(2021) 21:430
Li et al. BMC Neurol
https://doi.org/10.1186/s12883-021-02457-5

Open Access

CASE REPORT

Contrast-induced encephalopathy
mimicking stroke after a second cerebral DSA:
an unusual case report
Jiaying Li1,2†, Guanshu Qi1,3†, Huani Zhang1,2, Gang Chen1,2, Shuting Wang1,2, Minli Yan1,3 and Zhichao Sun1,2*

Abstract
Background: Contrast-induced encephalopathy (CIE) is a rare complication of the angiography process. CIE may
mimic stroke symptoms clinically and subarachnoid hemorrhage radiologically. Previous CIE cases occurred after the
initial digital subtraction angiography (DSA) scan. Here, we encountered an unusual case of CIE mimicking a stroke
with an internal carotid artery (ICA) aneurysm and ipsilateral ICA stenosis that occurred after a second DSA procedure.
Case presentation: A 77-year-old female with a history of hypertension and coronary heart disease underwent two
cerebral DSA procedures over 1 week. She was given the same nonionic and iso-osmolar Visipaque agent (smaller
than 200 ml) for both procedures. However, neurological complications only occurred after the second DSA procedure. On the first diagnostic cerebral DSA, she was diagnosed with an intracranial aneurysm of the left ICA with
moderate stenosis (approximately 50%) in the initial part of the ipsilateral ICA. However, after the second aneurysm
embolization procedure by DSA, she developed right hemiplegia, aphasia, and epilepsy, mimicking left middle
cerebral artery occlusion. An emergency CT showed a diffuse hyperdensity in the left subarachnoid space, mimicking SAH. MRI demonstrated that the lesion was hyperintense on T2WI, FLAIR imaging, and DWI but was normal on
ADC mapping. On postoperative Day 6, her neurologic deficits had completely resolved after initial fluid restriction,
corticosteroid treatment, and rehydration.
Conclusion: This case indicates that clinicians should consider the occurrence of CIE following any angiography
procedure, even if the initial cerebral DSA procedure is successful and without complications.
Keywords: Cerebral angiography, Contrast media, Encephalopathy, Stroke
Background
Contrast-induced encephalopathy (CIE) is a rare neurological complication of diagnostic and therapeutic cerebral angiography. The incidence of CIE patients is 0.06%
for those undergoing CAG, 0.3–1% for those undergoing vertebral angioplasty, and 2.9% for those undergoing
*Correspondence: sunzhichao@zcmu.edu.cn
†
Jiaying Li and Guanshu Qi contributed equally to this work.
2
Department of Radiology, The First Affiliated Hospital of Zhejiang
Chinese Medical University (Zhejiang Provincial Hospital of Traditional
Chinese Medicine), Hangzhou, 310006, China
Full list of author information is available at the end of the article

endovascular coil treatment of posterior circulation
aneurysm [1–4]. CIE may mimic a stroke clinically and
subarachnoid hemorrhage (SAH) radiologically, creating a diagnostic dilemma. Previous CIE case reports
occurred after the initial cerebral digital subtraction angiography (DSA) within 12 h of the procedure [5]. Most
patients recover completely within 48–72 h without any
neurological impairment, but there are rare cases of irreversible or even fatal CIE [4–6]. Here, we encountered an
unusual and unreported CIE case with internal carotid
artery (ICA) aneurysm and ipsilateral ICA stenosis that
occurred after the second cerebral DSA procedure using

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a nonionic and iso-osmolar contrast agent, not the first
DSA.

Case presentation
A 77-year-old female presented with slurred speech,
facial weakness, and left limb numbness and was admitted into our hospital. The patient had a history of hypertension and coronary heart disease, without diabetes or
smoking. The patient’s hepatic function, renal function,
coagulable state, and other laboratory tests were normal.
Brain MRI without contrast revealed a subacute cerebral
infarction near the right side of the lateral ventricle. The
patient was given supportive treatment and improved.
Nonetheless, an intracranial aneurysm of the left ICA
was incidentally found on cranial MR angiography
(MRA). Afterward, this patient underwent a diagnostic
cerebral angiography and an additional therapeutic cerebral angiography.
After the second therapeutic angiography, the patient
presented with right hemiplegia and aphasia when she
was resuscitated from anesthesia. Neurological examination revealed mixed aphasia, left eye gaze, reduced pupillary light reflex, loss of right muscle strength (level 0/5), a
positive right Babinski sign, and lack of response to painful stimuli. At first, we suspected stroke due to the clinical findings which mimicked a left middle cerebral artery
(MCA) occlusion. According to the TOAST criteria, the
“stroke” symptom could be classified as large artery atherosclerosis [7]. However, the patient’s clinical findings
did not match the imaging results which showed a patent left MCA. Therefore, CIE was suggested. The patient
was given 200 mg methylprednisolone QD IV, 124 mL of
20% mannitol Q8H and rehydration fluids after emergent
CTA and MRI examinations. 54 h later, the patient suddenly developed a generalized tonic-clonic seizure lasting

