Epilepsy Flashcards
What is epilepsy?
Recurrent tendency to spontaneous, intermittent, abnormal electrical activity in part of brain, manifesting in seizures
Unprovoked event in which changes of behaviour, sensation, or cognitive processes are caused by excessive hypersynchronous neuronal discharges in brain
Chronic disorder - need at least 2 seizures to be defined as epilepsy
How common is epilepsy?
Incidence age-dependent, highest at extremes of life with most cases starting before 20 or after 60
Can often go into remission
Seizures usually last 30-120 seconds
0.7-0.8% population prevalence
Lifetime risk > 3%
Lifetime risk single seizure 5%
What are the 2 types of epilepsy?
Primary generalised (40%)
- Simultaneous onset of electrical discharge throughout whole cortex (involving both hemispheres), with no localising features referable to only one hemisphere
- Bilateral symmetrical and synchronous motor manifestations
- Always associated with LOC or awareness
Partial/focal seizures
- Focal onset, with features referable to part of one hemisphere eg temporal lobe
- Often underlying structural disease
- Electrical discharge restricted to limited part of cortex of one cerebral hemisphere
- May later become generalised
What is important to ask in a seizure history?
What happened? - before, during, after
Circumstances
Epilepsy risk factors
Previous unrecognised seizures
Alcohol
Medications lowering seizure threshold
Driving licence
What can cause epilsepsy?
2/3 idiopathic
Primary generalised
Developmental - juvenile
Hippocampal sclerosis - temporal lobe epilepsy, often due to childhood febrile convulsions, surgical resection of damaged temporal lobe often cures it
Brain surgery
Cortical scarring
- Head injury before onset
- Cerebrovascular disease eg cerebral infarction or haemorrhage incl perinatal and cerebral palsy
- CNS infection eg meningitis, encephalitis, cerebral abscesses
Space occupying lesion eg tumour
Vascular
Immune eg NMDA receptor antibody and potassium channel antibody encephalitis
Alzheimer’s or dementia
Metabolic abnormalities eg hyponatraemia, hypocalcaemia, acute hypoxia, uraemia, hepatic encephalopathy, porphyria
Genetic eg tuberous sclerosis
Drugs eg ciclosporin, lidocaine, quinolones, tricyclic antidepressants, antipsychotics, lithium, stimulant drugs
Alcohol withdrawal
What are the risk factors for epilepsy?
FHx
Premature born babies who are small for age
Abnormal blood vessels in brain
Alzheimer’s/dementia
Use of drugs eg cocaine
Stroke/brain tumour/infection
Childhood febrile convulsions
Significant head injury
What are the elements of a seizure?
Prodrome - lasting hours/days, not part of seizure, results in change of mood/behaviour
Aura - part of seizure where patient aware and may precede other manifestations, strange feeling of gut, deja vu, strange smells, flashing lights, impartial (focal) seizure (often temproal lobe)
Post-ictal - headache, confusion, myalgia, sore tongue, temporary weakness after focal seizure in motor cortex (Todd’s palsy), dysphasia following temporal lobe focal seizure
What are the primary generalised seizures?
Generalised tonic-clonic seizures
Typical absence seizures
Myoclonic seizures
Tonic seizure
Atonic
How do generalised tonic-clonic seizures?
Often no aura
LOC
Tonic phase - rigid, stiff limbs - often fall to floor if standing
Clonic phase - generalised, bilateral, rhythmic muscle jerking lasing seconds-minutes
Eyes remain open and tongue often bitten
Incontinence of urine/faeces
Followed by post-ictal phase of several hours
How do typical absence seizures present?
Disorder of childhood
Ceases activity, stares and pales for a few seconds
Suddenly stops talking mid-sentence and carries on where lest off
Often don’t realised that they’ve had an attack
On EEG - 3-Hz spike and wave activity
Tend to go on to develop generalised tonic-clonic seizures
How do myoclonic seizures present?
Sudden isolated jerk of limb, face, or trunk
May suddenly be thrown to ground or have violently disobedient limb
How do tonic seizures present?
Sudden sustained increased tone with characteristic cry/grunt
Intense stiffening of body
Stiffening not followed by jerking
How do atonic seizures present?
Sudden loss of muscle tone and cessation of movement resulting in fall
What are the types of focal seizures (partial?
Simple partial seizure
Complex partial seizure
Partial seizure with secondary generalisation
How does a simple partial seizure present?
Not affecting consciousness or memory
Awareness unimpaired with focal motor, sensory, autonomic, or psychic symptoms
No post-ictal symptoms
How does a complex partial seizures present?
Affecting awareness or memory before, during, or immediately after seizure
Most commonly arise from temporal lobe
Post-ictal confusion common with seizures arising from temporal lobe, recovery rapid after seizures in frontal lobe
