Download document

Story of a 58 year old
obese man’s retina
Extra Case 5
A 58 year old obese man presents
distressed, after experiencing a loss of
vision in the right eye approximately 2 hours
previously. He describes the sensation of a
black curtain suddenly dropping in front of
that eye, lasting just under five
minutes. There were no associated ocular
symptoms, such as eye pain, and his vision is
now normal. He is feeling physically fit, and
he denies any other additional complaints in
a review of symptoms.
PMHx: HTN for 5 years – variable compliance with
medication and follow up
Meds: Atenolol 50mg daily
SHx: Smoker
Q1 What condition is the
patient describing? What
are the possible
aetiologies?
Q1 What condition is the patient describing? What
are the possible aetiologies?
• The obese man is describing a condition called
amaurosis fugax. It is a sudden transient loss of
vision in one eye. Only about a quarter of patients
with transient monocular vision loss (TMVL)
actually experience the classic ‘dark curtain’
descending over their field of vision: the rest
experience blindness, dimming, fogging, or blurring
of their vision. Duration of visual loss ranges from
only a few seconds to a few hours depending on the
aetiology of the vision loss. Eg. Obscured vision
due to papilledema may last only seconds, while a
severely atherosclerotic carotid artery may be
associated with duration of one to ten minutes.
• There are 5 main categories of aetiology; embolic,
hemodynamic, ocular, neurologic, and idiopathic.
Q1 What condition is the patient describing? What
are the possible aetiologies?
Embolic and hemodynamic causes
• Atherosclerotic carotid artery: presents as type of
TIA  unilateral embolic obstruction of retinal or
ophthalmic artery  ischemic retina. BUT can also
be caused by hypoperfusion. "Unilateral visual loss
in bright light may indicate ipsilateral carotid artery
occlusive disease and may reflect the inability of
borderline circulation to sustain the increased
retinal metabolic activity associated with exposure
to bright light."
• Cardiac emboli obstructing either retinal,
ophthalmic and/ or ciliary arteries secondary to AF,
valvular disease etc
• Temporary vasospasm – related to exercise and
systemic hemodynamic challenge
• Giant cell arteritis – granulomatous inflammation
within the central retinal and posterior ciliary
arteries of eye.
Q1 What condition is the patient describing? What
are the possible aetiologies?
Ocular causes
• Close-angle glaucoma
• Transiently elevated ICP
Neurological causes
• Optic neuritis
• Papilloedema – usually accompanied by
headache. Optic disc swelling renders the
small, low-pressure vessels that supply the
optic nerve head vulnerable to
compromise
• Multiple Sclerosis - unilateral conduction
block secondary to demyelination and
optic neuritis
• Migraine
On examination:
BP 150/95 mm Hg. Visualisation of the retina with a direct
opthalmoscope reveals the finding below.
Q2 What is
demonstrated in this
fundus photograph?
Q2 What is demonstrated
in this fundus photograph?
The opacity is called a Hollenhorst plaque –
either a cholesterol emboli which usually
dislodges from the carotid arteries, or
calcific/ platelet-fibrin fragments from a
stenosed aortic valve. The embolus normally lodges
at a bifurcation point. The pathology caused by the
Hollenhorst plaque is called Retinal Artery Occlusion
(Can be CRAO or BRAO) where the affected retina
(with the exception of the fovea) becomes pale and
swollen and opaque while the central fovea still
appears reddish.
Q3 What additional
physical examination
would you perform as
part of your initial
assessment?
Q3 What additional physical examination would you
perform as part of your initial assessment?
• Cardiovascular examination –
especially looking for
atherosclerotic plaques in the
carotid arteries and valvular disease
in the heart.
• Neuro examination – PEARLA, visual
fields and acuity again etc
• Slit lamp examination
• Also need to find any evidence of
coagulopathies!
A carotid Doppler
ultrasonography indicates
a severe 80% stenosis of
the right internal carotid
artery. There is also mild
stenosis (50%) in the
region of bifurcation of the
left common carotid
artery.
