晕的临床特点

目的 探讨水平半规管良性阵发性位置性眩晕(benign paroxysmal positional vertigo,BPPV)的临床特点.方法 回顾性分析2003年8月至2010年12月诊治的239例水平半规管BPPV患者的临床表现.结果 水平半规管BPPV占同期全部BPPV患者的25.7％(239/931).平卧侧头试验见水平向地性眼震者197例,眼震的平均潜伏期为(0.88±0.72)s,持续时间(26.36±19.71)s;水平离地性眼震者42例,平均潜伏期(2.69±1.83)s,持续时间(53.48±43.12)s;其中39例眼震表现为水平略带扭转向上而非纯水平,占16.3％(39/239).离地组眼震潜伏期明显长于向地组(t=-6.33,P＜0.001),眼震持续时间亦明显长于向地组(t=-3.99,P＜0.001).水平向地性眼震者予以Barbecue翻滚法治疗,192例经(1.6±0.8)个循环复位成功;水平离地性眼震者经左右侧头训练后,40例眼震转化为向地性,经(1.9±0.8)个循环后复位成功.结论 水平半规管BPPV占同期BPPV的比例较预期高.水平向地性眼震患者可直接给予Barbecue翻滚法治疗,水平离地性眼震患者应先行左右侧头训练,再给予Barbecue翻滚法复位.     

Adverse effects of semicircular circle angles variation on Epley repositioning procedure: a study on reconstruction of Micro-CT images 3D

Abstract

Background: For patients with posterior semicircular canal (PSC) BPPV, Epley re-position maneuver and some improvement methods are the most efficient treatment methods. But there were still 9.43% patients who were not benefit from Epley re-position maneuver.

Objective: To measure the angles of semicircular canals and evaluate its effect on Epley maneuver.

Methods: Fifteen skull specimens, containing 30 temporal bone specimens were included. After Micro-CT scanning, 3D reconstruction was loaded with the CT image. The angles between each semicircular canal and each standard skull plane were measured. Furthermore, the angles’ effect on Epley maneuver was evaluated according to the three-dimension (3D) model.

Results: Angles of PSC plane: Frankfurt plane was 71.54?±?6.51, sagittal plane was 53.77?±?5.36°, and the coronal plane was 43.33?±?3.56°. Angles between PSC and the sagittal plane of skulls had an adverse effect on Epley maneuver, when it was less than 45°.

Conclusion: 1. Variation could be found in angles between the semicircular canals and the standard planes of skulls, which meant variation of semicircular canals’ location existing in skulls. 2. The variation of angles between PSC and sagittal plane could have an adverse effect on the Epley maneuver when the angle was less than 45°, which may cause the Epley maneuver to be invalid.     

Transmastoid Approach for Resurfacing the Superior Semicircular Canal Dehiscence with a Dumpling Structure

Background:

Superior semicircular canal dehiscence (SSCD) is gradually recognized by otologists in recent years. The patients with SSCD have a syndrome comprising a series of vestibular symptoms and hearing function disorders which can be cured by the operation. In this study, we evaluated the characteristics of patients with SSCD and determined the effectiveness of treating this syndrome by resurfacing the canal via the transmastoid approach using a dumpling structure.

Methods:

Patients with SSCD, confirmed by high-resolution computed tomography and hospitalized at Beijing Tongren Hospital between November 2009 and October 2012, were included in the study. All of the patients underwent the unilateral transmastoid approach for resurfacing the canal, and received regular follow-up after surgery. Data from preoperative medical records and postoperative follow-up were comparatively analyzed to evaluate the effect of surgery.

Results:

In total, 10 patients and 13 ears (three left ears, four right ears, three bilateral ears) were evaluated in the study, which included 7 men and 3 women. Different symptoms and distinctive manifestations of vestibular evoked myogenic potential were found in these patients. After surgery, 4 patients had complete resolution, 5 had partial resolution, and 1 patient, with bilateral SSCD, had aggravation. None of the patients suffered from serious complications such as sensorineural hearing loss, facial paralysis, cerebrospinal fluid leakage, or intracranial hypertension.

Conclusions:

In patients with unilateral SSCD, resurfacing the canal via the transmastoid approach using a dumpling structure is an effective and safe technique. However, more consideration is needed for patients with bilateral SSCD.     