Page 2 of 5

about half a minute. She achieved remission after symptomatic treatment. 72 h later, the patient’s right hemiplegia and aphasia began to improve, as the muscle strength
of the right lower limb increased to 3/5 and the right
upper muscle strength remained at 0–1/5. Finally, after
fluid restriction dehydration, short-term corticosteroid
treatment, and rehydration resuscitation, all neurologic
deficits achieved complete remission on a postoperative
Day 6.
The first diagnostic cerebral DSA procedure was conducted to further confirm the existence of the left intracranial ICA saccular aneurysm with a size of 6.9 × 6.0 mm,
with a total of 150 mL nonionic, iso-osmolar Iodixanol
(Visipaque, 320 mg I/ml, Bayer Healthcare, USA) IV. It
also showed extracranial moderate stenosis (approximately 50%) in the initial segment of the left ICA. The
internal carotid artery and vertebral artery angiography showed the anterior, middle, and posterior cerebral
arteries. One week later, the patient underwent a second angiographic treatment for aneurysm embolization
under general anesthesia. On this second procedure, the
6F intracranial support catheter (Navien, RFX072–10508MP, EV3, America) was guided over the stenotic left
ICA to the extracranial distal segment of ICA (the level
of first cervical vertebra) without local artery vasospasm,
stenosis, or the stasis of the contrast agent. A total of
160 mL Iodixanol was injected during the second therapeutic DSA.
After the second interventional DSA procedure, an
emergent head CT angiography (CTA) scan showed the
left cerebral hemisphere swelling, shallowing of the sulci,
and diffuse high-density in the subarachnoid space without any cerebral artery occlusion or stenosis (Fig. 1). 4 h
later, brain MRI showed diffuse swelling in the left cortex
with a normal signal on T2-weighted imaging (T2WI),

Fig. 1 Emergent brain CT angiography (CTA). Axial brain CTA showing the left cerebral hemisphere swelling and diffuse high-density in the
subarachnoid space

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fluid-attenuated inversion recovery (FLAIR), and mild
hyperintense on diffusion-weighted imaging (DWI)
(Fig. 2). 20 h later, repeat brain CT showed the resolution
of left cerebral hemisphere swelling and diffuse high-density (Fig. 3). However, 28 h later, repeat non-contrasted
brain MRI showed mild gyral hyperintense in the left
hemisphere on T2WI, FLAIR imaging, and DWI with a

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normal ADC mapping (Fig. 4). There were no indications
of acute cerebral infarction.

Discussion and conclusions
Contrast-induced encephalopathy (CIE) is a rare and selflimited complication associated with angiography procedures. The neurologic manifestations of CIE can mimic

Fig. 2 Brain MRI after 4 hours. Brain MRI showed normal signal on axial T2WI (A) and sagittal FLAIR (B), but mild gyral hyperintense on axial DWI (C)
in the left brain (dotted square); subacute cerebral infarction near the right lateral ventricle (white arrow with tail)

Fig. 3 Repeat brain CT after twenty hours. Axial brain CT showed the resolution of left cerebral hemisphere swelling and diffuse high-density

Fig. 4 Repeat brain MRI after twenty-eight hours. Repeat brain MRI showed mild gyral hyperintense on axial T2WI (A), FLAIR (B), and DWI (C) in the
left brain (dotted square); subacute cerebral infarction near the right lateral ventricle (white arrow with tail)