Q4. What additional
investigations would you
order at the same time?
Q4. What additional investigations would you order at
the same time?
• Unless symptoms are very typical for migraine,
some diagnostic testing is required.
• Erythrocyte sedimentation rate and C-reactive
protein should be performed in all individuals over
age 50 years with transient monocular or binocular
visual loss to exclude giant cell arteritis (GCA)
• Other tests are ordered according to symptoms and
clinical setting and may include
• cardiac workup (ECG, Holter monitoring and
echocardiography)
• Coagulation profile
• Fasting Lipids (chol and TG)
• Somehow test Intraocular pressure
• magnetic resonance imaging (MRI)
• electroencephalogram (EEG)
• FBC (to screen for conditions such as polycythemia
vera and essential thrombocythemia)
After evaluating the results of all
investigations, you discuss possible
treatment 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.
Q5 Presented with this
new history, what
treatment would you
recommend for the
patient? Why?
Q5 Presented with this new history, what treatment
would you recommend for the patient? Why?
• Re-current TIA’s? ie: One TMVL
(amaurosis fugax) and one transient
cerebral ischemic episode.
• TMVL carries a lower risk for stroke
in the setting of high-grade carotid
disease, compared with cerebral
ischemia. Ie. at higher risk for stroke
now….
• Since has had TIA in past now might
consider follow-up investigations like
CT/ MRI and standard treatment of
post TIA – hinges on stroke
prophylaxis
As an aside… Treatment options for uncomplicated
(Central) Retinal artery occlusion are as follows…
•
•
•
•
•
Immediate lowering of IOP to a target pressure of 15 mm
Hg using medical management, ocular massage, and
anterior chamber paracentesis. This hopefully dislodges
the embolus to a point further down arterial circulation
and improves retinal perfustion.
Start timolol early in the treatment of RAO.
Acetazolamide and mannitol should also be used when
CRAO is suspected because there are few downsides to
starting these medications early.
CO2 therapy (give patient a bag to rebreath in) carbon
dioxide dilates retinal arterioles, and oxygen increases
oxygen delivery to ischemic tissues.
Thrombolytics may be useful if initiated within 4-6 hours
of visual loss, but they may not be much help if the
embolus is cholesterol, talc, or calcific. Thrombolytics
are introduced via the proximal ophthalmic artery,
delivering increased concentrations directly to the
retinal artery and minimizing systemic complications.
Results of noncontrolled retrospective studies have been
mixed. As of 2007, a European controlled study is
underway.
Treatment with IV thrombolytics as with cerebral
infarction has been discussed but currently is not the
standard of care.
Q6 Discuss the various
treatment options for
TIAs.
Q6 Discuss the various treatment options for TIAs.
MEDICATION: Noncardioembolic attacks
• In presumed or angiographically verified atherosclerotic
changes in the extracranial or intracranial cerebrovascular
circulation, antithrombotic medication is prescribed (Aspirin,
clopidogrel, dipyridamole etc)
• Treatment with aspirin, (over 100mg) once daily orally,
significantly reduces the frequency of TIA and stroke
• Anticoagulant drugs are not recommended; there is no benefit
over antiplatelet therapy and risk of serious hemorrhagic
adverse effects is greater (NOTE: is recommended in
cardioembolic events)
SURGERY
• Carotid thromboendarterectomy
– Reduces the risk of ipsilateral carotid stroke, especially when
TIAs are of recent onset (< 1 month)
– Indicated when there is a surgically accessible high-grade
stenosis (70–99% in luminal diameter) on the side appropriate
to carotid ischemic attacks and there is relatively little
atherosclerosis elsewhere in the cerebrovascular system
OTHER THERAPEUTIC PROCEDURES
•
Cigarette smoking should be stopped
•
Treat any cardiac sources of embolization, hypertension,
diabetes mellitus, hyperlipidemia, arteritis, or hematologic
disorders appropriately
•
Weight reduction and regular physical activity should be
encouraged when appropriate
And that’s our story
The end