MD Notes

creation date: 2026-06-07 00:09
tags: Pathologies

Epilepsy

Background

Definitions

Epilepsy is a condition characterized by recurrent unprovoked seizures. Epilepsy incidence is highest in younger and older age groups.

Seizures (as an umbrella term) is discussed broadly separately.

Etiology & Pathogenesis

Every individual exist on a seizure-susceptibility continuum. Factors may result in the threshold lowering and thus increasing risk:

  • Medications
  • Genetic factors
  • Electrolyte abnormalities
  • Sleep state
  • Brain inflammation/injury

Seizures occur with the excitation of susceptible cerebral neurons, leading to synchronous discharges of progressively larger groups of connected neurons. This likely involves excessive glutamate (excitatory) and reduced GABA (inhibitory) activity.

In the case of epilepsy, unprovoked refers to seizures in the absence of causes or >7 days following acute injury/insult. This generally thus involves genetic susceptibility or chronic pathologic processes.

Clinical Presentation

Signs & Symptoms

Epileptic seizures may present in a variety of types and syndromes. Syndromes consist of distinct phenotypes characterized by specific clinical and electroencephalographic features.

The seizure types are broadly categorized to:

Focal (partial)
Involves one lobe of one hemisphere

  • Focal aware / simple partial seizure
    • No impairment of awareness
    • Motor: unilateral jerking, tonic posturing of one limb/face
    • Sensory: paresthesia, visual phenomena, auditory changes, olfactory/gustatory hallucinations
    • Autonomic: epigastric rising sensation, flushing, tachycardia, piloerection
    • May have aura
  • Focal impaired awareness / complex partial seizure
    • Impairment of awareness
    • Behavioural arrest (suddenly stops activity, stares)
    • Automatism: lip smacking, chewing, picking at clothes, fidgeting, walking aimlessly, mumbling
    • May appears confused, intoxicated, or psychotic
    • Post-ictal: confusion, fatigue, sometimes transient aphasia or focal deficits
  • May progress to bilateral tonic-clonic (secondarily generalized seizure)

Generalized
Simultaneous activation of both side of brain

  • Generalized tonic-clonic (grand mal)
    • Tonic: sudden loss of consciousness, fall, generalized stiffening, lateral tongue biting, incontinence
    • Clonic: symmetric rhythmic jerking of all limbs
    • Post-ictal: deep sleep, confusion, headache, myalgias, transient agitation
  • Tonic seizures
    • Brief bilateral increase in tone (stiff extension/flexion of limbs, axial stiffening)
  • Clonic seizures
    • Repetitive jerking movements without prominent tonic phase
  • Myoclonic seizures
    • Very brief shock-like jerks of muscles, often in morning after waking
    • May manifest as dropping objects
  • Atonic seizures
    • Sudden loss of muscle tones (head nods or chin drops, sudden falls)
  • Absence seizures
    • Brief sudden pause in activity with impaired awareness
    • Staring, unresponsiveness
    • May have subtle automatisms (eyelid flutter, lip smacking, minor hand movements)
    • No post-ictal period
    • Classically in school-age children

These features are applicable to adults and children older than 6. However, younger children may have fewer complex behaviours. Children are also more likely to have seizures but are more apt to disappear later.

History & Physical Exam

History should include:

  • Whether seizure was witnessed
  • The lead up to the seizure, including possible precipitants or triggers
  • Characteristics of movement if there were any
  • Prodromes and post-ictal period
  • History of seizures, medication use, substance use
  • History of malignancy or immunosuppresion
  • For patients with known epilepsy, whether there has been changes to medication use

Physical includes:

  • Neurologic exam with attention to focal deficit and eye movements

Diagnosis

Criteria

Epilepsy is clinically diagnosed by any one of the following:

  • At least two unprovoked (or reflex) seizures occurring >24 hours apart
  • One unprovoked (or reflex) seizure and a probability of further seizures ≥60% over the next 10 years
  • Diagnosis of an epilepsy syndrome

Important definitions include:

  • Unprovoked: not occurring due to some acute trigger or within 7 days of stroke, head trauma or during metabolic derangement
  • ≥60% recurrence rate: generally though to be met if etiology is prior stroke, traumatic brain injury, cavernous malformation, AV malformations, CNS infections, presence of epileptiform abnormality on EEG, or significant lesion on neuroimaging

Seizures lasting longer than 5-10 minutes or serial clinical seizures without interictal return to baseline consciousness is diagnostic of status epilepticus.

Work-up

Laboratory studies
Standard evaluation following first seizure are:

  • POC glucose
  • Serum electrolytes (including extended)
  • Serum lactate
  • CBC
  • Renal function
  • Liver function
  • Urinalysis

Toxicology screen may be indicated if suspected.

Additional evaluation

  • ECG - for any loss of consciousness
  • Neuroimaging - indicated for all patients for new onset seizures (urgent noncontrast CT if intracranial lesion is suspected; otherwise outpatient MRI)
  • EEG - supports diagnosis, especially if not obvious
  • Lumbar puncture - if acute infectious process is suspected

Differential

Primary conditions to consider are:

  • Syncope (including convulsive syncope)
  • Transient ischemic attack
  • Migraine
  • Panic attack and anxiety
  • Psychogenic nonepileptic seizure (PNES)
  • Transient global amnesia
  • Narcolepsy with cataplexy
  • Paroxysmal movement disorders

In children, additionally consider other nonepileptic paroxysmal events (non-exhaustive):

  • Neonates: apnea, jitteriness, benign neonatal sleep myoclonus
  • Infants: apnea, dystonic drug reactions, sleep-related movement disorder, abnormal eye movements
  • Children: migraine syndrome, staring spells, movement disorders, sleep disorders

Red Flags / Complications

Complications include:

  • Traumatic injuries including tongue lacerations
  • Underlying cause

Convulsive status epilepticus can lead to brain damage and requires identification and treatment.

Management

Immediate Post-Seizure Management

Most seizures remit spontaneously within 2 minutes. Thus, immediate management does not require antiseizure medications and consist of obtaining IV access.

Note, in the case of acute symptomatic seizures (not epilepsy), treatment of underlying causes are performed (eg. correction of hypoglycemia).

Pharmacological

As there is an increased risk of seizure recurrence, antiseizure medications are typically started. The exact timing and whether to use medication is individualized depending on the risk of recurrence, risk of harm from recurrence, and the risk of harm from treatment.

Selection of antiseizure medication depends on balance of effectiveness and tolerability. Options are as follow depending on the seizure type.

Focal seizures and secondarily generalized seizures:

  • Lamotrigine
  • Levetiracetam
  • Oxcarbazepine
  • Carbamazepine
  • Lacosamide

Absence seizures:

  • Ethosuximide
  • Valproate
  • Lamotrigine

Genetically mediated generalized tonic-clonic seizures:

  • Lamotrigine
  • Levetiracetam
  • Valproate
  • Topiramate
  • Zonisamide

Myoclonic seizures:

  • Levetiracetam
  • Valproate
  • Zonisamide
  • Clonazepam

Tonic/atonic seizures:

  • Valproate
  • Lamotrigine
  • Clobazam
  • Conisamide
  • Levetiracetam

Focal motor/epilepsia partialis continua:

  • Phenytoin
  • Carbamazepine
  • Oxcarbazepine

References

Tools / Guidelines

Additional Reading

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