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title: "Childhood Stroke"
docid: "dc608435-4c6c-4b53-985a-4630cd24d5ce"
authors:
- key: "47381de4-c9fd-4999-8dd0-1808cd72db6b"
value: "Luke L. Linscott, MD"
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name: "Pediatrics"
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name: "Traumatic and Vascular Lesions"
slug: "traumatic-and-vascular-lesions"
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name: "Childhood Stroke"
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lastUpdated: "11/01/21"
pageDescription: "Childhood Stroke"
pageKeywords: "Pediatrics, Diagnosis, Brain, Traumatic and Vascular Lesions, Childhood Stroke"
pageTitle: "Childhood Stroke | STATdx"
enhancedTitle: "Childhood Stroke"
type: "DX"
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---
# KEY FACTS
- ## Terminology
- Acute alteration of neurologic function due to loss of vascular integrity
- ## Imaging
- NECT: ↓ attenuation of affected gray matter
- Insular ribbon sign → loss of distinct insular cortex
- Hyperdense middle cerebral artery (MCA) sign → thrombosed MCA
- MR: ↓ diffusion within ~ 30 minutes of arterial occlusion
- Cytotoxic edema is evident in affected territory on FLAIR/T2 by 4-6 hours after arterial occlusion
- Enhancement of infarct typically occurs after 5-7 days
- CTA/MRA: Critical for early evaluation & identification of possible etiology (e.g., dissection, arteriopathy)
- MR perfusion imaging can provide valuable information regarding region at risk in setting of acute stroke
- Arterial spin labeling can provide useful perfusion information without contrast administration
- MR vessel wall imaging is helpful to identify inflammatory arteriopathy
- ## Top Differential Diagnoses
- Complex migraine
- Seizure-related injury
- Acute encephalitis
- Mitochondrial encephalopathies
- Posterior reversible encephalopathy syndrome
- ## Pathology
- Major causes: Cardiac disease (~ 25%), moyamoya-type arteriopathy, dissection, vasculitis, hematologic/metabolic
- No underlying cause discovered in ~ 25% of cases
- ## Clinical Issues
- Incidence: 2-3/100,000 per year in USA
- Mortality: 0.6/100,000
- Children typically present later than adults (> 24 hours)
- Focal deficit may be masked by lethargy, coma, irritability
- Treatment in pediatric acute stroke is often conservative
- Thrombolysis/thrombectomy not well studied in children
- Capacity for recovery in children much better than adults
# TERMINOLOGY
- ## Synonyms
- Cerebrovascular accident, cerebral infarct, cerebral ischemia
- ## Definitions
- Acute alteration of neurologic function due to loss of vascular integrity
# IMAGING
- ## General Features
- ### Best diagnostic clue
- Cytotoxic edema & restricted diffusion (acutely) in affected vascular territory
- ### Location
- Proximal & distal middle cerebral artery (MCA) territories are most commonly affected
- ### Morphology
- Stroke caused by arterial occlusion typically conforms to 1 arterial territory
- ## CT Findings
- ### NECT
- ↓ attenuation of affected gray matter (GM) with loss of normal GM-white matter (WM) differentiation
- ↓ in WM attenuation is less pronounced
- Often wedge-shaped & localized to 1 arterial territory
- Diffuse ischemic injury can lead to reversal sign with GM diffusely ↓ in attenuation relative to WM
- Insular ribbon sign → loss of distinct insular cortex
- Hyperdense middle cerebral artery (MCA) sign → ↑ density of acutely thrombosed MCA
- Hemorrhagic transformation (HT)
- Symptomatic HT in 3%; asymptomatic HT in 30%
- Asymptomatic HT is usually parenchymal
- WM or deep nuclear hemorrhage is often mass-like → hematoma within infarcted tissue
- ### CECT
