Metabolic Disorders primarily affecting white matter

Metabolic Disorders primarily affecting white matter

Bhagwan Moorjani

American Society of Neuroimaging

37th Annual Meeting

Disclosure

? Nothing to disclose ? Images were obtained form the following

sources

? Bhagwan Moorjani personal collection ? Barkovich pediatric neuroimaging books and

online ? Amirsys online library ? ? Mary Rutherford Imaging ? AJNR

Radiologic Evaluation

? Does not take into account the clinical presentation ? Age is important to know ? Major symptom is also important to know

? Pattern recognition ? White matter vs gray matter vs mixed ? Need to differentiate between delayed myelination

(improving) or hypomyelination (permanent) ? Confluent or multifocal ? Progressive or static ? Atrophy or edema ? Symmetric or asymmetric

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Clinical Evaluation

? Is it developmental delay or regression

? Global ? Motor ? Speech and language

? Is there a 2nd predominant symptom

? Epilepsy ? Ataxia ? Behavioral changes/cognitive/dementia

Head Circumference

Macrocephalic ? Canavan ? Alexander ? Tay Sachs (GM2

gangliosidosis) ? Vanishing White Matter ? Van der Knaap Disease ? L-2-hydroxyglutaric aciduria ? NF1 ? Hypomelanosis of Ito

Microcephalic/Normal ? ALD ? MLD ? Cockayne Disease ? Pelizaeus Merzbacher

disease ? Zellweger Disease ? Krabbe

White Matter Disorders

? Knowledge of normal myelination pattern is essential

? General rules:

? Caudal to cranial ? Posterior to anterior

? MRI provides the best imaging modality

? T1 matures at 12-14 months ? T2 matures at 24-26 months

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1 month

9 months

36 months

From Alberico

Definitions

? Myelination delay

? progression of myelination pattern after 6 months

? Static/permanent myelination pattern

? Pattern is unchanged on 2 MRIs after 6-12 months apart in children over 1 year of age

MR Imaging Definition

? Leukodystrophy

? T2 W ? hyperintensity ? T1 W ? variable

? Hypomyelinating leukodystrophy

? T2 W ? hyperintensity ? T1 W ? iso or hyperintense

? Demyelinating Leukodystrophy/other myelin

? T2 W ? hyperintensity ? T1 W - hypointense

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White Matter Disorders What structures are involved

? Subcortical U fibers ? Diffuse subcortical involvement ? Thalami involvement ? Brainstem ? particularly corticospinal tract ? Lack of myelination ? Nonspecific white matter pattern

White Matter Disorder

MRI predominance

? Diffuse ? Periventricular ? Subcortical ? Cerebellar ? Brainstem ? Cortex

Subcortical white matter (U- fibers)

? Alexander disease ? Frontal, small NAA peak, large head

? Van der Knaap disease ? Subcortical cyst

? Canavan Disease ? Galactosemia ? Salla Disease

? Free sialic acid in urine ? 4-hydroxybutyric aciduria (6p22.3)

? Cerebellar atrophy ? succinic semialdehyde dehydrogenase deficiency

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Leukodystrophies

? Abnormal signal in white matter ? Symmetric usually ? Periventricular, deep or subcortical in location ? Failure to achieve myelination milestones ? MRS abnormalities reflect neuronal loss and

increased cellular turnover ? Some have contrast enhancement

? ALD: zone of active inflammation ? Alexander: ventricular lining, periventricular rim, frontal

WM, optic chiasm, fornix, BG, thalamus, dentate nucleus

Leukodystrophies Differential Diagnosis

? Radiation and Chemotherapy injury ? Viral encephalitis ? ADEM ? MS ? In neonates: HIE

? Periventricular pattern

Alexander Disease

? Clinical S/S: macrocephaly, seizures ? Mutation: GFAP, Chromosome 17q21 ? Imaging

? Extensive WM changes with frontal predominance ? Abnormal signal in BG and thalami ? Enhancement: ventricular lining, periventricular rim,

frontal WM, optic chiasm, fornix, BG, thalamus, dentate nucleus

? Give contrast to all unknown cases of hydrocephalus and abnormal WM

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