Paediatric Epilepsy Flashcards
What is epilepsy?
A symptom - a chronic neurological condition characterised by recurrent epileptic seizures
Why is epilepsy a common condition?
Prevalence of 0.5%
It is not a single condition - it is symptom of many different diseases
Can be difficult to diagnose
No single treatment
Why is epilepsy misdiagnosis rate high?
- There is no diagnostic test
2. The diagnosis is made predominantly on clinical history description of events
What is the percentage that the epilepsy is resistant to medication?
25%
More likely if lesional
What is an option if there is localised onset to seizures in epilepsy?
Surgical treatment
Define where the seizure onset is
What does imaging of childhood epilepsy consist of?
- Pathological substrate
- Source of epileptic seizures
- Localisation of function
- Secondary effects of epilepsy
- Underlying pathophysiology
What is pathological substrate concerned with?
The cause of epilepsy
Magnetic resonance imaging
What are examples of source of epileptic seizures?
- SPECT
- PET
- MRI
What is MRI concerned with?
Localisation of function
Underlying pathophysiology
What is PET and MRI concerned with?
Secondary effects of epilepsy
What is key in magnetic resonance imaging in childhood epilepsy?
- Malformation cortical development
2. Cortical grey matter
What is band heterotopia?
Also known as double cortex syndrome is a form of diffuse grey matter heterotopia affecting almost only women
More lateralised abnormalities
What is Hemimegalencephaly (HME)?
A rare neurological condition in which one half of the brain, or one side of the brain is abnormally larger than the other
What are examples of HME?
- Dysplasia
- Polymicrogyria
- Multifocal dysplasia
- Benign tumours
What is lissencephaly?
Smooth brain
Is a set of rare brain disorders where the whole or parts of the surface of the brain appear smooth - it is caused by defective neuronal migration during the 12th to 24fh weeks of gestation resulting in a lack of development of brain folds (gyri) and grooves (sulci)
What are the optional sequences ?
- Susceptibility weighted images
- Diffusion tensor imaging
- Arterial spin labelling (perfusion)
Why do we have to optimise the grey-white differentiation?
Look specifically at the grey matter
What is also needed to be optimised?
Angle of sequences is important
- straight horizontal/vertical - poor views of temporal lives
- we want to angle our sequences parallel or perpendicular to the axes of temporal lobes
Get food view and avoid partial volume effects particularly with the mesen-temporal structures
What shows abnormalities particularly in grey matter?
FLAIR
What is the timing of scan and maturation?
Very early in 2 years of life - slightly different sequences are required because myelination is incomplete
Lesions May appear or disappear with myelination and therefore repeating imaging are therefore necessary
It is not a waste of time to do imaging in the first 2 years of life because you may see an abnormality that may subsequently become less apparent as they become older
Compare images - early and late life in early onset epilepsy
What are the MRI findings?
- 26 (51%) aetiologically relevant abnormalities
2. 11 (21%) non specific structural abnormalities
What are examples of 11 developmental malformations?
- 2 Tuberous sclerosis
- 2 Lobar/ multilobar focal cortical dysplasia
- 3 bilateral polymicrogyria ( 1 with cerebellar hypoplasia)
- 1 Hemimegalencephaly (+ bilateral polymicrogyria )
- 1 Microcephaly, absent corpus callosum
- 1 LisdencephAly
- 1 Occipital AVM
What are the 15 acquired lesions?
14- secondary to infection, HIE, metabolic conditions, seizures
1 a probably MTS
What are non-specific structural abnormalities?
Lack of white matter bulk, thin corpus callosum, delayed myelination, arachnoid cyst
When should imaging be performed?
Neuroimaging: should perform “soon” after request
- MRI investigation of choice in people with epilepsy
- Particularly important for children
- who have developed epilepsy < 2 years
- Have any suggestion of focal onset
- Seizures continue despite first line medication c
What is the most common abnormalities that are determined?
Cortical dysplasia
What is the epilepsy surgery?
The removal or modification of part of the brain with the aim of alleviating seizures
What are the aims of surgery?
- Primary outcome aims
- seizure freedom/reduction - Secondary outcome aims:
- neurodevelopmental gains
- behavioural improvement
What is the spectrum of paediatric epilepsy surgery?
- If we are looking at candidates that come for epilepsy surgery
- In children the most common cause is cortical dysplasia
- Hemispherectomy and multilobar take a good 30% cases we operate on
- The earlier the onset of epilepsy, the wider area of dysplasia
What has been the most common operation performed on adult?
Hippocampal sclerosis
There are now less procedures for hippocampal sclerosis
Tumours and cortical dysplasia are increasing
What are examples of resective surgery: aims of evaluation
- Localisation of responsible tissue
- Localisation of function
- Evaluation of outcome aims
What are examples of localisation of responsible tissue?
- Clinical evaluation
- Interictal EEG
- Video EEG ictal recording
- Optimised structural MRI
- Functional imaging
What are examples of localisation of function?
- Clinical evaluation
- Neuropsychology
- Functional MRI
What is example of evaluation of outcome aims?
Neuropsychiatric evaluation
What are features of focal cortical dysplasia in infant?
- Grey/white matter blurring
- Abnormal signal in T2 if the subcortical white matter
- Abnormal gyration/salvation
- Trans mantle sign
What is FCD2a?
- Not always seen on MRI
- Blurring of grey/white matter junction
- More challenging than IIB
What is 1.5T Avanto, 12-channel head coil?
- It takes 15-25 minutes (1.5-1mm isotropic resolution)
- 3 images above and a B0 and B1 map
- Data is combined from 3 scans
What is automated detection of FCD?
- Artificial neural network classifier time localise Cortical lesions in a cohort of children from GOSH (sensitivity 73%)
- All code and data matrices for classifier training and validation freely available
What is SPECT?
- Use of a ligand to determine study of cerebral perfusion
- Interictal hypoperfusion at seizure focus in 40-70% cases
- Ictal hyperperfusion in 72-99% cases
What is FDG PET in childhood epilepsy?
Areas of hypometabolism correlate with structural malformations not readily apparent on MRI
What is EEG activated MRI?
- Visualises brain functions non-invasively
- Functional maps based on the signal intensity differences between physiological states (e.g. ‘activation’ and ‘rest’)
- Blood Oxygenation Level Dependent (BOLD) contrast