Vol.2, No.5, 332-334 (2013) Case Reports in Clinical Medicine
http://dx.doi.org/10.4236/crcm.2013.25089
Posterior reversible encephalopathy syndrome
induced after blood transfusion for severe anemia
Kei-ichiro Wada1, Masayoshi Kano1, Yutaka Machida1, Nobutaka Hattori2, Hideto Miwa1*
1Department of Neurology, Juntendo University Nerima Hospital, Tokyo, Japan;
*Corresponding Author:
2Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
Received 6 June 2013; revised 30 June 2013; accepted 10 July 2013
Copyright © 2013 Kei-ichiro Wada et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Posterior reversible encephalopathy syndrome
(PRES) is a clinicoradiological syndrome char-
acterized by headache, confusion, seizures, and
cortical visual loss, as well as subcortical ede-
ma without infarction on neuroimaging. We re-
port a 56-year-old woman who developed typi-
cal manifestations of PRES, 6 days after blood
transfusi on for severe anemia. Acu te volume over-
loads by transfusion may exceed the capacity of
autoregulation of perfusion pressure, possibly
resulting in vasogenic edema. We propose that
it is clinically important to recognize that rapid
correction of anemia by blood transfusion may
carry the risk of inducing PRES.
Keyw ords: Posterior Reversibl e Enceph alopathy
Syndrome; Anemia; Blood Transfusion
1. INTRODUCTION
Posterior reversible encephalopathy syndrome (PRES),
or reversible posterior leukoencephalopathy syndrome, is
a clinicoradiological syndrome characterized by head-
ache, confusion, seizures, and cortical visual loss, as well
as subcortical edema without infarction on neuroimaging
[1-3]. It was first described by Hinchey et al. [1] in 1995
based on 15 patients who had subcortical edema without
cerebral infarction. To date, a wide variety of clinical con-
ditions have been reported to cause PRES, such as hy-
pertension, exposure to toxic agents, infection, eclampsia,
autoimmune disease, and other conditions [1-3]. Recently,
we encountered a patient with PRES that was induced
after blood transfusion for severe anemia.
2. CASE REPORT
A 56-year-old Japanese woman was admitted to the
gynecology section in our hospital because of genital
bleeding and abdominal pain. Her past medical and fam-
ily histories were unremarkable, and in particular, she
had no past history of hypertension. After admission, she
was diagnosed with cancer of the corpus uteri. She had
severe anemia with a hemoglobin level of 2 g/dL, and
received blood transfusion with a total of 2 L packed red
blood cells. After transfusion, her hemoglobin level re-
covered to 9.2 g/dL for 4 days. Six days after the last
blood transfusion, she suddenly developed status epilep-
ticus, and was referred to our neurological section.
She was immediately treated with general anesthesia
by intravenous administration of midazolam with pheny-
toin. Two days later, she recovered from anesthesia, but a
drowsy state continued for a few days. On neurological
examination, her pupils were equal, and promptly reac-
tive to light. She could open her eyes if verbal stimuli
were given, but she could not recognize any objects. She
could not maintain her gaze on any objects, and just
stared into space, suggesting that she had cortical blind-
ness. Oculocephalic reflexes, towards either horizontal or
vertical directions, were not disturbed. She was mute. No
obvious motor paresis was noted in both upper and lower
extremities. Deep tendon reflexes were all normal in both
limbs. There were no signs of meningeal irritation. La-
boratory examination revealed mild anemia (9.2 g/dL),
leukocytosis (36,500/L) and elevated C-reactive protein
(4.5 mg/dL). Other routine blood tests, blood coagulation
tests, autoantibodies, and neoplastic markers were within
normal limits. Cerebrospinal fluid examination revealed
a mild increase in protein level (52 mg/dL). Brain mag-
netic resonance imaging (MRI), which included T1-, T2-
and diffusion-weighted images, fluid-attenuated inver-
sion recovery (FLAIR) images, and apparent diffusion
coefficient mapping, were performed. The FLAIR im-
ages demonstrated high-intensity signal areas in bilateral
parietal lobes (Figure 1). Within 10 days, her conscious-

K. Wada et al. / Case Reports in Clinical Medicine 2 (2013) 332-334 333
Figure 1. FLAIR imaging (a), (b) and diffusion-weighted MRI
(c), (d). FLAIR images demonstrate high-intensity signal areas
in bilateral parietal lobes.
ness disturbance fully recovered, as did her visual func-
tions. Abnormal MRI findings also disappeared simulta-
neously. During the course of illness, her blood pressure
generally had been stable within normal ranges (<130
mmHg) except that acute elevation of blood pressure was
transiently noted at the onset of status epileptics, while the
maximum systolic/diastolic blood pressure was 180/70
mmHg.
