Download Bennett, A

Title:
Transient Cortical Blindness Following Cerebral Angiography in a 34 year old male
Abstract:
A 34 YO male with a subarachnoid hemorrhage underwent cerebral angiography to rule
out an aneurysm. Neurotoxicity to the contrast agent led to acute encephalopathy, headache,
cerebral infarcts, and cortical blindness that recovered in days.
I. Case History
•Patient demographics: 34 year old white male
•Chief complaint:
The patient experienced lightheadedness and presyncope at the gym while doing squats.
He presented to the ER later that week with left retrobulbar headache and was found to have a
subarachnoid hemorrhage in the left frontal-parietal lobe. A four vessel catheter-based cerebral
angiography with the contrast agent Ultravist, was performed to rule out an aneurysm. Upon
completion of the procedure and within minutes, the patient became bilaterally blind, with
associated headache and disorientation.
•Ocular history:
o
o
o
o
Myopia OU
h/o contact lens wear many years ago
No ocular trauma OU
No ocular surgery OU
•Medical history
o Non-aneurysmal Subarachnoid hemorrhage in the left frontal-parietal convexity
with valsalva
•Medications
o Acetaminophen tablet 650 mg po Q4H prn for headache
II. Pertinent findings
•Clinical
Initial examination by optometry took place in the angiography suite after a stat page
from the neurology department. Immediately upon completion of a cerebral angiography, the
patient complained of vision changes. The neurology resident performed confrontation fields and
found the patient to be full to finger count in both eyes. However, over the following 30
minutes, the patient reported progressive visual deterioration, which culminated in complete
bilateral blindness. Upon optometry’s arrival to the scene, the patient was disoriented, and
thrashing about with a severe headache. The patient was not able to cooperate with testing but
maintained a brisk pupillary response to light in each eye, had no afferent pupillary defect, no
purposeful gaze, and his eyes would roll back when being manually opened for testing. There
was no verifiable response to the OKN tape for either eye. Vision was unable to be quantified.
However, IOP was normal and fundoscopy was unremarkable with flat, pink discs OU with a
well-perfused posterior pole OU. The angiography failed to show aneurysm. The patient was
sedated, given Calcium channel blockers to control vasospasms and lower blood pressure, and an
MRI was performed. Unfortunately, there was motion artifact of the imaging but another MRI
was performed the next morning with improvement of image quality. The MRIs were negative
for new hemorrhaging but were positive for an acute infarct within the right cerebellum with a
smaller infarct in the right temporal lobe. The strokes were not cause for the cortical blindness
as they were not in a location to cause such symptoms. The patient was intubated and sedated for
next two days.
Two days later the patient was extubated and was examined bedside in intensive care.
The patient recalled feeling “pressure in my head” during the angiography and confirmed that his
vision was not blurry but was black. Upon awakening from sedation, the patient was
symptomatic for blur but admitted that his vision had been improving throughout the day. He
was having trouble reading the keys on his cell phone with his current spectacles. A persistent
headache with a severity of 1/10 was also present. The patient had not been previously
examined by an optometrist through the VA but had an eye exam 2 years prior was with no
health concerns. A corrected, distance Snellen equivalent acuity of 20/30 OD and OS was
obtained. Resolution of smaller letters may have been possible at that time but vision was
quantified to the fullest extent of a bedside exam with a Feinbloom chart at 7 feet. Near acuities
were 20/20 in each eye. Confrontation fields revealed a questionable inferior-temporal defect
OD as the patient had more difficulty in this quadrant. All other quadrants were FTFC OD and
OS and no visual extinction was noted. Facial amsler was grossly normal. Snowflake Amsler,
done to pick up a small paramacular scotoma, was full in each eye. Red cap desaturation was of
equal color and brightness in each eye. Pupils remained briskly responsive to light, equal, and
round with no APD. Extraocular motilities were full range of motion in both eyes with no
diplopia or pain. A questionable right beat nystagmus was observed. However, the patient
seemed to have more difficulty with this gaze that may account for the finding. There was no
nystagmus on up or down gaze. Color vision with Ishihara was 4/11 OD and 5/11 OS. The
patient denied knowledge of prior color vision defect, and the patient’s mother, who was present
during the exam, confirmed “he was always able to correctly identify crayon colors as a child”.
Anterior segment was unremarkable and IOPs were 15 mmHg OD and 18 mmHg OS. On
dilated fundus exam, several vitreous floaters were noted in the periphery of both eyes and over
the optic nerve in the right eye. There was a foveal light reflex in both eyes, a clear macula OU,
normal vasculature with no emboli, and a intact and perfused retina. Optic nerves appeared
healthy, flat, and pink, with a spontaneous venous pulsation in both eyes.
