外半规管BPPV
历史：
1985年McClure认为外半规管和上半规管也可能有耳石症，并报道7例水平半规管耳石症，患者平卧位向一侧转头诱发头晕，呈水平眼震，快向向地，患侧更明显，并认为是外半规管后臂的耳石活动引起。
In 1989, Pagnini et al. 3 reported 15 cases of LSC-BPPV, hypothesizing that the endolymphatic current induced by the floating of otoconial debris on the posterior arm of the LSC causes the nystagmus. When the patient lies supine, after rotating the head on the impaired side, the otoliths settle along the canal, towards the ampulla, due to gravity, generating an ampullopetal, and, therefore, an excitatory, endolymphatic current, and the consequent geotropic nystagmus (Ny) beating to the impaired ear. If the patient’s head is turned on the healthy side, the otoliths float towards the utricular orifice generating an ampullofugal, thus inhibitory, endolymphatic current (Figs. (Figs.1,1, ,2).2). Consequently, the Ny will be geotropic once again and, therefore, beating to the healthy side. The Authors stress a greater intensity of the nystagmus on the impaired side explained by Ewald’s second law 4 which postulates that the response to an excitatory stimulus is always more intense than that following an inhibitory stimulus. This was also the first report of forms originating as apogeotropic paroxysmal positional nystagmus that transformed spontaneously into geotropic.
1995年Baloh等报道了3例Roll试验中表现为持续背地性眼震的水平半规管BPPV。
1996年Steddin等报道水平半规管耳石症患者表现背地性眼震，考虑是嵴顶结石症。
Over the last few years, many therapeutic approaches have been suggested for LSC-BPPV.
After early unsuccessful endeavours to remove the otolithic mass by head shaking in the supine position 9, other Authors 10–12 suggested the rehabilitation “barbecue rotation” techniques. These involve an ampullofugal push on the endocanalar otolithic mass by rotating the patient’s head briskly to the healthy side in the supine position, in single 90° steps, in order to exploit the inertial lag of the otoconia that are free to float into the canal endolymph. The overall angle of rotation varies from 180° to 360°. In 1994, Vannucchi et al. 13 devised a rehabilitation technique for the LSC-BPPV. Ascribing the pathogenetic mechanism to the canalolithiasis, the Authors have set up a procedure based on a slow gravitational sedimentation of the otoliths outside the non-ampullary LSC segment. This simple method which suits any patient, consists in forcing the patient to remain immobile on the healthy side – Forced Prolonged Position (FPP) – for at least 12 hours, in order to maintain the simple segment of the LSC in a vertical position, with the utricular orifice facing downwards; the result of the technique is checked after 72 hours. The Authors reported a 90% cure rate of LSC-BPPV, following the FPP.
In 1995 14, Epley devised a technique of canalith repositioning for the LSC-BPPV, without supplying any case studies.
In 1998, Gufoni and Mastrosimone 15 proposed a new technique: the patient sits upright on the examination table with his/her legs downwards; he/she is then tilted rapidly on one side – on the healthy side in the geotropic form, on the impaired side in the apogeotropic form; the head is then turned 45° downwards after which the examiner waits 2-3 minutes; finally, the patient is returned to the original position. The results described in a later report show a 90% cure rate in these cases.
In 1999, Asprella Libonati and Gufoni 16 proposed a variation to the barbecue rotation manoeuvre: the patient lies in the supine position and his/her head is briskly turned 90° towards the healthy side, then, while keeping the head turned, he/she is returned to the seated upright position and his/her head is slowly brought back in axis with the body; finally, he/she is returned to the supine position.
In 2003, Asprella Libonati et al. 17 described an original therapeutic strategy for the LSC-BPPV, known as “step-by-step rehabilitation under videonystagmoscopic (VNS) control”. The rationale of this strategy is to monitor whether the ampullofugal progression of the debris in the canal occurs by observing the nystagmus evoked during each step of the liberatory technique (barbecue, Vannucchi-Asprella, Gufoni or others). According to Ewald’s second law, the nystagmus with the fast phase beating to the healthy side indicates an ampullofugal deflection of the cupula caused by the floating of debris, heavier than the endolymph, towards the utricle. In this way, it is possible to adopt a more flexible approach, thus changing the therapy during the performance of the manoeuvre in order to achieve complete rehabilitation in one treatment session.
