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title: "AHLE"
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docid: "0ec0bca6-abee-4931-a6ed-43541b626261"
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authors:
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- key: "5cff4116-3654-4b3a-bb75-5ebe0b8c9850"
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value: "Anne G. Osborn, MD, FACR"
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breadcrumbs:
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-
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name: "Brain"
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slug: "brain"
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treeNodeId: "6d8829f1-14d7-45af-8675-255189aa526a"
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name: "Diagnosis"
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slug: "diagnosis"
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treeNodeId: "51c00394-446e-4a38-94af-d3b1d14d34e8"
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name: "Pathology-Based Diagnoses"
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slug: "pathology-based-diagnoses"
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treeNodeId: "d9d3a8ed-f21b-4831-8c77-591a3500ef77"
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-
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name: "Infectious, Inflammatory, and Demyelinating Disease"
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slug: "infectious-inflammatory-and-demyel-"
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treeNodeId: "7210f860-fe5f-4a2d-81cc-4fe06c769607"
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-
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name: "Inflammatory and Demyelinating Disease"
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slug: "inflammatory-and-demyelinating-dis-"
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treeNodeId: "62ab4dc3-dbf6-45a9-8532-f0e962aa62dc"
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-
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name: "AHLE"
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slug: "ahle"
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treeNodeId: null
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category: "Brain"
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documentVersionId: "05d076c7-6110-4f03-952a-c22726d85e4d"
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imageCount: 12
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isBookmarked: false
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isComparable: true
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isInCompareCart: false
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lastUpdated: "08/05/20"
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pageDescription: "AHLE"
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pageKeywords: "Brain, Diagnosis, Pathology-Based Diagnoses, Infectious, Inflammatory, and Demyelinating Disease, Inflammatory and Demyelinating Disease, AHLE"
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pageTitle: "AHLE | STATdx"
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enhancedTitle: "AHLE"
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type: "DX"
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breadcrumbs:
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- "Brain"
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- "Diagnosis"
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- "Pathology-Based Diagnoses"
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- "Infectious, Inflammatory, and Demyelinating Disease"
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- "Inflammatory and Demyelinating Disease"
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- "AHLE"
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---
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# KEY FACTS
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- ## Terminology
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- Hyperacute, fulminant hemorrhagic perivascular demyelinating disorder
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- Usually viral or immunization related
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- ## Imaging
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- Best imaging: MR with T2* GRE, SWI
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- CT: May be normal if only microbleeds present
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- MR
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- Multifocal scattered or confluent WM hyperintensities on T2/FLAIR
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- T2* shows multifocal blooming microbleeds in WM (often striking sparing of cortex)
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- Most striking in corpus callosum
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- Less common: Large, lobar, confluent hemorrhages
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- SWI significantly more sensitive than GRE
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- ## Top Differential Diagnoses
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- Acute disseminated encephalomyelitis (ADEM)
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- Multiple sclerosis
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- Acute necrotizing encephalopathy
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- Other brain "microbleeds"
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- Critical illness associated (e.g., ARDS ± on ECMO)
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- Trauma (DAI), fat emboli, HUS/TTP
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- Sepsis, vasculitis, hemorrhagic viral fevers
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- High-altitude cerebral edema
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- ## Clinical Issues
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- Demographics
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- AHLE represents ~ 2% of ADEM cases
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- All ages but children, young adults most common
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- Presentation and course
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- Fever, then rapid neurologic deterioration
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- 60-80% mortality without treatment
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- ## Diagnostic Checklist
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- T2* (GRE or SWI) MR in all febrile CNS illnesses with rapid clinical deterioration
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# TERMINOLOGY
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- ## Abbreviations
