Postgraduate Medicine

ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20

Cortical blindness
Walter G. Drymalski
To cite this article: Walter G. Drymalski (1980) Cortical blindness, Postgraduate Medicine, 67:4,
149-156, DOI: 10.1080/00325481.1980.11715430
To link to this article: http://dx.doi.org/10.1080/00325481.1980.11715430

Published online: 07 Jul 2016.

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Date: 08 July 2017, At: 17:25

Cortical blindness
The changing incidence and shifting etiology

Walter G. Drymalski, MD

Con si der
What are the most common
characteristics of cortical
blindness?
Under what circumstances is the
disorder difficult to diagnose?
Which diagnostic test is the most
useful for fo/low-up evaluation?

The incidence and etiology of cortical blindness-a disorder that usually
occurs after cerebrovascular accidents, cardiorespiratory arrest, severe
head trauma, or bacterial meningitis-may be changing with the development of effective means of cardiopulmonary resuscitation, as three cases
discussed here show.
For a long time cortical blindness
bas been considered a rare event
resulting from bilateral damage to
the occipital lobes or the optic radiations of the brain beyond the lateral geniculate body. The causes
are few.
In the pediatrie age-group,
causes include head trauma, meningitis, and cardiorespiratory arrest.1-3 The head trauma is
usually sufficiently severe to result
in generalized CNS depression,
but prognosis for recovery of sight
is favorable. 2 Transient cortical
blindness in children after seemingly minor head trauma also has
been reported. 1 Cortical blindness
as a sequela of bacterial meningitis
is rare, and the incidence attributable to each of the various pa thogens is not known.
In adults, the most common
causes are cerebrovascular accidents and episodes of cardiorespiratory arrest. ln the largest series
to date (58 cases), Symonds and
Mackenzie• reported in 1957 that
cortical blindness was caused almost exclusively by thrombosis or
embolization of cerebral vessels.
They believed that most of the episodes of cortical blindness were
caused by microemboli from vertebral or basilar artery plaques or

'VOL 67/NO 4/ APRIL 1980/POSTGRADUATE UEOICINI' • CORTICAL IILINDNE88

thrombi lodged in the distal posterior circulation. In a smaller series
reported in 1957 by Bergman,5
cerebrovascular occlusion caused
cortical blindness in 7 of 12 patients; carbon monoxide poisoning,
trauma, Hodgkin 's disease, and
progressive subcortical leukoencephalopathy were also reported as
causes.
Recent case studies
It is important to note that the
foregoing studies were completed
prior to the 1960s-before effective methods of cardiopulmonary
resuscitation were developed. More
recent reports2-6·s of cortical blindness in adults and the three following cases-which occurred in a
two-year period at two community
hospitals-may indicate an incidence higher than originally suspected and a shift in the primary
etiology from cerebrovascular accidents to severe hypoxic or hypotensive episodes occurring during cardiorespiratory arrest.
CASE t-A 71-year-old man was
brought to the emergency department of Borgess Hospital, Kalamazoo, Michigan, in October 1975 by
ambulance for evaluation of increasing dyspnea over the previous
24 hours. The patient had been
continued
149

Cortical blindness should be suspected when a
patient with normal pupillary reflexes complains of
blindness even though the results of an ophthal·
moscopic examination are normal.

Walter G. Drymalski
Dr Drymalski is a fellow in
rheumatology, University of
Michigan Medical sèhool, Ann
Arbor, and Wayne County
General Hospital, Eloise,
Michigan. He was a resident in
internai medicine, Bronson
Methodist and Borgess hospitals, Southwestern Michigan
Area Health Education Center,
Kalamazoo. His current research interests are in hypertrophie pulmonary osteoarthropathy.

receiving treatment for angina
pectoris and severe congestive
heart failure. His wife said that his
mental clarity and ability bad been
declining within the past few years.
On physical examination, the patient did not respond to commands
and bad peripheral cyanosis. Pupils
were dilated but reactive; systolic
blood pressure was 50 mm Hg with
supraventricular tachycardia in a
rate of 130 to 150/min. Cardiopulmonary resuscitation was begun.
The patient improved steadily,
and in 72 hours the resuscitation
was stopped. At that time he was
awake although disoriented to
place and time. He also complained of blindness. lnitially, the
complaint was attributed to the patient's dementia; therefore, complete assessment was delayed for
severa! days.
Over the next few days, the patient began to deny his blindness,
although examination revealed