搜索关键词：
horizontal semicircular canal BPPV， lateral semicircular canal BPPV,
(horizontal OR lateral) AND BPPV AND diagnosis
发病率：
不同作者报道的各不一样。
2001 uno报道有30%。
2003 Parnes报道不到5%。
自愈：
外半规管BPPV比后半规管BPPV更快自愈。
治疗次数:
1.单次门诊仅复位1次
2.反复复位直至诱发试验阴性（有学者认为是否是疲劳现象）
关注的问题：
1。如何判断患侧
(lateral OR horizontal) AND bppv AND diagnosis
2。如何治疗
文献阅读体会：
对外半规管BPPV诊断手法中耳石运动的理解，无疑，在G Asprella Libonati[1]的报道中描述最为清晰。Pagnini1989[2]对半规管空间方位的描述和结石运动的结石也很准确。
总体来讲，根据Eward第一定律，水平滚转试验诱发水平眼震，认识是一致的。
向地眼震，考虑后臂结石，表现为向患侧翻身，耳石向壶腹运动，反之，向健侧翻身，耳石离壶腹运动，根据Eward第二定律，可以判断眼震强烈侧为患侧。对此，认识也是一致的。
背地眼震，通常考虑前臂侧结石和嵴帽结石，并需要根据眼震持续时间不同来进行区分，其中眼震持续时间<60 s诊断为前臂管结石, 眼震持续时间>60 s诊断为嵴帽结石，根据Ewald第二定律，眼震较弱侧诊断为患侧。对此，存在争议。
首先，背地眼震，除了考虑前臂侧结石和嵴帽结石，还需要考虑短臂侧（壶腹嵴椭圆囊侧）结石；其次，前臂侧结石和疏松结合的嵴帽结石性质上基本一致，根据眼震持续时间60s为界区分管石和嵴帽结石缺乏科学数据支持，也没有充分证据显示可以据此区分短臂侧结石和嵴帽结石。
外半规管眼震方向转换和眼震强度转换是很重要的现象，必须重视其地位意义。
朱梓建2018报道对外半规管BPPV重复2次水平滚转试验，对35例眼震方向可转换型外半规管BPPV和38例眼震方向不转换型外半规管BPPV进行比较分析。
该文数据存在不足之处为：1.水平滚转试验可以导致耳石复位，没有相关数据比如第一次滚转试验阳性，第二次滚转试验阴性。2.没有记录眼震方向改变在哪个步骤发生，比如右侧外半规管短臂侧结石和嵴帽结石可表现为：右侧翻身 背地眼震；左侧翻身 向地眼震；右侧翻身 向地眼震；左侧翻身 向地眼震,也可以表现为：右侧翻身 背地眼震；左侧翻身 向地眼震；右侧翻身 无眼震；左侧翻身 无眼震。左侧外半规管短臂侧结石和嵴帽结石可表现为右侧翻身 背地眼震；左侧翻身 背地眼震；右侧翻身 向地眼震；左侧翻身 向地眼震,也可以表现为右侧翻身 背地眼震；左侧翻身 背地眼震；右侧翻身 向地眼震；左侧翻身 眼震消失。实际上，这里没有考虑到外半规管后臂结石的情况。
最为重要的一点是，可以复位的背地眼震外半规管BPPV，都应该是眼震方向转换型的。
文中对于两侧滚转试验均为背地眼震的患者，采用Gufoni法患侧卧位转为向地眼震，和保持患侧卧位没有本质区别。
在临床实践中，先行Dix-Hallpike试验，后行水平滚转试验，针对背地眼震，如果出现右侧翻身 背地眼震；左侧翻身 向地眼震，可以判断为右侧外半规管短臂侧结石和嵴帽结石，可以再向左侧翻身45°-90°进行复位治疗；否则，回复平卧位，右侧翻身，出现向地眼震，可以判断为左侧外半规管短臂侧结石和嵴帽结石，继续右侧翻身45°-90°进行复位治疗。如果眼震方向没有发生转换，判断为紧密粘附的嵴帽结石，根据眼震强度判断患侧，采取患侧卧位或者摇头等方式使得耳石脱落。简而言之，外半规管BPPV，水平滚转试验出现背地眼震，则继续左右翻身直到出现向地眼震，继续同方向翻身45°-90°，此方向为健侧。 针对向地眼震，如果出现右侧翻身 向地眼震；左侧翻身 向地眼震，可以根据眼震强度判断患侧（右侧外半规管后臂），继续左侧翻身45°-90°进行复位治疗;如果出现右侧翻身 向地眼震；左侧翻身 没有眼震，提示左侧外半规管后臂结石已经复位，可以坐起休息后再复查水平滚转试验。
