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Hannah's Neuro > The Cellular Basis of Epilepsy and Behavioural Illness > Flashcards

The Cellular Basis of Epilepsy and Behavioural Illness Flashcards

1
Q

What is SUDEP?

A

Sudden unexplained death in epilepsy

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2
Q

What causes an epileptic seizure?

A

Excessive, hyper-synchronous activity of populations of neurons in the brain, due to an imbalance between inhibition and excitation of cortical neurons and neuronal networks

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3
Q

What are the clinical manifestations of an epileptic seizure?

A

Varies depending on the regions of the brain involved at onset and during the secondary spread

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4
Q

What are the 3 broad classifications of epilepsy?

A

Genetic (idiopathic/primary)
Structural/metabolic (symptomatic/secondary)
Unknown (cryptogenic)

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5
Q

Why is it important to determine a patient’s specific epileptic syndrome?

A

Because prognosis, treatment and genetic implications vary greatly between the syndromes

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6
Q

List 4 characteristics of genetic epilepsies

A

Usually onset during childhood/teenage years
May remit
Usually respond well to medication
Likely to have genetic basis (e.g. mutation in ion channels)

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7
Q

List 3 characteristics of structural/metabolic epilepsies

A

More common with age (most common for a new diagnosis of epilepsy from mid-life onwards)
Uncommonly remit
Often incompletely controlled with medication

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8
Q

List 4 possible mechanisms for the development of epileptic neuronal networks

A

Alternations in neuronal network components (e.g. loss of inhibitory neurons, gain of excitatory neurons, aberrant sprouting)
Alterations in intrinsic neuronal cellular excitability
Alterations in synaptic transmission
Alterations in extra-neuronal environment (e.g. glial function)

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9
Q

What are the 3 main underlying molecular changes in mesial temporal sclerosis (MST)?

A

Cell loss in CA1, CA3 and dentate hilus regions of the hippocampus
Abnormal sprouting
Gliosis (glial cell proliferation)

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10
Q

What effect do seizures have on epileptogenesis?

A

Accelerate epileptic changes

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11
Q

What is the largest age demographic for new onset epilepsy?

A

> 60 y.o.

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12
Q

What is the most common aetiology of new onset epilepsy in infancy and early childhood?

A

Congenital/perinatal CNS insults (e.g. ischaemic insult during birth or development)

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13
Q

What is the most common aetiology of new onset epilepsy in late childhood and early adulthood?

A

Idiopathic

Genetic

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14
Q

What is the most common aetiology of new onset epilepsy in adults and the elderly?

A

Structural/metabolic (e.g. trauma, ischaemia, tumours, haemorrhage, degenerative disease)

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15
Q

What is the hypothesised cause of idiopathic generalised epilepsies (IGE)?

A

Genetically determined

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16
Q

List 3 broad groups of targets for mutations believed to have a role in causing epilepsy

A

Voltage-gated ion channels
Ligand-gated ion channels
Non-ion channel genes (involved in neural migration, other structural elements)

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17
Q

Describe the inheritance patterns of IGE

A

Most are complex

5-10% Mendelian monogenic inheritance patterns

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18
Q

Does genetics have a role in acquired epilepsy?

A

May contribute to an individual’s vulnerability to acquiring epilepsy after some insult
Those with acquired epilepsy are 3x more likely to have a family history than those without

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19
Q

What imaging modality is most commonly used to evaluate epilepsy?

A

MRI

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20
Q

What imaging modality is most commonly used to evaluate epilepsy? Why?

A

MRI; sensitive and specific, high spatial resolution and tissue contrast

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21
Q

In what % of cases of medically refractory focal epilepsy is MRI successful in detecting the focal lesion? What does the ability to detect this lesion mean for patient outcomes?

A

70%

Strongly predictive of outcome following epilepsy surgery

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22
Q

How is MST usually treated?

A

Most patients are refractory to medical therapy but have good prognosis with epilepsy surgery

23
Q

List 4 features of an MRI of MST

A

Hippocampal atrophy
Increased T2 signal
Decreased T1 signal
Loss of cytoarchitecture

24
Q

What is focal cortical dysplasia?

A

A focal region of disturbed cortical development and architecture with unknown aetiology (not genetic)

25
Q

List 4 features of an MRI of focal cortical dysplasia

A

Focal thickening of the cerebral cortex
Blurring of the grey/white interface
Gyral abnormalities (e.g. polymicrogyria, macrogyria)
May be associated with a region of increased T2 signal

26
Q

What is epilepsy primarily a disease of?

A

The grey matter

27
Q

What is a periventricular nodular heterotopia? Is it bilateral or focal?