150

on! y gross perception of light and
complete inability to identify objects or colors. A neurologie consultant found normal optic fundi
and cranial nerves, bilateral carotid bruits on auscultation, and no
nystagmus in response to optokinetic stimulation with a rotating
drum. He also found the patient to
be disoriented to place and time
and noted occasional visual hallucinations.
In other respects, the patient improved, and he was discharged on a
regimen for treatment of congestive heart disease. Within a month
he was readmitted for exacerbation
of congestive heart failure. No
change in blindness was noted at
that time, and although he was oriented and cooperative, visual field
examination was not requested.
CASE 2-A 41-year-old man was
admitted to Bronson Methodist
Hospital, Kalamazoo, Michigan, in
July 1976 for essential hyperten-

sion. He bad adult-onset type 1
(insulin-dependent) diabetes meiJitus and was taking 40 units of
isophane (NPH) insulin daily. He
bad bad a myocardial infarction
two years before this admission
and a right hemispheric cerebrovascular accident one year before.
Blood pressure with the patient
seated was 180/120 mm Hg, carotid pulses were full and without
bruits, and heart rate was regular
with an atrial gallop. Neurologie
examination showed increased
deep tendon reflexes on the left
side and slight ataxia. Methyldopa,
propranolol, and furosemide were
administered.
On the third day, the patient became agitated and complained of
being unable to see. Examination
at that time showed reactive pupils,
normal fundi, blood pressure of
140/100 mm Hg, and blood glucose leve! of 105 mg/dl. The cornplaint of blindness was not believed
initially, and chlorpromazine was
administered to control agitation.
By the fourth day, the patient
was disoriented and more agitated.
Left-sided hemiparesis developed;
blood pressure was llO/ 60 mm
Hg. The patient stated that he
could see, although when examined
he was unable to identify objects or
visually follow their movement.
The neurologie consultant
agreed that cortical blindness, as
manifested by intact pupillary
reflexes and absence of response to
optokinetic stimulation, may have

CORTICAL IILINDNE88 • VOL 67/NO 4/ APRIL 1980/POSTGRADUATE UEOICINI'

Other than complaints of
blindness, the most
common symptom of cortical blindness is deniai
of blindness, known as
Anton's syndrome.

occurred. A radioisotope brain
scan showed decreased uptake in
the left parietal lobe and several
small foci of decreased uptake in
the right posterior parietal lobe.
After prolonged hospitalization
for intensive physical therapy, the
patient recovered only minimal use
of his left leg and no apparent use
of his left arm, although evaluation
was complicated by his deniai of
that arm. The patient continued to
deny his blindness but was unable
to consistently identify colors or
figures. Visual field examination
was not done during his hospitalization.
During more than one year of
follow-up, no significant change in
the patient's blindness was noted.
CASE ~A 65-year-old man was
brought to the emergency department at Borgess Hospital in September 1977 with a complaint of
rapid onset of dyspnea white resting. Two days previously, digoxin
therapy had been started for probable aortic stenosis with dyspnea
on exertion. At that time, the patient also had had symptoms consistent with angina pectoris, and an
ECG had shown left bundlebranch block.
Shortly after arrivai, the patient
had respiratory arrest, and intubation and resuscitation were begun.
When his condition stabilized, he
was transferred to the intensive
care unit. White being examined
there, he opened his eyes in response to noises or voices but would

