---
title: "Acute Ischemic Stroke"
docid: "69a7a1f7-9c78-4ad1-82dd-9b13f2e717b3"
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- key: "07a2c087-6202-49e7-870b-7aa162d18f06"
value: "Bronwyn E. Hamilton, MD"
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name: "Acute Ischemic Stroke"
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lastUpdated: "04/18/16"
pageDescription: "Acute Ischemic Stroke"
pageKeywords: "Vasculature, Diagnosis, Extracranial Cerebral Arteries, Acute Ischemic Stroke"
pageTitle: "Acute Ischemic Stroke | STATdx"
enhancedTitle: "Acute Ischemic Stroke"
type: "DX"
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breadcrumbs:
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---
# KEY FACTS
- ## Terminology
- Interrupted blood flow to brain resulting in cerebral ischemia/infarction with variable neurologic deficit
- ## Imaging
- Major artery (territorial) infarct
- Generally wedge-shaped; both GM & WM involved
- Embolic infarcts
- Often focal/small, at GM-WM interface
- NECT
- Hyperdense vessel (high specificity, low sensitivity)
- "Dense MCA" sign: Acute thrombus in middle cerebral artery
- Loss of GM-WM distinction in 1st 3 hours (50-70%)
- "Insular ribbon" sign: Loss of GM-WM differentiation of insular cortex
- MR
- Best diagnostic clue is high signal on DWI with corresponding low signal on ADC
- ↓ CBF and ↓ CBV on perfusion MR (or CT)
- ## Top Differential Diagnoses
- Hyperdense vessel mimics
- Parenchymal hypodensity (nonvascular causes)
- ## Pathology
- Severely ischemic core
- CBF < (6-8 mL)/(100 g/min)
- Peripheral penumbra
- CBF = (10-20 mL)/(100 g/min)
- ## Clinical Issues
- 2nd most common cause of death worldwide
- Leading cause of morbidity in USA
- Treatment
- IV thrombolysis (< 3 hours of symptom onset)
- IA thrombolysis (selected acute strokes < 6 hours)
- Clinical diagnosis inaccurate in 15-20% of strokes
# TERMINOLOGY
- ## Synonyms
- Stroke, brain attack, cerebrovascular accident
- ## Definitions
- Interrupted blood flow to brain resulting in cerebral ischemia/infarction with variable neurologic deficit
# IMAGING
- ## General Features
- ### Best diagnostic clue
- High signal on DWI with corresponding low signal on ADC
- Decreased cerebral blood flow (CBF) and cerebral blood volume (CBV) on CT or MR perfusion
- ### Location
- 1 or more vascular territories or at border zones (watershed)
- ### Size
- Dependent on degree of compromise and collateral circulation
- ### Morphology
- Territorial infarct
- Conforms to arterial territory
- Generally wedge-shaped
- Both gray matter (GM) and white matter (WM) are involved
- Embolic infarcts (often focal, at GM-WM interface)
- ## CT Findings
- ### NECT
- Hyperdense vessel (high specificity, low sensitivity)
- Represents acute thrombus in cerebral vessel(s)
- Hyperdense M1 segment of middle cerebral artery (MCA) in 35-50%; most common vessel involved
- "Dot" sign: Occluded MCA branches in sylvian fissure (16-17%)
- Loss of gray-white matter (GM-WM) distinction in 1st 3 hours (50-70%)
- Obscuration of deep gray nuclei
- Loss of cortical "ribbon"
- Parenchymal hypodensity
- If > 1/3 MCA territory initially hypodense, then larger lesion usually develops later
- Temporary transition to isodensity (up to 54%) at 2-3 weeks post ictus (CT "fogging")
- Gyral swelling, sulcal effacement 12-24 hours
- "Hemorrhagic transformation" in 15-45%
- Delayed onset (24-48 hours) most typical
- Can be gross (parenchymal) or petechial
- ### CECT
- Enhancing cortical vessels: Slow flow or collateralization acutely
- Absent vessels: Occlusion
- Perfusion CT (pCT): Assess ischemic core vs. penumbra; identify patients who benefit most from revascularization
- pCT calculates CBF, CBV, time to peak (TTP)
- Deconvolution can give mean transit time (MTT)
- Cortical/gyral enhancement after 48-72 hours
- CTA: Identify occlusions, dissections, stenoses, collaterals