A

Generalised malformation due to abnormal neural migration, resulting in nodular masses of grey matter diffusely lining the ventricular walls
May be bilateral or focal

28
Q

Is there a genetic basis for periventricular nodular heterotopia?

A

Can be inherited in the case of bilateral heterotopia

29
Q

What is the most common cause of new onset partial seizures aged 35-55 years?

A

Low grade tumours

30
Q

List 3 of the most common types of low grade tumours causing partial epilepsy

A

Gliomas (most common)
Meningiomas
Dysembryoplastic neuroepithelial tumour

31
Q

What is the most epileptogenetic site for a low grade tumour?

A

Centro-temporo-parietal region

32
Q

What are the 2 types of vascular lesions causing epilepsy?

A

Cavernomas

Arteriovenous malformations

33
Q

List 3 MRI features of focal encephalomalacia

A

Irregular area of atrophy of the cerebral cortex and underlying white matter
Surrounding region of increased T2 signal (due to gliosis)
May be associated with a large cystic region

34
Q

What is focal encephalomalacia?

A

A focal lesion resulting from previous destructive insult (e.g. trauma, stroke, infection)

35
Q

What do anti-epileptic drugs treat?

A

The symptoms, not the underlying condition

36
Q

List 3 non-medical treatments for epilepsy

A

Surgery
Neurostimulators
Diet

37
Q

What are the 2 requirements for a candidate for epilepsy surgery?

A

Continuing uncontrolled seizures interfering with quality of life, despite trials of several appropriate AEDs
Epilepsy syndrome must be surgically remediable (must be focal, must be a brain region that can be resected with acceptably low risk)

38
Q

Distinguish between psychopathology and neuropathology

A

Psychopathology refers to clinical symptoms

Neuropathology refers to anatomical changes underlying these symptoms

39
Q

List 5 characteristics of catatonia

A 
Motor immobility
Excessive motor activity
Extreme negativism or mutism
Peculiarities of voluntary movement
Echolalia or echopraxia (repetition of actions of words)
40
Q

Describe the progression of neurodevelopment

A

Involves cortical grey matter thinning, which begins at the posterior regions (the sensory cortex), and finishes with the prefrontal and frontal cortex and the lateral temporal regions

41
Q

What is the hypothesised defect in childhood and adolescent schizophrenia and other disorders?

A

Problems with synaptic formation or synaptic pruning

42
Q

When does synaptic pruning begin and when does it end?

A

Synaptic spine density begins to decrease from age 5 and stabilises in the 3rd decade

43
Q

List 3 changes of anatomical connectivity observed in schizophrenia and other behavioural disorders

A

Decreased neuronal size
Decreased neuronal connections
Altered cell skeleton

44
Q

List 3 risk factors for the development of behavioural disorders

A 
Genetic/epigenetic risk
Perinatal risk (e.g. hypoxia during birth)
Prenatal risk (e.g. pyrexia, starvation)
45
Q

In which area is there notable loss of neuronal connections in schizophrenia and other behavioural disorders? What proteins involved in synaptic connections are downregulated at these sites?

A

Decreased connections between the thalamus and cortex

Decreased expression of synapsin, gap43 and connexins

46
Q

What are the 3 broad classification of factors involved in the molecular pathology behind behavioural disorders? Give some specific examples for each

A

Neurochemical (e.g. dopamine, glutamate, GABA)
Anatomical (e.g. decreased dendrites via alterations in MAP2 expression, decreased glia and microglia)
Trophic/signalling (e.g. Wnt/GSK3B)

47
Q

What were the findings of multiple studies measuring glial density in bipolar disorder, schizophrenia and major depressive disorder?

A

Decreased glial density (especially in layers 5 and 6, the deeper layers of the cortex, and especially in major depressive disorder)

48
Q

What gene relating to microglial activation is upregulated in schizophrenia?

A

Gene for calprotectin, a pro-inflammatory marker expressed by glia

49
Q

What were the findings of a study observing the behaviour of Hoxb8 mutants?

A

Expressed behaviour similar to OCD, which could be resolved by transplantation of wild-type bone marrow

50
Q

What is one of the observed neurodevelopmental abnormalities in autism?

A

Early peak overgrowth in the dorsolateral prefrontal cortex

51
Q

What is the HLA haplotype found to be over-expressed by activated microglia and astroglia in autism?

A

HLA-DR

52
Q

What is the main cellular abnormality in the autistic DLPFC?

A

Increased microglial density and volume (due to over-activation)

53
Q

What is the genetic basis of autism?

A

Appears to be SNPs which confer either risk or resilience factors; SNPs may be in the same gene but have different effects

Hannah's Neuro (31 decks)

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