- Enhancement of infarcted territory typically occurs after 5-7 days
- ### CTA
- Invaluable for demonstrating focal vascular abnormalities in acute setting
- Intimal flap in acutely dissected vessel
- Major arterial occlusion may prompt thrombolysis or mechanical thrombectomy in appropriate setting
- ## MR Findings
- **T1**: Acute: ↓ signal with gyral swelling
- Chronic: ± ↑ signal in cortical laminar necrosis
- **T1 FS**: Allows identification of mural hematoma (↑ signal) in dissected vessel
- **T2**: Loss of flow void in thrombosed vessel
- **FLAIR**: ↑ signal with gyral swelling (within 4-6 hours)
- Abnormal sulcal ↑ signal (climbing ivy sign) of chronic slow flow collaterals in setting of longstanding proximal vascular occlusion
- **DWI**: Most sensitive for early detection of ischemia
- Acute: Restricted diffusion (↑ DWI, ↓ ADC signal) ≤ 30 minutes after ischemic insult
- Subacute (7-14 days): Pseudonormalization of signal
- ↑ DWI, ADC ≈ brain parenchyma
- Chronic: Facilitated diffusion in gliotic brain
- ↑/≈ DWI, ↑ ADC
- **SWI/T2* GRE**: May see ↑ size & number of cortical vessels****
- Suggests ↑ extraction fraction & possibly recoverable brain
- **T1 C+**: Cortical & leptomeningeal enhancement is seen after 5-7 days following acute infarct
- Enhancing climbing ivy sign
- **MRA**: Can detect arterial occlusion & stenosis in large- & medium-sized cerebral vessels
- Important to identify underlying dissection or arteriopathy
- **PWI**: Provides valuable information about affected brain
- Ischemic penumbra: ↓ perfusion, no DWI change (PWI-DWI mismatch)
- May define brain that is salvageable with acute stroke therapy
- Arterial spin labeling can provide useful perfusion information without contrast administration
- **MRS**: ↑ lactate is hallmark of ischemia/infarct
- Not specific
- **Vessel wall imaging**: Vessel wall enhancement suggests inflammatory arteriopathy
- Vessel wall enhancement patterns improve discrimination of underlying stroke etiology
- ## Ultrasonographic Findings
- ### Grayscale ultrasound
- Affected territory is hyperechoic in acute/subacute stage
- ### Color Doppler
- Direct Doppler evaluation is ideal for surveillance of vascular occlusion in neonate with open sutures
- Transcranial Doppler evaluation of circle of Willis through temporal squamosa
- ↑ velocities can predict stenoses detectable by MRA
- Used as screening tool in children with sickle cell anemia
- ## Angiographic Findings
- Catheter angiography is rarely necessary in acute evaluation of childhood stroke
- Only justified if contemplating endovascular therapy
- Best modality for detailed evaluation of primary arteriopathies
- ## Nuclear Medicine Findings
- PET & SPECT techniques can be used to
- Identify salvageable regions at risk (ischemic penumbra)
- Demonstrate effects of synangiosis surgery in moyamoya-type vasculopathies
- ## Imaging Recommendations
- ### Best imaging tool
- CT is initial imaging test for signs/symptoms of stroke; excellent for excluding hemorrhagic stroke (more common in children vs. adults)
- MR with DWI, MRA, PWI
- ### Protocol advice
- Contrast can help in assessing timing of injury & performing perfusion imaging
# DIFFERENTIAL DIAGNOSIS
- ## Complex Migraine
- ↓ (early) or ↑ (late) perfusion with normal DWI
- Engorgement of vessels on SWI
- ## Seizure-Related Injury
- Swelling & restricted diffusion secondary to persistent seizure activity
- Differentiation by clinical presentation & EEG
- [Acute Encephalitis](/document/acute-encephalitis/a45f63bb-c25b-481d-a001-9c520c58060b)
- Acute parenchymal inflammation secondary to infectious agents, typically viral
- Slower onset with encephalopathy
- [Mitochondrial Encephalopathies](/document/mitochondrial-encephalopathies/40004435-b768-4baf-a31e-651f8a174fe2)
