A middle-aged man with sudden visual loss

Published on 10/04/2015 by admin

Filed under Surgery

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1190 times

Problem 40 A middle-aged man with sudden visual loss

Sumu Simon, Robert Fitridge

A 61-year-old man presents to the emergency department with complaints of sudden transient right monocular visual loss. During the interview, he gives a history of two such episodes over the past 24 hours, the last being just about an hour ago. During each episode, his vision became grey and washed out and cleared completely within 5–10 minutes. He denies other symptoms such as headache, nausea, ocular pain, redness, aura or visual haloes. You have been treating this patient for essential hypertension for approximately 5 years, although he has not been completely compliant with medication and follow-up for blood pressure monitoring. He has no other significant medical history, and his only medication is atenolol 50 mg daily. He is obese and is a habitual smoker. He is feeling physically fit, and you are unable to elicit any additional complaints in a review of symptoms. He has a bruit heard in the right neck.

Q.1

What condition is the patient describing? What are the possible aetiologies?

On examination, you measure the blood pressure at 150/95 mmHg. There is no evidence of postural hypotension. Vision, visual fields, pupillary responses, anterior segment examination, gonioscopy and applanation tonometry findings are normal. Visualization of the retina with a direct ophthalmoscope reveals the finding illustrated in Figure 40.1.

image

Figure 40.1

Q.2

What sign is present in this fundus photograph? What additional physical examination would you perform as part of your initial assessment?

Q.3

What additional investigations would you order at the same time?

After completing the clinical examination, you arrange carotid Doppler ultrasonography. This indicates a severe (85%) stenosis of the origin of the right internal carotid artery. There is also mild stenosis (no more than 50%) in the region of bifurcation of the left common carotid artery.

Q.4

What treatment would you recommend to this patient?

After evaluating the results of all investigations, you discuss possible medical treatment and surgical intervention with the patient. The patient tells you that on the evening prior to the review appointment, while he was sitting watching television, his left arm became weak and he was unable to pick up his coffee cup. On trying to stand, he found his left leg was dragging, and he was forced to sit down. The episode lasted approximately 10 minutes.

The patient decides in favour of the suggested surgical procedure. In preparation for this, the surgeon orders the radiological study illustrated in Figure 40.2.

image

Figure 40.2

Q.5

What is this study? Are the findings consistent with the proposed surgical procedure?

The patient undergoes successful carotid surgery. Postoperatively he is maintained on aspirin and is referred to the cardiac rehabilitation service to improve his lifestyle.

Answers

A.1 This patient has presented with transient monocular visual loss (TMVL) or ‘amaurosis fugax’. TMVL is characterized by sudden onset of unilateral visual loss lasting no longer than 24 hours. Commonly of ischemic aetiology, the vascular condition can be in the eye or its vicinity, or can be remote.

TMVL can be due to impaired arterial perfusion (retinal, choroidal or optic nerve ciliary arteries) or to venous stasis. Impending central retinal vein occlusion and central retinal vein occlusion can present with TMVL.

Common causes include arteriosclerosis, hypercoagulable and hyperviscosity states. Though rare, vasculitis and retinal migraine (vasospasm of the retinal arteries) can present with transient visual loss. It is important to consider the possibility of temporal arteritis which may involve the ophthalmic arteries, and has the potential to lead rapidly to arterial occlusion and devastating bilateral blindness. This is most often seen in elderly patients, and other symptoms may include headache, scalp tenderness often apparent when brushing the hair, and jaw claudication, which may occur on chewing food. Polymyalgia rheumatica may co-exist.

