bruns眼震

封面摄影：邓敏兴老师

bruns眼震

石家庄市第二医院 郭伟宾 译

感谢上海长征医院李斐老师指导

A 35 year-old woman presented with insidious onset of hearing loss on the left side along with progressive unsteadiness of gait and diminution of vision.

一名35岁女性表现为左侧隐袭性听力丧失，逐渐出现步态不稳和视力下降。

She had features of increased intracranial pressure. Clinical examination revealed gross papilledema in both eyes with secondary optic atrophy.

她有颅内压增高的征象。体检发现两眼明显的视乳头水肿和继发性视神经萎缩。

A right-sided lower motor neuron type of facial palsy was present. Corneal reflex was absent on the right side. Eye movements were full.

右侧下运动神经元性面瘫。右侧角膜反射消失。眼球活动充分。

A coarse right-beating nystagmus with rightward gaze and a fine primary-position left-beating nystagmus (which was appreciated by ophthalmoscopy) that increased on leftward gaze, consistent with Bruns nystagmus, was noticed.

向右凝视时可见粗大的右向眼震，原位可见细小左向眼震(这是用检眼镜评估的)，向左凝视时眼震增强，与brun眼震一致。

Hence, a space-occupying lesion in the right cerebellopontine angle was considered.

因此，考虑到了右侧桥小脑区的占位性病变。

Contrast-enhanced computed tomography revealed vestibular schwannoma on the right side, measuring 5×5 cm (Figure 1 and video). Unfortunately, the patient worsened clinically and died before neurosurgical intervention. Histopathologic confirmation of the tumor was not done.

增强CT显示右侧前庭神经鞘瘤，直径5×5厘米(图1和视频)。不幸的是，病人临床恶化，在神经外科手术前死亡。肿瘤的组织病理学检查未做。

Figure 1. Contrast-enhanced computed tomographic image of the brain.Vestibular schwannoma is seen in the right cerebellopontine angle. The ventricles are dilated due to increased intracranial pressure.

图1.脑部增强CT图像。前庭神经鞘瘤位于右侧桥小脑角区。脑室因颅内压升高而扩张。

Bruns nystagmus has a localizing value in cerebellopontine angle tumors.It is associated with large tumors with maximal diameters greater than 3.5 cm.

Brun眼震在桥小脑角肿瘤中具有定位价值。它与最大直径大于3.5cm的肿瘤有关。

It is a form of jerk nystagmus that is asymmetrical,involving a combination of gaze evoked coarse (large-amplitude, low frequency) nystagmus on looking to the side of the lesion and fine (small amplitude, high-frequency) primary position nystagmus that increases on looking to the side opposite the lesion(Figure 2).

这是一种不对称的跳动性眼震，包括向病灶侧凝视诱发的粗大眼震(大振幅、低频)，以及原位细小眼震(小振幅、高频)并且向病灶对侧注视时增强(图2)。

Figure 2. Oculographic nystagmus waveforms, showing the right-sided coarse nystagmus with an exponentially decreasing slow-phase velocity (A)and the left-sided fine nystagmus with a constant (linear) slow-phase velocity (B). R indicates right; L, left.

图2.眼震波形，右向粗大眼震慢相速度呈指数下降(A)，左侧细小眼震慢相速度呈恒定(线性)(B). R表示右；L，表示左.

Jerk nystagmus is characterized by alternating slow and fast components.The slow component refers to deviation of the eyes away from focusing the object of interest on the fovea, due to failure of the neural circuit in maintaining the gaze. The saccadic fast component is corrective in nature, focusing the object of visual interest back on the fovea.

跳动性眼震的特点是有慢相和快相成分交替。慢相是因为在保持注视的神经回路出现病变，使双眼漂移，从而目标影像不能投射至视网膜中央凹。快相急跳成分在本质上是纠正性的，它再次将目标影像投射至视网膜中央凹。

（Jerk眼震是指存在快慢相交替的眼震，慢相的产生是因为眼球注视维持障碍，快相是中枢发现眼球发生漂移后的矫正。李斐老师指导语）

In Bruns nystagmus, the slow components of the coarse and fine nystagmus are different in nature and are attributed to different neural networks.

在Brun眼震中，粗大眼震和细小眼震的慢相成分本质上是不同的，属于不同的神经网络。

The velocity of the slow phase of the ipsilateral coarse nystagmus decreases exponentially and is attributed to the compression of the neural integrator (particularly the cerebellar flocculus) that maintains eccentric gaze holding, whereas the velocity of the slow phase of the primary-position fine nystagmus is constant and is attributed to the ipsilateral peripheral vestibular dysfunction.

同侧粗大眼震慢相的速度呈指数下降，其原因是保持偏心凝视的神经整合器(尤其是小脑绒球)受到压迫，而原位细小眼震的慢相速度恒定是因为同侧前庭周围功能障碍。

This primary-position fine nystagmus (with saccadic resets away from the side of the lesion) increases when looking in the direction of fast phases as stated in Alexander’slaw (Figure 2).

原位细小眼震(急跳重置到病变的对侧)看向快相的方向时增强，如Alexander定律所述(图2)。

Hence, Bruns nystagmus may be viewed as a unique situation in which 2 different neural circuits are simultaneously involved (flocculus and peripheral vestibular components), localizing the lesion to the cerebellopontine angle.

因此，Brun眼震可以看作是一种独特的情况，它同时累及2个不同的神经回路(绒球和周围前庭成分)，将病变定位到桥小脑角区。