- Symmetric basal ganglia involvement is common
- Usually have manifestations beyond CNS
- [Posterior Reversible Encephalopathy Syndrome](/document/acute-hypertensive-encephalopathy--/efc6f9c2-dad9-4eb8-bad2-421bfaf1ec57)
- Patchy cortical/subcortical edema is most common in parietal & occipital lobes, typically in setting of hypertension
- Diffusion restriction is uncommon
# PATHOLOGY
- ## General Features
- 6 major causes of arterial stroke in children
- Cardiac disease (~ 25%)
- Congenital heart disease, valvular heart disease, arrhythmias, & cardiomyopathies
- Moyamoya-type arteriopathy
- Sickle cell disease
- Neurofibromatosis type I
- Idiopathic
- Arterial dissection (e.g., trauma)
- CNS vasculitis
- Hematologic/metabolic (e.g., coagulopathy)
- Idiopathic (~ 25%)
- No underlying cause discovered
# CLINICAL ISSUES
- ## Presentation
- ### Most common signs/symptoms
- Depends on patient age, etiology, & involved artery
- < 1 year: Seizures, encephalopathy > focal neurologic
- > 1 year: Usually focal neurologic (e.g., hemiplegia)
- Speech difficulties, gait abnormality, seizure
- Embolic cause: Sudden onset of symptoms
- Stenoocclusive cause: Gradual/intermittent (e.g., TIA)
- Focal deficit may be masked by lethargy, coma, irritability
- Preceding transient events occur in 25%
- Children typically present later than adults (> 24 hours)
- Poor recognition/understanding of symptoms by child, caregiver, physician
- ## Demographics
- ### Age
- Incidence/mortality greatest < 1 year
- ### Epidemiology
- Incidence: 2-3/100,000 per year in USA
- Mortality: 0.6/100,000
- Underrecognized as significant source of morbidity in pediatric population
- ## Natural History & Prognosis
- Capacity for recovery is better than in adults, due to
- Better compensatory mechanisms, collateral recruitment, neuronal plasticity
- Fewer concomitant risk factors
- ## Treatment
- Clinical window of opportunity/benefit is not as well understood in children as compared to adults
- Mainstay of chronic therapy for fixed vascular lesions & vasculopathies: Aspirin
- Transfusion therapy for at-risk children with sickle cell disease
# DIAGNOSTIC CHECKLIST
- ## Image Interpretation Pearls
- Use same imaging signs as adults
- Have low threshold for use of CTA
4fee7a61-bc2c-4ce0-a2d5-84ed346ac7d5
## References
# Selected References
1. [van Es ACGM et al: Endovascular treatment for acute ischemic stroke in children: experience from the MR CLEAN Registry. Stroke. 52(3):781-8, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=33617341%5Bpmid%5D)
1. [Visser MJ et al: Automated perfusion-diffusion magnetic resonance imaging in childhood arterial ischemic stroke. Stroke. 52(10):3296-304, 2021](http://www.ncbi.nlm.nih.gov/pubmed/?term=34404238%5Bpmid%5D)
1. [Donahue MJ et al: Neuroimaging advances in pediatric stroke. Stroke. 50(2):240-8, 2019](http://www.ncbi.nlm.nih.gov/pubmed/?term=30661496%5Bpmid%5D)
1. [Dlamini N et al: Arterial wall imaging in pediatric stroke. Stroke. 49(4):891-98, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=29581340%5Bpmid%5D)
1. [Khalaf A et al: Pediatric stroke imaging. Pediatr Neurol. 86:5-18, 2018](http://www.ncbi.nlm.nih.gov/pubmed/?term=30122281%5Bpmid%5D)
1. [Beslow LA: Stroke diagnosis in the pediatric emergency department: an ongoing challenge. Stroke. 48(5):1132-3, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28336680%5Bpmid%5D)
1. [Satti S et al: Mechanical thrombectomy for pediatric acute ischemic stroke: review of the literature. J Neurointerv Surg. 9(8):732-7, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=27448827%5Bpmid%5D)