not follow commands. Within three
hours irregular, unstereotyped,
jerking movements of the extremities developed. The neurologie consultant, who felt these signs were
consistent with myoclonic-type seizures, advised against immediate
treatment because the movements
were infrequent. Cranial nerves
were thought to be intact, and no
focal abnormalities were identified.
The next day, the patient appeared more alert. He followed
simple commands but with a tendency toward perseveration. He also
began talking at intervals and, during one of these periods, complained of blindness.
On examination, the pupils reacted to light, but there was no
blinking response to threatening
gestures. Optokinetic stimulation
also produced no response.
The following day, he no longer
complained of blindness and, at
one time, seemed successful in
identifying objects. However, later
the same day, an EEG showed
diffuse slowing, particularly in the
occipital regions. Photic stimulation produced no response on the
EEG.
Five days after admission, the
patient still did not respond to
optokinetic stimulation, and the
EEG, which showed sorne increase
in background slow-wave activity,
still indicated no significant change
with photic stimulation.
The ophthalmologic consultant
found a cholesterol embolus in the

VOL 67/NO 4/ APRIL 1980/POSTGRADUATE UEOICINI' o CORTICAL IILINDNE88

right temporal field but believed
that the fundi were otherwise normal. Visual field examination was
not performed because the patient
was unable to cooperate.
Eight days after the patient's admission, gastrointestinal bleeding
developed, followed by renal faiture. Peritoneal dialysis was unsuccessful, and the patient died six
days later.
Autopsy showed aortic stenosis
with marked left ventricular hypertrophy, acute bronchopneumonia,
and acute ischemie colitis. Grossly,
the brain was normal, but microscopie study revealed focal laminar
vacuolization and neuronal degeneration throughout the cortex,
including sections taken from calcarine sulci.
Clinical presentation
Cortical blindness should be suspected when a patient with normal
pupillary reflexes complains of
blindness even though the results
of an ophthalmoscopic examination
are normal. Too often the cornplaint of blindness is attributed to
dementia or hysteria, which can
delay diagnosis, as in cases 1 and 2.
Cortical blindness is far more
difficult to diagnose in patients
who cannot easity communicate
their loss of sight, such as the very
young, the very debilitated, and
those on respirators. In addition,
diagnosis is difficult in patients
with Anton's syndrome-a form of
anosognosia. In these types of pacontinued
151

Besides the ophthalmoscopic examination, other
essential diagnostic tests include bedside
examinations, such as optokinetic stimulation,
EEG with photic stimulation, and visual field
assessment.

Table 1. Characterietiçs of cortical
blindneee
Claseictriad
Blindness. evidenced by
Failure to react to threatening
gestures
No response to optokinetic
stimulation
Consistent EEG findings
Intact pupillary reflexes
Normal fundi

Additional findinge
Unformed visual hallucinations
Deniai of blindness (Anton's
syndrome)

tients, close and consistent clinicat
observation will detect decreased
visual attentiveness and sightless
behavior.
In about 50% of patients whose
blindness is caused by emboli or
other occlusive vascular events, history of significant prodromes is evident. The most frequent complaint
is transient visual impairment; Jess
often the complaint is vertigo, and
!east often brief Joss of consciousness suggesting vertebrobasilar
insufficiency. 4 In addition, white
Joss of vision is usually acute, it
may also occur progressively over
severa! da ys in a minority of patients.4
Of the clinicat symptoms associated with cortical blindness, none
is constant or pathognomonic. One
of the most common is Anton's
syndrome. This syndrome, which in
the past was considered to occur
only with cortical blindness, bas
also occurred with blindness
caused by damage to the retina or

152

optic nerve.9 As indicated in cases
l and 2, in which deniai of blindness occurred only after an initial
complaint of blindness, Anton's
syndrome may, at times, arise from
the patient's confusion at the hospital staffs failure to confirm his or ,
ber initial complaint.
Spatial disorientation, Joss of visuai imagery, Joss of color vision,
and visual agnosia also have been
associated with cortical blindness,
although they were not common
occurrences in the Symonds and
Mackenzie study, 4and their incidence in cases occurring after cardiorespiratory arrest bas not been
reported. In addition, these phenomena were absent in two of the
three cases cited here.
Finally, visual hallucinations
may accompany cortical blindness.
As cases l and 2 demonstrate, it
may be difficult to distinguish
these hallucinations from those of
preexistent or concurrent dementia. In case l the patient bad probable preexistent dementia, which
could have been exacerbated by his
hospitalization and Joss of sight,
causing more obvious confusion
and hallucination. In case 2 onset
of visual hallucinations and cortical
blindness occurred simultaneously
with onset of abnormal behavior.
Physical examination
Specifie bedside examinations are
necessary to confirm cortical blindness in patients with normal pupillary responses to light and normal

