澳大利亞JohnMurtagh全科病案研究 （三十一）——突然單側視力消失

JohnMurtagh（著）， 楊 輝（譯）

作 （譯）者單位：3165澳大利亞維多利亞州， 澳大利亞Monash大學

1 病史

一位65歲的商店店主前來就診。他就診的原因是6 h前左眼突然看不見東西。左眼視力消失僅持續了5 min， 然后就完全恢復了。他形容當時 “好像眼前垂下了一張黑幕， 擋住了所有的光線”。在視力消失的過程中， 他沒有其他不適癥狀。

他是我的老病人， 我知道他有高血壓和糖尿病。現在他每天吃的藥包括降血糖藥二甲雙胍850 mg和抗高血壓藥培哚普利10 mg。他還吸煙， 每天抽15支。他不飲酒。

我還知道他的家族史， 他父親67歲的時候死于腦卒中，母親69歲的時候死于乳腺癌。

2 針對病案提出的問題及答案

2.1 問題1：根據上面這個簡單的病史， 你的初步診斷是什么， 鑒別診斷是什么?

答案：初步診斷是一過性單眼盲， 或稱為暫時性單眼失明癥、單側黑朦癥。它是暫短性腦缺血發作 （TIA）的臨床表現。極有可能的原因， 是一個從左頸動脈分叉脫落的血栓經過了視網膜動脈。這常常是頸動脈狹窄的第一個臨床證據。大約有20%的暫短性腦血管發作表現為暫時性黑朦癥。

鑒別診斷包括如下情況：（1）視網膜脫離；（2）視網膜出血；（3）視網膜靜脈血栓；（4）急性青光眼；（5）顳動脈炎；（6）視神經炎。這些嚴重的眼科或血管疾病往往不會表現為一過性的失明， 視力消失的病程往往較長， 而且有些疾病造成永久性失明。另外， 還要考慮到偏頭疼 （非典型性偏頭疼的先兆）和低血糖。

2.2 問題2：在體檢的時候， 應該主要關注哪些方面?

答案：主要應檢查病人的視力。還應該做神經學檢查和心血管檢查， 著重發現導致視網膜或腦血管血栓的可能原因。神經學檢查包括：（1）視覺分辨能力；（2）視野；（3）檢眼鏡檢查。心血管檢查包括：（1）脈搏；（2）血壓 （雙側）；（3）心臟和頸動脈聽診。

2.3 問題3：你認為最好做哪些一線的檢查?

答案：進一步的檢查應該主要針對尋找視網膜栓塞的可能原因， 包括：（1）頸動脈多普勒超聲波檢查；（2）心電圖檢查發現是否心律失常； （3）對心瓣膜進行超聲心動圖檢查，發現是否存在血栓。如果有可能的話， 可以做腦血管CT或核磁共振檢查， 以排除腦梗死、小范圍出血或腫塊病變。

3 進一步的討論

請討論初步的治療計劃。

4 討論結果

這是一個典型的暫時性單眼失明癥的病例。很多暫短性腦缺血發作的病人都有相同的癥狀。對待這樣的病人， 應該當作醫療急診來處理， 因為病人很有可能繼續發展成為腦卒中（腦梗死）。

比較理想的辦法， 是馬上讓病人住進腦血管病房。如果病人對阿司匹林不過敏， 則可以馬上給病人300 mg阿司匹林。如果病人對阿司匹林過敏， 則應該使用替代性的抗血小板藥物（如氯吡格雷）。抗血小板/抗凝藥治療 （特別是對頸動脈缺血）可以預防30%的暫短性腦缺血發作演變為腦卒中或死亡。

在醫院里， 可以根據腦血管病房的檢查能力和專業經驗，采取動脈內囊切除術或經皮腔內血管成形術 （放支架）。

History

A 65 year old shopkeeper presents because of an episode of loss of vision in his left eye about six hours previously.The visual loss lasted for about 5 minutes only and then recovery was complete.He described the event as though′a curtain came down from above and blocked out the light′.He had no other symptoms at the time of the episode.

You learn thathehas ahistory ofhypertension and Type 2 diabetesmellitus.His current drug therapy is metformin 850mg and perindopril10mg daily.He smokes15 cigarettes a day but does not drink alcohol

Family history：father died of a stroke aged 67 and mother died ofbreast cancer aged 69.Questions 1.Based on thisbriefhistory what is your provisional diagnosis and differential diagnoses?

2.What are the relevant components of the physical exam ination?

3.What would be the appropriate first line investigations?

Answers

1.The provisional diagnosis is transientmonocular blindness known as amaurosis fugax-a transient ischaemic attack（TIA）.Themost likely cause is passage ofan embolus through the retinalartery from embolisation of the left carotid artery bifurcation.It is often the first clinical evidence of carotid artery stenosis.About 20% of all TIAs present asamaurosis fugax.

The differential diagnoses include the following although these seriouseye or vascular conditions are not transient and thus have more prolonged（even permanent）lossof vision.Retinaldetachment Retinalhaemorrhage Retinalvein thrombosis Acute glaucoma Temporalarteritis Optic neuritis

Consider alsomigraine（the auraofatypicalm igraine）and hypoglycaem ia

2.The key components of the physicalexamination are the patient′s應該嚴肅地告訴病人要戒煙。同時要對病人的高血壓病和心臟病進行評估。另外還應該做血脂檢查。

1 Tiller J（Chair）.Therapeutic guidelines：Neurology[ M] .Version 3，Melbourne：Therapeutic Guidelines Ltd， 2007：167-184.

（文后附原文）vision， a neurological examination and a cardiovascular examination focussed on searching for apotential cause of retinalor cerebralembolisation

Neurologicalexamination Visualacuity Visual fields Ophthalmoscopy Cardiovascular Pulse Blood pressure（both arms）Auscultation-heartand carotid arteries

3.The investigation which should focus on finding the potential source of retinal embolisation includes Duplex ultrasound of carotid arteries ECG to check for arrhythm ias Echocardiography to focuson valvesand presence of thrombosis

It is advisable to have a cerebral CT scan or magnetic resonance imaging（if available）to exclude an infarct， small haemorrhage ormassoccupying lesion.

Question

Discuss the initialmanagement.Answer

This is a classic presentation of amaurosis fugax and like all TIAs thereforemust be treated as amedicalemergency as itmay be the fore-runner of amajor stroke（cerebral infarct）.Ideally the patient should be adm itted to a strokeunit in amajor hospital.If the patient is not allergic to aspirin， aspirin 300mg should be commenced immediately.If the patient is known to be allergic to aspirin an alternative anti-platelet agent such as clopidogrel should be used.Anti-platelet therapy（especially for carotid ischaemia）gives30% protection from strokeor death after TIA-compared with no treatment.Depending on investigations and the expertise of the stroke unit carotid endarterectomy or percutaneous transluminal angioplasty（stenting）may be undertaken.The patient should be strongly advised to cease smoking and his diabetic and hypertensive status evaluated.Investigations should also include serum lipids.

Reference

Tiller J（Chair）.Therapeutic guidelines：Neurology（Version 3）.Melbourne：Therapeutic Guidelines Ltd.2007：167-84