- ## MR Findings
- ### T1WI
- Early cortical swelling and hypointensity, loss of GM-WM borders
- ### T2WI
- Cortical swelling, hyperintensity after 12-24 hours
- May normalize 2-3 weeks post ictus (MR "fogging")
- ### FLAIR
- Parenchymal hyperintensity appears (6 hours post ictus) while other sequences normal
- Intraarterial FLAIR hyperintensity is early sign of major vessel occlusion or slow flow
- ### T2* GRE
- Detection of acute blood products
- Arterial "blooming" (thrombosed vessel) from clot susceptibility
- ### DWI
- Hyperintense restriction from cytotoxic edema
- Improves hyperacute stroke detection to 95%
- Best correlates with "ischemic core" (final infarct size); some diffusion abnormalities reverse
- May have reduced sensitivity in brainstem and medulla during 1st 24 hours
- Restriction typically lasts 7-10 days
- High signal can persist up to 2 months post ictus
- After 10 days, T2 effect may predominate over low ADC: T2 "shine-through"
- Corresponding low signal on ADC maps
- May normalize after tissue reperfusion
- Hyper- or isointensity on ADC map (T2 "shine-through") may mimic diffusion restriction
- Distinguish cytotoxic from vasogenic edema in complicated cases
- May be helpful to evaluate new deficits after tumor resection
- ### PWI
- Dynamic contrast bolus or arterial spin-labeling techniques
- Maximum slope gives relative CBF and CBV
- Deconvolution gives absolute values
- Bolus-tracking T2* gadolinium PWI with CBV map
- ↓ perfusion; 75% larger than DWI abnormality
- DWI/PWI mismatch may identify penumbra (potentially viable but at-risk tissue)
- ### T1WI C+
- Variable enhancement patterns evolve over time
- Hyperacute: Intravascular enhancement (stasis from slow antegrade or retrograde collateral flow)
- Acute: Meningeal enhancement (pial collateral flow appears in 24-48 hours, resolves over 3-4 days)
- Subacute: Parenchymal enhancement (appears after 24-48 hours, can persist for weeks/months)
- MRA: Major vessel occlusions, stenoses, status of collaterals
- MRS: Elevated lactate, decreased NAA
- Conventional MR sequences positive in 70-80%
- Restricted diffusion improves accuracy to 95%
- Diffusion tensor imaging (DTI)
- Multidirectional diffusion-weighted images; at least 6 directions can be used to calculate DTI trace and generate ADC maps
- Higher spatial resolution
- May be more sensitive for small ischemic foci, emboli, cortical strokes
- ## Angiographic Findings
- Conventional: Vessel occlusion (cut off, tapered, "tram track")
- Slow antegrade flow and slow retrograde collateral flow
- Intraluminal thrombus = filling defect
- Neurointerventional: Intraarterial (IA) fibrinolytic therapy for treatment of selected acute nonhemorrhagic stroke within 6-hour window
- IA mechanical clot removal with retriever device
- ## Imaging Recommendations
- ### Best imaging tool
- MR + DWI; T2* GRE
- ### Protocol advice
- NECT as initial study to exclude hemorrhage/mass
- CT perfusion and CTA if available
- MR using DWI/FLAIR/GRE ± MRA, PWI
- DSA with thrombolysis in selected patients
# DIFFERENTIAL DIAGNOSIS
- ## Hyperdense Vessel Mimics
- High hematocrit (polycythemia)
- Microcalcification in vessel wall
- Diffuse cerebral edema makes vessels appear relatively hyperdense
- Normal circulating blood always slightly hyperdense to normal brain
- ## Parenchymal Hypodensity (Nonvascular Causes)
- Infiltrating neoplasm (e.g., astrocytoma)
- Cerebral contusion
- Inflammation (cerebritis, encephalitis)
- Evolving encephalomalacia
- Dural venous thrombosis with parenchymal venous congestion and edema
# PATHOLOGY
- ## General Features
- ### Etiology
- Common causes
- Thrombotic vs. embolic, dissection, vasculitis, hypoperfusion
- Unusual causes
- Complicated vasculopathy, including posterior reversible encephalopathy syndrome and reversible cerebral vasoconstriction syndrome; venous stroke
