Acute encephalopathy with biphasic seizures & late reduced diffusion-MRI

Case Report: 21 months pyrexic  male with seizures & unconsciousness. MRI shows extensive, symmetrical, restricted diffusion lesions  in cortical & subcortical white matter regions of supra & infra tentorial compartments in general particularly involving interhemispheric fissure, sylvian & central sulci locations, thalami, basal ganglia (most in putamen), corpus callosum (mainly splenium), brain stem(mainly pons), middle cerebellar peduncles, cerebellar hemispheres with reduced ADC values & blooming foci in SW (possible micro- haemorhage) with no perilesional edema or significant mass effect or midline shift, herniation- not specific to etiology, however could represent diffuse lesions variety of AESD ( acute encephalopathy with biphasic seizures & late reduced diffusion). DD- unusual HIE, substance toxicity related brain injury .

Teaching points by Dr MGK Murthy, Dr GA Prasad, Mr Venkat

1.  Encephalopathy is classified into multiple syndromes, such as
  •  Acute encephalopathy with biphasic  seizures and late reduced diffusion (AESD)- lesions in the cerebral subcortical white matter
  •  Mild Encephalopathy with a Reversible  Splenial lesion (MERS)- lesions in splenium of the corpus callosum
  • Acute necrotizing encephalopathy (ANE)   - lesions in bilateral thalami.

2.  Acute encephalopathy with  callosal, subcortical and thalamic lesions can co-exist  in AESD. AESD is characterized by an initial prolonged febrile seizure followed by a cluster of partial seizures several days later. Laboratory not very helpful except excluding  viral or ADEM aetiologies  with CSF showing  neither pleocytosis nor increased protein 

3. MRI could be normal for the first 48 hours . Later shows  cortical edema  &  subcortical white  matter bright signal on DW  named “bright tree appearance” (days 3-9). Possible  explanation  is excitotoxicity, as evidenced by the increase  in glutamine and glutamate complex detected by MR spectroscopy.

4. Sequel, including  intractable epilepsy or motor and intellectual deficits may follow, when MR shows   cortical  and basal ganglia, thalamic lesions. Mainstay of  Treatment  is  Steroids & Mannitol.
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