Neurocrit Care
DOI 10.1007/s12028-015-0186-x

PRACTICAL PEARL

Mucor Thrombus
E. L. Scharf1 • H. J. Cloft1 • E. Wijdicks1

Ó Springer Science+Business Media New York 2015

Abstract
Background To describe a rare presentation of ischemic
stroke secondary to angioinvasive mucormycosis and
endovascular retrieval of mycotic thrombus with stenting
of the compressed vessel.
Summary of Case We report a case of angioinvasive
mucormycosis that externally compressed and invaded the
internal carotid artery causing ischemic cerebral infarction.
A sample of the thrombus was obtained using a stent
retriever. Subsequent pathological analysis was shown
to be consistent with the diagnosis of angioinvasive
mucormycosis. The thrombosed and compressed segment
was recanalized with the deployment of a stent.
Conclusions The endovascular placement of an expandable
stent in the setting of angioinvasive mucormycosis restored
good cerebral blood flow in a proximal internal carotid artery
occlusion. The patient’s aphasia resolved following this
intervention. Artifacts of CT angiography may result in the
overestimation of acute arterial occlusions. Endovascular
carotid stenting may be a palliative measure in the setting of
angioinvasive rhino-cerebro-orbital mucormycosis.

Introduction
Mucoraceae are a family of fungi that contain four genera
Absidia, Mucor, Rhizomucor, anidia, Mucor, Rhizomucor,
and Rhizopus well described as opportunistic pathogens in
& E. L. Scharf
scharf.eugene@mayo.edu
1

Department of Neurology, Mayo Clinic, 200 First Street SW,
Rochester, MN 55905, USA

humans. Although spores are ubiquitous in the environment, immunocompetent individuals are naturally resistant.
Known presentations of mucormycosis include pulmonary,
cutaneous, gastrointestinal, renal, rhino-orbital-cerebral,
and disseminated fungemia [1]. Immunocompromised
individuals are at increased risk for this fungal infection,
particularly in the setting of burns, corticosteroid use,
hematological malignancy, and solid organ or bone marrow
transplant. Rhizopus species withstand acidic environments
because these species possess aldo–keto reductases [2].
Neurological complications of mucormycosis previously
described include carotid artery occlusion [3–8], ophthalmic artery occlusion [9], and cavernous sinus
thrombosis [10]. This case report describes a rare presentation of carotid occlusion and ischemic stroke that resulted
from an angioinvasive Mucor thrombus that was retrieved
and the occluded vessel was stented.
Case History
A 56-year-old man with a history of sarcoidosis and multiple myeloma on treatment with lenalidomide and
dexamethasone and pulmonary embolism on long-term
anticoagulation underwent an MRI for left eye pain and
diplopia. On examination, the patient had a left sixth cranial nerve palsy. MRI showed left orbital optic nerve
sheath enhancement. Plasmacytoma, infection, and
inflammatory pseudotumor were considered in the differential. CSF sampling was non-diagnostic and cultures were
negative. The patient was started empirically on high-dose
methylprednisolone monthly and voriconazole, with significant symptomatic improvement. The patient underwent
cyclophosphamide priming and proceeded to autologous
bone marrow transplantation. Day 7 post-transplant his left
eye pain recurred and head MRI showed abnormal

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enhancement at the apex along the left cavernous sinus.
Over the following week, the patient’s vision acutely
deteriorated to light perception and repeat MRI of the face
and orbit now showed narrowing of the left supraclinoid
internal carotid artery. He was scheduled for craniotomy
and biopsy of the mass lesion and his low molecular weight
heparin was held in advance of his surgery. During the
outpatient preoperative evaluation on the day prior to his
biopsy, he was found to have acute onset fluctuating
aphasia and right hemiparesis. He was transported to the
emergency department and NIHSS in the emergency
department was noted to be six. He underwent non-contrast
head CT with angiography. There were no early signs of
cerebral ischemia and CT angiography showed good arterial collateralization through the circle of Willis (Fig. 1a,
b). On reconstructed images of CT angiography, the extent
of the carotid occlusion appeared to involve the entire left
carotid artery (Fig. 2a). He was not a candidate for intravenous thrombolysis because of use of heparin within the
last 48 h and known intracranial mass. Platelet count was
91.
The patient was brought to the angiography suite
approximately 3 h after onset of symptoms. Cerebral
angiography showed an occlusion in the cavernous segment of the left internal carotid artery (Fig. 2b). A catheter
could not be passed into the thrombosed segment which
was noted to have a firm texture suggestive of tumor.
A Solitaire device was deployed and retrieved across the
occluded segment. Flow was briefly restored with persistent narrowing. A small amount of material was retrieved
with a stent retriever and sent for pathological analysis.
The carotid re-occluded and an enterprise stent was placed
to prevent further re-occlusion. Followup left carotid

Fig. 1 a Axial-computed
tomographic angiography.
Arterial collateralization is
present through the circle of
Willis filling the left middle
cerebral artery. b Distal
branches the left middle
cerebral artery show
comparable contrast
enhancement in comparison to
the non-occluded right middle
cerebral artery suggesting
adequate collateral flow