- Early: Critical disturbance in CBF
- Severely ischemic core: CBF < (6-8 mL)/(100 g/min)
- Normal CBF ~ (60 mL)/(100 g/min)
- Oxygen depletion, energy failure, terminal depolarization, ion homeostasis failure
- Bulk of final infarct → cytotoxic edema, cell death
- Later: Evolution from ischemia to infarction depends on many factors (e.g., hyperglycemia influences "destiny" of ischemic brain tissue)
- Ischemic penumbra: CBF = (10-20 mL)/(100 g/min)
- Theoretically salvageable tissue
- Target of thrombolysis, neuroprotective agents
- ### Associated abnormalities
- Cardiac disease, prothrombotic states
- Additional stroke risk factors: C-reactive protein, homocysteine
- ## Gross Pathologic & Surgical Features
- Acute thrombosis of major vessel
- Pale, swollen brain; GM-WM boundaries blurred
- ## Microscopic Features
- After 4 hours: Eosinophilic neurons with pyknotic nuclei
- 15-24 hours: Neutrophils invade, and necrotic nuclei look like "eosinophilic ghosts"
- 2-3 days: Blood-derived phagocytes
- 1 week: Reactive astrocytosis, ↑ capillary density
- End result: Fluid-filled cavity lined by astrocytes
# CLINICAL ISSUES
- ## Presentation
- ### Most common signs/symptoms
- Focal acute neurologic deficit
- Paresis, aphasia, decreased mental status
- ## Demographics
- ### Age
- Usually older adults
- ### Gender
- No gender predilection
- ### Epidemiology
- 2nd most common cause of death worldwide
- Among leading causes of morbidity in USA
- ## Natural History & Prognosis
- Clinical diagnosis inaccurate in 15-20% of strokes
- Malignant MCA infarct (coma, death)
- Up to 10% of all stroke patients
- Fatal brain swelling with increased ICP
- ## Treatment
- "Time is brain": IV thrombolytic therapy window < 3 hours
- IA window < 6 hours except for vertebrobasilar thrombosis (up to 24 hours because of high morbidity and mortality)
- Patient selection most important factor in outcome
- Symptom onset < 6 hours
- No parenchymal hematoma on CT
- < 1/3 MCA territory hypodensity
# DIAGNOSTIC CHECKLIST
- ## Consider
- DWI positive for acute stroke only if ADC correlates
- Rarely, ischemia may mimic tumor or encephalitis
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## References
# Selected References
1. [Parrilla G et al: Hemorrhage/contrast staining areas after mechanical intra-arterial thrombectomy in acute ischemic stroke: imaging findings and clinical significance. AJNR Am J Neuroradiol. 33(9):1791-6, 2012](http://www.ncbi.nlm.nih.gov/pubmed/?term=22538076%5Bpmid%5D)
1. [Wang DJ et al: The value of arterial spin-labeled perfusion imaging in acute ischemic stroke: comparison with dynamic susceptibility contrast-enhanced MRI. Stroke. 43(4):1018-24, 2012](http://www.ncbi.nlm.nih.gov/pubmed/?term=22328551%5Bpmid%5D)
1. [Harris AD et al: Diffusion and perfusion MR imaging of acute ischemic stroke. Magn Reson Imaging Clin N Am. 17(2):291-313, 2009](http://www.ncbi.nlm.nih.gov/pubmed/?term=19406360%5Bpmid%5D)
1. [Kranz PG et al: Does diffusion-weighted imaging represent the ischemic core? An evidence-based systematic review. AJNR Am J Neuroradiol. 30(6):1206-12, 2009](http://www.ncbi.nlm.nih.gov/pubmed/?term=19357385%5Bpmid%5D)
1. [Lee KY et al: Distal hyperintense vessels on FLAIR: an MRI marker for collateral circulation in acute stroke? Neurology. 72(13):1134-9, 2009](http://www.ncbi.nlm.nih.gov/pubmed/?term=19211928%5Bpmid%5D)
1. [Sanossian N et al: Angiography reveals that fluid-attenuated inversion recovery vascular hyperintensities are due to slow flow, not thrombus. AJNR Am J Neuroradiol. 30(3):564-8, 2009](http://www.ncbi.nlm.nih.gov/pubmed/?term=19022866%5Bpmid%5D)
1. [Soares BP, Chien JD, Wintermark M. MR and CT monitoring of recanalization, reperfusion, and penumbra salvage: everything that recanalizes does not necessarily reperfuse! Stroke. 40(3 Suppl):S24-7, 2009](http://www.ncbi.nlm.nih.gov/pubmed/?term=19064812%5Bpmid%5D)