1. [Wilson JL et al: Endovascular therapy in pediatric stroke: utilization, patient characteristics, and outcomes. Pediatr Neurol. 69:87-92.e2, 2017](http://www.ncbi.nlm.nih.gov/pubmed/?term=28233666%5Bpmid%5D)
1. [Madaelil TP et al: Mechanical thrombectomy in pediatric acute ischemic stroke: clinical outcomes and literature review. Interv Neuroradiol. 22(4):426-31, 2016](http://www.ncbi.nlm.nih.gov/pubmed/?term=26945589%5Bpmid%5D)
1. [Polan RM et al: Susceptibility-weighted imaging in pediatric arterial ischemic stroke: a valuable alternative for the noninvasive evaluation of altered cerebral hemodynamics. AJNR Am J Neuroradiol. 36(4):783-8, 2015](http://www.ncbi.nlm.nih.gov/pubmed/?term=25477354%5Bpmid%5D)
1. [Bernard TJ et al: Emergence of the primary pediatric stroke center: impact of the thrombolysis in pediatric stroke trial. Stroke. 45(7):2018-23, 2014](http://www.ncbi.nlm.nih.gov/pubmed/?term=24916908%5Bpmid%5D)
1. [Gemmete JJ et al: Arterial ischemic stroke in children. Neuroimaging Clin N Am. 23(4):781-98, 2013](http://www.ncbi.nlm.nih.gov/pubmed/?term=24156865%5Bpmid%5D)
1. [Kitchen L et al: The pediatric stroke outcome measure: a validation and reliability study. Stroke. 43(6):1602-8, 2012](http://www.ncbi.nlm.nih.gov/pubmed/?term=22474056%5Bpmid%5D)
1. [Beslow LA et al: Hemorrhagic transformation of childhood arterial ischemic stroke. Stroke. 42(4):941-6, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21350202%5Bpmid%5D)
1. [Cárdenas JF et al: Pediatric stroke. Childs Nerv Syst. 27(9):1375-90, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21336993%5Bpmid%5D)
1. [Dowling MM et al: Intracardiac shunting and stroke in children: a systematic review. J Child Neurol. 26(1):72-82, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21212453%5Bpmid%5D)
1. [Lanni G et al: Pediatric stroke: clinical findings and radiological approach. Stroke Res Treat. 2011:172168, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21603166%5Bpmid%5D)
1. [Larrue V et al: Etiologic investigation of ischemic stroke in young adults. Neurology. 76(23):1983-8, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21646623%5Bpmid%5D)
1. [Munot P et al: Characteristics of childhood arterial ischemic stroke with normal MR angiography. Stroke. 42(2):504-6, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21193747%5Bpmid%5D)
1. [Sedney CL et al: Cervical abnormalities causing vertebral artery dissection in children. J Neurosurg Pediatr. 7(3):272-5, 2011](http://www.ncbi.nlm.nih.gov/pubmed/?term=21361766%5Bpmid%5D)
1. [Lopez-Vicente M et al: Diagnosis and management of pediatric arterial ischemic stroke. J Stroke Cerebrovasc Dis. 19(3):175-83, 2010](http://www.ncbi.nlm.nih.gov/pubmed/?term=20434043%5Bpmid%5D)
1. [Shellhaas RA et al: Mimics of childhood stroke: characteristics of a prospective cohort. Pediatrics. 118(2):704-9, 2006](http://www.ncbi.nlm.nih.gov/pubmed/?term=16882826%5Bpmid%5D)
## Images
### Selected Images
![Axial DWI MR in a 4-day-old term neonate presenting with seizures shows diffusion restriction <img src='img/arrows/CS.png'/> throughout the left middle cerebral artery (MCA) territory, consistent with a perinatal arterial ischemic stroke (PAIS).](images/app.statdx.com_image_thumbnail_a3c930b4-482e-4cf0-90e4-b39fe2956e04_annotated_true_size_900_quality_90_0ab7ec77182d251abcc32ec93dc514df91cd0baa.jpg)
*Axial DWI MR in a 4-day-old term neonate presenting with seizures shows diffusion restriction <img src='img/arrows/CS.png'/> throughout the left middle cerebral artery (MCA) territory, consistent with a perinatal arterial ischemic stroke (PAIS).*
