Last updated:
March 8, 2026
Overview and Approach to Unexplained Seizures
A seizure is defined as a sudden change in consciousness, behaviour or movement of the body caused by electrical hypersynchronization of neuronal networks in the cerebral cortex. This sudden change tends to be transient. Seizures mainly present with motor symptoms, e.g. shaking, and non-motor symptoms, e.g. language, vision and sensory changes, confusion, or alterations of awareness.
Patients with epilepsy are physically normal and asymptomatic between events
Elements of a seizure
| Element | Description | Features |
|---|---|---|
| Prodrome | Precedes the seizure and last hours to days. | Changes in mood or behavior |
| Aura | A sensory experience that correlates to the epileptic event | Rising epigastric sensation, Gustatory/olfactory hallucination, Visual changes, Headache, Paresthesia, Psychiatric phenomena (deja vu, jamais vu) |
| Post-ictal states | Follows the seizure | Headache, Somnolence, aggression, confusion, cognitive impairment, temporary paralysis (Todd’s paralysis following a focal seizure in the motor cortex), dysphasia (focal seizure in the temporal lobe) |
- Patient History
- What is the frequency and duration of seizures?
- What happened before/after the event? (pre-ictal phase and post-ictal phase)
- Was there a preciding aura?
- Was there residual weakness or confusion post-ictal?
- Are there any automatisms? (Gives a clue as to the focus of origin)
- Was there tongue-biting?
- Was there incontinence?
- Has there been trauma OR drug/alcohol use? (triggers)
- Is there a Family History?
- Conditions that trigger seizures
- Medication non-compliance OR New drug that interferes with medication (break-through seizures)
- Sleep deprivation
- Stress
- Alcohol (being drunk raises the seizure threshold, the problem is recovering from the buzz which causes a lower seizure threshold)
- Alcohol withdrawal (chronic alcohol use going cold turkey)
- Hypoglycemia
- Differentials for seizures (VITAMIN D)
- Vascular malformation (CT, MRI)
- Infection, Inherited conditions
- Trauma
- Alzheimer’s
- Metabolic derangement (hypocalcemia, Hyponatremia, Hypernatremia, Hypermagnesemia, Hypomagnesemia, Hyperglycemia, Hypoglycemia)
- Idiopathic
- Neoplasms
- Drugs (fluoroquinolones, bupropion, imipramine, meperidine, metronidazole, INH)
- Investigations
- RBS: exclude extreme hypoglycemia or hyperglycemia
- CBC: rule out systemic or CNS infections
- U/E/Cs: rule out hyponatremia, hypernatremia, hypocalcemia and uremia
- Urine toxicology screen: rule out cocaine, amphetamines, heroin PCP, GHB
- Blood Alcohol Concentration: >0.06 after binge drinking; alcohol withdrawal
- Head CT: structural lesions, injury (TBI), elevated intracranial pressure (contraindication to lumbar puncture)
- EEG
- MRI
- Treatment
- Seizure precautions
- Establish IV access
- Abort the seizure using AEDs
- What diagnosis should you consider if convulsions last more than 3 minutes?
- Status epilepticus
- Non-epileptic seizure
Focal (partial) seizure
Focal seizures involve one part of the brain. The patient may not lose consciousness and may have altered awareness.
| Focal seizure | Description |
|---|---|
| Simple focal seizure | The patient is aware. Can involve sensory, motor, psychiatric, or autonomic symptoms |
| Complex focal seizure | The patient has altered awareness. Might appear dazed and confused. Symptoms are similar to simple focal seizures |
Localising features of focal seizures
| Location | Features |
|---|---|
| Temporal lobe | Automatisms, Dysphasia, Deja vu, Jamais vu, Emotional disturbance, Elation, Derealization, Hallucination, Delusions, Bizarre associations |
| Frontal lobe | Motor features, Jacksonian march, Motor arrest, Subtle behavior disturbances, Dysphasia or speech arrest, Post-ictal |
| Parietal lobe | Sensory disturbance, Motor symptoms if it spreads to the pre-central gyrus |
| Occipital lobe | Visual phenomena – spots, lines, flashes |
Generalized seizure
Generalised seizures arise from both cerebral hemispheres.
| Type | Description | Features |
|---|---|---|
| Absence (petit mal) seizure | Loss of consciousness. Non-motor. Classically seen in children. The child looks out into space for a few seconds and snaps back into reality | Blank stare < 10 seconds that starts and ends abruptly, Automatisms (lip smacking, hand wringing, motor tics), 3 Hz spike and wave on EEG |
| Tonic-clonic (grand mal) seizure | Loss of consciousness with stiffening and jerking of all limbs (may have on without the other) | Loud moan (air coming out of closed epiglottis) followed by stiffening and jerking (involving all four limbs). Tongue biting (look for tongue laceration esp. in patients who live by themselves) and Urinary incontinence. There may be post-ictal confusion and drowsiness |
| Myoclonic seizure | No loss of consciousness. There is a sudden jerk of a limb, face, or trunk. “My flying-saucer epilepsy” | Sudden jerk of part of the body (arm or leg). They may fall over suddenly or have a violently disobedient limb |
| Atonic seizure | Sudden loss of muscle tone causing fall. | Sudden loss of muscle tone < 15 seconds, falls over. Wakes up confused (there is actually LOC, but they wake up soon after hitting the ground) |
- How would you differentiate an atonic seizure from syncope?
- Seizures have haziness and confusion after loss of consciousness.
- In syncope, the patient will be generally OK after recovering.
Common causes of seizures
| Age group | Common causes |
|---|---|
| Neonates and infants (< 1 year) | Genetic, Congenital structural maldevelopment, perinatal injury, perinatal/postnatal infection (meningitis), metabolic disorder (hypoglycemia, hypocalcemia), west syndrome |
| Young children (<10 y) | Febrile, Genetics, Infection, Traumatic Brain Injury, Congenital brain malformation, Metabolic disorders, Accidental poisoning |
| Adolescents (10-18 years) | Traumatic brain injury, Encephalitis, Genetic disorders, Illicit substance abuse |
| Adults (18-60y) | Alcohol withdrawal, Traumatic brain injury, Illicit substance use, Neoplasm, Infection, Metabolic acidosis |
| Older adults (60+ years) | Traumatic brain injury, Cerebrovascular disease, Neoplasm, Abscess, Neurodegenerative disease |
First Aid DOs and DON’Ts in Patient who are in active Seizure
- DO NOT
- DO NOT Put anything in the patient’s mouth to prevent tongue biting (it is anatomically impossible to choke on the tongue. Also tongue biting may have already happened)
- DO NOT Restrain the patient
- DO
- Gently lean the patient on their side with the head turned to the same side (to prevent aspiration)
- Cushion the patients head (to prevent head injury)
- Loosen or remove tight or dangerous clothing around the head and neck (necklaces, glasses)
- Remove dentures
- Call for help immediately