1. [Chen Z et al: Evaluating ischemic stroke with diffusion tensor imaging. Neurol Res. 30(7):720-6, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=18513464%5Bpmid%5D)
1. [Provenzale JM et al: Optimization of perfusion imaging for acute cerebral ischemia: review of recent clinical trials and recommendations for future studies. AJR Am J Roentgenol. 191(4):1263-70, 2008](http://www.ncbi.nlm.nih.gov/pubmed/?term=18806174%5Bpmid%5D)
1. [Lell MM et al: New techniques in CT angiography. Radiographics. 26 Suppl 1:S45-62, 2006](http://www.ncbi.nlm.nih.gov/pubmed/?term=17050518%5Bpmid%5D)
1. [Bourekas EC et al: Intraarterial thrombolytic therapy within 3 hours of the onset of stroke. Neurosurgery. 54(1):39-44; discussion 44-6, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14683539%5Bpmid%5D)
1. [Diaz J et al: Cerebral ischemia: new risk factors. Cerebrovasc Dis. 17 Suppl 1:43-50, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14694279%5Bpmid%5D)
1. [Fiebach JB et al: Stroke magnetic resonance imaging is accurate in hyperacute intracerebral hemorrhage: a multicenter study on the validity of stroke imaging. Stroke. 35(2):502-6, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14739410%5Bpmid%5D)
1. [Fiehler J et al: Predictors of apparent diffusion coefficient normalization in stroke patients. Stroke. 35(2):514-9, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14739409%5Bpmid%5D)
1. [Gass A et al: Diffusion-weighted MRI for the "small stuff": the details of acute cerebral ischaemia. Lancet Neurol. 3(1):39-45, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14693110%5Bpmid%5D)
1. [Kelly PJ et al: Inflammation, homocysteine, and vitamin B6 status after ischemic stroke. Stroke. 35(1):12-5, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14657454%5Bpmid%5D)
1. [Kidwell CS et al: Comparison of MRI and CT for detection of acute intracerebral hemorrhage. JAMA. 292(15):1823-30, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=15494579%5Bpmid%5D)
1. [Mahagne MH et al: Voxel-based mapping of cortical ischemic damage using Tc 99m L,L-ethyl cysteinate dimer SPECT in acute stroke. J Neuroimaging. 14(1):23-32, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14748205%5Bpmid%5D)
1. [Nakajima M et al: Relationships between angiographic findings and National Institutes of Health stroke scale score in cases of hyperacute carotid ischemic stroke. AJNR Am J Neuroradiol. 25(2):238-41, 2004](http://www.ncbi.nlm.nih.gov/pubmed/?term=14970023%5Bpmid%5D)
1. [Borisch I et al: Preoperative evaluation of carotid artery stenosis: comparison of contrast-enhanced MR angiography and duplex sonography with digital subtraction angiography. AJNR Am J Neuroradiol. 24(6):1117-22, 2003](http://www.ncbi.nlm.nih.gov/pubmed/?term=12812936%5Bpmid%5D)
1. [Eastwood JD et al: Quantitative assessment of the time course of infarct signal intensity on diffusion-weighted images. AJNR Am J Neuroradiol. 24(4):680-7, 2003](http://www.ncbi.nlm.nih.gov/pubmed/?term=12695203%5Bpmid%5D)
1. [Leary MC et al: Validation of computed tomographic middle cerebral artery "dot"sign: an angiographic correlation study. Stroke. 34(11):2636-40, 2003](http://www.ncbi.nlm.nih.gov/pubmed/?term=14593125%5Bpmid%5D)
1. [Tomandl BF et al: Comprehensive imaging of ischemic stroke with multisection CT. Radiographics. 23(3):565-92, 2003](http://www.ncbi.nlm.nih.gov/pubmed/?term=12740462%5Bpmid%5D)
1. [Toyoda K et al: Fluid-attenuated inversion recovery intraarterial signal: an early sign of hyperacute cerebral ischemia. AJNR Am J Neuroradiol. 22(6):1021-9, 2001](http://www.ncbi.nlm.nih.gov/pubmed/?term=11415892%5Bpmid%5D)
## Images
### Selected Images
. Acute ischemia is often identified by subtle loss of the gray-white matter interfaces with blurring of the basal ganglia and an "insular ribbon" sign on the initial CT.](images/app.statdx.com_image_thumbnail_d7b90847-cdd7-4a27-af45-d16fbaf0825c_annotated_true_size_900_quality_90_ae4a6e1524c3805d3bfd0264856d430bf0f42ad8.jpg)