Li et al. BMC Neurol

(2021) 21:430

stroke, as shown in this case. This patient presented with
right hemiplegia, aphasia, and seizure after a cerebral
interventional procedure. The clinical syndrome mimicked a left MCA occlusion, according to the TOAST
criteria, which could be classified as large-artery atherosclerosis. However, the patient’s clinical findings did not
match the imaging results. CIE was suggested as the main
cause of this presentation. The patient required 6 days to
recover from the neurological deficits with fluid restriction to reduce intracranial pressure, short-term corticosteroid treatment, and subsequent fluid resuscitation.
At the present, the mechanism of CIE is not clear. The
widely accepted mechanism suggests that the contrast
media disrupts the blood-brain barrier (BBB) and penetrates the interstitial space, leading to direct neuronal
toxicity and brain edema [8, 9]. In this case, age, chronic
hypertension, and coronary heart disease may be the risk
factors that lead to BBB and cerebral automatic regulation impairments. In theory, a higher-osmotic and ionic
contrast concentration may induce the contraction of
endothelial cells and lead to greater permeability. Previous cases reported that all types of contrast agents
regardless of their permeability or ionic states can induce
CIE [10, 11], even if the iso-osmotic contrast agent was
used such as in this case.
The first diagnostic cerebral DSA confirmed the presence of the left ICA intracranial saccular aneurysm and
extracranial moderate stenosis. It was suggested that
resolving the ipsilateral ICA stenosis first may lead to
aneurysm rupture due to the sudden increase in cerebral
blood flow [12]. The patient also showed no symptoms of
left ICA stenosis. Thus, 1 week later, she underwent the
second therapeutic DSA procedure after which the neurological complications occurred. She was given the same
iso-osmolar contrast agent and a large volume of contrast
(smaller than recommended for the prevention of toxicity
200 mL) [3]. Yet CIE occurred following the second DSA.
This finding is likely the result of the contrast agent distributing into the ipsilateral cerebral hemisphere during
subsequent treatment. Although the unresolved moderate stenosis of ipsilateral ICA may be related to CIE, the
abnormal imaging manifestations occurred on the left
hemisphere, including the occipital lobe supplied by the
left posterior cerebral artery. This contradicted imaging
findings which suggested a patent PCA.
It is important to combine clinical symptoms with
imaging manifestations to diagnose CIE. The imaging
manifestation of extravasation of contrast media can
mimic SAH on CT imaging, including the brain edema,
hyperdensity of the subarachnoid space, cortical and
subcortical local enhancement [1–11]. CIE should be
differentiated from acute cerebral infarction. DWI and

Page 4 of 5

ADC sequences can quantify water diffusion to make a
distinction between CIE and acute cerebral infarction.
Acute cerebral infarction is described as diffusion-limited due to cytotoxic edema, which behaves as hyperintense on DWI and hypointense on ADC. In contrast,
CIE can usually exhibit gyral hyperintense on FLAIR
and T2WI, with or without high signal on DWI, but
ADC mapping is normal.
CIE may overlap with atypical posterior reversible
encephalopathy syndrome (PRES) between clinical and
neuroradiological features. But the brain imaging of
PRES reveals symmetric abnormalities predominantly
involving the parieto-occipital regions of both cerebral
hemispheres, which presents as hyperintense on T2WI
and FLAIR imaging due to vasogenic edema [13, 14]. In
this case, imaging showed abnormal signals in a unilateral brain hemisphere including frontal, temporal, parietal and occipital lobes. DSA and postoperative CTA
showed no cerebral vascular vasospasm and stenosis.
Thus, the clinical and radiological findings were consistent with CIE in our case.
In conclusion, although the first cerebral DSA procedure was successful and without complications, clinicians should still consider the occurrence of CIE
following any angiography procedure. In patients with
risk factors and internal carotid artery stenosis, even
more attention should be given to the diagnosis of
CIE. In the future, additional studies will be needed to
explore whether internal carotid artery stenosis, the
number of cerebral angiographies, and the interval time
of angiography are risk factors for CIE.
Abbreviations
ADC: Apparent diffusion coefficient; BBB: Blood-brain barrier; CIE: Contrastinduced encephalopathy; CTA​: Computer tomography angiography; DSA:
Digital subtraction angiography; DWI: Diffusion-weighted imaging; ICA:
Internal carotid artery; MCA: Middle cerebral artery; MRI: Magnetic resonance
imaging; PRES: posterior reversible encephalopathy syndrome; SAH: Subarachnoid hemorrhage.
Acknowledgements
Not applicable.
Authors’ contributions
JY L: manuscript conception, manuscript design, writing and editing. GS Q:
manuscript design, critical review of the article and clinical care of the patient.
HN Z: manuscript design, acquisition of data. G C and ST W: interventional surgery for the patient and clinical care of the patient. ML Y: analysis of data and
clinical care of the patient. ZC S: manuscript conception, design, critical review
of the manuscript and interventional surgery for the patient. All authors read
and approved the final manuscript.
Funding
This work was supported by the Natural Science Foundation of Zhejiang Province (LGD19C040002), and the Zhejiang Traditional Chinese Medicine Administration (2020ZB091). The funder is the corresponding author in our study.
Availability of data and materials
Not applicable.

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Declarations

5.

Ethics approval and consent to participate
The ethics committee of the First Affiliated Hospital of Zhejiang Chinese Medical University has approved this study (NO. 2020-KL-033-01).

6.

Consent for publication
Written informed consent was obtained from the patient for publication of
this case report and any accompanying images. A copy of the written consent
is available for review by the Editor of this journal.

7.

Competing interests
The authors declare that they have no competing interests.

8.

Author details
1
The First Clinical Medical College of Zhejiang Chinese Medical University,
Hangzhou 310053, China. 2 Department of Radiology, The First Affiliated
Hospital of Zhejiang Chinese Medical University (Zhejiang Provincial Hospital
of Traditional Chinese Medicine), Hangzhou, 310006, China. 3 Department
of Neurology, The First Affiliated Hospital of Zhejiang Chinese Medical
University (Zhejiang Provincial Hospital of Traditional Chinese Medicine),
Hangzhou 310006, China.

