Epilepsy Flashcards
Define:
- Epilepsy
- Seizure
- Convulsion
- Fit
Epilepsy:
recurrent paroxysmal transient disturbance of brain function due to disturbance of electrical activity of the brain
disturbance is unrelated to infection/acute cerebral infarct
Seizure:
sudden attack or recurrence of disease e.g. epileptic seizure
Convulsion: violent involuntary contraction of voluntary mm
Fit: sudden acute attack or manifestation of disease, especially one marked by convulsions or unconsciousness
Briefly discuss the aetiology of
a. Primary Epilepsy
b. secondary Epilepsy
List 6 conditions which are etiological agents for secondary epilepsy
a. Primary Epilepsy
*aetiology unknown
- in most cases, an inherited disposition is believed to be the cause
the precise nature of the genetic anomaly is unknown
- represents 75% of cases of epilepsy in young adults
- often secondary epilepsy is undiagnosed as such and hence is classified erroneously as Primary
- usually begins between 2-14 years
b. Secondary epilepsy
*Epilepsy occurring secondary to structural or metabolic disease
Conditions that may cause secondary epilepsy:
- hyperpyrexia
- CNS infection
- metabolic disturbance (hypoglycaemia, hypoparathyroidism)
- convulsive agents and toxic agents (lead, alcohol, cocaine)
- cerebral hypoxia (anaesthesia)
- expanding brain lesions
- brain defects (congenitial)
- anaphylaxis
- cerebral infarct/haemorrhage
- withdrawal from substance (i.e. alcohol, drugs etc)
*The seizures experienced do not reoccur once the illness ceases unless the illness has resulted in a permanent lesion/scarring of the CNS
Conditions know to be aetiological agents for epilepsy
- CNS maldevelopment
- Brain tumour
- Arteriovenous malformation
- Post stroke defects
- Traumatic brain injury
- Infections: encephalitis, meningitis
Briefly discuss the classification of epilepsy
- classification is based on the clinical manifestations of each type of epilepsy not aetiology
- the accepted classification system has been developed by the ILAE
I. FOCAL ONSET
A. simple partial seizure =s (consciousness not impaired)
* with motor signs (jacksonian seizures)
*with somatosensory symptoms (hallucinations)
*with autonomic symptoms or signs
* with psychic symptoms (incl dysphasic, dysmnesic, cognitive and affective symptoms)
B. complex partial seizures
* any simple partial seizure onset followed by impaired consciousness
* impaired consciousness only
II. GENERALISED ONSET A. absence seizures * With impairment of consciousness only *With clonic spasms *With atonic components *With tonic components *With automatisms *With autonomic components B. myoclonic C. clonic D. tonic E. tonic - clonic F.atonic due to incomplete data
III. UNKNOWN ONSET
IV. FOCAL TO BILAREAL TONIC CLONIC
V. UNCLASSIFIED (the condition is yet to be classified)
***see diagram in lecture notes
Indicate the frequency of each of the major types of Epilepsy
I. FOCAL ONSET
- seizures are localised to a small part of the brain
they may secondarily spread to affect the entire brain
II. GENERALISED ONSET
- seizures affect the entire brain at once
50/100,000 per year
- Seizures (incl non epileptic) affect 2% of the population
- Epilepsy affects 0.5%
- Most epilepsy pt. only have one type of seizure, 30% have two or more
- 90% of epileptics have grand mal attacks
- 60% have these alone
- 30% also have other seizure types
- 25% have absence or petit mal attacks
- 4% have these alone
- 21% also have other types
- 18% of epileptics have psychomotor attacks
- 6% have these alone
- 12% also have other types
- Most common = idiopathic 66% of cases
- ≈75% of epilepsy in young adults is idiopathic epilepsy
- Any age group may be affected: most frequently diagnosed in early childhood, adolescence & >65 years of age
- Usually first manifests between 2-14 yoa
- Prevalence: 50/100,000 pop.
