Epilepsy Flashcards
What is a seizure?
A seizure is the transient occurrence of signs or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
Seizures can manifest as a disturbance of consciousness, behaviour, cognition, emotion, motor function, or sensation
An isolated seizure can be caused by toxic, metabolic, structural, and infectious factors and should not be confused with epilepsy
What is epilepsy?
Epilepsy is a neurological disorder in which a person experiences recurring seizures
The International League Against Epilepsy describes epilepsy as a disease of the brain defined by any of the following conditions:
o At least two unprovoked seizures occurring more than 24 hours apart.
o One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years.
o Diagnosis of an epilepsy syndrome.
What is the aetiology of epilepsy?
A cause of epilepsy is only identified in about one third of people with the disorder:
- Structural — abnormalities visible on structural neuroimaging, for example stroke, trauma, or malformation of cortical development. The underlying basis for a structural abnormality can be genetic or acquired.
- Genetic — epilepsy resulting from a known or presumed genetic mutation (not necessarily inherited) in which seizures are a core symptom of the disorder, for example Dravet syndrome.
- Infectious — epilepsy results from a known infection in which seizures are a core symptom of the disorder (rather than seizures due to acute infection such as meningitis). Examples include tuberculosis, cerebral malaria, HIV, and congenital infection such as Zika virus.
- Metabolic — epilepsy results from a known or presumed metabolic disorder in which seizures are a core symptom of the disorder (which may occur as a result of a genetic defect). Examples include porphyria, amino-acidopathies, or pyridoxine deficiency.
- Immune — epilepsy that results directly from an immune disorder (where there is evidence of auto-immune mediated central nervous system inflammation) in which seizures are a core symptom of the disorder. Examples include anti-NMDA receptor encephalitis and anti-LG11 encephalitis.
What is the classification of epilepsy?
Focal seizures Generalised tonic-clonic seizures Myoclonic seizures Absence seizures Tonic seizures
What is a focal seizure?
Focal seizures (focal is now preferred to partial): originate within networks limited to one hemisphere, discretely localised or more widely distributed.
What is the classification of focal seizures?
They may be divided into simple focal (motor or sensory) with retained awareness or focal dyscognitive seizures (impaired awareness). Focal seizures may progress into generalised seizures.
Simple focal seizures (no loss of consciousness).
Focal dyscognitive seizures:
o With impairment of consciousness at onset.
o Simple focal onset followed by impairment of consciousness.
Focal seizure evolving to generalised tonic-clonic (GTC) convulsions.
o II. Generalised seizures (convulsive or non-convulsive with bilateral discharges involving subcortical structures); associated with impairment of consciousness and distortion of the electrical activity of the whole or a large part of both sides of the brain.
o May be tonic-clonic (the term generalised tonic-clonic is now preferred to ‘grand mal’), isolated tonic or clonic, myoclonic (brief, shock-like muscle contractions) or absence (‘petit mal’).
o Unclassified epileptic seizures (usually used when an adequate description is not available).
What are the risk factors for epilepsy?
Premature birth.
Complicated febrile seizures.
A genetic condition that is known to be associated with epilepsy, such as tuberous sclerosis or neurofibromatosis.
Brain development malformations – usually associated with epilepsy developing before adulthood.
A family history of epilepsy or neurologic illness.
Head trauma, infections (for example meningitis, encephalitis), or tumours — can occur at any age.
Comorbid conditions such as cerebrovascular disease or stroke — more common in older people.
Dementia and neurodegenerative disorders (people with Alzheimer’s disease are up to ten times more likely to develop epilepsy than the general population).
What is the presentation of GTC seizures?
Epilepsy may be difficult to diagnose in the early stages, especially in the absence of a witnessed account.
A clear history from the patient and an eyewitness to the attack provide the most important diagnostic information.
Generalised seizures cause a disturbance in consciousness. The classic GTC seizure progresses through tonic, clonic and postictal phases. The postictal phase is often associated with headache and drowsiness.
GTC seizures are often associated with tongue-biting and incontinence. Whatever the cause, the patient may have amnesia for both the event and its exact circumstances.
What is the presentation of absence seizures?
Absence seizures cause an interruption to mental activity for less than 30 seconds. They rarely persist into adulthood.
Blank spells
What features suggest genetic generalised epilepsies?
Childhood or teenage onset.
Triggered by sleep deprivation and alcohol.
Early morning tonic-clonic seizures or myoclonic jerks.
Short absence seizures photoparoxysmal response on electroencephalography (EEG).
Generalised 3 per second spike and wave or polyspike and wave on EEG.
What features suggest focal seizures?
History of potential cause.
Aura.
Focal motor activity during seizure.
Automatisms.
What features suggest complex focal seizures?
Motor: automatism, lip-smacking, plucking at clothes, hair.
Sensory: transient paraesthesiae.
Autonomic: odd epigastric sensation, nausea, abnormal taste or smell.
Psychiatric: unreality, déjà vu, fear.
What are the symptoms and signs of epilepsy?
There may be a clear precipitating cause - eg, inadequate sleep, alcohol abuse or medications such as tricyclic antidepressants, which lower the seizure threshold.
It is common for seizure frequency to vary throughout the menstrual cycle. In ovulatory cycles, peaks occur around the time of ovulation and in the few days before menstruation. In anovulatory cycles, there is an increase in seizures during the second half of the menstrual cycle.
Possible seizure-related symptoms include:
Sudden falls.
Involuntary jerky movements of limbs whilst awake.
Blank spells.
Unexplained incontinence of urine with loss of awareness, or in sleep.
Odd events occurring in sleep - eg, fall from bed, jerky movements, automatisms.
Episodes of confused behaviour with impaired awareness.
Possible simple focal seizures.
Epigastric fullness sensation.
Déjà vu.
Premonition.
Fear.
Elation, depression.
Depersonalisation, derealisation.
Inability to understand or express language (written or spoken).
Loss of memory, disorientation.
Olfactory, gustatory, visual, auditory hallucinations.
Focal motor or somatosensory deficit, or positive symptoms (jerking, tingling).
Signs
o Examination is usually unremarkable.
o Check for any neurological or cerebrovascular signs.
o Skin examination may reveal café-au-lait spots (neurofibromatosis), port-wine stain (Sturge-Weber syndrome) or adenoma sebaceum (tuberous sclerosis).
What is sudden unexpected death?
Sudden unexpected death in epilepsy (SUDEP) is defined as sudden, unexpected, unwitnessed, non-traumatic, non-drowning death of a person with epilepsy, with or without a seizure, excluding documented status epilepticus, and in whom post-mortem examination does not reveal a structural or toxicological cause of death.
The risk of SUDEP can be minimised by optimising seizure control and being aware of the potential consequences of nocturnal seizures.
What are the main risk factors for SUDEP?
Seizure type and frequency: GTC seizures are the principal risk factor for SUDEP. Early identification of treatment-resistant epilepsy and referral for assessment for epilepsy surgery to reduce seizure frequency may reduce incidence of SUDEP.
SUDEP is the most common cause of death directly related to epilepsy and most frequently occurs in people with chronic epilepsy.
Information provided to people with epilepsy and carers should take account of the small but definite risk of SUDEP .