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cerebral angiography after stent placement showed
restoration of a small amount of flow but persistent marked
narrowing, approximately 70 % (Fig. 3a, b). Post stent
angioplasty was deferred as a compromise to respect the
concern for vessel fragility and the risk of rupture secondary to the unknown mass. Given the patient’s history of
malignancy associated hypercoagulability, pulmonary
embolism, and recent discontinuation of anticoagulation,
post procedurally he was maintained on intravenous
unfractionated heparin. He was treated with a loading dose
of clopidogrel and aspirin the following morning. Subsequently, intravenous heparin was discontinued and he was
maintained on dual antiplatelet therapy to minimize risk of
stent thrombosis. Systolic blood pressure was kept below
160 mmHg. Post procedurally his aphasia improved but he
had persistent left cranial nerve neuropathy, right facial
weakness, and right paresis. Histopathological analysis of
the luminal thrombus with silver stain and periodic acid–
Schiff stain (Fig. 4) revealed non-septated and broad
branching hyphae favoring Zygomycetes species. The
patient was admitted to hospital and repeat head CT with
thin slice sequencing through the sinuses showed a large
mucosal enhancement now in the sphenoid sinus that was
amenable to sphenoidotomy and biopsy. Fungal culture of
this sample confirmed Rhizomucor species.

Discussion
This case, the first to our knowledge, demonstrates the
successful stenting of the cavernous segment of the internal
carotid artery in the setting of an acute stroke secondary to
an angioinvasive fungal infection. The source of the

Neurocrit Care
Fig. 2 a Computed
tomographic angiography
3-dimensional reformat suggests
a total occlusion of the left
carotid with collateral filling of
the left middle cerebral artery.
b Digital subtraction
angiography completed an hour
later shows a focal occlusion of
the supraclinoid segment of the
left internal carotid

Fig. 3 Digital subtraction
angiography of the left internal
carotid artery shows
recanalization but persistent
stenosis of the supraclinoid
segment of the left internal
carotid. a Right anterior oblique
view, b left anterior oblique
view

Fig. 4 Histopathological
sample of acute thrombus.
a Grocott’s methenamine silver
(GMS) shows darkly staining
carbohydrate rich fungal cell
walls, 91000. b Periodic acid–
Schiff (PAS) staining shows
broad widely branching nonseptated hyphae suggestive of
Rhizopus species, 91000

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thrombus was likely external compression and cavernous
sinus invasion from the known intracranial mass. This is
supported by the slowly progressive left cranial neuropathy
and left monocular visual loss punctuated by sudden onset
right hemiparesis and aphasia. It reasonable to consider
proximal embolization from seeded cardiac valves secondary to disseminated fungemia; however, the patient had
a normal transthoracic echocardiogram 3 months prior and
negative blood cultures 2 months prior to his presentation
of acute stroke.
There are several points to consider in this case. First,
there was a discrepancy between the size of the carotid
occlusion when comparing the images from the CT
angiogram and the conventional cerebral angiogram. The
reconstructed images of the CT angiogram suggest a total
occlusion of the affected internal carotid artery. The actual
occlusion found by digital subtraction angiography was
focal within the ophthalmic segment. The discrepancy of
this ‘‘pseudo-occlusion’’ results from significant delay in
contrast uptake in the occluded vessel. A delayed CTA
scan might have shown more contrast in distal segments of
the occluded artery and more accurately reflected the true
location of the occlusion and should be considered if
conventional angiography is not available. This particular
finding is clinically relevant because a longitudinally
extensive total carotid occlusion would normally not be
subject to endovascular intervention. Recognition of this
potential radiological artifact is critical because it has
implications for clinical management.
Second, this case supports recently published data [11–
14] on the effectiveness of endovascular management of
acute stroke. The patient presented with severe disabling
focal neurological deficits and absolute contraindications to
intravenous thrombolysis within 6 h of symptoms onset.
Perfusion imaging to assess for ischemic penumbra was
deferred in this case. This decision was justified because
the initial head CT did not show a large region of ischemia,
there was good collateral flow, perfusion imaging would
have resulted in additional delay, and it would not have
changed the clinical management. In this case, the head CT
and angiography provided enough evidence to pursue
endovascular management of acute stroke. Although the
NIHSS was six, the patient was found to have an acute
large vessel occlusion. The discrepancy between his clinical exam and radiographic findings underscores the
importance of arterial collateralization in acute stroke. The
degree of arterial collateralization present on CT angiography served well as a proxy for perfusion. Importantly, the
CT angiogram showed patent anterior communicating
collateral circulation of the left ACA and MCA. Thus, in a
carotid occlusion with excellent collateral flow distally, the
interventionalist must be cognizant of the risk of creating
an embolic occlusion of an otherwise patent anterior

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cerebral and middle cerebral arteries when manipulating
the clot.
Finally, the nature of the thrombotic occlusion, a luminal invasion, and external compression from an aggressive
fungus added significant complexity to the management.
Intracranial arterial stenting was justified because of the
persistent narrowing and re-occlusion of the affected
artery. The results of the SAMMPRIS Trial [15] for
endovascular intra-arterial stenting do not apply in this case
because the patient would have been excluded for known
progressive neurological signs within 24 h prior to enrollment, the patient had no known prior intracranial stenosis,
the patient had a history of therapeutic anticoagulation, and
most importantly the patient’s large vessel occlusion was
secondary to an invading fungal mass and not intracranial
atherosclerosis. Therefore, palliative stenting was appropriate based on plausible clinical reasoning. As a result of
the stenting, the patient regained language function which
had positive impact on his quality of life. Surgical
debridement of the infection was not offered after review
of the patient’s comorbidities and consideration of the
intracranial extension of the infection. In consultation from
an infectious disease specialist he received caspofungin
which was discontinued secondary to liver toxicity. He was
next treated with liposomal amphotericin which resulted in
cytopenias and he became transfusion dependent. The
patient discharged to hospice and died 1 month after hospital admission.

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