Four days after the initial angiography event, the patient presented to the eye clinic for
formal testing. He reported a subjective normalization of vision since the third day status post
cerebral angiography and could now see his phone without difficulty. He experienced an
intermittent headache that was relieved with Tylenol. Corrected, distance visual acuities were
20/20 in each eye. Pupils were equal, round, reactive to light, and with no APD. Confrontation
fields were full in all quadrants OD/OS, and extraocular motilities were full range of motion OU
with no diplopia, pain, or nystagmus. Color vision had normalized in both eyes with normal
Ishihara and D15. Undilated fundus exam was unremarkable. Fundus photos were taken for
photodocumentation and Humphrey Visual Fields were clean with no neurological defects in
either eye.
•Physical
Decreasing vision within 30 minutes following the cerebral angiography was the first
clue that a complication had occurred. The patient then complained of a headache with a rapid
deterioration of cognition soon thereafter. He became disoriented and increasingly agitated.
There were no other focal neurological deficits as the patient was able to move all four limbs
spontaneously. Speech, although incoherent at times, was preserved. Blood pressure was on the
lower side of normal.
•Laboratory studies
o
o
o
o
o
Sickle cell anemia trait
EGFR
Creatinine
Weight
Height
•Radiology studies
o Non-contrast CT of head and neck
o Small Left frontal subarachnoid hemorrhage without mass effect or
midline shift.
o MRI #1 ; before the angiography
o FLAIR hyperintensity in the left frontopariental sulci, which are consistent
with subarachnoid hemorrhage.
o 4 Vessel Cerebral angiography with ULTRAVIST contrast
o No brain aneurysm, AV Malformation, or dural AV fistula.
o Focal vasospasm of vessels in near the left Middle Cerebral Artery and the
SAH.
o There are a few focal areas of moderate stenosis involving distal parietooccipital left middle cerebral artery (MCA) branches. These findings are
suspicious for a vasculitis, or less likely, vasospasm related to known
subarachnoid hemorrhage. No evidence of intracranial aneurysm.
o MRI #2 ; immediately after angiography; sedated
o Acute infarct within the right cerebellum and within the right temporal
lobe. No evidence of hemorrhagic transformation was noted and the
subarachnoid hemorrhage in left frotoparietal sulci remained unchanged.
o MRI #3 ; one day s/p angiography, sedated
o Acute infarct within the right cerebellum and right temporal lobe.
o Unchanged subarachnoid hemorrhage in the sulci of the left frontoparietal
convexity. No evidence of progressive reversible encephalopathy
syndrome (PRES) in the current study.
•Others
o Humphrey Visual Field: 24-2
o OD/OS: clear with no defects
o Fundus photos
o OD/OS: unremarkable
III. Differential diagnosis
•Primary/leading
o Neurotoxicity to the contrast agent, ULTRAVIST, which is used in catheter-based
cerebral angiography. This condition is proposed to be on the same continuum as
posterior reversible encephalopathy syndrome (PRES).
•Differential Diagnosis of Cortical blindness
o Bilateral Occipital lobe infarct
o Ischemic
o Hemorrhagic
o Psychogenic blindness
o OKN distinguishes this by having response
o However, patient was confused and testing was inconclusive
o Cerebral Vasoconstriction
IV. Diagnosis and discussion
•Elaborate on the condition
High concentrations of hypertonic contrast agents used in cerebral angiography can
disrupt the blood brain barrier, especially when the agent is repeatedly injected over several
minutes. If the blood brain barrier is compromised, leakage of the contrast agent into the
cerebrospinal fluid can occur. The contrast agent can then cause serious reactions, neurotoxicity,
and electrolyte imbalance that can lead to encephalopathy (2). There is a predilection for the
occipital lobe as there is less sympathetic vascular innervation, reduced ability to compensate for
changes in blood pressure with vasodilation or vasoconstriction, and thereby worse auto
regulation of the posterior vasculature (3). The endothelium becomes damaged by the agent,
vasculature becomes overwhelmed, vasogenic edema builds in the occipital regions of the brain,
and visual symptoms are experienced.
Cortical blindness is characterized by a loss of vision secondary to a lesion affecting the
geniculocalcarine visual pathway in the brain (1). Cortical blindness can be attributed to a variety
of causes, with the most common being spontaneous ischemic stroke (32%), stroke secondary to
cardiac surgery (20%), and cerebral angiography (12%) (1). Most patients have sudden onset of
blindness but prior amaurosis, partial field loss progressing to complete field loss, and gradual
decreases in vision were also reported (1).
Proposed mechanisms of cortical blindness due to angiography are disruption of the
blood-brain barrier, secondary toxicity, concurrent hypotension, embolism, cortical hemorrhage,
or vasospasm. One study found that cortical blindness occurred in 0.8% of all vertebral
angiographies (1).
If the parietal lobe shows defects then it is usually associated with cognitive deficits
without a significant vision reduction (1). Anton’s syndrome, the denial of cortical blindness,
occurred but was very rare (1, 3). Absent OKN responses were noted in almost every patient
(1).
This case report argues that neurotoxicity falls on a continuum and is related to PRES.