![Axial DWI MR in a 4-day-old term neonate presenting with seizures shows diffusion restriction <img src='img/arrows/CS.png'/> throughout the left middle cerebral artery (MCA) territory, consistent with a perinatal arterial ischemic stroke (PAIS).](images/app.statdx.com_image_thumbnail_a3c930b4-482e-4cf0-90e4-b39fe2956e04_size_174_quality_85_80f5ab910133900e39d9bb5b819a3b9d41218bbd.jpg)
*Axial DWI MR in a 4-day-old term neonate presenting with seizures shows diffusion restriction <img src='img/arrows/CS.png'/> throughout the left middle cerebral artery (MCA) territory, consistent with a perinatal arterial ischemic stroke (PAIS).*
![Axial T2 MR in the same patient 2 years later shows cystic encephalomalacia <img src='img/arrows/CS.png'/> throughout left MCA territory &amp; passive enlargement of the left lateral ventricle <img src='img/arrows/CO.png'/>. Patients with PAIS who do not present near birth with seizures may later present with early hand preference or extremity weakness.](images/app.statdx.com_image_thumbnail_be6b168d-b342-49c4-9de1-5e6a0226ff5c_annotated_true_size_900_quality_90_685838e55d91cbe0c752474ca3a75ad7b5594d01.jpg)
*Axial T2 MR in the same patient 2 years later shows cystic encephalomalacia <img src='img/arrows/CS.png'/> throughout left MCA territory &amp; passive enlargement of the left lateral ventricle <img src='img/arrows/CO.png'/>. Patients with PAIS who do not present near birth with seizures may later present with early hand preference or extremity weakness.*
![Axial FLAIR MR in a 2-year-old girl shows multiple areas of cytotoxic edema <img src='img/arrows/CS.png'/> in both cerebral hemispheres in this patient with moyamoya-type vasculopathy.](images/app.statdx.com_image_thumbnail_7199d868-43a2-4218-bcf0-550d4b57028a_annotated_true_size_900_quality_90_8b262bcefd2fc927baa9f8c52665245fd01c0231.jpg)
*Axial FLAIR MR in a 2-year-old girl shows multiple areas of cytotoxic edema <img src='img/arrows/CS.png'/> in both cerebral hemispheres in this patient with moyamoya-type vasculopathy.*
![Axial DWI MR in the same patient with moyamoya-type vasculopathy shows diffusion restriction in the right frontoparietal foci of signal abnormality <img src='img/arrows/CS.png'/>, suggesting an acute/subacute infarct. However, there is no diffusion restriction in the left parietal region <img src='img/arrows/WO.png'/>, suggesting this infarct is of an older age. Acute stroke should prompt careful arterial evaluation.](images/app.statdx.com_image_thumbnail_2ed900c4-b7c2-4d7c-98d7-ec2fdc3a765b_annotated_true_size_900_quality_90_36d86a963b4e78d21f25bde022e6ec6ecb27cd17.jpg)
*Axial DWI MR in the same patient with moyamoya-type vasculopathy shows diffusion restriction in the right frontoparietal foci of signal abnormality <img src='img/arrows/CS.png'/>, suggesting an acute/subacute infarct. However, there is no diffusion restriction in the left parietal region <img src='img/arrows/WO.png'/>, suggesting this infarct is of an older age. Acute stroke should prompt careful arterial evaluation.*
### Additional Images
![Axial NECT in a 15-year-old girl with dilated cardiomyopathy shows a large area of low attenuation in the right MCA territory <img src='img/arrows/CS.png'/>. Note the sulcal effacement &amp; loss of the gray matter-white matter differentiation.](images/app.statdx.com_image_thumbnail_20436327-00d8-4e86-83a0-411f6da8bddd_annotated_true_size_900_quality_90_fc343c2a802a63468922a8d5c17d35d42531777f.jpg)
*Axial NECT in a 15-year-old girl with dilated cardiomyopathy shows a large area of low attenuation in the right MCA territory <img src='img/arrows/CS.png'/>. Note the sulcal effacement &amp; loss of the gray matter-white matter differentiation.*
