Leukodystrophy Teaching Points-MRI

One year  male child born in caesaerian delivery to non-consanguinous parents,  presents with abnormal movements and delayed milestones with no fever are trauma. The MR imaging shows extensive centrifugal pattern of restricted diffusion of myelin edema in supratentorial (posterior to the anterior gradient) &  infratentorial locations with apparent “Tigroid” appearance with T2 shine through in nature with no significant reduction in ADC with no mass effect or  bleed or volume loss or circle of Willis flow voids abnormality. Though the features are not specific, could suggest leukodystrophies or metabolic etiologies. Case and teaching points by Dr MGK Murthy.

Teaching points :

•  Various edema  are vasogenic  and (isotropically increased) or  interstitial or cytotoxic  and  myelin (intramyelinic) varieties (isotropically restricted water diffusion).
• Absent or low grade myelin edema is seen in MPS,  GM gangliosidoses,  Zell Weger disease, Adrenomyeloneuropathy,  L-2 hydroxyglutaric acid uria,  non ketotic hyperglycinemia,  classical phenyl ketonuria  and Vander knap disease. Vanishing white matter or  medium grade myelin edema is seen in metachromatic leukodystrophy (MLD), X-linked adrenoleukodystrophy and  HMG co-enzyme lyase deficiency. High grade edema is seen in Krabbe disease, Canavan disease, hyperhomocystinemias  andMaple syrup urine disease.
• MLD,  globoid cell leukodystrophy ,  Canavan disease  and X-linked ALD are genetically determined and referred to as classical varieties. Recent additions of leukodystrophies include megalencephalic leukoencephalopathy with subcortical cysts,  Aicardi goutiere syndrome, vanishing white matter disease or leukodystrophy with brain stem and spinal cord involvement  and high lactate.
• White matter diseases present with corticospinal tracts symptoms as against grey matter diseases (polio dystrophies) showing extrapyramidal symptoms.
• MLD variety shows progressive centrifugal white matter disease with posteroanterior gradiant with TIGROID pattern in centrum semiovale (due to sparing of the myelin around the transmedullary vessels). Krabbe disease suggests simultaneous and early involvement of supra and infratentorial regions.