Subcortical bilateral anterior temporal poles involved early

Diagnosis age 20-40 years is common, unique to CADASIL

External capsule involvement somewhat specific, but other WM regions, thalamus, BG, pons also commonly involved

Frontal lobe predominant involvement developing into confluent lesions will become more prominent after age 50

Migraine-like symptoms common, but CADASIL lesions larger than typical punctate lesions in migraineurs

Can have a multiple sclerosis-like appearance early in the disease, although callosal involvement is rare

Pial & leptomeningeal involvement with extension via perivascular spaces

Peripheral WM hyperintensities, intense enhancement

Parenchymal lesions can extend to the periventricular WM; usually confluent

Associated T2 hypointensity in dura & leptomeninges is characteristic, but can be seen with secondary lymphoma & metastasis

MR positive in 25%, involves hippocampus, WM, cerebellum

Lesions usually ill-defined, no enhancement

May mimic olivopontocerebellar degeneration (OPCD)

Multiple subcortical & cortical infarcts, often with peripheral subarachnoid hemorrhage

Peripheral segmental symmetric stenoses typical, not seen in CADASIL or chronic hypertensive disease

Scattered lesions 2-3 mm typical, usually less than 10 mm

May be DWI + & may enhance

Cortical involvement unusual

Myalgia, arthralgias, petechial rash of the palms & soles suggest Lyme disease

Midbrain, substantia nigra, cerebellum, & anterior horn of the spinal cord involvement typical

Moderate-sized lesions, ill-defined, leptomeningeal enhancement

Similar to neurosarcoid in distribution, T2 signal, & enhancement

Necrotizing vasculitis with paranasal sinus & orbital involvement

Limbic encephalitis: Hyperintensity in amygdala, hippocampus, cingulate gyrus, & inferior frontal lobe WM

Paraneoplastic cerebellar degeneration: Bilateral peripheral cerebellar & pontine involvement

Mild edema in the acute phase; atrophy in the chronic phase

Multifocal, often confluent periventricular hyperintensity

Radiating enhancement pattern along deep medullary veins

Cruciate T2 hyperintensity in lower pons

Cerebellar hemispheres more involved than vermis, with “fine comb” cerebellar folia in dominant form

Lateral cerebellar hemisphere atrophy with “fish mouth” deformity in recessive form

Multifocal large or diffuse T2 hyperintensity extending into the gyri with callosal involvement; no enhancement

Similar features to progressive multifocal leukoencephalopathy with differing past medical history

Diffuse atrophy with severe WM volume loss late

Presents in childhood or early adolescence

Early focal cortical swelling & gray-white differentiation loss, usually does not enhance

Atrophy of the cerebral hemisphere or a lobe late

Begins in childhood, progressive seizures, hemiparesis, cognitive deterioration

Globus pallidus, hippocampi, substantial nigra & dentate nuclei, T2 & T1 hyperintensity

Encephalopathy due to deposition of unconjugated bilirubin

Enhancing multiple rare T2 lesions

Nonenhancing multiple rare T2 lesions

Anterior temporal lobe: CADASIL, trauma

Limbic system/cerebellum: Paraneoplastic syndromes, herpes

Olive, pons, cerebellum: OPCD, multisystem atrophy

Unilateral hemisphere: Rasmussen encephalitis, Sturge-Weber, Dyke-Davidoff-Mason

Deep white matter: Granulomatous angiitis, intravascular lymphoma, Hashimoto, multiple sclerosis, arteriolosclerosis

Basal ganglia: Kernicterus, hypoxia, West Nile, Leigh, Wilson