鲁宏华2016对重复滚转试验对外半规管管石症的定位意义进行了探讨，其操作手法和顺序为仰卧于30度斜枕，正中位-右转头-正中位-左转头-正中位，转头角度约为70度，完成2个循环，并记录眼震。此试验设计比较独特，转头角度70度有助于避免诊断试验导致耳石复位，缺点是转头角度较小理论上敏感性会减弱。
试验结果非常有意思，外半规管后臂BPPV，居然50%的患者循环1和循环2的眼震强弱强度相反且右侧有24例（总数25例），偏差非常厉害，难以解释。 文中对转头角度进行了探讨，认为采用转头70°符合人体头颈活动范围。
作者的另一篇文章《良性阵发性位置性眩晕两种位置试验的择优方案探讨》中报道170例DIX-HALLPIKE(+)的患者，滚转试验均为阴性，这和我们的经验完全相反。我们的数据显示DIX-HALLPIKE(+)的患者有1/4出现同侧水平滚转试验（+）。
Asprella2005提出使用Asprella single diagnostic manoeuvre来区分后半规管BPPV和外半规管BPPV，可以减少诊断过程诱发眩晕不适。对此，有一定参考意义，但并不十分赞同。但其所提出的Vannucchi-Asprella manoeuvre很有启发意义，对部分外半规管背地眼震有效，虽然作者对此的理论解释并不正确。
外半规管BPPV眼震方向转变是很重要的现象。
由此提出外半规管BPPV耳石精准定位策略：
必须要考虑的因素是诊断试验的方法和顺序，会使得半规管BPPV耳石位置发生改变。 Dix-Hallpike会使得同侧外半规管前臂的结石脱出进入后臂。所以，如果重点是研究外半规管BPPV，应该先选择水平滚转试验。 水平滚转试验同样会使得后半规管长臂侧的结石位置发生变化，但对于低头平卧Dix-Hallpike试验不会产生影响。
首先设定，外半规管耳石位于短臂侧，长臂侧前臂和后臂。
1.从坐位躺下，观察眼震（阳性率值得怀疑),这时水平眼震主要考虑长臂侧后臂结石；
2.45°转头试验：向左侧转头45°，向右侧转头90°，向左侧转头90°。这时水平向地眼震考虑长臂侧后臂结石，眼震强烈侧位患侧；背地眼震考虑短臂侧结石或者嵴帽结石。
2.1 水平向地眼震，继续健侧滚转复位 2.2 背地眼震，健侧卧位，坐起。 2.2.1 平卧，健侧转头90°，没有眼震，考虑短臂侧结石，仍有眼震，考虑嵴帽结石（长臂侧） 2.2.2 患侧卧位，lempert复位法 3.没有眼震 60°转头试验：向右侧转头60°，向左侧转头60°，向右侧转头60°。这时候背地眼震，考虑长臂侧前臂结石，行翻滚复位法。
问题：
先低头60°，使得外半规管长臂侧的结石进入前臂，再躺下进行翻滚实验，背地眼震发生率是否会提升？
争议：
有一些很有意思的争议。
无疑，Asprella对外半规管BPPV有着充分的理解，最为关键的，是他对半规管解剖的描述非常正确。
Califano2008报道低头60度或然后头部后仰，可以将外半规管BPPV从背地眼震转变为向地眼震类型。 Asprella2010年撰文提出提出不同意见， 1.假性自发性眼震2003年Asprella-Libonati首先描述，并在2006年描述了头部前俯后仰引起眼震方向改变。 2.不赞同只有背地眼震患者才检查HPT试验的结论，应为在长达5年的时间，在所有LSC-BPPV患者进行HPT检查，没有观察到向地眼震转变为背地眼震，也没有观察到其他副作用。
实际上，最为关键的是检查的定位意义。Asprella提出Asprella Single Manoeuvre，从坐位躺下，外半规管后壁结石，眼震方向朝向健侧；前臂结石/嵴帽结石，眼震方向朝向患侧。
Riga2013对背地眼震LSC-BPPV进行了详尽的分析，尤其是水平滚转试验和第二定位体征。Riga对半规管解剖的描述是正确的。
文中也提到了眼震方向改变对定位的意义，即眼震方向发生改变侧的对侧为患侧，但是认为并非常见。 The affected side may also be diagnosed as the side opposite that on which spontaneous inversion occurs, although this phenomenon is not frequent.
理论上，半规管前臂的结石和嵴帽结石，如果能够复位，必须要实现眼震类型转换（向地/背地），包括诊断过程和治疗过程。