ophthalmoscopic findings (ie, no
sign of optic atrophy, generalized
retinal degeneration, or papilledema). Table l lists classic characteristics of the disorder. One of the
most common is the absence of
blinking as a reflex to threatening
gestures made by the examiner.
Also common is the absence of
blinking when a bright light is
shone on the face of a patient who
bas been in semidarkness. The latter response may occasionally be
normal in the absence of significant retained cortical vision, but
also may be the first response to
return during recovery.
Optokinetic stimulation tests for
nystagmus should be given to conscious patients. These tests involve
use of a revolving drum with
alternating dark and light vertical
stripes or pulling a long piece of
material with alternating designs
across the patient's visual field. In
patients with normal pupillary
reflexes, cortical blindness is confirmed if one of these maneuvers
does not produce nystagmus. The
hysterical patient cannot voluntarily suppress nystagmus, white the
patient whose blindness is caused
by other factors will not have normal pupillary reflexes.
EEG with photic stimulation bas
been proposed as a diagnostic and
prognostic test for cortical blindness.2·10 Responses consistent with
cortical blindness are failure to
suppress background activity with
photic stimulation and the absence
continued

CORTICAL IILINDNE88 o VOL 67/NO 4/ APRIL 1980/POSTGRADUATE UEOICINI'

After cardiorespiratory
arrest, the most common
visual field defect is
loss of central vision
with varying degree of
peripheral sparing.

of short-latency visually evoked response waves.z.a.:; However, studies
have not shown any consistent ability for this procedure to predict recovery of sight. 3
ln the cooperative patient, assessment of visual fields may be
one of the most useful methods for
follow-up of cortical blindness. Patterns of visual field Joss may also
delineate the pathogenesis.
ln their study, Symonds and
Mackenzie• found that the most
common visual field pattern (in 27
of 58 cases) was recovery of central vision with continued absence
of any peripheral vision. Only four
patients demonstrated Joss of central vision with partial or complete
spa ring of peripheral vision. The
others either remained totally blind
( 14) or regained varying amounts
of central and peripheral vision
(13). The authors noted that the
area of central vision in the striate
cortex is closest to the occipital
poles. They proposed that since the
occipital poles receive a rich collateral supply from the "watershed"
of the middle and posterior cerebral arteries, they most likely
would be spared from specifie occlusive events occurring within the
occipital regions.
It is important to note that none
of the cases discussed by Symonds
and Mackenzie included histories
of cardiac or respira tory arrest
with subsequent resuscitation.
Other studies have shown that the
cerebrovascular "watershed" areas

Figure 1. "Watershed" area of middle and posterior cerebral arteries shown in view of optic
pathways exposed from below.

are usually the first to be affected
by generalized hypoxia because
they are the farthest from the origins of cerebral circulation 11
(figure 1). The conclusion seems
obvious: ln cortical blindness occurring after cardiorespiratory arrest, the most common visual field
defect is Joss of central vision with
varying degrees of peripheral spar-

VOL 67/NO 4/ APRIL 1980/POSTGRADUATE MEDICINE • CORTICAL IILINDNE88

ing, rather than the preservation of
central vision seen with focal occlusive events in the posterior or middle cerebral arteries.
Unfortunately, there are not an
adequate number of case reviews
in recent literature to document
this hypothesis. Hoyt and Walsh6
reported a case of cardiac arrest in
which visual field testing showed
continued
155

The majority of patients with cortical blindness have
at least soma recovery of sight, but the extent
of recovery appears to be determined by the cause
of the disorder. The amount of ti me for recovery
has not been determined.

