International League Against Epilepsy (ILAE) classification systems 2017
- 4 levels or different ways of diagnosis based on available information
- Seizure type: based on onset
- *Degree of awareness usually is not specified.
- ¹Due to inadequate information or inability to place in other categories
- Epilepsy based on seizure type
- Originate: one point that rapidly spread to whole brain (both hemispheres) though subcortical and/or cortical structures
- Generalized seizures do not need to necessarily include the entire cortex but both hemisphere is needed
- Can be asymmetric
- EEG:
- Show generalized spike-wave or generalized paroxysmal fast activity
- The term focal has replaced partial
- Origin: one hemisphere
- Arise from either subcortical structures or neocortex.
- EEG
- Focal or multifocal discharges on interictal EEG.
- Epilepsies that have both generalized and focal seizures.
- Includes several epilepsy syndromes, particularly those with onset in early childhood, such as
- Dravet syndrome
- Lennox-Gastaut syndrome,
- But may also be relevant for epilepsies associated with diffuse or focal structural, genetic, or metabolic etiologies.
- EEG show both generalized and focal/multifocal discharges, or epileptiform discharges may be absent.
- Epilepsies with seizures in which it cannot be clearly determined whether onset is focal or generalized.
- Eg
- Epileptic spasms, which may appear generalized despite being caused by a focal lesion.
- The term unknown should also be used in an individual who presents with a generalized tonic-clonic seizure and normal examination but whose EEG and neuroimaging is either noninformative or unavailable.
- Epilepsy syndrome
- Epilepsy with aetiology (determined by Neuroimaging, Genetics, specific autoantibodies)
- Following neurologic insult: either acutely (i.e., < 1 week) or remotely (> 1 week, and usually < 3 mos from insult)
- Stroke:
- 4.2% had a seizure within 14 days of a stroke.
- Risk increased with severity of stroke
- Post traumatic seizure:
- Closed head injury
- Adults:
- Severe head injury (LOC >24 hrs, amnesia > 24 hrs, focal neuro deficit, CT contusion, or intracranial hematoma)
- 30% incidence
- Mild and moderate head injury
- 1% incidence
- Children (<15): brief LOC or amnesia
- 2.6%
- Risk of early PTS is high in children
- 94.5% develop them within 24 hrs of the injury
- Can result in
- Elevation of ICP,
- Alterations in BP,
- Changes in oxygenation,
- Excess neurotransmitter release.
- Both adults and paeds
- 10–13% within 2 yrs after “significant” head trauma (LOC> 2 mins, GCS<8 on admission, epidural hematoma…)
- Relative risk: 3.6 x general population.
- Risk of late PTS is higher in adults
- If don't develop seizure within 3 yrs of injury= will not develop seizure
- Risk of late PTS affected by presence of Early PTS?
- Paeds: no relation
- Adults:
- Mild: no relation
- Severe: inc. Risk of late
- Risk of developing late PTS may be higher after repeated head injuries.
- Penetrating trauma
- 50% of penetrating trauma cases followed 15 yrs
- High risk of PTS
- Acute subdural, epidural, or intracerebral hematoma (SDH, EDH or ICH)
- Open-depressed skull fracture with parenchymal injury
- Seizure within the first 24 hrs after injury
- Glasgow Coma Scale score < 10
- Penetrating brain injury
- History of significant alcohol abuse
- ± cortical (hemorrhagic) contusion on CT
- Treatment:
- Closed head injury only
- No treatment studied effectively impedes epileptogenesis (i.e., neuronal changes that ultimately lead to late PTS)
- In high-risk patients, AEDS reduce the incidence of early PTS
- However, no study has shown that reducing early PTS improves outcome
- Once epilepsy has developed, continued AEDs reduce the recurrence of further seizures
- Methods
- Begin levetiracetam, phenytoin (study was only done for PHT) or carbamazepine within 24 hrs of injury in the presence of any of the high risk criteria
- If phenytoin used load with 20mg/kg → maintain high therapeutic levels
- Use phenytoin for max 2 wks
- Phenytoin has adverse cognitive effects when given long-term as prophylaxis against PTS.
- If not tolerating PHT use phenobarbital
- Temkin 1990
- 73% reduction of risk of early PTS with PHT started with 24hrs and maintain (10-20mg/l) high therapeutic levels
- Levetiracetam (Hazama 2018): Levetiracetam vs phenytoin
- Useful in severe head injury only
- Both had similar reduction in seizure
- Levetiracetam less complication
- Reduction in seizure incidence in Keppra groups (not statistically significant)
- Taper AEDs after 1 week of therapy except in the following cases:
- Penetrating brain injury
- Development of late PTS (i.e., a seizure > 7 days following head trauma)
- Prior seizure history
- Patients undergoing craniotomy
- For patients not meeting the criteria to discontinue AEDs after 1 week
- Maintain ≈ 6–12 mos of therapeutic AED levels
- Recommend EEG to rule out presence of a seizure focus before discontinuing AEDs (shown to have poor predictive value, but probably advisable for legal purposes) for the following:
- Repeated seizures
- Presence of high risk criteria
- CNS infection:
- Meningitis
- Cerebral abscess
- Subdural empyema
- Febrile seizures
- Febrile seizure. A seizure in infants or children associated with fever with no defined cause and unaccompanied by acute neurologic illness (includes seizures during vaccination fevers)
- Complex febrile seizure. A convulsion that lasts longer than 15minutes, is focal, or multiple (more than one convulsion per episode of fever)
- Simple febrile seizure. Not complex
- Recurrent febrile seizure. More than one episode of fever associated with seizures
- Most common type of seizure
- Prevalence: 2.7%
- Risk of epilepsy
- Higher for patients with
- Underlying neurological abnormalities
- Underlying development abnormalities
- Family history
- No proof that younger the child with febrile seizure the greater the risk
- Low incidence (1%) of having afebrile seizures (i.e., epilepsy) after a simple febrile seizure and the fact that AEDs probably do not prevent this development, there is little support for prescribing anticonvulsants in these cases.