- Incidence: 50/100,000 per year
- Treatment: 70% of epileptics are successfully treated with established anti- epileptic drugs, over 50% of these patients will eventually be able to stop medication
- Annual cost of epilepsy in the UK is £2 billion
- ~ 250, 000 people in Australia have this condition
Discuss the Pathology of Epilepsy
Primary Generalised Epilepsy (Grand Mal and Petit Mal)
No discernible anatomical changes seen with autopsy but: CT & MRI often show foci of:
• atrophy
• calcification
• malformations (e.g. developmental)
Secondary epilepsies (especially focal)
Many have definable lesions in the CNS e.g.
• zones of neuronal loss and gliosis (scars)
• hamartomas (a focal non-neoplastic growth resulting from faulty development in an organ)
• vascular malformations
• tumours
PET (positron emission tomography) is good for locating regions of hypoperfusion of hypometabolism. It should be noted that scars etc. have been found in non-epileptogenic areas of the brain as well i.e. not all lesions are epileptogenic, many are incidental findings.
Briefly discuss the pathophysiological theories pertaining to epilepsy
A paroxysmal, excessive discharge of cerebral neutrons results when a sudden imbalance occurs between the excitatory and inhibitory forces within a network of cortical neutrons inferior of a sudden onset net excitation
it is not known why it starts, spreads or stops
The pathophys of focal onset and generalised onset are different
but in both cases overall cellular excitability is increased, but the mechanisms of synchronisation appear to substantially differ
The following abnormalities have been implicated:
- intrinsic neuronal membrane changes that result in abnormal ionic conductance
- abnormal neurotransmitter synthesis resulting in:
- deficient inhibitory neurotransmitters
- excessive excitatory neurotransmitters
- deficient, genetically regulated, intracellular enzymes that affect the neurons ability to pump ions and repolarise
- glial cell abnormalities
Somehow these factors result in a group of neurons which are characterised by:
- hyperexcitability
- chronic partial depolarisation
- irregular firing at rates of 70-100/sec
- cell membranes with increased ionic permeability
Because of the above many factors may result in neuronal activation and cause an epileptic attack such as:
- hyoerthermia
- hypoxia
- hypoglycaemia
- related sensory stimulation
list four factors which may induce a seizure in an epileptic
Because of the above many factors may result in neuronal activation and cause an epileptic attack, such as:
• hyperthermia
• hypoglycaemia
• hyponatraemia
• hypoxia
• hypocalcaemia
• related sensory (e.g. photic) stimulation
• Visual stimuli (such as strobe lights / stobe effect on tv / driving with flash of trees during sunset)
List and describe the parts of the typical or generic epileptic seizures
Epileptic seizures and their effects can be divided into several stages:
- PRODROMAL – (‘before the journey’) May have changes in mood, appetite etc. several hours or a few days prior to the seizure. Not all patients undergo this stage.
- AURA - This is the first experienced symptom. It reflects the anatomical focus in which the seizure begins - it is usually somatic/special sensory in nature
- THE ATTACK (ICTUS) – depending on the type of epilepsy will determine the specific classification and pattern of this seizure. E.g. in absent seizures we may witness a blank stare
- AROUSAL - Patient gradually regains consciousness / awareness. Seizure activity ceases here.
- POSTICTAL PERIOD - i.e. the post-attack period / post ictus. Observe HA & drowsiness, also may observe focal neurological abnormalities which may remain for minutes (usually) or even hours or days. Sleep sometimes helps with this and sometimes memory is impaired. This stage will be different depending on what type of seizure they have experienced.
Write notes on partial seizures
Focal: Most often a localised lesion or abnormality exists in the CNS grey matter. e.g. - scars - tumours - AV-malformations - focal inflammation
• Neurons in/around the lesion have a propensity to discharge abnormally.
• During the focal epileptic attack, the dysfunctional neurons fire synchronously.
• Some focal seizures project neuronal discharges back into the midbrain reticular formation and diencephalic reticulum from which the discharge spreads and becomes generalised.
• In spite of the above, we must realise that the picture is incomplete.
• It is a well-known fact that seizure discharges can be initiated in an entirely normal cortex.
