麻痹性斜视一直是斜视诊断中的一个难点，今天先来学习第Ⅳ颅神经麻痹的临床表现。
10.7 Isolated Fourth Nerve Palsy
第七节 孤立性第Ⅳ颅神经麻痹
Symptoms【症状】
Binocular vertical (or oblique) diplopia, difficulty reading, sensation that objects appear tilted; may be asymptomatic.
双眼垂直复视或斜向复视，当遮盖一眼后复视消失，双眼同时视物时，一个物象高于另一个物象；阅读困难；视物倾斜；也可无症状。
Signs
(See Figures 10.7.1 and 10.7.2.)
Critical. Deficient inferior movement of an eye when attempting to look down and in. The three-step test isolates a palsy of the superior oblique muscle (see below).
【主要体征】眼球试图下转和内转时下转运动受限。Parks三步法确定上斜肌麻痹。方法见后。
Other. The involved eye is higher (hypertropic) when patient looks straight ahead. The hypertropia increases when looking in the direction of the uninvolved eye or tilting the head toward the ipsilateral shoulder. The patient often maintains a head tilt toward the contralateral shoulder to eliminate double vision.
【其他体征】
1.第一眼位患眼眼位高(上斜视)。
2.眼球向健眼方向运动或向患侧歪头时，上斜程度增加。
3.患者常向患眼对侧歪头以减轻复视。
Differential Diagnosis【鉴别诊断】
All of the following may produce binocular vertical diplopia, hypertropia, or both.
下述疾病均可产生双眼垂直复视或/和上斜视:
• Myasthenia gravis: Variable symptoms with fatigability. Ptosis common. See 10.11, Myasthenia Gravis.
1.重症肌无力 傍晚劳累后复视加重，常伴有上睑下垂。依酚氯胺(即腾喜龙)试验阳性。参见本章第十一节重症肌无力。
• Thyroid-related orbitopathy: May have proptosis, eyelid lag, stare, or injection over the involved rectus muscles. Positive forced-duction test. See 7.2.1, Thyroid-Related Orbitopathy.
2.甲状腺相关性眼眶病 可有眼球突出、眼睑迟滞、凝视、受累直肌充血。被动牵拉试验阳性。参见第七章第二节第一部分甲状腺相关性眼眶病。
• Orbital inflammatory pseudotumor: Pain and proptosis are common. See 7.2.2, Idiopathic Orbital Inflammatory Pseudotumor.
眼眶炎性假瘤，到了第六版都改为：
Idiopathic orbital inflammatory syndrome: Pain and proptosis are common. See 7.2.2, Idiopathic Orbital Inflammatory Syndrome.
3.眶内炎症性病变(炎性假瘤) 常见疼痛及眼球突出。参见第七章第二节第二部分特发性眶内炎性假瘤。
• Orbital fracture: History of trauma. Positive forced-duction test. See 3.9, Orbital Blow-out Fracture.
4.眼眶骨折 有外伤史，可导致下直肌陷入眶内或纤维化，被动牵拉试验阳性。参见第三章第九节眼眶爆裂性骨折。
• Skew deviation: The three-step test does not isolate a particular muscle. Rule out a posterior fossa or brainstem lesion by MRI of the brain. See 10.13, Internuclear Ophthalmoplegia.
5.反向偏斜 Parks三步法试验无法确定病变肌肉。可做颅脑磁共振排除后颅窝或脑干病变。参见本章第十三节核间性眼肌麻痹。
• Incomplete third nerve palsy: Inability to look down and out, usually with adduction weakness. Intorsion on attempted downgaze. Three-step test does not isolate superior oblique. See 10.5, Isolated Third Nerve Palsy.
6.第Ⅲ颅神经不全麻痹 不能向下和向外注视，通常合并内转无力，试图向下凝视时眼内旋，Parks三步法不能确定为上斜肌病变。参见本章第五节孤立性第Ⅲ颅神经麻痹。
• Brown syndrome: Limitation of elevation in adduction due to restriction of superior oblique tendon. May be congenital or acquired (e.g., trauma, inflammation). Restriction on forced duction test. See 8.6, Strabismus Syndromes.
7.上斜肌腱鞘综合征(Brown综合征) 由于上斜肌肌键受限，眼球内收时上转受限。可为先天性或获得性(如外伤、炎症引起)。被动牵拉试验阳性。参见第八章第六节斜视综合征。
• GCA: Extraocular muscle ischemia causing nonspecific motility deficits or neural ischemia mimicking cranial nerve palsy. Age older than 50 years, usually associated systemic symptoms. See 10.17, Arteritic Ischemic Optic Neuropathy (Giant Cell Arteritis).
8.巨细胞性动脉炎(GCA) 眼外肌缺血致非特异性眼球运动受限，或神经缺血造成类似颅神经麻痹样眼球运动障碍。50岁以上发病，通常伴有全身症状。参见本章第十七节动脉炎性缺血性视神经病变（巨细胞性动脉炎）。
Etiology【病因学】
More common: Trauma, vascular infarct (often the result of underlying diabetes or hypertension), congenital, idiopathic, or demyelinating disease.
1.常见病因 外伤；血管梗塞，常见于糖尿病、高血压患者；先天性；特发性或脱髓鞘性疾病。
Rare: Tumor, hydrocephalus, aneurysm, GCA.
2.少见病因 肿瘤，脑积水，动脉瘤，巨细胞性动脉炎。