Califano2013提出了一种少见的外半规管BPPV类型，定义为眼震方向不变的外半规管BPPV，眼震方向朝向健侧，即患侧卧位背地眼震，健侧卧位向地眼震，通常背地眼震强于先地眼震，实际上就是半规管长臂的前臂结石/嵴帽结石。作者观察研究了1234例BPPV，925为PSC-BPPV，37例ASC-BPPV,272例LSC-BPPV,其中189例向地眼震，78例背地眼震，5例眼震方向不变。这也提示，前臂结石的发病率并不高。文章解释了向地眼震和背地眼震的原理，即向地眼震是由于外半规管后臂结石，背地眼震是由于前臂结石或嵴帽结石。
支持前臂结石的依据：1.患侧卧位耳石从背地转换向地 2.转换后患侧卧位诱发强烈向地眼震。
Califano2013对眼震方向不变的解释，假定了外半规管长臂体部局部狭窄为原因，事实上缺乏直接证据。所有外半规管长臂侧嵴帽结石，其有效的治疗方法，必然导致结石类型转换。
论文里面没有提到是先做右侧水平滚转实验还是左侧水平滚转实验。
Imai2008有报导一例右侧卧位背地眼震，左侧卧位向地眼震。
He showed a right-beating persistent nystagmus in the first supine position (Supine 1 in Figure 4). The first rotation of the head to the right in supine induced a persistent left-beating nystagmus for the initial 15 s that then gradually declined (Right 1 in Figure 4). Thereafter, patient 2 showed geotropic positional nystagmus as follows. When his head was firstly rotated to the left in supine position, he showed a transient left-beating nystagmus (Left 1 in Figure 4). When the head was rotated to the right again in supine position, he showed a transient rightbeating nystagmus (Right 2 in Figure 4). When the head was returned to the straight-forward position in the second supine position, he showed a transient left-beating nystagmus (Supine 2 in Figure 4).
刘清源2014也有2例报导。
高波2003年报导46例外半规管BPPV，其中5例患者各种手法诱发出同一方向的眼震。
其实关于“Transformation of apogeotropic nystagmus into geotropic”的报导都是。
nuti1998报导患侧卧位向健侧翻身180度可以使得背地眼震转为向地眼震，部分患者直接治愈。
We generally began the manoeuvres from a position with the pathological ear downward and the patient supine, rotating the head rapidly 90° (to nose-up position) and then a further 90° to bring the pathological ear uppermost. These two steps were followed by a slow rotation back to the pathological side. Patient permitting, the manoeuvre was repeated up to three times.