*Coronal graphic illustrates a left M1 occlusion. A proximal occlusion affects the entire middle cerebral artery (MCA) territory, including the basal ganglia, which are perfused by lenticulostriate (perforating) arteries . Acute ischemia is often identified by subtle loss of the gray-white matter interfaces with blurring of the basal ganglia and an "insular ribbon" sign on the initial CT.*
*Coronal graphic illustrates a left M1 occlusion. A proximal occlusion affects the entire middle cerebral artery (MCA) territory, including the basal ganglia, which are perfused by lenticulostriate (perforating) arteries . Acute ischemia is often identified by subtle loss of the gray-white matter interfaces with blurring of the basal ganglia and an "insular ribbon" sign on the initial CT.*
in a patient with acute stroke symptoms.](images/app.statdx.com_image_thumbnail_cd6ff05d-2068-480a-aca5-aaa34b8c816d_annotated_true_size_900_quality_90_770644d4466fb8eb403758d518b3098b5807d48d.jpg)
*Axial NECT demonstrates a hyperdense MCA sign representing acute thrombus in a patient with acute stroke symptoms.*
*Axial NECT shows subtle loss of the right temporal gray-white matter interfaces representing an "insular ribbon" sign.*
in the right hemisphere related to hyperacute MCA ischemia. The CBF and CBV color maps cephalad to this slice showed a large MCA wedge-shaped defect. There was a similar perfusion abnormality on the TTP maps (not shown). Lack of a mismatch between CBV and TTP maps suggests that no ischemic penumbra is present.](images/app.statdx.com_image_thumbnail_5cc848a6-5f37-47ba-a21a-e67604191219_annotated_true_size_900_quality_90_f486338b48928fc19f790476769c9e0319a3b8ff.jpg)
*Axial pCT (CBF) shows decreased blood flow in the right hemisphere related to hyperacute MCA ischemia. The CBF and CBV color maps cephalad to this slice showed a large MCA wedge-shaped defect. There was a similar perfusion abnormality on the TTP maps (not shown). Lack of a mismatch between CBV and TTP maps suggests that no ischemic penumbra is present.*
representing acute ischemia in a left MCA distribution. There is sparing of the basal ganglia, consistent with distal M1 occlusion.](images/app.statdx.com_image_thumbnail_0f80c43f-b4da-4fef-ad8a-86bcbd6d4bd6_annotated_true_size_900_quality_90_684828ab35ac603104d554bb52944edd88ea6ff5.jpg)
*Axial DWI MR shows a large wedge-shaped hyperintensity related to restricted diffusion representing acute ischemia in a left MCA distribution. There is sparing of the basal ganglia, consistent with distal M1 occlusion.*
*Axial NECT shows a hypodense wedge-shaped region of acute infarct with mild mass effect and sulcal effacement related to a right M1 embolic occlusion due to a calcified thrombus .*
*Axial NECT demonstrates bilateral posterior circulation hypodensities in a 20-month-old boy presenting with seizures after recent circumcision complicated by hematoma.*
*Axial NECT shows hyperdense thrombus in the distal basilar artery of a 66-year-old woman with altered sensorium. Percutaneous thrombolysis is usually considered at later time points, up to 24 hours, because of the high morbidity and mortality associated with basilar thrombosis.*
*Axial DWI MR shows hyperintensity related to restricted diffusion in a patient with vertebrobasilar disease and a posterior inferior cerebellar artery acute infarct. MR is superior to CT in evaluation of a posterior fossa stroke.*
*Coronal CTA MIP reconstruction shows a focal filling defect within the proximal M1 segment in a patient with acute MCA ischemia. Intraarterial thrombolysis may be helpful if the patient presents to the emergency department within 6 hours of symptoms onset.*