TMVL that lasts only for a few seconds is called transient visual obscurations and is typically seen in optic disc oedema (with or without drusen) and in congenital anomalies of the optic disc. The most frequent remote cause for TMVL is carotid stenosis (due to atherosclerosis) rather than cardiac source emboli. The site of carotid stenosis is usually at the termination or at the bifurcation of the common carotid artery or at the origin of the internal carotid artery. Cardiac emboli are associated with atrial fibrillation, mural thrombi (after myocardial infarction) and diseased valves. Other remote causes includes stenosis of the aortic arch and ophthalmic arteries, systemic hypotension and diminished cardiac output. Rarely carotid artery dissection can present with TMVL and may be associated with neck pain and Horner’s syndrome.

Ocular disorders such as intermittent angle closure glaucoma, hyphaema, optic nerve demyelination (Uthoff’s phenomenon) and keratoconus can also mimic transient visual loss and need to be ruled out by ophthalmologic evaluation.

A.2 Figure 40.1 illustrates an embolus at the branch of a retinal artery.

This is most likely a cholesterol embolus or ‘Hollenhorst plaque’, originating from the carotid arterial system.

When evaluating a patient with transient monocular visual loss, a careful cardiovascular examination is essential, including measurement of pulse and blood pressure, examination of carotid and temporal arteries, and assessment of the heart. Remember that the absence of a carotid bruit does not rule out significant carotid disease. Indeed, the most severely diseased carotids often do not have an associated bruit. This patient has an elevated blood pressure, possibly reflecting poor compliance with antihypertensive medication, which is a risk factor for carotid atherosclerosis.

A.3 Essential investigations should include:

• Urinalysis and fasting serum glucose level.
• Fasting serum lipid profile.
• ECG.
• Carotid duplex ultrasound.

Other investigations which may be useful:

• Echocardiography (transthoracic/transoesophageal) is indicated if a significant cardiac abnormality, aortic arch atheroma, atrial appendage thrombus or mural thrombi is suspected.
• Erythrocyte sedimentation rate (ESR) is an important part of evaluation for vasculitis.
• C-reactive protein: CRP is more sensitive (100%) than ESR (92%) in detecting giant cell arteritis. The specificity rate for combined ESR and C-reactive protein in temporal arteritis is 97%.
• In a young person, or if clinical examination suggests an unusual cause, other tests such as autoimmune screening, coagulation studies and tests for hyperviscosity syndromes should be considered to rule out vasculitis and hypercoagulable/hyperviscosity states.
• Doppler of ophthalmic artery – this can reveal stenosis or occlusion of the ophthalmic artery.
• Fundus fluorescein angiography – to evalute choroidal and retinal perfusion abnormalities.

A.4 This patient has suffered a second episode of right monocular blindness and left-hand weakness, while awaiting confirmation of the diagnosis. He is at high risk of having a stroke.

• Aspirin (100–300 mg daily) has a proven role in reducing the risk of stroke. In the absence of contraindications, this medication can be started immediately if the diagnosis of carotid atheroma is suspected.
• Carotid duplex ultrasound scan (Figure 40.2) of the right internal carotid artery shows a peak systolic velocity of 428 cm/s, end diastolic velocity of 155 cm/s. This equates to a severe internal carotid artery stenosis in the range of 80–99%.
• Contrast-enhanced MR angiogram (Figure 40.3) shows a high-grade stenosis at origin of the right internal carotid. A CT angiogram (Figure 40.4) confirms this lesion as a high-grade stenosis with focal mixed calcified and soft plaque at origin of the right internal carotid, with plaque extending into the common carotid artery (note: not all three imaging modalities are required, but they are presented here in a single patient for educational purposes).
• Carotid endarterectomy is definitive therapy when performed by a skilled vascular surgeon who has an acceptable complication rate. Endarterectomy significantly reduces the risk of subsequent stroke for patients with retinal or cerebral ischaemic symptoms related to severe (70–99%) carotid stenotic lesions. Patients with moderate stenoses (50–69%) may benefit from this surgery, but are generally managed medically. Patients with mild stenoses (less than 50%) have no benefit from intervention. The role for carotid endarterectomy in the treatment of asymptomatic carotid arterial stenosis is still debated. In this patient, with a high-grade symptomatic right internal carotid arterial stenosis, right carotid endarterectomy would be recommended.
• Carotid artery stenting, via a percutaneous approach, is an emerging procedure and has been shown to have similar outcomes to surgery in high-risk patients. Using this approach in lower-risk patients is currently being evaluated in clinical trials. Some controversy exists regarding patient selection for surgery versus stenting.
• Pharmacological stroke prevention should be continued after the surgery.
• Risk factor reduction is essential. This patient has a number of significant cardiovascular risk factors.
• Control of blood pressure is important, and tight control will reduce his absolute risk of stroke and of cardiac disease. Cessation of smoking is another important preventative measure. If the glucose measurement indicates diabetes mellitus or the lipid profile is abnormal, appropriate dietary and pharmacological measures should be instituted.
image

