Neuro -- White Matter Disease/metabolic

Front 1

What is the DDX of multifocal white matter lesions?

Back 1

DEMYELINATING CONDITIONS:
- Multiple sclerosis (involves corpus callosum and periventricular WM)
- Acute disseminated encephalomyelitis (involves subcortical and deep WM)
- Lyme disease
- SSPE
INFECTION
- AIDS
- Progressive multifocal leukoencephalopathy (PML): involves the subcortical U fibers. No enhancement.
- Encephalitis: pts are typically acutely ill with fever and alteration in consciousness. Typically also involves the gray matter.
INFLAMMATORY
Neurosarcoidosis: dirty white matter
VASCULAR:
Vasculitides: multifocal gray and white matter lesions. GRE may demonstrate multiple foci of hemorrhage. DSA reveals alternating stenoses and dilatation involving the cerebral arterial vasculature.
Small vessel ischemic disease: typically spares the corpus callosum and subcortical U fibers; no enhancement. May be advanced for age in pts with HTN, diabetes, and hyperlipidemia.
TOXIC/METABOLIC
- Typically symmetric white matter lesions
NEOPLASMS:
- Gliomatosis cerebri: infiltrating glial tumor that affects two or more lobes and is frequently bilateral. Minimal enhancement with relative preservation of underlying brain architecture.
- Lymphoma

Front 2

1. What is the etiology of subacute sclerosing panencephalitis (SSPE)?
2. What are the imaging findings of SSPE?

Back 2

1.
- Demyelinating condition
- 2/2 reactivation of latent measles virus.
- Seen between 5-15 years.
2.
- Increased signal intensity is seen in the CORTEX and SUBCORTICAL WHITE MATTER of the parietal and temporal lobes.
- With PROGRESSION, there is involvement of PERIVENTRICULAR WHITE MATTER and BRAINSTEM.

Front 3

1. What are the findings in MS?
2. How do you differentiate between tumefactive MS and a glioma?

Back 3

1.
- MS plaques are located in the CORPUS CALLOSUM and PERIVENTRICULAR WHITE MATTER.
- Uncommonly, they occur in the POSTERIOR FOSSA and gray matter structures such as BASAL GANGLIA and THALAMUS.
- Lesions of MS LACK MASS EFFECT or surrounding edema.
- INCOMPLETE RIM OF ENHANCEMENT representing the leading edge of demyelination which may help in differentiating tumefactive MS from glioma.
2. When the differential includes brain tumor vs. tumefactive MS, a follow up scan may be very helpful to assess the evolution and avoid unnecessary biopsy. Similarly, optic neuritis may mimic an optic glioma. Again, follow up imaging is helpful.

Front 4

What are the findings in ADEM?

Back 4

- Patchy bilateral asymmetric areas of T2 hyperintensity that cause little mass effect.
- In addition to the SUPRATENTORIAL WM, lesions are COMMON in the CEREBRLLUM and BRAINSTEM and DEEP GRAY MATTER. NOTE: thalamic involvement is rare in MS but not uncommon in ADEM.
- Although ADEM is a monophasic illness, not all lesions enhance at the same time because some lesions may be developing while others are resolving.

Front 5

1. What portions of the brain are typically affected in osmotic demyelination?
2. What are the findings in central pontine myelinolysis?
3. What are the findings in extrapontine myelinolysis?

Back 5

1.
- Osmotic demyelination typically affects the PONS known as CENTRAL PONTINE MYELINOLYSIS.
- Less commonly, osmotic demyelinatin can affect the thalamus,
putamina, and periventricular white matter. This is known as EXTRAPONTINE MYELINOLYSIS.
2. CPM:
- Diffuse central pontine hyperintensity on T2WI.
- No mass effect or enhancement
- SPARING of the CORTICOSPINAL TRACTS.
3. Extrapontine myelinolysis:
- Bilateral and symmetric increased T2SI of putamina, thalami, and periventricular white matter.
NOTE: EPM can occur in the absence of CPM.

Front 6

What is the DDX of predominantly parieto-occipital white matter hyperintensity?

