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Canavan Disease


KEY FACTS

Terminology

  • Progressive autosomal-recessive spongiform leukodystrophy

    • a.k.a. spongy degeneration of infancy

  • Aspartoacyclase deficiency (autosomal recessive)

Imaging

  • White matter

    • Involves subcortical U fibers

    • Spares internal capsule and corpus callosum

  • Gray matter

    • Thalami, globi pallidi (GP), ± dentate nuclei

    • Spares caudate, putamen

  • ↑ T2 + DWI signal, normal to ↓ apparent diffusion coefficient in involved areas

  • MRS shows ↑ NAA/Cr, ↓Ch/Cr

Top Differential Diagnoses

  • Maple syrup urine disease

  • Pelizaeus-Merzbacher disease

  • Merosin-deficient congenital muscular dystrophy

  • Alexander disease

Pathology

  • Deficiency of aspartoacylase → NAA ↑ in brain and urine

  • Spongiform degeneration of white matter; GP and thalami with swollen astrocytes

Clinical Issues

  • Early severe hypotonia and macrocephaly

  • Evident by 4 months

  • ↑ risk for Ashkenazi Jewish patients (1 in 40 carriers)

  • Relentless, progressive neurodegenerative disorder

    • Chronic vegetative state with autonomic crises

    • Death by end of 1st decade

  • No proven treatment (gene therapy under evaluation)

    • Acetate supplementation

Axial T2WI MR in a 6-month-old infant boy shows diffusely increased signal in the cerebral white matter, thalami
, and right globus pallidus
with relative sparing of the internal capsule, corpus callosum, caudate, and putamen.

Axial T1WI MR in the same 6-month-old infant shows diffusely decreased signal in the white matter, thalami
, and globi pallidi
. Normal signal intensity is present within the internal capsule, corpus callosum, caudates, and putamina.

Axial DWI MR in the same 6-month-old infant shows diffusely increased signal (reduced diffusivity) in the cerebral white matter and globi pallidi
. Normal diffusivity is seen in the myelinated internal capsule and corpus callosum. Caudates and putamina appear unaffected.

Axial long echo (TE = 144 ms) proton MRS acquired in the centrum semiovale at 1.5T shows a marked relative increase in NAA
and decrease in choline
relative to Cr for age.

TERMINOLOGY

Abbreviations

  • Canavan disease (CD)

Synonyms

  • Spongiform leukodystrophy, spongy degeneration of CNS, Canavan-van Bogaert-Bertrand disease, aspartoacylase deficiency, ASPA deficiency, ASP deficiency, aminoacylase 2 deficiency, ACY2 deficiency

Definitions

  • Progressive fatal autosomal-recessive spongiform leukodystrophy

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