Figure 40.3

image

Figure 40.4

A.5 As an imaging tool performed prior to carotid endarterectomy, invasive carotid angiography has been replaced by spiral CT angiography and magnetic resonance angiography. These latter two procedures are much less invasive and pose less risk to the patient. Carotid Doppler examination is still widely used and, in expert hands, remains a sensitive tool for the detection of carotid disease.

In this patient, the CT angiogram confirms a severe stenosis at the take-off of the right internal carotid artery, consistent with his symptoms of right amaurosis fugax and left-sided weakness. Yet the artery remains patent. This is an important observation, as endarterectomy cannot be performed on a completely occluded vessel. In other words, the angiographic findings are consistent with the proposed surgical procedure.

Revision Points

Transient Monocular Vision Loss

Definition

Transient ischaemic attack with sudden complete monocular loss of vision with complete recovery within 24 hours.

Differential Diagnoses

• Cardiac disease.
• Aortic arch atheroma.
• Temporal arteritis.
• Hypercoagulability syndromes.
• Vasculitis.
• Optic disc oedema and congenital disc anomalies.

History Focus

• Hypertension.
• Smoking.
• Diabetes mellitus.
• Hyperlipidaemia.
• Cardiac disease.

Examination Focus

• Pulse.
• Blood pressure.
• Rhythm (atrial fibrillation).
• Carotid arteries.
• Temporal arteries.
• Ocular examination.

Investigations

• Carotid Doppler ultrasound.
• CT angiography or MR angiography if intervention contemplated.
• Urinalysis.
• Fasting serum glucose.
• Fasting serum lipid profile.
• Electrocardiogram.
• Consider erythrocyte sedimentation rate, C-reactive protein.

Treatment

• Treat reversible risk factors.
• If no contraindications, commence aspirin (300 mg daily).
• Consider carotid endarterectomy.

Issues to Consider

• Revise the anatomy of the cerebral circulation. For each major vessel, what would be the clinical effect of a transient occlusion (TIA) in that vessel?
• How does warfarin compare with aspirin in the secondary prevention of ischaemic strokes?
• What complications of endarterectomy would you warn the patient about when seeking consent?
• What is the current evidence for stenting versus surgery for carotid disease?

Further Information

Amick A., Caplan L.R. Transient monocular visual loss. Comprehensive Ophthalmology Update. 2007;8(2):91-98.

Biousse V., Trobe J.D. Transient monocular vision loss. American Journal of Ophthalmology. 2005;140:717-722.

, http://neurosurgery.mgh.harvard.edu/. The website of the neurosurgical vascular service at Harvard with lots of information about carotid endarterectomy

, www.emedicine.com/emerg/topic604.htm. Transient ischaemic attacks

, www.pvss.org. Website of the Peripheral Vascular Surgical Society with information for patients and professionals including case studies, an atlas and intraoperative photographs

Related posts:

Rectal bleeding in a 45-year-old woman A 42-year-old woman with hypertension A listless 45-year-old man Acute respiratory failure in a 68-year-old man ‘Jack has leg weakness’ Default ThumbnailThe routine check-up