9.

10.
11.

Received: 28 March 2021 Accepted: 20 October 2021
12.

References
1. Niimi Y, Kupersmith MJ, Ahmad S, Song J, Berenstein A. Cortical blindness,
transient and otherwise, associated with detachable coil embolization of
intracranial aneurysms. AJNR Am J Neuroradiol. 2008;29(3):603–7. https://​
doi.​org/​10.​3174/​ajnr.​A0858.
2. Potsi S, Chourmouzi D, Moumtzouoglou A, Nikiforaki A, Gkouvas K,
Drevelegas A. Transient contrast encephalopathy after carotid angiography mimicking diffuse subarachnoid haemorrhage. Neurol Sci.
2012;33(2):445–8. https://​doi.​org/​10.​1007/​s10072-​011-​0765-3.
3. Harada Y, Kairamkonda SR, Ilyas U, Pothineni NVK, Samant RS, Shah VA,
et al. Pearls & Oy-sters: contrast-induced encephalopathy following coronary angiography: a rare stroke mimic. Neurology. 2020;94(23):e2491–4.
https://​doi.​org/​10.​1212/​WNL.​00000​00000​009590.
4. Leong S, Fanning NF. Persistent neurological deficit from iodinated
contrast encephalopathy following intracranial aneurysm coiling. A case
report and review of the literature. Interv Neuroradiol. 2012;18(1):33–41.
https://​doi.​org/​10.​1177/​15910​19912​01800​105.

13.

14.

Nakao K, Joshi G, Hirose Y, Tanaka R, Yamada Y, Miyatini K, et al. Rare
cases of contrast-induced Encephalopathies. Asian J Neurosurg.
2020;15(3):786–93. https://​doi.​org/​10.​4103/​ajns.​AJNS_​68_​20.
Zhao W, Zhang J, Song Y, Sun L, Zheng M, Yin H, et al. Irreversible
fatal contrast-induced encephalopathy: a case report. BMC Neurol. 2019;19(1):46. Published 2019 Mar 28. https://​doi.​org/​10.​1186/​
s12883-​019-​1279-5.
Adams HP Jr, Bendixen BH, Kappelle LJ, et al. Classification of subtype of
acute ischemic stroke. Definitions for use in a multicenter clinical trial.
TOAST. Trial of org 10172 in acute stroke treatment. Stroke. 1993;24(1):35–
41. https://​doi.​org/​10.​1161/​01.​str.​24.1.​35.
Liu MR, Jiang H, Li XL, Yang P. Case report and literature review on lowOsmolar, non-ionic iodine-based contrast-induced encephalopathy. Clin
Interv Aging. 2020;15:2277–89. https://​doi.​org/​10.​2147/​CIA.​S2809​31.
Zevallos CB, Dandapat S, Ansari S, Farooqui M, Quispe-Orozco D,
Mendez-Ruiz A, et al. Clinical and imaging features of contrast-induced
neurotoxicity after Neurointerventional surgery. World Neurosurg.
2020;142:e316–24. https://​doi.​org/​10.​1016/j.​wneu.​2020.​06.​218.
Spina R, Simon N, Markus R, Muller DW, Kathir K. Contrast-induced
encephalopathy following cardiac catheterization. Catheter Cardiovasc
Interv. 2017;90(2):257–68. https://​doi.​org/​10.​1002/​ccd.​26871.
Quintas-Neves M, Araújo JM, Xavier SA, Amorim JM, Cruz E, Silva V, et al.
Contrast-induced neurotoxicity related to neurological endovascular
procedures: a systematic review. Acta Neurol Belg. 2020;120(6):1419–24.
https://​doi.​org/​10.​1007/​s13760-​020-​01508-x.
Khan UA, Thapar A, Shalhoub J, Davies AH. Risk of intracerebral aneurysm
rupture during carotid revascularization. J Vasc Surg. 2012;56(6):1739–47.
https://​doi.​org/​10.​1016/j.​jvs.​2012.​07.​027.
de Falco A, De Simone M, d’Onofrio F, Spitaleri D, de Falco FA. Posterior
reversible encephalopathy syndrome overlapping contrast-induced
encephalopathy after coronary angiography. Neurol Sci. 2019;40(9):1951–
3. https://​doi.​org/​10.​1007/​s10072-​019-​03810-w.
Fugate JE, Rabinstein AA. Posterior reversible encephalopathy syndrome:
clinical and radiological manifestations, pathophysiology, and outstanding questions [published correction appears in lancet Neurol. 2015
Sep;14(9):874]. Lancet Neurol. 2015;14(9):914–25. https://​doi.​org/​10.​1016/​
S1474-​4422(15)​00111-8.

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