前庭及半规管轻度发育异常致眩晕的临床上特点

目的 探讨前庭及半规管轻度发育异常畸形所致眩晕的临床表现特点及可能的病理生理机制.方法 回顾性分析中山大学附属第三医院内耳病门诊的5例最终确诊为前庭扩大伴水平半规管畸形所致眩晕患者的病史特点、眩晕发作特点与持续时间以及听功能、前庭功能与影像学特点.结果(1)病史特点:4例幼年时有粗大运动发育延迟及潜在的平衡功能不良,1例无法提供幼时病史,成年后可长期保持听及前庭功能正常.(2)首次眩晕发作多能提供导致颅压或腹压骤然增高的诱因,如头部被撞击,用力擤鼻、便秘等.(3)发作性眩晕、渐进性听力下降等临床表现类似梅尼埃病及大前庭水管综合征,但眩晕持续时间不符合梅尼埃病特征,而听力下降程度及听力曲线类型有别于梅尼埃病及大前庭水管综合征.(4)部分患者眩晕与体位有关,但体位诱发试验结果不符合良性阵发性位置性眩晕特征.(5)影像诊断提示前庭扩大伴水平半规管轻度发育异常.结论 前庭扩大伴水平半规管发育不良是耳源性眩晕的少见病因,幼年时粗大运动发育延迟及平衡功能不良病史、听功能、前庭功能及影像检查可明确诊断.     

Angular displacement perception modulated by force background

We had recumbent subjects (n = 7) indicate the amplitude of imposed, passive yaw–axis body rotations in the 0, 1, and 1.8 g background force levels generated during parabolic flight maneuvers. The blindfolded subject, restrained in a cradle, aligned a gravity-neutral pointer with the subjective vertical while in an initial position and then tried to keep it aligned with the same external direction during a body rotation, lasting less than 1.5 s about the z-axis 30°, 60°, or 120° in amplitude. All the rotations were above semicircular threshold levels for eliciting perception of angular displacement under terrestrial test conditions. In 1 and 1.8 g test conditions, subjects were able to indicate both the subjective vertical and the amplitude of the body rotation reasonably accurately. By contrast in 0 g, when indicating the subjective vertical, they aligned the pointer with the body midline and kept it nearly aligned with their midline during the subsequent body tilts. They also reported feeling supine throughout the 0 g test periods. The attenuation of apparent self-displacement in 0 g is discussed in terms of (1) a possible failure of integration of semicircular canal velocity signals, (2) a contribution of somatosensory pressure and contact cues, and (3) gravicentric versus body-centric reference frames. The significance of the findings for predicting and preventing motion sickness and disorientation in orbital space flight and in rotating artificial gravity environments is discussed.     

The presigmoid retrolabyrinthine approach: Technical note

BackgroundThe retrolabyrinthine approach is classified among the posterior petrosectomies. Its goal is to achieve an enlarged mastoidectomy while sparing the intrapetrous neurotologic structures in order to offer maximal exposure of the posterior cerebellopontine angle compound.MethodsThe stages of the procedure are subsequently the skeletonization of the sigmoid sinus, wide opening of the mastoid antrum and exposure of the semicircular canals. We present herein the technique, indications and limitations of the retrolabyrinthine approach.ConclusionThe retrolabyrinthine approach is a demanding technique. Nowadays the retrolabyrinthine approach is routinely combined to additional resections of the petrous bone, so-called “combined petrosectomies”, to target the jugular foramen or the petroclival area.     

多层螺旋CT双斜位MPR对骨半规管的全程显示研究

目的:利用多层螺旋CT各向同性扫描进行双斜位多平面重组(multiplanarreformation,MPR)后处理,重建出各半规管全貌。方法:搜集观察对象105例(男52,女53),210耳,年龄范围为9个月至71岁,利用多层螺旋CT各向同性扫描对颞骨进行检查,然后对所得图像进行双斜位多平面重组(multiplanarreformation,MPR)后处理,重建出各半规管全貌。结果:通过双斜位多平面重组(MPR)后骨半规管和外骨半规管均能在一个平面上显示其全貌,部分前骨半规管(105例中6例,5.7%)未能显示全貌。结论:多层螺旋CT各向同性扫描后双斜位多平面重组(MPR)后处理能够很好的显示各骨半规管的全貌。     

上半规管良性阵发性位置性眩晕的临床分析

目的探讨上半规管良性阵发性位置性眩晕（anterior semicircular canal benign paroxysmal positional vertigo,AC-BPPV）的临床特点。方法回顾性分析16例AC-BPPV患者临床特点,并对耳石复位的疗效进行评估。结果①在Dix-Hallpike检查中,16例患者都诱发出垂直向下的眼震,其中11例双侧出现眼震,5例单侧出现眼震。②13例患者能明确受累侧别,其中5例为左侧AC受累,8例为右侧AC受累;3例受累侧别难以判断。③对13例受累侧别明确的患者采取反向颗粒复位手法治疗,5例痊愈,4例有效、4例无效;对4例无效患者再行Semont方法治疗,其中2例有效,2例仍无效。对3例受累侧别难以判断的患者采用Yacovino方法治疗后均痊愈。结论 AC-BPPV在临床中并不少见,耳石复位法疗效明确,可根据患者实际情况选择适当的复位方式。