11/14/24, 10\:54 AM Neurological Causes of Visual Loss
Neurological Causes of Visual Loss
Table of contents
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A comprehensive topic overview
Introduction
Loss of vision can be caused by ophthalmological (due to eye pathology) and neurological (due to nervous system
pathology) conditions. This article will cover neurological causes of visual loss.
Loss of vision can have a signi
independent risk factor for falls.
1
The Royal National Institute of Blind People (RNIB) estimated an incidence of 0.14% of the UK population experienced new
sight loss or blindness in 2016-17.
An extrapolated lifetime risk of all cause of sight loss (including treatable causes) was estimated at 36.3% in the UK. This
means one in three people are at risk of sight loss requiring intervention or treatment during their lifetime.
2
Stratifying patients with visual loss into life-threatening, sight-threatening and non-emergency is a vital skill. In addition,
knowing if the visual loss is ophthalmological or neurological is important to know the correct referral pathway.
For more information on ophthalmological causes of sudden loss of vision, see the Geeky Medics guide to sudden painless
loss of vision.
Aetiology
Visual loss can be caused by pathophysiological processes throughout the visual pathway (Figure 1, Table 1).
Figure 1. Diagram illustrating the visual system and anatomically important structures.
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Table 1. A non-exhaustive list of conditions of the visual system corresponding to the
visual pathway diagram in Figure 1.
Neurological visual loss results from nervous system pathology which occurs anywhere along the visual pathway, from the
optic nerve to the visual cortex in the occipital lobe of the brain. Anatomically, these are termed retrobulbar, as they occur
posterior to the globes.
The most common neuro-ophthalmological symptoms include altered colour perception, diplopia, loss of vision and
characteristic visual . This article will focus on conditions where vision loss is the principal symptom.
Establishing the time course of symptoms along with a focused history can be a valuable indicator as to what pathological
process is occurring.
This will help guide optimal management aiming to avoid any permanent visual de
Sudden onset of neurological visual loss is often vascular in aetiology and includes cerebrovascular disease (TIA and
stroke).
Subacute onset is more suggestive of infective or in
Gradual or worsening vision loss is more consistent with a degenerative pathology or a space-occupying lesion.
Transient and intermittent symptoms can be seen in various neurological conditions, including migraine with aura,
amaurosis fugax, TIA and optic neuritis.
Optic neuritis
Optic neuritis is an in
usually, monocular vision loss.
It is the presenting feature of multiple sclerosis (MS) in 15-20% of patients and occurs at some stage in at least half of
patients diagnosed with MS.
3
Aetiology
Optic neuritis generally refers to acute demyelinating optic neuritis which is highly associated with MS but can also be
idiopathic, in which case it is described as a clinically isolated syndrome (CIS).
Rarely, optic neuritis can result from systemic disorders. These include infections such as tuberculosis and syphilis and
autoimmune/in
4
Risk factors
Optic neuritis is most common in women between 18-50 years old and in Caucasian populations.
Clinical features
Typical symptoms of demyelinating optic neuritis include\:
Eye pain that is characteristically worse on eye movement
Monocular vision loss developing over hours to days; this varies from a slight blur to no light perception
Impaired colour vision in the a
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Typical clinical examination
Reduced visual acuity
Relative a
Visual
Only 33% of patients have overt optic disc swelling (papillitis) with hyperaemia. The remaining 66% have retrobulbar optic
neuritis, with a normal fundoscopic examination (Figure 2).
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Figure 2. A sagittal illustration of the globe and optic nerve
Investigations
Optic neuritis is a clinical diagnosis. However, MRI of the brain and orbits is usually requested to look for other areas
suggestive of demyelination which could indicate a diagnosis of MS.
Management
Vision starts to recover within a month without treatment. There is no e
treatment, however, systemic corticosteroids have been shown to hasten visual recovery.
6
Patients should be referred to neurology if MS is suspected.
Complications
Following recovery and despite the return of normal visual acuity, clinical
optic nerve pallor (atrophy) commonly persist (Figure 4).
Figure 3. Optic disc pallor as seen in cases of resolved optic neuritis.
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Key points
Optic neuritis usually refers to acute demyelinating optic neuritis which is highly associated with MS.
Optic neuritis typically presents with monocular symptoms including pain on eye movement, variable vision loss
occurring over hours to days and impaired colour vision
Symptoms gradually resolve over several weeks without treatment
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Migraine with aura
Migraine with aura is the most common cause of transient vision loss in young adults.
Aetiology
Migraine is a complex condition, and the pathophysiology is not fully understood. It can be precipitated by a trigger, with
common examples include hormonal changes and dysregulation of sleep and meals.
Risk factors
There is a strong genetic predisposition to developing migraine with aura.
Other common risk factors proposed include female sex, stress, obesity, diabetes, and head injury.