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- Acute hemorrhagic leukoencephalitis (AHLE)
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- Acute disseminated encephalomyelopathy (ADEM)
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- ## Synonyms
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- Acute hemorrhagic encephalomyelitis (AHEM)
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- Weston-Hurst disease
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- ## Definitions
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- Hyperacute, fulminant, hemorrhagic perivascular demyelinating disorder
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- Usually post viral or immunization related
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- May be exceptionally severe, fulminant form of ADEM
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# IMAGING
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- ## General Features
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- ### Best diagnostic clue
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- T2* shows multifocal petechial white matter (WM) microhemorrhages with striking sparing of cortex
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- Less common: Large, lobar, confluent hemorrhages
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- ### Location
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- WM
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- Corpus callosum, subcortical WM (U fibers)
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- Less common: Basal ganglia, midbrain, pons, cerebellum
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- ### Size
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- Punctate microbleeds > large, lobar hemorrhages
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- ## CT Findings
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- ### NECT
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- May be normal if only microbleeds present
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- ± WM edema with hypodensity
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- ## MR Findings
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- ### T1WI
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- Often normal
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- ### T2WI
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- Multifocal scattered or confluent WM hyperintensities
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- Most striking in corpus callosum
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- May have reversible corpus callosum splenium lesion
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- ### T2* GRE
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- Multifocal blooming microbleeds
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- SWI significantly more sensitive than GRE
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- ## Imaging Recommendations
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- ### Best imaging tool
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- MR with T2* GRE, SWI
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# DIFFERENTIAL DIAGNOSIS
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- [Acute Disseminated Encephalomyelitis](/document/adem/a3fafeb7-5861-4364-beb8-c0e30220564e)
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- AHLE may be most severe form of ADEM
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- ADEM usually less fulminant
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- ADEM lacks lobar or perivascular hemorrhages of AHLE
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- [Multiple Sclerosis](/document/multiple-sclerosis/7892b2a2-f52a-4d7f-9858-a326f2b7ab04)
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- Acute fulminant multiple sclerosis
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- Lacks hemorrhage, high fever, marked leukocytosis
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- ## Acute Necrotizing Encephalopathy
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- Rare complication of acute viral infection, such as influenza A
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- Children < 4 years most common
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- Bilateral, symmetric lesions in thalami typical
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- WM predominance rare
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- ## Other Etiologies of Brain Microbleeds
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- Diffuse, traumatic vascular injury
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- Critical illness-associated (e.g., ARDS ± on ECMO)
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- Sepsis, vasculitis
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- Fat emboli
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- HUS/TTP
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- Hemorrhagic infections
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- Viral (H1N1, coronavirus), malaria, rickettsia
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- High-altitude cerebral edema
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# PATHOLOGY
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- ## Gross Pathologic & Surgical Features
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- Predominantly involves WM of brain ± spinal cord
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- May affect basal ganglia but usually spares cortical gray matter
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- Focal confluent &/or multifocal petechial WM hemorrhages
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- ## Microscopic Features
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- Fibrinoid necrosis of vessel walls
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- Perivascular demyelination, hemorrhages
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# CLINICAL ISSUES
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- ## Presentation
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- ### Most common signs/symptoms
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- Fever, then rapid neurologic deterioration
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- Somnolence, impaired consciousness
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- ### Other signs/symptoms
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- Long-tract signs
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- ## Demographics
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- AHLE represents ~ 2% of ADEM cases
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- All ages but children, young adults most common