- No other drug really appears well suited to treating FSz
- Carbamazepine and phenytoin appear ineffective,
- Valproate may be effective but has serious risks in the<2 yrs of age group.
- Phenobarbital (Farwell 1990)
- No significant reduction in seizures in the phenobarbital group
- IQ in the group treated with phenobarbital was 8.4 points lower (95% confidence interval) than the placebo group, and there remained a significant difference several months after discontinuing the drug.
- If have recurrent febrile seizure (Rossman 1993)
- Recurrence rate can be reduced by administering diazepam 0.33mg/kg PO q 8 hrs during a febrile episode (temp>38.1 °C) and continuing until 24 hrs after the fever subsides.30
- Birth asphyxia
- Underlying CNS abnormality
- Congenital CNS abnormalities
- Degenerative CNS disease
- CNS tumour: metastatic or primary
- Hydrocephalus
- AVM
- Acute systemic metabolic disturbance
- Uraemia
- Hyponatremia
- Hypoglycaemia (especially profound hypoglycaemia),
- Hypercalcemia
- Alcohol-withdrawal
- 33-75% of habituated drinkers within 7–30 hours of cessation or reduction of etoh intake
- 1–6 tonic-clonic generalized seizures without focality within a 6 hour period
- Seizure risk persists for 48 hrs
- Single loading dose of PHT is frequently adequate for prophylaxis.
- Evaluation
- CT done for
- First EtOH withdrawal seizure
- Focal findings
- > 6 seizures in 6 hrs
- Evidence of trauma
- LP: r/o meningitis
- Treatment:
- Benzodiazepines administered during detoxification reduces the risk withdrawal seizures
- Most EtOH withdrawal seizures are single, brief, and self-limited → do not need treatment
- Seizure >4 mins → treatment diazepam or lorazepam
- Persisting seizure → phenytoin
- Long term treatment for
- A history of previous alcohol withdrawal seizures
- Recurrent seizures after admission
- History of a prior seizure disorder unrelated to alcohol
- Presence of other risk factors for seizure (e.g. subdural hematoma)
- Cocaine toxicity
- Opioids (narcotics)
- Phenothiazine antiemetics
- With administration of flumazenil (Romazicon®) to treat benzodiazepine (BDZ) overdose (especially when BDZs are taken with other seizure lowering drugs such as tricyclic antidepressants or cocaine)
- Phencyclidine (PCP): originally used as an animal tranquilizer
- Cyclosporine: can affect Mg++ levels
- Eclampsia
- Idiopathic:
- No abnormality found on CT or MRI, no evidence of drug withdrawal
- Management controversial (van Donselaar 1992)
- An EEG was performed, which, if normal, was followed by a sleep deprived EEG with the following observations
- Temporal lobe epilepsy
Seizure type | Motor onset | Nonmotor onset (absence) |
Generalized onset seizures | - Tonic-clonic - Clonic - Tonic - Myoclonic - Myoclonic-tonic-clonic - Myoclonic-atonic - Atonic - Epileptic spasms | - Typical - Atypical - Myoclonic - Eyelid myoclonia |
Focal onset seizures | - Aware - Impaired awareness - Unknown awareness - Automatisms - Atonic* - Clonic - Epileptic spasms* - Hyperkinetic - Myoclonic - Tonic - Focal to bilateral tonic-clonic | - Aware - Impaired awareness - Unknown awareness - Autonomic - Behavior arrest - Cognitive - Emotional - Sensory - Focal to bilateral tonic-clonic |
Unknown onset seizures | - Tonic-clonic - Epileptic spasms | - Behavior arrest |
Unclassified seizures¹ | ㅤ | ㅤ |
Generalized epilepsy
Focal epilepsy
Generalized and focal epilepsy
Unknown if generalized or focal epilepsy
Early (<7 days post injury)
Late (>7 days post injury)
Initiate
Discontinue
Definition
Numbers
Risk of epilepsy | After |
1% | Simple febrile seizure |
6% | Complex febrile seizure |
9% | Prolonged seizure |
29% | Focal seizure |
Treatment
Electrolyte disorders
Drug related, including:
2 yr seizure rate | EEG feature |
12% | If both EEGs were normal |
83% | If one or both EEGs showed epileptic discharges |
41% | The presence of nonepileptic abnormalities in one or both EEGs |
Type of epileptic discharge | Recurrence rate |
Focal epileptic discharges | 87% |
Generalized epileptic discharges | 78% |
- Removed simple partial, complex partial and secondarily generalized as hard to define and often used incorrectly
Old classification
- ILAE classification 1981
- Simple partial seizures (no loss of consciousness)
- Complex partial seizures
- With impairment of consciousness at onset
- Simple partial onset followed by impairment of consciousness
- Partial seizures evolving to generalised tonic-clonic (GTC) convulsions.
- Absence
- Myoclonic
- Clonic
- Tonic
- Tonic-clonic
- Atonic
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