Clinical features
Typical symptoms of migraine with aura include\:
Evolving positive visual phenomenon such as
resolve. Often described as bilateral and present when eyes are closed, typically lasting 10-60 minutes.
Can be associated with or followed by a headache.
An aura of atypical duration or accompanied by negative features, such as hemianopia, are rarer.
For more information, see the Geeky Medics guide to headache history taking.
Clinical examination of migraine with aura (including visual
Investigations
Migraine with aura is a clinical diagnosis and does not often require further investigation.
If there is any unexplained focal neurological de
as serum in
Management
Acute medical therapy is taken at the onset of migraine symptoms. These include analgesics such as high dose aspirin,
ibuprofen or triptans.
Primary prevention aims to manage the frequency of migraines. Avoidance of triggers and lifestyle modi
included here along with medical prophylaxis, such as propranolol or amitriptyline, which are considered when there is a
signi
The combined oral contraceptive pill should be discontinued in patients with migraine with aura due to the small increased
risk of ischaemic stroke.
8
Complications
without infarction.
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Rarely infarction or seizure can occur along with prolonged symptoms, which include status migrainosus or persistent aura
Key points
Migraine with aura is the most common cause of transient vision loss in young adults.
It typically presents as evolving visual phenomenon that demonstrates complete reversibility, with phenomena most
commonly lasting 10-60 minutes.
It is managed acutely with NSAIDs or triptans, and in some cases with medical prophylaxis (e.g. propranolol).
The combined oral contraceptive pill should be discontinued due to the small increased risk of ischaemic stroke.
Amaurosis fugax
Amaurosis fugax translates as “
transient ischaemic attack (TIA).
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Almost all patients will present once the episode has resolved. An accurate history detailing the timing of events and
characteristics of vision loss is crucial.
Aetiology
Amaurosis fugax describes a transient monocular vision loss which is a result of ischaemia to the retina, choroid, or optic
nerve from an arterial embolus, usually in the retinal artery from ipsilateral carotid artery disease (Figure 5).
10
Figure 4. Illustration of the blood supply to the eye, all of which arises
from the internal carotid artery.
Risk factors
Amaurosis fugax usually occurs in patients over the age of 50 with vascular risk factors, such as hypertension,
hypercholesterolaemia, smoking and previous history of TIA/stroke (cerebrovascular disease).
Clinical features
The typical presentation of amaurosis fugax is transient vision loss in one or both eyes occurring abruptly, reaching
maximum severity within seconds and lasting seconds to minutes, followed by full visual recovery.
It is most commonly a negative visual phenomenon, described as a blackout, or ‘greying out’ of vision.
An ophthalmological examination will typically be normal.
Investigations
Relevant investigations include\:
Intemporal/giant cell arteritis must be excluded
Carotid artery imaging\: to assess for carotid artery stenosis
Cardiac investigations\: looking for atrial
Neuroimaging is not indicated unless there is clinical suspicion of an alternative diagnosis that would be detected with CT
or MRI scanning.
Management
Patients presenting acutely are o
within 24 hours is required.
Once the diagnosis is con
blood pressure control).
Complications
The risk of ischaemic stroke in patients with amaurosis fugax is estimated to be around 2% per year. This increases to 8.4%
in the presence of signi
11
Key points
Amaurosis fugax is a form of TIA, usually from an arterial embolus arising from carotid artery disease.
Transient vision loss occurs in one or both eyes lasting seconds to minutes followed by full recovery.
Acute management often involves 300mg aspirin, unless contraindicated.
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Urgent referral to a specialist TIA clinic is required who will formally diagnose, assess risk and manage risk factors.
The risk of ischaemic stroke following amaurosis fugax is around 2% per year.
Pituitary adenoma
Pituitary adenomas account for up to 15% of symptomatic intracranial neoplasms and are the most common cause of optic
chiasm compression in adults.
Other pathologies that a
metastases.
Aetiology
The adenoma compresses the optic chiasm leading to vision loss. The most common pituitary pathology presenting with
vision loss is a non-functioning pituitary macroadenoma.
12
Risk factors
Pituitary adenomas occur predominantly in adulthood.
3% of cases are associated with multiple endocrine neoplasia (MEN type 1) however, the majority occur in isolation.
Genetic factors have been shown to contribute to risk.
Clinical features
Typical symptoms of pituitary adenoma include\:
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Headache\: the most common presenting symptom
Vision changes\: loss of peripheral vision is often so insidious that many patients remain asymptomatic with or without the
presence of a visual
Symptoms of pituitary dysfunction\: including weight gain, mood changes/irritability, loss of libido, dizziness, erectile
dysfunction and infertility
Typical clinical examinations
12
Reduced visual acuity in advanced chiasmal compression
Signs of pituitary dysfunction\: such as gynecomastia and acromegaly
Visual
Figure 5. Illustration of complete bitemporal
hemianopia suggestive of chiasmal pathology
and associated loss of the temporal visual
in both eyes.