![Axial DWI MR in the same patient confirms restricted diffusion in the right MCA territory <img src='img/arrows/CS.png'/>. Also note the focus of restricted diffusion in the left periventricular region <img src='img/arrows/WO.png'/>. Multiple infarcts in multiple vascular territories should raise suspicion of a proximal embolic source.](images/app.statdx.com_image_thumbnail_0cf1ee69-2d45-47fc-abbf-a405593abc8e_annotated_true_size_900_quality_90_c3fbd5e76773f37c39afe7fa5e53e21920941d8c.jpg)
*Axial DWI MR in the same patient confirms restricted diffusion in the right MCA territory <img src='img/arrows/CS.png'/>. Also note the focus of restricted diffusion in the left periventricular region <img src='img/arrows/WO.png'/>. Multiple infarcts in multiple vascular territories should raise suspicion of a proximal embolic source.*
![Axial DWI MR in a 16-year-old boy involved in a motor vehicle collision (MVC) shows multiple small foci of diffusion restriction <img src='img/arrows/CS.png'/>, consistent with small infarcts. Multiple infarcts should raise concern for dissection, especially when confined to a single arterial territory.](images/app.statdx.com_image_thumbnail_08013541-3569-428b-a073-46a440578918_annotated_true_size_900_quality_90_e88d994a3efe08014119586abc3d1b283fd47527.jpg)
*Axial DWI MR in a 16-year-old boy involved in a motor vehicle collision (MVC) shows multiple small foci of diffusion restriction <img src='img/arrows/CS.png'/>, consistent with small infarcts. Multiple infarcts should raise concern for dissection, especially when confined to a single arterial territory.*
![Axial CTA in the same patient with multiple infarcts shows vessel wall irregularity &amp; an intimal flap in the left internal carotid artery (ICA) <img src='img/arrows/WS.png'/>, consistent with dissection. The right ICA <img src='img/arrows/CS.png'/> is small &amp; showed areas of irregularity on other images (not shown). The findings are consistent with bilateral ICA dissections.](images/app.statdx.com_image_thumbnail_4087c464-48ba-4d24-bfaa-8b3e28717e77_annotated_true_size_900_quality_90_2398208c6d0186ddb2a4b3ede41b920daa5f972f.jpg)
*Axial CTA in the same patient with multiple infarcts shows vessel wall irregularity &amp; an intimal flap in the left internal carotid artery (ICA) <img src='img/arrows/WS.png'/>, consistent with dissection. The right ICA <img src='img/arrows/CS.png'/> is small &amp; showed areas of irregularity on other images (not shown). The findings are consistent with bilateral ICA dissections.*
![Axial T1 C+ MR in a 2-year-old girl shows cortical enhancement <img src='img/arrows/CS.png'/> in the region of a right frontoparietal infarct, suggesting that it is at least a week old.](f529ad80-3bab-4832-9bfd-37ffd148e5d8)
*Axial T1 C+ MR in a 2-year-old girl shows cortical enhancement <img src='img/arrows/CS.png'/> in the region of a right frontoparietal infarct, suggesting that it is at least a week old.*
![Axial 3D TOF MRA in a 2-year-old with multiple infarcts of various ages shows multiple tiny foci of flow-related signal in the bilateral thalami <img src='img/arrows/CS.png'/>. This appearance is consistent with lenticulostriate collaterals of moyamoya-type vasculopathy in the setting of bilateral carotid terminus occlusions.](e1364043-c1b5-4d16-94a3-fc68e9a0f9d1)
*Axial 3D TOF MRA in a 2-year-old with multiple infarcts of various ages shows multiple tiny foci of flow-related signal in the bilateral thalami <img src='img/arrows/CS.png'/>. This appearance is consistent with lenticulostriate collaterals of moyamoya-type vasculopathy in the setting of bilateral carotid terminus occlusions.*
![Axial T2 MR in a high school football player who developed vomiting, confusion, &amp; vertigo during a game shows gyral swelling &amp; hyperintense signal in the medial temporal lobe <img src='img/arrows/WS.png'/>, which is in the vascular territory of the left posterior cerebral artery. Intracranial MRA acquired at the same time showed a small embolus in the left posterior cerebral artery (PCA).](dc16aa78-80c3-4b6b-97d0-2794e588c407)