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- ## Natural History & Prognosis
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- Rapid clinical deterioration; death within days typical course
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- Mortality: 60-80%
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- ## Treatment
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- Aggressive IV steroids, immunoglobulin, plasmapheresis
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# DIAGNOSTIC CHECKLIST
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- ## Consider
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- T2* (GRE or SWI) MR in all febrile CNS illnesses with rapid clinical deterioration
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- ## Image Interpretation Pearls
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- Corpus callosum, subcortical WM microbleeds with striking sparing of overlying cortex typical for AHLE
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8f325204-5ce7-4da8-b816-cb545fa5b054
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## Images
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### Selected Images
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*Close-up view of autopsied brain in a patient with acute hemorrhagic leukoencephalitis (AHLE) shows innumerable tiny microbleeds in the subcortical and deep white matter (WM) <img src='/img/arrows/BO.png'/> and corpus callosum <img src='/img/arrows/BS.png'/>. Note the overlying cortex is almost completely spared <img src='/img/arrows/BC.png'/>. (Courtesy E. Rushing, MD.)*
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*Close-up view of autopsied brain in a patient with acute hemorrhagic leukoencephalitis (AHLE) shows innumerable tiny microbleeds in the subcortical and deep white matter (WM) <img src='/img/arrows/BO.png'/> and corpus callosum <img src='/img/arrows/BS.png'/>. Note the overlying cortex is almost completely spared <img src='/img/arrows/BC.png'/>. (Courtesy E. Rushing, MD.)*
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*Close-up view of autopsied brain in a patient with acute hemorrhagic leukoencephalitis (AHLE) shows innumerable tiny microbleeds in the subcortical and deep white matter (WM) <img src='/img/arrows/BO.png'/> and corpus callosum <img src='/img/arrows/BS.png'/>. Note the overlying cortex is almost completely spared <img src='/img/arrows/BC.png'/>. (Courtesy E. Rushing, MD.)*
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*Axial FLAIR MR in a 28-year-old man with rapidly declining mental status after a flu-like illness shows patchy hyperintensities in the corpus callosum <img src='/img/arrows/WC.png'/> and deep/subcortical WM <img src='/img/arrows/WS.png'/>.*
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*Axial FLAIR MR in a 28-year-old man with rapidly declining mental status after a flu-like illness shows patchy hyperintensities in the corpus callosum <img src='/img/arrows/WC.png'/> and deep/subcortical WM <img src='/img/arrows/WS.png'/>.*
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*Axial T2* GRE MR in the same patient shows multiple tiny hypointensities in the corpus callosum <img src='/img/arrows/BC.png'/> and deep/subcortical WM <img src='/img/arrows/BS.png'/>. The cortex is largely spared.*
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*Axial T2* GRE MR in the same patient shows multiple tiny hypointensities in the corpus callosum <img src='/img/arrows/BC.png'/> and deep/subcortical WM <img src='/img/arrows/BS.png'/>. The cortex is largely spared.*
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*Axial T2* SWI MR MIP shows the innumerable microbleeds in the corpus callosum <img src='/img/arrows/CC.png'/> with diffuse involvement of the hemispheric WM <img src='/img/arrows/CS.png'/> in this patient with AHLE.*
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*Axial T2* SWI MR MIP shows the innumerable microbleeds in the corpus callosum <img src='/img/arrows/CC.png'/> with diffuse involvement of the hemispheric WM <img src='/img/arrows/CS.png'/> in this patient with AHLE.*
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### Additional Images
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*Axial FLAIR MR in a 25-year-old man with fever and rapidly decreasing mental status shows no definite abnormalities.*
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*Axial FLAIR MR in a 25-year-old man with fever and rapidly decreasing mental status shows no definite abnormalities.*
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*Axial T2* GRE MR in the same patient shows a few punctate "blooming" foci in the corpus callosum genu <img src='/img/arrows/WO.png'/> and splenium <img src='/img/arrows/WS.png'/>. The remainder of the WM appears normal.*
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*Axial T2* GRE MR in the same patient shows a few punctate "blooming" foci in the corpus callosum genu <img src='/img/arrows/WO.png'/> and splenium <img src='/img/arrows/WS.png'/>. The remainder of the WM appears normal.*
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*Axial SWI MR n the same patient shows innumerable tiny "blooming" microbleeds in the corpus callosum <img src='/img/arrows/BO.png'/> and subcortical and deep WM <img src='/img/arrows/BS.png'/>. The cortex is largely spared.*
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*More cephalad axial T2* SWI MR shows innumerable tiny "blooming" foci in the WM, especially in the corpus callosum <img src='/img/arrows/BC.png'/>. These imaging findings are characteristic of AHLE.*
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*Autopsy shows 2 areas of gross hemorrhagic necrosis <img src='/img/arrows/BS.png'/>. These findings and clinical history of prior flu-like illness with rapidly progressive fatal clinical course are characteristic of AHLE. (Courtesy R. Hewlett, MD).*
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*Axial T2* GRE MR in a patient with rapid decline after a flu-like illness shows a large left frontal hemorrhage <img src='/img/arrows/WO.png'/> with numerous "blooming" foci in multiple WM lesions <img src='/img/arrows/BS.png'/>. Diagnosis was AHLE. (Courtesy R. Ramakantan, MD).*
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*Axial NECT in a patient with AHLE shows patchy hemorrhages in the corpus callosum splenium <img src='/img/arrows/WS.png'/>.*
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*Axial T2* SWI MR MIP in the same patient shows the microbleeds are heavily concentrated in the corpus callosum <img src='/img/arrows/BC.png'/> and hemispheric WM <img src='/img/arrows/BS.png'/>. Note involvement of the internal capsules and relative sparing of the basal ganglia and cortex.*
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