Friday 12 August 2011

Vasculitis Induced Infarct MRI

A 31 y o female came with mild fever, neck stiffness. Previous MRI brain on admission was normal. Csf evaluation suggestive of Tubercular Meningitis. 
After two days of admission pt started worsening, so follow up MRI brain done. 
Axial Flair images show patchy T2 hyper intensities with restricted diffusion in right basal ganglia and cranial portion of cerebellum, few punctate foci of restricted diffusion in thalami suggestive of Vasculitis induced infarcts.


Vasculitis or Inflammatory vasculopathy is a more general term indicating any vascular pathology.
Arteritis is a specifies arterial inflammation.
Angiitis is inflammation of either arteries or veins.

A non atheromatous inflammation and necrosis of blood vessel walls involves either arteries or veins.

CT relatively insensitive, may be normal. May see secondary signs such as ischemia as focal or multi focal areas of low attenuation in basal ganglia and or subcortical white matter.
MRI Brain with MR Angiography of Brain and Neck covering arch of Aorta is the investigation of choice.
Ischemic foci with or without restricted diffusion on Dw images depending upon age of infarct. T2*GRE images may show patchy low signal intensity hemosiderin staining owing to hemorrhage.
MR Angiography findings are variable may be normal to vessel irregularities, minimal focal or multi focal stenosis to completely occluded vessel. Affects intracranial vessels of any size.

Vasculitis can be primary or secondary, caused by broad spectrum of infectious, inflammatory, drugs etc.
Etiology wise
o Bacterial meningitis
Infarction due to vascular involvement seen in 25%. H. Influenzae most common organism, common in children
o Tuberculous meningitis
Vessels at the skull base and perforators most commonly involved as exudates commonly seen at basal cisterns.
o Mycotic arteritis (aspergillus, cocci, etc)
Actinomyces may invade vessel walls leading to hemorrhage
o Viral arteritis
Herpes simplex most common in North America
HIV-associated vasculitis increasing, especially in children
o Syphilis arteritis
Two forms: Syphilitic meningitis and gummatous vasculitis
Diffuse vasculitis involves cortical arteries and veins.
Gummatous vasculitis usually affects proximal MCA branches
o Polyarteritis nodosa
Most common systemic vasculitis to involve the CNS (though late)
Microaneurysms due to necrosis of the internal elastic lamina in 75%
o Cell mediated arteritides
Giant cell arteritis (granulomatous infiltration of the arterial walls)
Takayasu (primarily involves aorta, great vessels, branches)
Temporal arteritis (systemic; involves temporal, other extracranial arteries)
o Wegener
May cause intracerebral and meningeal granulomas or vasculitis
CNS involved in 15-30% due to direct invasion from nose/sinuses
Chronic systemic arteritis involving lungs, kidneys and sinuses
o Sarcoid (CNS involvement in 3-5% of cases)
Can extend along perivascular spaces, involve penetrating arteries
Meningitis, vasculitis involving vessels at the base of the brain
o Granulomatous angiitis (PACNS)
Primary angiitis isolated to the CNS (idiopathic)
Manifest as multiple intracranial stenoses
o Collagen vascular disease (SLE, rheumatoid, scleroderma)
SLE: Most common to involve the CNS, Vasculitis relatively uncommon (variable findings; small vessel irregularities/stenoses/occlusions up to fusiform aneurysms), CVA seen in 50% due to cardiac disease or coagulopathy
o Drug abuse vasculitis
Drug can injure vessels directly or secondarily (usually hypersensitivity to contaminants)
Associated with both legitimate and illegal "street" drugs including amphetamines, cocaine, heroin, and phenylpropanolamine and ergots
o Radiation
Acute arteritis produces transient white matter edema
Chronic changes more severe with vessel obliteration and brain necrosis, leukomalacia, calcifying micro angiopathy and atrophy.
Effects compounded with concomitant chemotherapy
o Moyamoya disease
Sometimes referred to as "idiopathic progressive arteriopathy of childhood"
Moyamoya is an angiographic pattern, not a specific disease; may be acquired as well as inherited
Any slowly progressive occlusion of the supraclinoid ICAs may develop Moyamoya pattern
The pattern has been reported with NF, atherosclerosis, radiation therapy.
Prognosis depends upon the rapidity and extent of the vascular occlusions as well as the development of effective collaterals

Several different classification systems have been proposed
- Primary intracranial vs secondary to a systemic disease
- True vasculitis (angiitis) vs noninflammatory vasculopathy.
- Infectious vs noninfectious
- Can be divided into those due to immune complex deposition vs cell-mediated disorders vs miscellaneous.

Clinical Presentation is often a stroke related to manifestations of vascular stenosis or occlusion
Variable age group from childhood (moyamoya disease) to adulthood
no gender predilection
Prognosis varies depending upon etiology; typically progressive if untreated
Should be treated aggressively with a combination of immunosuppressant.

Reference : Diagnostic imaging Osborn.

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