Investigations
If a visual
established. A pituitary MRI will then be arranged by secondary care if deemed necessary.
Management
Management varies depending on the lesion, but if the visual
chance of restoring vision.
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Complications
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Pituitary apoplexy is a life-threatening complication, where sudden haemorrhage or infarction of the tumour occurs. It
presents with severe headache, nausea, loss of vision and reduced consciousness.
Corticosteroids must be started immediately followed by con
decompression may also be indicated.
Key points
Pituitary adenoma is the most common cause of optic chiasm compression in adults and can present with vision loss
Headache and bitemporal hemianopia are the most common clinical features, however many patients are asymptomatic
Urgent endocrine assessment is required to establish a biochemical diagnosis, often followed by a pituitary MRI
Transsphenoidal surgery o
Pituitary apoplexy is a life-threatening vascular event that can occur
Ischaemic stroke
Any intracranial lesion along the visual pathway can cause vision loss. Vascular causes are the most common in adults,
followed by traumatic brain injury and brain tumours.
This section will discuss a new presentation of homonymous hemianopia as a result of ischaemic stroke. The FAST (face,
arm, speech, time) screening tool may miss this presentation.
Aetiology
Homonymous hemianopia occurs due to a unilateral lesion posterior to the chiasm (retro-chiasmal), which a
contralateral visual
Homonymous hemianopia presents in both anterior and posterior circulation stroke syndromes, under the Oxford stroke
classi.
Isolated homonymous hemianopia can be classi
Risk factors
Ischaemic stroke usually occurs in patients over the age of 50 with vascular risk factors, such as hypertension,
hypercholesterolaemia, smoking and previous history of cerebrovascular disease.
Over 40% of POCS are attributed to cardioembolism (e.g. atrial
Clinical features
a
Patients usually describe monocular vision loss or di
Other acute neurological de
Clinical examination
Optic tract lesions will present with homonymous hemianopia and ipsilateral RAPD with temporal vision loss, optic
nerve atrophy (“optic tract syndrome”) ± hemiparesis
Optic radiations lesions will present as incongruous (asymmetric) homonymous hemianopia ± aphasia, memory de
seizures, and hallucinations
Occipital cortex lesions will present as isolated homonymous hemianopia that is highly congruous (equal) ± macular
sparing
dysarthria, and ataxia
Brainstem lesions present with any combination of homonymous hemianopia, cranial nerve palsy, nystagmus, vertigo,
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Figure 6. Illustration of complete right homonymous
hemianopia as a result of a left-sided ischaemic stroke,
detailing the loss of both temporal visual
and nasal visual
Investigations
Rapidly developing neurological symptoms should immediately raise suspicion of an acute neurovascular event, with the
presence of isolated homonymous hemianopia raising the index of suspicion to a posterior circulation stroke.
An urgent non-contrast CT scan should be performed to exclude intracranial haemorrhage. CT is less sensitive in
detecting posterior circulation (60%) compared to anterior circulation (>90%) strokes.
14
MRI o15
MRI with DWI
sequencing within 12 hours of the event is highly sensitive (92%) in identifying acute ischaemic stroke.
16
Identi
also be carried out.
Management
Acute stroke management includes resuscitation and direct admission to a specialist stroke unit after an initial
assessment.
If within 4.5 hours of the onset of symptoms, with no contraindications, thrombolysis may be o
If thrombolysis is contraindicated or not available, 300mg aspirin orally along with a proton pump inhibitor must be o
within 24 hours when haemorrhage is excluded unless also contraindicated.
14
In some UK centres, thrombectomy is available as an acute treatment of ischaemic stroke.
Stroke prevention strategies are key to preventing recurrence and aim to control modi
15
Advice to cease driving is crucial, however, up to 50% of visual
so observation is important.
17
Referral to low vision services for rehabilitation assessment can be bene
after six months is rare.
In the United Kingdom, patients must be advised to inform the Driver and Vehicle Licensing Agency (DVLA).
Complications
An important complication to consider is a further stroke or vascular cerebral event.
Key points
Homonymous hemianopia occurring in isolation is classi
and is a rare cause of vision loss
Other neurological de
location along the visual pathway
A suspected acute stroke must be referred directly to a specialist stroke unit for management and prevention strategy
implementation
Over 50% of visual
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Final summary
If a patient’s vision loss is suspected to be a result of a life-threatening or sight-threatening condition, they must be referred
urgently. Importantly, assessing whether vision loss is ophthalmological or neurological in nature will allow the most
appropriate referral and onward management.
References
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Contents
Reviewer
Introduction
Dr Kathryn A W Knight
Aetiology
Neurology registrar
Optic neuritis
NHS Tayside
Migraine with aura
Amaurosis fugax
Pituitary adenoma
Ischaemic stroke
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