DNET

Overview
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Seizure Classification
Generalized onset seizure
- Motor Onset
- Non-Motor Onset
Focal Onset Seizure
- By Onset Feature
- Focal to Bilateral Tonic-Clonic
- Hemispheric lateralization
- Lobar localization
  - Frontal
  - Temporal
  - Parietal
  - Occipital
Unknown Onset Seizure
Epilepsy Classification
Generalized Epilepsy
Focal Epilepsy
Generalized and Focal Epilepsy
Unknown Epilepsy
Epilepsy Syndromes
Neonatal/Infantile
- Self-limited neonatal seizures and Self-limited familial neonatal epilepsy
- Self limited familial and non-familial infantile epilepsy
- Early myoclonic encephalopathy
- Ohtahara syndrome
- West syndrome
- Dravet syndrome
- Myoclonic epilepsy in infancy
- Epilepsy of infancy with migrating focal seizures
- Myoclonic encephalopathy in non-progressive disorders
- Febrile seizures plus, genetic epilepsy with febrile seizures plus
Childhood
- Epilepsy with myoclonic-atonic seizures
- Epilepsy with eyelid myoclonias
- Lennox-Gastaut syndrome
- Childhood absence epilepsy
- Epilepsy with myoclonic absences
- Panayiotopoulos syndrome
- Childhood occipital epilepsy (Gastaut type)
- Photosensitive occipital lobe epilepsy
- Childhood epilepsy with centrotemporal spikes
- Atypical childhood epilepsy with centrotemporal spikes
- Epileptic encephalopathy with continuous spike-and-wave during sleep
- Landau-Kleffner syndrome
- Autosomal dominant nocturnal frontal lobe epilepsy
Adolescent/Adult
- Juvenile absence epilepsy
- Juvenile myoclonic epilepsy
- Epilepsy with generalized tonic-clonic seizures alone
- Autosomal dominant epilepsy with auditory features
- Other familial temporal lobe epilepsies
Any Age
- Familial focal epilepsy with variable foci
- Reflex epilepsies
- Progressive myoclonus epilepsies
Epilepsy Etiologies
Genetic Etiology
- Chromosomal abnormalities
- Gene abnormalities
Structural Etiology
- Malformations of cortical development
- Vascular malformations
- Hippocampal sclerosis
- Hypoxic-Ischemic
- Traumatic brain injury
- Tumors
- Porencephalic Cyst
Metabolic Etiology
Immune Etiology
- Rasmussen syndrome
- Antibody mediated
Infectious Etiology
Unknown Etiology
- Febrile infection related epilepsy syndrome
Epilepsy imitators

DNET

Imaging

Imaging for optimized detection of DNET:

MRI should include thin slice volumetric T1-weighted images, axial and coronal T2-weighted and FLAIR images.

Imaging characteristics of DNET:

DNET's are typically cortical lesions that lack significant mass effect or peri-tumoral edema
They are hypointense on T1-weighted images and hyperintense on T2-weighted images, typically with a 'bubbly appearance' due to their multicystic nature
They may show rings of enhancement, seen on FLAIR ('bright rim sign')
They may be associated with scalloping of the inner table of overlying skull bone, without actual skull bone erosion
They may show calcification (seen in ~30%), this may be best seen on CT or T2* weighted MR imaging

DNET's can co-occur with focal cortical dysplasia (which is usually found adjacent to the DNET) and/or with hippocampal sclerosis.

Imaging of a DNET

The three images below are a T2-weighted, T1-weighted and FLAIR image of a DNET in the same patient, demonstrating the multicystic appearance, with a 'bright rim sign' - a ring of enhancement, seen on the FLAIR image .

DNET 1

Imaging of a DNET with focal cortical dysplasia (FCD IIIb)

The image below is a coronal image showing a right basal temporal structural abnormality, which includes an area of gyral expansion, with cystic appearance, and neighboring abnormal signal in white matter, with blurring of the grey-white matter junction. This abnormality was confirmed following resection to be a DNET with adjacent focal cortical dysplasia (FCD IIIb).

DNET 2