loss of central vision with return of
sorne peripheral vision. Sabah8 reported complete recovery of visual
fields in two patients; however, the
visual fields were not tested immediately after cardiac arrest. Other
reports of occipital blindness after
cardiac arrest do not mention visuai field findings. 7 ln the cases 1
have reported here, visual field
testing was not performed in cases
1 and 2 because its potential usefulness was not appreciated at the
time; in case 3 the patient was not
cooperative enough to be tested.
Furthermore, when possible, visuai field testing should be an integral part of evaluation because it
assesses the patient's functional
visual status and allows rehabilitation to be tailored to individual
abilities. lt is important to remember that the patient who retains
central vision may have nearly normal visual acuity, but will behave
as though blind because of the severe restriction of peripheral visual
fields. Such a patient may act totally blind and be treated as such,
yet potential for rehabilitation is
far grea ter than that of the patient
with no sight preserved.
Prognosis
Prognosis for patients with cortical
blindness is hopeful. Two thirds or
more of those affected will have at
least sorne recovery of sight, although this may not be appreciated
without follow-up visual field examination. Only 14 of Symonds

156

and Mackenzie's4 58 cases resulted in permanent blindness. Of
Duchowny and associates'3 six pediatrie patients, only one remained
completely blind, while three recovered completely. Abraham and
associates 10 reported that of three
adult patients with cortical blindness, one remained completely
blind, one recovered completely,
and one recovered partially. Of
Bergman's5 seven patients who survived acute episodes, two had complete return of vision and three had
partial recovery.
To what extent the recovery of
sight is determined by the cause of
the disorder and the amount of
time required for recovery, whether complete or partial, have not
been delineated. Until more specifie information becomes available, it seems best to give each patient an optimistic forecast.
Summary
Once thought to be rare, cortical
blindness today appears to occur
more frequently. (fhree cases described here occurred within a twoyear period.) ln addition, the disorder may have undergone a shift in
etiology since the development of
effective means of cardiopulmonary
resuscitation within the past two
decades. Severe hypoxic or hypotensive episodes occurring during
cardiorespiratory arrest may have
become a more common cause of
cortical blindness in adults than

cerebrovascular accidents. Prognosis for recovery of at )east partial
sight is good, although proper visual
testing is required to determine the
extent of improvement.~
Address reprint requests to Walter G.
Drymalski, MD, Department of Internai
Medicine, Wayne County General Hospital,
Eloise, Ml 48185.

Referenc:es
1. Griffith JH, Dodge PR. Transient blindness following head injury in children.
N Engl J Med 1961;278:648-51
2. Ramet AB, MIUBOII JI, Wllmer E. Acute
cerebral blindness in children: six cases
studied clinically and electrophysiologically.
Neurology 1970;20:1147-56
3. Ducbowny MS, Weiss IP, Majlessi H, et
aL Visual evoked responses in childhood
cortical blindness after head trauma and
meningitis: a longitudinal study of six cases.
Neurology 1974;24:933-40
4. Symonds C, Mackenzie 1. Bilateral Joss of
vision from cerebral infarction. Brain 1957;
80:415-54
5. Bergman PS. Cerebral blindness. Arch
Neurol 1957;78:568-84
6. Hoyt WF, Walsh FB. Cortical blindness
with partial recovery following acute cerebral anoxia from cardiac arrest. Arch
Ophthalmol 1958;60: 1061-9
7. Weinberger HA, fanderWoude R, Maier
HC. Prognosis of cortical blindness following cardiac arrest in children. JAMA
1962; 179: 126-9
8. Sabah AH. Blindness after cardiac arrest. Postgrad Med J 1968;44:513-6
9. Redlich FC, Dorsey JF. Deniai of blindness by patients with cerebral disease. Arch
Neurol 1945;53:407-17
10. Abraham FA, Melamed E, Lery S. Prognostic value of visual evoked potentials in
occipital blindness following basilar artery
occlusion. Appl Neurophysiol 1975;38:
126-35
Il. Brierly JB. Cerebral hypoxia. ln: Blackwood W, Corsellis JA, cds. Greenfield's
neuropathology. 3rd cd. London: E Arnold,
1976:56-79

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