*Axial T2 MR in a high school football player who developed vomiting, confusion, &amp; vertigo during a game shows gyral swelling &amp; hyperintense signal in the medial temporal lobe <img src='img/arrows/WS.png'/>, which is in the vascular territory of the left posterior cerebral artery. Intracranial MRA acquired at the same time showed a small embolus in the left posterior cerebral artery (PCA).*
![Axial CTA of the cervical arteries in the same patient shows a subtle linear filling defect <img src='img/arrows/WS.png'/>, consistent with an intimal flap in the left vertebral artery.](f3b3551b-cb0b-4ac2-b489-4610cb12d28b)
*Axial CTA of the cervical arteries in the same patient shows a subtle linear filling defect <img src='img/arrows/WS.png'/>, consistent with an intimal flap in the left vertebral artery.*
![Axial NECT in a 2-da-old with congenital heart disease &amp; seizures shows a well-defined, wedge-shaped region of ↓ attenuation <img src='img/arrows/WS.png'/> corresponding to the left MCA vascular territory, consistent with an acute/subacute arterial ischemic stroke.](167963a3-a5d4-41ba-b048-101de8e48c69)
*Axial NECT in a 2-da-old with congenital heart disease &amp; seizures shows a well-defined, wedge-shaped region of ↓ attenuation <img src='img/arrows/WS.png'/> corresponding to the left MCA vascular territory, consistent with an acute/subacute arterial ischemic stroke.*
![Axial T1 C+ MR in an 8-year-old with a history of neurofibromatosis type I &amp; known bilateral carotid terminus occlusions (resulting in a moyamoya-type vasculopathy pattern) shows abnormal sulcal enhancement (the climbing ivy sign) <img src='img/arrows/CS.png'/> due to arterial collaterals distal to a proximal occlusion.](6333898f-b0d4-48d5-8092-4d9044f4121d)
*Axial T1 C+ MR in an 8-year-old with a history of neurofibromatosis type I &amp; known bilateral carotid terminus occlusions (resulting in a moyamoya-type vasculopathy pattern) shows abnormal sulcal enhancement (the climbing ivy sign) <img src='img/arrows/CS.png'/> due to arterial collaterals distal to a proximal occlusion.*
![Axial NECT shows a segment <img src='img/arrows/WO.png'/> of the left insular cortical ribbon that is no longer visible on this axial NECT in a 9-year-old with acute right hemiparesis. This subtle finding may be the first indicator of an acute stroke.](6db3a366-dbe9-4643-80e6-e15c54002d04)
*Axial NECT shows a segment <img src='img/arrows/WO.png'/> of the left insular cortical ribbon that is no longer visible on this axial NECT in a 9-year-old with acute right hemiparesis. This subtle finding may be the first indicator of an acute stroke.*
![Axial T1 C+ MR shows the typical climbing ivy pattern of arterial collateral enhancement <img src='img/arrows/CS.png'/> in distal territories caused by proximal occlusion from a moyamoya-type vasculopathy. Note the white matter infarct on the left <img src='img/arrows/WS.png'/>.](63ff6aa5-cff0-4e42-b280-c61fc310a0d3)
*Axial T1 C+ MR shows the typical climbing ivy pattern of arterial collateral enhancement <img src='img/arrows/CS.png'/> in distal territories caused by proximal occlusion from a moyamoya-type vasculopathy. Note the white matter infarct on the left <img src='img/arrows/WS.png'/>.*
![Coronal T2 MR shows multiple areas of infarction <img src='img/arrows/WS.png'/> resulting from left hemisphere herniation. Secondary infarction from herniation can cause more morbidity than the initial insult.](80ae88ad-05f4-453e-9598-a44242f3594f)
