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|Year : 2017 | Volume
| Issue : 5 | Page : 1191-1192
Canavan disease with typical brain MRI and MRS findings
Anil V Israni1, Anirban Mandal2
1 Department of Pediatrics, Maxcure Suyosha Woman and Child Hospital, Hyderabad, Telangana, India
2 Department of Pediatrics, Sitaram Bhartia Institute of Science and Research, New Delhi, India
|Date of Web Publication||6-Sep-2017|
Anil V Israni
Department of Pediatrics, Maxcure Suyosha Woman and Child Hospital, Hyderabad, Telangana - 500 081
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Israni AV, Mandal A. Canavan disease with typical brain MRI and MRS findings. Neurol India 2017;65:1191-2
A 15-month old boy, the second child born out of a non-consanguineous marriage, with no adverse perinatal events, presented with a history of delayed attainment of milestones. At 15 months of age, the child had no head control. There was only social smile, and the child could only speak monosyllables. The salient findings on examination were macrocephaly and marked axial and appendicular hypotonia with brisk deep tendon reflexes.
Magnetic resonance imaging (MRI) of the brain T2 axial image [Figure 1]a revealed marked symmetrical hyperintensity of cerebral white matter involving the subcortical arcuate fibres. Hyperintensities were also observed in the dentate nuclei on T2-weighted axial sections at the level of the cerebellum [Figure 1]b. The axial section [Figure 1]c showed extensive diffusion restriction symmetrically in the subcortical white matter. There was no hydrocephalus, mass effect, or midline shift. Single-voxel magnetic resonance spectroscopy (MRS) from the left parietal white matter showed N-acetyl-aspartate (NAA) peak with normal creatine and choline peaks [Figure 1]d, consistent with the diagnosis of Canavan disease.
|Figure 1: (a) MRI of brain, T2 axial image, showing marked symmetrical hyperintensity of cerebral white matter with involvement of the subcortical arcuate fibres; (b) T2-weighted axial section at the level of cerebellum showing hyperintensities in dentate nuclei; (c) Axial section showing extensive symmetrical diffusion restriction in the subcortical white matter; (d) Single voxel MRS from left parietal white matter showing NAA peak with normal creatine and choline peaks|
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The diagnosis was confirmed by elevated urine NAA levels and identification of a mutation within the aspartoacylase enzyme by polymerase chain reaction (PCR).
Canavan disease, also called as spongiform degeneration of cerebral white matter, is an autosomal recessive demyelinating disease caused by mutations in the aspartoacylase (ASPA) gene located in the short arm of chromosome 17, resulting in the deficiency of aspartoacyclase, which catalyzes the breakdown of NAA; excessive accumulation of NAA is responsible for the central nervous system changes in this disease. Canavan disease demonstrates bilateral symmetric T2 white matter hyperintensity, including involvement of the subcortical arcuate fibers. The involvement is diffuse throughout the cerebral white matter, does not show enhancement on computed tomography (CT) or MR imaging, and demonstrates variable involvement of the basal ganglia and cerebellar white matter. Differential diagnoses of Canavan disease based on imaging findings include other demyelinating diseases such as metachromatic leukodystrophy, adrenoleukodystrophy, Pelizaeus–Merzbacher disease (PMD), and Alexander disease. Both metachromatic leukodystrophy and adrenoleukodystrophy cause bilateral symmetric white matter hyperintensity on T2-weighted MRI with sparing of the subcortical white matter. In addition, adrenoleukodystrophy tends to progress in an orderly fashion from one portion of the brain to the next with an advancing edge of contrast enhancement. PMD demonstrates bilateral symmetric white matter T2 hyperintensity along with involvement of the subcortical arcuate fibers; however, PMD may also have marked cerebellar atrophy and progressive enlargement of cortical sulci. These findings were not seen in this case. Further, PMD does not present with macrocephaly, and MRS reveals normal NAA levels. Interestingly, cytotoxic edema with corresponding diffusion restriction on brain MRI has been noted as an early marker of Canavan disease in infants. Similar finding was also observed in our case.
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