PMD leukodystrophy :MRI

Case Report : 5 yr old boy clinically suspected to be having Pelizaeus Merzbacher(PMD)  variety of leukodystrophy  shows on MRI , a near total absence  of expected low signal of myelin on T2  with no Tigroid patches suggesting possibly classical form with diffuse variety of PMD

Teaching points by Dr MGK Murthy

MRI Tech : Mr Kartik

1.  Clinically could be suggested by the presence of  nystagmus/hypotonia/ pyramidal tract disease with exact aetiology is unknown

2.  Two varieties (a) classical (starts late infancy and is X linked )  (b) Connatal , starts at birth or early infancy and can be X linked or Autosomal recessive 

3. Basic defect  appears to be , deranged proteolipid protein (PLP1), leading to oligodendrocytes maldevelopment and death 

4. T2WI is very typical particularly in diffuse variety spreading to involve even the subcortical "U" fibres . Cerebellum and Brainstem amy be involved . 

T1WI shows Lack of  of bright signal in internal capsule/ corona radiata and optic radiation, due to lack of myelin

5.On histology, few islands of normal myelin  interspersed amongst mostly non myelinated regions could be identified in  the patchy variety of the disease  ,  and the same is reflected by "TIGROID"  stripes on imaging