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title: "Crossed Cerebellar Diaschisis"
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docid: "c1e384b3-3c6e-4f67-bf79-5187bd6a1b86"
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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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- "Acquired Toxic/Metabolic/Degenerative Disorders"
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- "Dementias and Degenerative Disorders"
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- "Crossed Cerebellar Diaschisis"
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---
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# KEY FACTS
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- ## Terminology
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- Diaschisis: Sudden loss of function in brain connected to (but at distance from) damaged area
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- CCD: ↓ blood flow/metabolism in cerebellar hemisphere contralateral to supratentorial infarct
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- ## Imaging
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- Acute: CT/MR perfusion shows ↓ CBF in cerebellar hemisphere opposite acute hemispheric infarct
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- ↑ TTP, ↓ CBF in cerebellum contralateral to infarct
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- Add DTI as subtle cases may show ↓ FA when conventional MR normal
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- F-18 FDG PET/CT shows diffusely reduced uptake in contralateral cerebellar hemisphere
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- Chronic: CT or MR shows atrophic cerebellar hemisphere opposite old cerebral hemispheric infarct/insult
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- ## Top Differential Diagnoses
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- Superior cerebellar artery infarct
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- CCD involved > just SCA territory
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- Encephalomalacia
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- Trauma, infection, surgery
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- Cerebellitis
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- Cerebellum swollen, hyperintense (not shrunken, atrophic)
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- Bilateral > unilateral
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- ## Pathology
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- CPC tract
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- Input to cerebellum via CPC tracts 40x all other afferent sources combined
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- Injury at any point along CPC can result in ↓ CBF, metabolism in contralateral cerebellar hemisphere
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- Most common cause: MCA infarct
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- Others: Status epilepticus, neoplasm, trauma, surgery,migraine, Rasmussen encephalitis, etc.
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- Occurrence & severity of CCD related to degree of low supratentorial perfusion & decrease in ADC value of infarct
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# TERMINOLOGY
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- ## Abbreviations
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- Crossed cerebellar diaschisis (CCD)
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- ## Definitions
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- Diaschisis: Sudden loss of function in brain connected to (but at distance from) damaged area
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- CCD: Decreased blood flow/metabolism in cerebellar hemisphere contralateral to supratentorial infarct
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- Caused by interrupted afferent input through corticopontocerebellar tract (CPC)
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- CCD occurs in both acute & chronic phases
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- Acute CCD results from functional deafferentation
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- Subacute, chronic CCD reflects transneuronal degeneration
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# IMAGING
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- ## General Features
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- ### Best diagnostic clue
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- Acute: CT/MR perfusion shows ↓ cerebral blood flow (CBF) in cerebellar hemisphere opposite acute cerebral hemispheric infarct
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- Chronic: CT or MR shows atrophic cerebellar hemisphere opposite old cerebral hemispheric infarct/insult
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- ### Location
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- Cerebellar hemisphere opposite cerebral hemispheric infarct
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- ## Imaging Recommendations
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- ### Best imaging tool
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- Acute: CT or MR perfusion
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- PET/CT also effective but expensive; variable availability
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- Chronic: MR with T2WI, FLAIR, DTI
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- ### Protocol advice
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- Add DTI as subtle cases may show ↓ fractional anisotropy (FA) when conventional MR normal
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- ## CT Findings
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- ### NECT
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- Acute: Normal
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- Chronic: Cerebellar atrophy contralateral to supratentorial infarct
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- ### CTA
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- Middle cerebral artery (MCA) occlusion
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- Cerebellar vessels appear normal
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- CT perfusion
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- ↑ TTP, ↓ CBF in cerebellum contralateral to infarct
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- ## MR Findings
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- ### T1WI
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- Unilateral cerebellar atrophy
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- ### T2WI
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- Folia shrunken, fissures enlarged
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- ### FLAIR
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- Except for atrophy, cerebellum usually normal
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- ### MRA
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- Posterior fossa vasculature normal
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- DTI
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- Shows ↓ FA in middle cerebellar peduncle
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- Visualizes altered CPC in chronic CCD that may not be seen on conventional MR
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- Arterial spin labeling (ASL) perfusion
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- ↓ CBF in cerebellum contralateral to cerebral hemispheric abnormality
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- ## Nuclear Medicine Findings
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- ### PET/CT
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- F-18 FDG PET/CT shows diffusely reduced uptake in contralateral cerebellar hemisphere
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- L-(methyl-11C) methionine (MET) uptake not reduced
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- ### Tc-99m sulfur colloid
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- Tc-99m ECD, HMPAO SPECT can demonstrate distant areas of ↓ CBF, metabolism (diaschisis)
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# DIFFERENTIAL DIAGNOSIS
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- ## Superior Cerebellar Artery Infarct
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- CCD involves most of cerebellum, not just superior cerebellar artery (SCA) territory
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- Contralateral MCA infarct absent
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- ## Encephalomalacia
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- No history of trauma, contralateral MCA infarct
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- [Cerebellitis](/document/cerebellitis/2a2d695e-63be-4839-9e1a-cd8813b005d6)
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- Cerebellum swollen, not shrunken
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- Bilateral > unilateral
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# PATHOLOGY
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- ## General Features
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- ### Etiology
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- CPC tract
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- Large afferent pathway derived from very extensive areas of cortex
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- Input to cerebellum via CPC tracts 40x all other afferent sources combined
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- 1st-order neurons arrive in ipsilateral pons
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- Synapse with 2nd-order neurons
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- Then cross to opposite cerebellar hemisphere via middle cerebellar peduncle
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- Injury at any point along CPC can result in ↓ CBF, metabolism in contralateral cerebellar hemisphere
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- Most common cause: MCA infarct
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- Others: Status epilepticus, neoplasm, trauma, surgery, migraine, Rasmussen encephalitis, etc.
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- Occurrence & severity of CCD related to degree of low supratentorial perfusion & decrease in ADC value of infarct
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# CLINICAL ISSUES
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- ## Natural History & Prognosis
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- CCD represents temporal continuum
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- Early, reversible functional hypometabolism
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- Cerebellum recovers (typical)
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- Irreversible degeneration in up to 20%
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- Cerebellar atrophy
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- Can be seen decades after initial insult
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d7407fea-fff9-488b-9712-71a4e559c250
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