• 1 gad enh or 9 T2 hyper lesions
• 1+ infratentorial lesions
• 1+ juxtacortical
• 3+ periventricular

• Devic's dz - transverse myelitis & B optic neuritis
  • severe
• Balo's dz - MS lesion w/ concentric demyelination & nl brain
• Schilder's dz - acute, rapid, B symmetric demyelination
  • large, well-circ involving centrum & occ lobes
• Marburg variant - repeated relapses w/ rapidly accumulating disability

• Lyme
• vasculidities
• HTN & ischemic wm lesions
• virchow-robin spaces
• migraine
• trauma (DAI)
• UBO's

• Causes - measles, varicella, mumps, rubella, EBV, CMV, M. pneumoniae
• multiple, large high T2 lesions which may enhance in a nodular or ring pattern
• usually affects cerebrum but may enlarge cord
• fulminant type is acute hemorrhagic leukoencephalitis (Hurst's dz)
• diffuse multifocal perivascular demylelination & hemmorhage in cerebral WM w/ sparing of U-fibers

• JC virus
• assoc w/ immunocompromise
• asymmetric parietal & frontal involvement, but can be anywhere
• low T1, high T2
• no enhancement, no mass effect

• symmetric supratentorial demyelination
• does not extend to GW junction
• no mass effect
• atrophy

• sequela of measles infection
• patchy WM demyelination sparing U-fibers
• asymmetric gray & white matter involvement in parietooccipital region

• older men & women
• assoc w/ HTN & lacunar infarction
• broad high signal areas w/i FPO WM
• U-fibers spared

• inherited arterial dz
• recurrent TIA, stroke, dementia, depression, pseudobulbar palsy, hemi/quadriplegia
• F/T/insula w/ subcortical U-fiber involvement
• High T2 in WM (periventricular, deep WM, BG, brain stem)

• occurs after anoxic episode severe enough to produce coma
• recovery after 24-48 hrs, then precipitous decline in 2-wk period to death
• high T2 throughout WM particularly involving corpus callosum, subcortical U-fibers, int/ext capsules
• diffusion positive

• high T2 in PO cortex & SCWM
• can extend to other regions
• enhancement variable
• does not restrict
• assoc w/
  1. malignant HTN
  2. toxemia of pregnancy
  3. renal dz
  4. immunosuppressive drugs (cyclosporine, FK-501)
  5. antiphospholipid ab syndrome
  6. porphyria

• alcoholic, debilitated, malnourished pt's w/ rapid correction of hyponatremia
• may involve extrapontine stx (thalamus, caudate, putamen, internal external & extreme capsules, claustrum, amygdala, cerebellum, deep gray matter)
• high T2 in pons w/ peripheral sparing and sparing of CST

• Biconvex shape (lentiform)
• Usually in the temporoparietal regions but can be in the occipital region
• Usually accompanied with a skull fracture and tear of a branch of the middle meningeal artery
• Does NOT cross suture lines, but can cross midline
• Usually has more mass effect, but not always, depending on size

• Subdural is crescent shaped typically along the temporoparietal regions as well, and is associated with tearing of the bridging veins
• DO cross sutures lines, but DO NOT cross midline
• Fracture less commonly associated
• Can be bilateral and also interhemispheric, and along the tentorium.

• Subarachnoid you look for blood in the fissures, the basilar cisterns, interhemispheric, or in the interpeduncular fossa
• Blood in/around the circle of willis = star of texaco sign
• Blood along the posterior falx around the sinuses, you can get the delta sign

• Approach to intraparenchymal hemorrhage
  • If Ca²⁺ near hemorrhage think AVM
  • Perform MR immediately (before blood products become bright on T1)
  • If negative, f/u to resolution
• Approach to subarachnoid hemorrhage
  • Obtain CTA while pt is on the table
• Non-aneurysmal SAH = Venous hemorrhage
  • Perimesencephalic Cisterns
  • Small amount of blood
  • Asymptomatic

