Stahl J S, Averbuch-Heller L, Remler B F, Leigh R J
Department of Neurology, University Hospitals of Cleveland and Cleveland Veterans Affairs Medical Center, Case Western Reserve University, OH 44106, USA.
Neurology. 1998 Oct;51(4):1093-9. doi: 10.1212/wnl.51.4.1093.
To compare the effects of botulinum toxin on static and dynamic aspects of eye movements, and thereby elucidate the mechanisms of its action on eye muscles.
Laboratory evidence indicates that static alignment and saccades are subserved by different extraocular muscle fiber types, and botulinum toxin may cause specific dysfunction of the fibers controlling static alignment. Diplopia is a well-known side effect of periorbital botulinum toxin injections in humans, and may be a clinical correlate of the laboratory findings.
Search coil recording of eye movements was performed in one patient with systemic botulism, and in three patients with diplopia following periorbital injection of botulinum toxin A.
In the patient with acute botulism, eye movement alignment, range, and saccadic velocity profiles were abnormal. In three patients with iatrogenic diplopia, static alignment was abnormal but movement range and saccadic velocities were within normal limits. Edrophonium improved the range of movements and saccadic velocities in the patient with systemic botulism but was ineffective in reversing ocular misalignment in the one iatrogenic patient to whom it was administered.
Precise alignment is subserved by orbital singly innervated muscle fibers, and the effects of botulinum toxin are greatest on these fibers. This predilection is apparent when the toxin dose is very small, as must have been the case in our patients with iatrogenic diplopia. The lack of a response to edrophonium probably reflects structural damage to muscle fibers. In contrast, larger doses of toxin produce an acute dysfunction of all extraocular muscle fiber types, which is responsive to edrophonium and consequently reflects partial blockade at the neuromuscular junction.
比较肉毒杆菌毒素对眼球运动静态和动态方面的影响，从而阐明其对眼肌作用的机制。
实验室证据表明，静态眼位矫正和扫视运动由不同类型的眼外肌纤维负责，肉毒杆菌毒素可能导致控制静态眼位矫正的纤维出现特定功能障碍。复视是人类眶周注射肉毒杆菌毒素的一种众所周知的副作用，可能是实验室研究结果的临床关联。
对一名全身性肉毒中毒患者和三名眶周注射A型肉毒杆菌毒素后出现复视的患者进行了眼动搜索线圈记录。
在急性肉毒中毒患者中，眼球运动的眼位矫正、范围和扫视速度曲线均异常。在三名医源性复视患者中，静态眼位矫正异常，但运动范围和扫视速度在正常范围内。依酚氯铵改善了全身性肉毒中毒患者的运动范围和扫视速度，但对其中一名接受该药物治疗的医源性患者的眼球错位没有矫正作用。
精确的眼位矫正由眼眶单支神经支配的肌纤维负责，肉毒杆菌毒素对这些纤维的作用最大。当毒素剂量非常小时，这种偏好就很明显，我们的医源性复视患者就是这种情况。对依酚氯铵无反应可能反映了肌纤维的结构损伤。相比之下，较大剂量的毒素会导致所有类型的眼外肌纤维出现急性功能障碍，这种功能障碍对依酚氯铵有反应，因此反映了神经肌肉接头处的部分阻滞。
