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12.头脉冲试验：水平VOR的检查 13.VOR固视抑制的检查 14.Dix-Hallpike试验 15.姿态和步态的检查 16.指指试验 dVOR：direct Vestibulo-ocular reflex（Oculo-vestibular reflex），一个古老而简单的三突触反射：前庭神经（Scarpa′s神经节）-前庭神经核-眼动神经核-眼动肌肉，头部运动时稳定眼的位置以看清靶标。 SO: superior oblique [ə'blik] IO: inferior oblique IR: inferior rectus ['rektəs] LR: lateral rectus SR: superior rectus MR: medial rectus AC: anterior canal [kə'næl] PC: posterior canal LC: lateral canal MLF: medial longitudinal [,lɑndʒə'tudnl] fasciculus [fə'sɪkjələs] ATD: ascending tract of Deiters BC: brachium ['brækɪəm] conjunctivum [kən'dʒʌŋktɪvəm] VN: vestibular nuclei III: oculomotor nucleus IV: trochlear['trɑklɪɚ] nucleus VI: abducens [æb'djuːsenz] nucleus 上图反过来如下图所示：
To test the horizontal VOR, the examiner holds the patient's head between both hands, asks him to fixate a target in front of his eyes, and very rapidly turns the patient's head horizontally by ca. 20–30° to the right and then to the left. （ca. : circa, ['sɜːkə] 大约）
In a healthy subject, this rotation of the head causes rapid, compensatory eyemovements in the opposite direction with the same angular velocity[vəˈlɑsəti]asthe head movements. In this way, the target remains stable on the retina['retɪnə].
In unilateral [juːnɪ'læt(ə)r(ə)l] labyrinthine[,læbə'rɪnθaɪn] failure , the eyes move during head rotationswith the head to the right, and the patient has to perform a so-called refixation saccade[sæ'kɑːd]to the left in order to fixate the target again .This is the clinical sign of adeficit of the VOR (in the high-frequency range) to the right.
Before performing this test, theexaminer must be sure that the VOR is intact. The patient is then asked tofixate a target in front of his eyes while moving his head as uniformly aspossible with the same angular velocity as the target in front of the eyes,first horizontally and then vertically, back and forth at moderate speed. Theexaminer should watch for corrective saccades, which indicate a disorder of thevisual fixation suppression of the VOR. Subsequently, the test is performed forthe vertical VOR.
Impaired visualfixation suppression of the VOR (which as a rule occurs with smooth pursuitabnormalities, as these two functions use the same neural pathways) typicallyindicates lesions of the cerebellum[,serɪ'beləm] ( flocculus['flɑkjələs] or paraflocculus [,pærə'flɑkjələs]) or of cerebellar pathways. Drugs,especially anticonvulsants[,æntɪkən'vʌlsənts]and sedatives ['sedətɪvs], and alcohol ['ælkəhɔl] can also impair visual fixationsuppression of the VOR, because of their effects on the cerebellum.
The so-called Dix–Hallpike maneuver isperformed to determine the presence of BPPV, generally starting from theposterior canal. While the patient is sitting, his head is first turned by 45°to one side, so that the posterior canal is parallel['pærəlel] to the positioningplane. Then the patient is rapidly put in the supine['supaɪn] position to theopposite side with the head hanging over the end of the examination couch [kaʊtʃ].
Flouren定律
If a BPPV of the left posterior semicircular ['semi'sə:kjulə] canal, for example, is present, this maneuver will induce,with a latency of a few seconds, a crescendo [krɪ'ʃendəʊ]–decrescendo [,diːkrɪ'ʃendəʊ]-like nystagmus, which from the examiner's viewpoint rotates and beatsclockwise toward the forehead. When the patient is returned to a sitting position, the nystagmus can change reversedirection. For horizontal canal BPPV, the patient's head is turned to the rightand left while lying supine.
外半规管：水平眼震，部分扭转 向地 or 离地 后半规管：扭转、向上、向地 前半规管：向下、扭转不明显
There are different variations[,vɛrɪ'eʃən] and degrees of difficulty of the Romberg test: standing with feet next to each other, one foot in front of the other (tandem Romberg), or on one foot. Each variation is performed with eyes first open and then closed; with eyes closed, the visual control of the swaying during standing is examined. A peripheral [pə'rɪfərəl] vestibular functional disorder and other sensory deficitslike a polyneuropathy [,pɒlɪnjʊə'rɒpəθɪ] typically cause swaying once the eyes are closed, especially under difficult conditions.
In psychogenic [,saɪko'dʒɛnɪk] balance disorders, which are oftencharacterized by a bizarre [bɪ'zɑː] swaying without any falls, the examiner distracts[dɪ'strækt] the patient by writing letters or numbers on his arm orback. This reduces the swaying and indicates that the stance disorder has apsychogenic origin. Another variant of the Romberg test is standing under theabove-described conditions but with head reclined backward. This generallyincreases the swaying. During theexamination of balance under static conditions, look for increased swaying forward/backward, right/left, as well as diagonally:
When examining the patient’s gait, thepatient has first to go straight ahead with the eyes open then eyes closed. Subsequently, the patient has to walk on animagined line heel to toe again with the eyes open and then closed. One has to look for steplength, gait variability[,veərɪə'bɪlətɪ], and whether the gait is broad ornarrow based or whether there is a deviation[diːvɪ'eɪʃ(ə)n] to the right or left. In bilateral vestibulopathy, gait is broadbased and becomes worse with the eyes closed. In a unilateral peripheral vestibular loss, this also is true with a gait deviation toward the side of hevestibular lesion. With increasing speed, gait improves. In cerebellar disorders, gait isbroad based with a great gait variability.
The patient is instructed to follow asprecisely [prɪ'saɪslɪ] as possible the examiner’s finger asit rapidly moves horizontally. Cerebellar ataxia[ə'tæksɪə] is often indicated by hypermetric [,haɪpə'metrɪk] movements with an intention tremor. This test is moresensitive than the finger-to-nose test.
（视频来源于《眩晕和头晕实用入门手册》随书所带光盘） 参考资料：Vertigo and Dizziness（Second Edition）,Thomas Brandt. 眩晕和头晕实用入门手册。 |
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Flouren定律