The manoeuvres to change nystagmus from the apogeotropic to the geotropic direction were successful in 13 patients out of 21.
Three patients of the apogeotropic group were excluded from the study because the manoeuvres resolved the nystagmus and vertigo.
Vannucchi2010报导30例背地眼震外半规管BPPV，认为
In the apogeotropic form the debris can be free floating in the anterior arm or attached to the cupula of the ampulla; if we observe transformation from the apogeotropic into the geotropic form this suggested a canalolithiasis, otherwise we have assumed a cupulolithiasis.
朱梓建2018报道眼震方向可转换型外侧半规管良性阵发性位置性眩晕35例，但对于具体眼震如何转换无具体描述。
鲁宏华2016在论文《重复滚转试验对水平半规管管石症定位的必要性探讨》指出重复滚转试验与首次滚转试验结果也常常相反，其不足之处是没有同时列出背地眼震情况，且管石症50%在第二次翻滚实验时强度发生改变和临床经验不符。
Baloh1995报道3例背地眼震LSC-BPPV，其中2例为后半规管BPPV复位后，并认为是复位的而是粘附到外半规管壶腹嵴（椭圆囊侧）。Baloh对半规管解剖的描述是正确的。
We propose that the static direction-changing positional nystagmus in our patients resulted when the debris left the posterior semicircular canal and became attached to the cupula of the horizontal semicircular canal.
Baloh提到背地眼震LSC-BPPV患耳在下眼震较强的解释是健耳在下的时候患耳侧解释位于壶腹嵴的下方会脱落进入椭圆囊。
参考文献：
Libonati, G. Asprella. "Diagnostic and treatment strategy of lateral semicircular canal canalolithiasis." Acta otorhinolaryngologica italica 25.5 (2005): 277. Asprella-Libonati G. Lateral semicircular canal benign paroxysmal positional vertigo diagnostic signs[J]. Acta Otorhinolaryngologica Italica, 2010, 30(4). Riga, Maria, et al. "Apogeotropic variant of lateral semicircular canal benign paroxysmal positional vertigo: is there a correlation between clinical findings, underlying pathophysiologic mechanisms and the effectiveness of repositioning maneuvers?." Otology & Neurotology 34.6 (2013): 1155-1164.
Koo, Ja-Won, et al. "Value of lying-down nystagmus in the lateralization of horizontal semicircular canal benign paroxysmal positional vertigo." Otology & Neurotology 27.3 (2006): 367-371.
Baloh R W, Yue Q, Jacobson K M, et al. Persistent direction‐changing positional nystagmus Another variant of benign positional nystagmus?[J]. Neurology, 1995, 45(7): 1297-1301.
Califano L, Vassallo A, Melillo MG, Mazzone S, Salafia F. Direction-fixed paroxysmal nystagmus lateral canal benign paroxysmal positioning vertigo (BPPV): another form of lateral canalolithiasis. Acta Otorhinolaryngol Ital. 2013;33(4):254-60.
Nuti D, Agus G, Barbieri M T, et al. The management of horizontal-canal paroxysmal positional vertigo[J]. Acta oto-laryngologica, 1998, 118(4): 455-460.
Imai T, Takeda N, Sato G, et al. Changes in slow phase eye velocity and time constant of positional nystagmus at transform from cupulolithiasis to canalolithiasis[J]. Acta oto-laryngologica, 2008, 128(1): 22-28.
Vannucchi P, Pecci R. Pathophysiology of lateral semicircular canal paroxysmal positional vertigo[J]. Journal of Vestibular Research, 2010, 20(6): 433-438. 朱梓建,刘强.眼震方向可转换型外侧半规管良性阵发性位置性眩晕35例临床分析[J].山东大学耳鼻喉眼学报,2018,32(05):53-57. 王武庆, 孙琴, 任同力. 重复检查对诊断良性阵发性位置性眩晕的意义[J]. 中华医学杂志, 2011, 91(46):3254-3256.