Clinical Manifestations Focal Aware:
Temporal lobe foci:
• olfactory hallucinations feelings of unreality (e.g. burning rubber)
• feelings of unreality
• autonomic activity (e.g. flushing)
• sexual sensations
Particularly distinctive characteristics of temporal lobe epilepsy seizures include the following:
• aura of a rising epigastric sensation (often likened to a roller coaster)
• psychic or experiential phenomena (such as déjà vu or fear)
Focal Impaired Awareness Seizures:
Are focal seizures in which awareness is impaired. There are bilateral EEG abnormalities during the attack. Focal Impaired Awareness seizures usually manifest with a behavioural arrest and staring that last 30 – 120 seconds. Patients are generally unaware and unresponsive during this period. The attack may begin with the patient experiencing a curious taste or smell. Automatisms are common and consist of repetitive, stereotyped, purposeless mild, movements involving:
• hands (e.g. picking, fidgeting, fumbling)
• mouth (chewing, lip smacking)
During the seizure, phenomena occur which are often misconstrued as a psychological disorder: • confusion • aimless wandering • fearfulness • incoherent speech • other inappropriate behaviour
Write notes on absence seizures (petit mal)
- Typically occur in children
- Sudden loss of awareness by the victim
- Ictus typically involves fluttering of the eye lids and a sudden arrest of motor activity
- Ictus is brief, lasting from about 5-45 sec
- No postictal confusion
- The patient is usually unaware that a seizure has occurred
- Patients may be classified as daydreamers, intellectually slow or even insolent because they may not respond when spoken to
Write notes on events occurring during tonic - clonic seizures (grand mal)
List and briefly describe the characteristics of each stage in this seizure
- usually loss of consciousness occurs at the outset
- some pt. experience a partial aura in which epigastric discomfort occurs
- some pt. have prodromal warnings (not auras) which may precede the attack by several hours. observe:
- mood changes, apprehension, insomnia, anorexia, episodes of repeated myoclonus - As the attack begins, many pt. cry out unconsciously
- Attack proceeds as follows:
- consciousness lost and pt. falls
- tonic contraction of mm occurs, i.e. mm stiffen in extension and breathing is usually arrested causing deep cyanosis
- the tonic phase lasts less than 1 mn
- clonic contraction of mm then occurs
- gradually the tonic extension gives way to a rapid succession of clonic contractions of the neck, trunk and extremities
- last 1 min
- flaccid relaxation stage we observe stertorous breathing, pallor and heavy salivation
- arousal phase occurs 2-3 mins after relaxation phase
- postictal manifestations:- HA, mm fatigue, mm weakness, drowsiness, confusion
- most pt. sleep for several hours following
- HA, mm fatigue, mm weakness, drowsiness, confusion
*urinary and faecal incontinence may occur
How is Epilepsy diagnosed?
Clinical picture • Syncope (fainting) • cardiac arrhythmias • hypoglycaemic attacks • psychogenic - hysterical attacks • narcolepsy / cataplexy syndrome • breath holding attacks • daydreaming • night terrors • Munchausen by proxy
The suggested necessary investigations for a first seizure are:
• Clinical examination
• Assessment of seizure ssx
• Routine laboratory tests (depending on clinical circumstances)
• CSF (if encephalitis or subarachnoid haemorrhage is suspected)
• Drug screening (depending on clinical circumstances)
• Standard EEG (within 24 hours)
• Sleep deprived EEG (within 1 week)
• High resolution MRI
Diagnosis is based mainly on:
• Clinical picture (onset type / secondary – were they aware or not? / assists us in classifiying & treatment)
• Electroencephalography
• History (previous history, familial etc.)
• Must exclude 2° epilepsy with: CT / MRI OR serum glucose OR serum Ca2+ CT/MRI
List 4 complications of epileptic seizures
- injury on falling during attack
- car accidents, drowning
- suffocation
- compression of Lx vertebrae or dorsal section or vertebrae
- biting of tongue
- brain damage (status epilepticus)
List the main therapeutic modalities used to treat epilepsy
- Pharmaceuticals – which depress brain activity
- Surgery
- Ketogenic diet – high fat low carb diet
- Marijuana oil
- If suffering from a secondary cause such as hypoglycemia – we treat this.
Side effects of anticonvulsant drug therapy
- Osteopenia
- Gingival hyperplasia
- Bone weakening
- feeling tired, stomach discomfort, dizziness, or blurred vision.