Both conditions cause reversible neurological deficits. PRES is defined as a condition presenting
with headache, increased confusion, visual changes, seizure, and characteristic radiological
findings of posterior cerebral white matter vasogenic edema (3). The parieto-occipital region is
typically involved (3). Predilection for white matter edema may be attributed to more densely
packed matter in the cortex that opposes infiltration of edema (3). Findings that are found on
imaging are focal areas of vasoconstriction that are consistent with impaired autoregulation, local
hypoperfusion, vasogenic edema, and rare cerebral infarction (3). Vascular narrowing can be
seen on catheter angiography or magnetic resonance angiography (MRA) (3). PRES can be
differentiated from bilateral posterior cerebral infarction as calcarine and paramedical areas of
the occipital lobe are usually spared with PRES (3). The cerebellum and brainstem are
frequently affected (3). As the name suggests, clinical findings are reversible as are the
radiological findings within days to weeks (3). There was an absence of seizures in a minority of
patients who most often had milder disease (3). Ocular health is often unremarkable but
hypertensive changes could be present as there is a higher incidence of PRES in patients with
high blood pressure (3).
Risk factors for neurotoxic reaction are significant fluid overload (>10% of baseline
weight), mean blood pressure increase of >25% from baseline, and Creatinine of greater than 1.8
mg/dl (3). Dosing of the contrast agent for cerebral angiography should be 300 mg I/mL with a
maximum dose for adults of 86 grams. However, dosage should be adjusted for age, body
weight, vessel size, and rate of blood flow within the intended vessels (4). Single injection
dosing for cerebral angiography for cerebral arteries should be between 3-12 mL and vertebral
artery single dosing should be in the range of 4-12 mL (4). The contrast agent will increase the
circulatory osmotic load and can cause hemodynamic disturbances in patients with cardiac, renal,
or hepatic disease (4). Sickling can be induced by the contrast agent in patients with sickle cell
disease but have not been noted in patients with sickle cell trait, such as our patient (4). In a
study performed by the Ultravist company, 1142 patients underwent angiography to quantify
adverse reactions. Adverse reactions were observed such as nausea (3.7%), abnormal vision
(1.1%), headache (4%), vasodilation (2.6%), and a large variety of other complications.
Incidence of adverse reaction was 24% of patients (4).
•Expound on unique features
A post approval adverse reaction to the contrast agent used in cerebral angiographies,
Ultravist, is cerebral ischemia, infarction, vasospasm, and transient cortical blindness. Transient
cortical blindness occurs in 0.3-1.0% of cerebral and vertebral angiographies (5). Complete
cortical blindness is much more rare than incomplete blindness (1). Our patient received the
correct dosage of the agent and did not have risk factors such as high blood pressure, older age,
or reduced kidney function.
V. Treatment, management
•Treatment and response to treatment
Neurotoxity to contrast agent is self-limiting, with the symptoms being caused by
neurotoxicity to the contrast agent. Neuroimaging should be done to aid in diagnosis. Treatment
of neurotoxicity involves facilitating clearance of contrast with hydration, sedation as required to
accomplish imaging and to safeguard the patient, and blood pressure control. Diuresis to remove
the agent has not been shown useful (5). Vision should recover to normal when the contrast has
been eliminated from the system, within an average of 3 days (5). Visual recovery is gradual,
beginning with light perception, followed by motion perception, and finally color vision recovery
(5).
•Bibliography, literature review encouraged
1. Aldrich, Michael S., Anthony G. Alessi, Roy W. Beck, and Sid Gilman. "Cortical
Blindness: Etiology, Diagnosis, and Prognosis." Annals of Neurology Ann Neurol.
21.2 (1987): 149-58. Web.
2. Kocabay, G., and C. Y. Karabay. "Iopromide-induced Encephalopathy following
Coronary Angioplasty." Perfusion 26.1 (2010): 67-70. Web.
3. Neill, Terry A. "Reversible Posterior Leukoencephalopathy Syndrome." Up to Date.
Ed. Micheal J. Aminoff and Janet L. Wilterdink. N.p., 29 Apr. 2015. Web. 6 Aug.
2015. <www.uptodate.com>.
4. "Ultravist." RxList. N.p., 24 May 2012. Web. 12 Aug. 2015.
<http%3A%2F%2Fwww.rxlist.com%2Fultravist-drug.htm>.
5. Yazici, Mehmet, Hakan Ozhan, Ozan Kinay, Baris Kilicaslan, Mustafa Karaca, Hasan
Cece, Serdar Biceroglu, and Oktay Ergene. "Transient Cortical Blindness after
Cardiac Catheterization with Iobitridol." Texas Heart Institute Journal (2007): 37375. Web.
VI. Conclusion
•Clinical pearls, take away points if indicated
This case report highlights the potential for neurotoxicity to the contrast agent, which can
occur immediately following catheter-based cerebral angiography. This condition can result in
temporary cortical blindness, headache, encephalopathy, and possible seizures. Prognosis is
good after clearance of the contrast agent, which generally takes about three days.