*Angiography in a 27-year-old man with a history of methamphetamine and tobacco use shows focal tight stenosis within the distal right M1 segment . He presented with stuttering symptoms of left-sided weakness and face droop.*
*Sagittal T2WI MR shows multiple watershed ischemic foci in the deep white matter in a "string of pearls" configuration.*
*Axial T2* GRE MR shows multifocal hemorrhages within an ischemic infarct in a 13-year-old boy with 3 weeks of fatigue, epistaxis, and acute loss of consciousness. He was found to have leukemia complicated by disseminated intravascular coagulation.*
indicating upward transtentorial herniation.](c449ce0d-6973-4cc5-ba76-0a95fe8c2a8b)
*Axial NECT shows cerebellar infarcts in a 34-year-old woman with bilateral vertebral artery dissections. Note effacement of basal cisterns and temporal horn dilation indicating upward transtentorial herniation.*
*Axial T2WI MR shows bilateral wedge-shaped occipital areas of hyperintensity in a 77-year-old woman, which do not allow for a reliable distinction between chronic and acute ischemia.*
*Axial DWI MR in the same patient accurately reflects the acute area of left occipital ischemia , while encephalomalacia is apparent in the right occipital lobe .*
*Axial NECT shows multifocal hypodensities in the left cerebellum , consistent with embolic infarction within the left PICA distribution in this 40-year-old man with longstanding insulin-dependent diabetes and chronic renal failure. He presented with acute severe headache, nausea, and vomiting without localizing neurological finding.*
*Axial CTA shows occlusion of the left vertebral artery . Compare with a normal dominant right vertebral artery .*
*Axial CTA shows intimal flap in a 47-year-old woman with bilateral internal carotid artery dissections.*
*Axial NECT shows hyperdense left deep nuclei in a patient post recent IV thrombolytic therapy followed by mechanical thrombectomy for left MCA occlusion. These may reflect contrast staining &/or hemorrhage. Contrast gradually fades over time and does not imply worse prognosis. Matching hypointensity on GRE suggests hemorrhage.*
*Axial T1 C+ MR shows heterogeneous gyriform enhancement in right MCA territory due to breakdown of BBB in subacute infarction. This appearance can mimic glioblastoma. Follow-up imaging may be important in patients without available imaging at the time of ictus to ensure appropriate evolution.*
.](65234520-550c-4ff3-8d2b-51022469fce6)
*Anteroposterior angiography shows left M1 occlusion and associated prominent lenticulostriate vessels .*
### Additional Images
*Axial DWI MR in a patient 2 hours after stroke onset shows restricted diffusion. Correlative ADC hypointensity was also demonstrated within the same geographic area (not shown).*
*Axial CECT shows abrupt right MCA cut-off in a patient with hyperacute stroke symptoms. (Courtesy J. Eastwood, MD.)*
*Axial DWI MR shows small emboli infarcts in the left hemisphere.*
*Axial CT perfusion map in the same patient reveals significantly prolonged mean transit time within the MCA distribution (red region).*
*Axial DWI MR shows restricted diffusion within the right occipital lobe in a patient with sudden onset of visual symptoms.*
*Axial FLAIR MR shows multiple foci of intraarterial high signal suggesting slow flow in this patient with left internal carotid artery dissection.*
*Coronal CTA shows slight irregularity within the reconstituted left vertebral artery segment , consistent with dissection in this symptomatic patient.*
*Axial single-phase arterial spin-labeling (ASL) perfusion shows hemispheric asymmetry, decreased on the left , in a patient with acute left internal carotid artery dissection.*
*Axial FLAIR MR shows classic deep white matter watershed ischemic foci in a "string of pearls" appearance.*
*Axial DWI MR in a 35-year-old woman post transsphenoidal surgery for Cushing disease shows multifocal infarctions as a complication of Enterobacter meningitis.*