3. DISCUSSION
The present patient exhibited conscious impairment,
status epilepticus, and cortical blindness. Brain MRI de-
monstrated white matter lesions in bilateral parietal re-
gions that could be clearly differentiated from ischemic
lesions. Both clinical and neuroimaging findings were
transient and fully disappeared. Although there are no
established consensual criteria for diagnosis of PRES,
based on clinical characteristics, we consider that the pre-
sent patient did have PRES. The pathophysiology of
PRES is thought to result from abnormalities in the trans-
membrane flow of intravascular fluid and proteins caused
by two phenomena: one is a cerebral autoregulatory fail-
ure, and the other is the loss of integrity of the blood-
brain barrier [2,3]. One important issue is the cause of
PRES in the present patient.
Many conditions are known to be potentially associ-
ated with PRES [2,3]. No medical treatments were given
to her prior to the onset of PRES, except blood transfu-
sion; therefore, it is possible to speculate that blood trans-
fusion and/or rapid correction of severe anemia possibly
contributed to inducing PRES in the present case. The
literature describes seven adult patients with PRES pos-
sibly associated with blood transfusion for anemia (Table
1) [4-9]. It is of particular interest that all the previously
reported patients were female. Mean age at onset was
49.8 ± 13.3 years (mean ± SD). The mean hemoglobin
level before and after blood transfusion was 5.0 ± 2.9 and
11.0 ± 1.7 g/dL, respectively. The mean time interval
between blood transfusion and onset of PRES was 7.3 ±
4.7 days. These clinical data were likely similar to those
of the present patient, supporting the speculation that
rapid correction of anemia by blood transfusion may po-
tentially induce PRES, particularly in women. We think
that such speculation is not unreasonable.
Although the exact pathophysiological mechanisms
underlying PRES remain undetermined, it has been sug-
gested that breakdown of cerebral autoregulation respon-
Table 1. Previously reported cases of PRES associated with blood transfusion.
Patient Age/sex Hb (g/dL) (pre/post)* Intervals** HT*** Causes of anemia Sequelae References
1 45/F 2.0/10.0 2 days + Myoma uteri None [4]
2 48/F 3.0/8.0 6 days + Myuoma uteri None [5]
3 47/F 1.5/10.9 7 days − Aplastic anemia Visual defect [6]
Numbness of extremity
4 58/F 7.7/10.9 8 days + Cancer surgery None [7]
5 77/F 9.2/13.3 17 days + Cancer surgery None [7]
6 32/F 5.7/12.5 5 days − Myoma uteri None [8]
7 42/F 5.7/11.7 6 days − Chronic renal failure None [9]
Alcoholic liver cirrhosis
*Hemoglobin (Hb) levels before and after blood transfusion; **Intervals between blood transfusion and onset of PRES.

K. Wada et al. / Case Reports in Clinical Medicine 2 (2013) 332-334
334
sible for an increase in cerebral blood flow may play a
pivotal role [2,3]. Blood transfusion may result in a rapid
increase in total blood volume, leading to rapid overload
of cerebral blood flow. Cerebral hyperperfusion, if it is
acutely induced and exceeds the capacity for autoregula-
tion of perfusion pressure in cerebral capillaries, could
result in the huge vasogenic edema responsible for PRES.
In addition, the possibility should not be excluded that
severe anemia per se also might be the predisposing fac-
tor contributing to the induction of PRES, because in-
sufficient oxygen supply due to severe anemia might
exert an unfavorable influence on endothelial cell func-
tions, possibly causing a breakdown of the integrity of
the bloodbrain barrier in capillary circulation.
Another issue is whether a rapid increase in blood
pressure, which is frequently associated with PRES [1-3,
10], simultaneously contributed to inducing PRES in the
present study. In this regard, we think that hypertension
might not have played a prominent role in the mecha-
nism underlying PRES in the present case. During the
course of illness, hypertension was only transiently ob-
served, and an extreme increase in blood pressure (>180
mmHg) was not noted. Second, three of the seven previ-
ously reported patients (Table 1) had no hypertension,
suggesting that an acute increase in blood volume, but
not acute hypertension, may play a predominant role in
inducing PRES, if it occurs after blood transfusion for
correction of anemia.
Finally, we propose that it is clinically important to
recognize that rapid correction of anemia by blood trans-
fusion may carry a risk of inducing PRES.
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