Back 6

1. PRES
2. Cyclosporine induced neurotoxicity
3. Seizure (status epilepticus)
4. Watershed ischemia (b/w the MCA and PCA territories)

Front 7

1. Where are signal abnormalities associated with seizures/status epilepticus seen?
2. What are the imaging findings?

Back 7

1. Because the POSTERIOR CIRCULATION is prone to loss of autoregulation and disruption of BBB, white matter abnormalities are more commonly seen in PARIETO-OCCIPITAL regions in cases of status epilepticus. WM abnormalities may also be seen in the CEREBELLUM.
2.
- T2 hyperintensity involving GRAY and WHITE MATTER of the PARIETOCCIPITAL and POSTERIOR TEMPORAL REGIONS with a WM predominance.
- Patchy PARENCHYMAL ENHANCEMENT may be seen due to disruption of blood brain barrier.
- Imaging abnormalities resolve over days to weeks.

Front 8

1. What are the findings in carbon monoxide poisoning?

Back 8

1.
- SYMMETRIC ow attenuation/T2 hyperintensity in the GLOBUS PALLIDUS and WHITE MATTER.
- White matter involvement is diffuse and symmetric.
- T1 HYPERINTENSITY may also be seen in the globus pallidus representing petechial hemorrhage or dystrophic calcifiication.
- Cerebellum may also be involved.

Front 9

1. What are the characteristics of Canavan disease?
2. How do you differentiate Canavan disease from Alexander disease?

Back 9

1.
- AR WM disease caused by the deficiency of the enzyme N-acetylaspartase -- leads to accumulation of acetylaspartate (can be detected with MR spectroscopy).
- Increased T2 SI first in the subcortical white matter which eventually involves the deep white matter.
- INTERNAL CAPSULE is SPARED.
2. NOTE: both diseases result in MACROCEPHALY. Alexander disease has frontal lobe predominance. The INTERNAL CAPSULE is INVOLVED.

Front 10

1. What is the etiology of adrenoleukodystrophy?
2. What are the imaging findings?

Back 10

1. X-linked disorder due to enzymatic defect in the metabolism of very long-chain fatty acids, the accumulation of which leads to demyelination. It affects 5-10 year old boys.
Symptoms include learning difficulties, hearing/vision problems, gait abnormalities, signs of adrenal insufficiency (bronze skin, N/V, fatigue).
2.
- Hypoattenuation/T2 hyperintensity in the PERITRIGONAL/OCCIPITAL WHITE MATTER surrounding the atria and SPLENIUM of corpus callosum.
- Linear enhancement along the leading edge of the demyelination.
- CORTICOSPINAL TRACTS in the PONS and MEDULLA demonstrate high T2SI (this finding is not present in other leukodystrophies).
- Over time involvement will progress to the frontal white matter.
- Subcortical U fibers are spared.

Front 11

What are the imaging findings in metachromatic leukodystrophy?

Back 11

- Diffuse low density/hyperintensity in the white matter of the FRONTAL lobes.
- "Leopard skin" sign: linear hypointensities radiating from the ventricular margins within hyperintense periventricular white matter and the centrum semiovale on T2W MRI images. The sign represents a specific pattern of demyelination, with sparing of perivascular white matter. The spared perivascular white matter is seen as dark spots or dark linear areas against a background of bright affected white matter, giving the appearance of the skin of a leopard.
- Sparing of the subcortical U fibers.
NOTE: this is in contradistinction to adrenoleukodystrophy which hugs the periatrial white matter and involves the splenium. Also, there is no enhancement in metachromatic leukodystrophy.

Front 12

1. What is Leigh disease?
2. What are the imaging findings in Leigh disease?

Back 12

1. AKA subacute necrotizing encephalomyelopathy is a mitochondrial d/o resulting in impaired production of ATP.
2.
- T2 hyperintensity in the PUTAMINA b/l with atrophy of the putamina with time.
- Variable T2 hyperintensity in the caudate heads, periaqeuductal gray matter, thalami, and dorsomedial medulla.
- MR spect shows elevated lactate peak.

Front 13

Chemotherapeutic agents that cause white matter changes

Back 13

Cyclosporine, tacrolimus can lead to white matter signal abnormality.