*Coronal T2 MR shows multiple areas of infarction <img src='img/arrows/WS.png'/> resulting from left hemisphere herniation. Secondary infarction from herniation can cause more morbidity than the initial insult.*
![Axial DWI MR shows a characteristic watershed distribution of infarction in the right cerebral hemisphere. This infarct was the result of a carotid terminus stenosis that developed from bacterial meningitis &amp; vasculitis.](2f63d07a-0f89-49ce-8810-2c9d1ee922df)
*Axial DWI MR shows a characteristic watershed distribution of infarction in the right cerebral hemisphere. This infarct was the result of a carotid terminus stenosis that developed from bacterial meningitis &amp; vasculitis.*
![Axial NECT in a 14-year-old boy with acute right hemiparesis shows a hyperdense MCA sign <img src='img/arrows/WS.png'/>, indicating acute thrombus in a proximal middle cerebral artery branch.](9df8cd0b-6d68-467c-8b9c-af6dde1f6cfb)
*Axial NECT in a 14-year-old boy with acute right hemiparesis shows a hyperdense MCA sign <img src='img/arrows/WS.png'/>, indicating acute thrombus in a proximal middle cerebral artery branch.*
![Coronal FLAIR MR in the same patient shows edema in the insular cortex &amp; frontal operculum supplied by the affected MCA branch <img src='img/arrows/WS.png'/>. The patient had complete recovery without direct treatment, &amp; no etiology was found.](fbbd6bf9-9fa8-4dc8-af4d-f4295840073e)
*Coronal FLAIR MR in the same patient shows edema in the insular cortex &amp; frontal operculum supplied by the affected MCA branch <img src='img/arrows/WS.png'/>. The patient had complete recovery without direct treatment, &amp; no etiology was found.*
![Axial FLAIR MR in a 13-year-old girl with seizures after using ephedra shows foci of ↑ cortical &amp; subcortical white matter signal in the right PCA &amp; left superior cerebellar artery distributions <img src='img/arrows/WS.png'/>.](0e9f8a37-be57-4405-9495-a44649f1def6)
*Axial FLAIR MR in a 13-year-old girl with seizures after using ephedra shows foci of ↑ cortical &amp; subcortical white matter signal in the right PCA &amp; left superior cerebellar artery distributions <img src='img/arrows/WS.png'/>.*
![Sagittal oblique volume-rendered MRA in the same child shows multiple foci of arterial narrowing <img src='img/arrows/WS.png'/> &amp; dilation <img src='img/arrows/WO.png'/> due to a primary arteritis of the CNS.](a09d3907-0d0a-4fbb-b7e9-a576765c3b7d)
*Sagittal oblique volume-rendered MRA in the same child shows multiple foci of arterial narrowing <img src='img/arrows/WS.png'/> &amp; dilation <img src='img/arrows/WO.png'/> due to a primary arteritis of the CNS.*
![Axial CECT shows a subtle linear filling defect <img src='img/arrows/WC.png'/> in the left ICA of a child presenting with a left hemisphere infarct after mandibular surgery. The defect represents an arterial dissection.](935f0b6f-b82f-4816-827d-d655b80c3672)
*Axial CECT shows a subtle linear filling defect <img src='img/arrows/WC.png'/> in the left ICA of a child presenting with a left hemisphere infarct after mandibular surgery. The defect represents an arterial dissection.*
![Axial T2 MR shows predominately cortical/subcortical swelling &amp; abnormal signal <img src='img/arrows/WS.png'/> of the left parietal lobe, typical of a subacute left MCA territory infarct. Approximately 1/3 of childhood strokes will not have an underlying etiology diagnosed.](8e6dea72-c90f-4204-a73b-05e766c665d5)
*Axial T2 MR shows predominately cortical/subcortical swelling &amp; abnormal signal <img src='img/arrows/WS.png'/> of the left parietal lobe, typical of a subacute left MCA territory infarct. Approximately 1/3 of childhood strokes will not have an underlying etiology diagnosed.*