• Common Locations
  • AComm (33%)
  • PComm (33%)
  • MCA Bifurcation (20%)
  • Basilar Tip

• > 2.5 cm
• Common location is cavernous carotid

• Type 1
  • dural AV fistula
  • acquired lesion
  • most common spinal AVM
  • 1A - single feeding artery
  • 1B - multiple feeding arteries
  • nidus w/i or on dura of proximal nerve root sleeve in neural foramen
  • progressive myelopathy & (rarely) SAH
  • tx is surgical excision of nidus or endovascular glue
• Type 2
  • glomus AVM
  • intramedullary location
  • compact nidus
  • high-flow, produce flow-voids
  • drainage into coronal venous plexus
  • engorgement of post and/or anterior median vein
  • perimedullary flow voids
  • cord scalloping
  • serpentine enhancement
  • may cause enhancement in distant locations in cord
• Type 3
  • Juvenile-type AVM
  • more diffuse
  • less prone to hemorrhage
  • adolescents & young adults
  • poorer prognosis, not amenable to surg excision
  • typically cervical region
  • can involve extramedullary, extradural, and extraspinal structures
  • multiple arterial feeders, often from several different levels
• Type 4
  • Perimedullary (conus/cauda equina) fistulas
  • vary in severity
  • 4A - slow flow, mod enlg veins, single feeding art
    • tx surgically
  • 4C - high flow, markedly dil veins, multiple feeders
    • tx endovascularly
  • progressive myelopathy, SAH (50%), acute paraplegia

• Based on:
  • Size
  • Eloquence
  • Drainage (deep vs superficial)

• Tonsilar invagination through the foramen magnum into the spinal canal with variable degrees of tonsilar ectopia
• There is normal position of the 4th ventricle
• Syringohydromyelia is an associated finding
• Two components are necessary for the diagnosis - tonsilar herniation and syringohydromyelia
• May have associated basilar invagination, assimilation of C1 to the occiput, and Klippel-Feil

• Dysgenesis of the hindbrain with caudally displaced 4th ventricle and caudal elongation of the medulla and vermis
• Concurrent anomalies include: myelomeningocele, mesencephalic beaking (tectal beaking), enlarged massa intermedia, accessory anterior commissure, absence of the corpus callosum (which manifests as elevated third ventricle), partial absence of the falx, and cervicomedullary kinking
• Abnormalities of the bony vault include Luckenshadel (or lacunar) skull (appears as soap bubble lucencies in the upper calvaria)
• A dysplasia of bone and underlying dura
• Can be seen with any cause of meningocele and myelomeningocele

* A rare lesion that consists of herniation of cerebellum into a high cervical or occipital encephalocele

* Consists of extreme cerebellar hypoplasia without associated displacement

• Hyperacute (0-6 hrs)
  • iso T1/T2
  • high DWI/low ADC
    • DWI may be positive within 2 hours
• Acute (6 hrs-4 days)
  • low T1/high T2
  • mass effect
  • high DWI/low ADC
• Subacute (4-14 days)
  • low T1/high T2
  • resolving mass effect
  • T2 shine through on diffusion
  • pseudonormalization of ADC
• Chronic
  • encephalomalacia
  • high T2
  • T2 shine through on diffusion
  • high ADC

• IV w/i 3 hrs
• catheter directed w/i 6hrs

• Lateral medullary infarct
• affects CN 9,10
• causes hoarsness and dysphagia

• Recurrent artery of Heubner (aka medial lenticulostriate)
  • branch of ACA
  • caudate head, ant limb of internal capsule, septum pellucidum
• Lateral lenticulostriate
  • branch of MCA
  • lentiform nucleus, caudate capsule, internal capsule
• Thalamic and midbrain perforators
  • branch of PCA
• SCA
  • superior cerebellum
• AICA
  • inferolateral pons
  • middle cerebellar peduncle
  • anterior cerebellum