Study on the Use of Visual Evoked Potentials for Early Diagnosis of Subclinical Visual System Impairment

对49例可疑视神经病变患者和28例正常人进行了连续单眼图形反转刺激30 min的新方案。在正常对照组中，P100潜伏期保持正常（低于118 msce）30 min。患者组的结果分为三类; 1）正常，2）1型异常，3）2型异常。只有当P100潜伏期在30 min内保持正常（低于118 msec）时，结果才被视为“正常”。当P100潜伏期最初是正常的，并且至少有一个随后的反应被延迟（长于118毫秒）或不存在，结果被称为“1型异常”。当最初的反应已经延迟或不存在时，结果被称为“2型异常”。在模式反转刺激的常规方法中，仅检测类型2异常的情况。我们的研究结果表明，这种新的协议增加了检测视神经病变的能力。与提高的检出率相对应的分数似乎由具有1型异常的眼睛代表。通过使用这种新的测试方法，与通过100-150次求和获得的一个或两个诱发电位的测量相比，视神经亚临床病变的检测从29%上升到48%。在22例多发性硬化患者中，21例（96%）显示1型或2型异常。在12例眼科检查无异常的多发性硬化患者中，9例（75%）表现为1型或2型异常。我们的新方案连续刺激30分钟是非常有用的检测亚临床视神经病变。

A new protocol of continuous monocular pattern reversal stimulation for 30 min was applied to 49 patients with suspected optic nerve pathology and 28 normal adults. A peak latency of P100 in each eye was monitored for 30 min. In normal controls, p100 latency remained normal (below 118 msce) for 30 min. Results in the patient group were divided into three categories; 1) Normal, 2) Type 1 abnormality, and 3) Type 2 abnormality. Only when P100 latency remained normal (below 118 msec) for 30 min, the result was regarded as "normal". When P100 latency was initially normal and at least one of subsequent responses was delayed (longer than 118 msec) or absent, the result was called "type 1 abnormality". When an initial response was already delayed or absent, the result was called "type 2 abnormality". In a conventional method of pattern reversal stimulation, only cases of type 2 abnormality are detected. Our results revealed that this new protocol increases capability of detecting optic nerve pathology. The fraction corresponding to the improved detection rate seemed to be represented by eyes with type 1 abnormality. By using this new testing method, the detection of subclinical lesions of the optic nerve rise from 29 % to 48 %, compared to that of the conventional method which is measurement of one or two evoked potentials obtained by 100-150 summations. In 22 patients with multiple sclerosis, 21 patients (96%) showed either type 1 or type 2 abnormality. In 12 patients with multiple sclerosis without abnormality on ophthalmologic examination, 9 cases (75 %) showed either type 1 or type 2 abnormality. Our new protocol of continuous stimulation for 30 min is very useful for detecting subclinical optic nerve lesions.