Signs and Symptoms
- Seizures can vary in their outward effects
- Symptoms range from uncontrolled shaking movements with loss of consciousness (tonic-clonic seizure) to subtle momentary loss of awareness (absence seizure)
- Episodes usually last less than two minutes
- Loss of bladder control may occur
- Seizures can be provoked or unprovoked
Types of Seizures
- Focal seizures often begin with certain experiences known as an aura
- These experiences can include sensory, cognitive, autonomic, olfactory, or motor phenomena
- In complex partial seizures, a person may appear confused or dazed and cannot respond to questions or direction
- Jerking activity may start in a specific muscle group and spread to surrounding muscle groups
- Unconscious activities known as automatisms may occur, such as smacking of the lips or attempts to pick something up
- There are six main types of generalized seizures: tonic-clonic, tonic, clonic, myoclonic, absence, and atonic seizures
- Generalized seizures involve a loss of consciousness and typically happen without warning
- Tonic-clonic seizures present with limb contractions followed by shaking of the limbs
- Tonic seizures produce constant muscle contractions
- Clonic seizures involve shaking of the limbs in unison
Causes
- Seizures can be caused by various factors
- About 25% of those who have a seizure have epilepsy
- Some seizures are acute symptomatic or provoked seizures, associated with conditions like infection, stroke, or toxicity
- In many cases, the cause of seizures is unknown
- Different age groups have different common causes of seizures, such as hypoxic ischemic encephalopathy in babies and febrile seizures in children.
- Medication and drug overdoses can result in seizures.
- Certain medications and drug withdrawal can also cause seizures.
- Common drugs involved in seizures include antidepressants, antipsychotics, cocaine, insulin, and lidocaine.
- Withdrawal seizures commonly occur after prolonged alcohol or sedative use, known as delirium tremens.
- Herbal medicines such as ephedra, ginkgo biloba, and wormwood can provoke seizures in people at risk of developing epilepsy.
- Infection with the pork tapeworm can cause neurocysticercosis, which is responsible for up to half of epilepsy cases in areas where the parasite is common.
- Parasitic infections like cerebral malaria can also cause seizures, especially in children under five years of age.
- Infections such as encephalitis or meningitis can lead to seizures.
- Stress can induce seizures in people with epilepsy and is a risk factor for developing epilepsy.
- High blood pressure, known as hypertensive encephalopathy, can cause seizures.
- Eclampsia, a condition during pregnancy accompanied by seizures or decreased consciousness, can also lead to seizures.
- Very high body temperatures, typically above 42°C (107.6°F), can be a cause of seizures.
- Head injuries may result in non-epileptic post-traumatic seizures or post-traumatic epilepsy.
- People with celiac disease have a higher prevalence of seizures (3.5 to 5.5%).
Mechanism and Tests
- In epileptic seizures, a group of neurons fire abnormally, excessively, and synchronously due to problems within the brain.
- This abnormal firing results in a wave of depolarization known as a paroxysmal depolarizing shift.
- Changes in ion channels or malfunctioning inhibitory neurons can decrease the resistance of excitatory neurons to fire, leading to seizures.
- Mutations in ion-channel genes and ion-channel abnormalities contribute to the development of epileptic seizures.
- Seizure activity may be propagated through the brain's endogenous electrical fields, involving changes in potassium and calcium levels.
- EEG aids in locating the focus of an epileptic seizure
- EEG helps determine the type of seizure or syndrome present
- EEG is recommended after a second seizure in children
- CT scan and MRI are recommended after a first non-febrile seizure to detect structural problems in the brain
- MRI is generally a better imaging test except when intracranial bleeding is suspected
- Differentiating an epileptic seizure from other conditions such as syncope can be difficult
- Conditions that can mimic a seizure include decerebrate posturing, psychogenic seizures, tetanus, dystonia, migraine headaches, and strychnine poisoning
- 5% of people with a positive tilt table test may have seizure-like activity due to cerebral hypoxia
- Convulsions may occur due to psychological reasons known as psychogenic non-epileptic seizures
- Non-epileptic seizures can occur due to various other reasons
Management and History
- Move sharp or dangerous objects away from a person experiencing a seizure
- Place the person in the recovery position if not fully conscious and alert after the seizure
- Seizure longer than five minutes or multiple seizures within five minutes is a medical emergency known as status epilepticus
- Bystanders should not force objects into the mouth of a person having a seizure
- Treatment progression for actively seizing person includes initial response, first line, second line, and third line treatments
- First-line medication for actively seizing person is a benzodiazepine, with lorazepam being recommended
- Diazepam and midazolam are alternatives to benzodiazepines
- Barbiturates or propofol may be used if benzodiazepines are ineffective after two doses
- Second-line therapy for adults is phenytoin or fosphenytoin, and phenobarbital for children
- Third-line medications include phenytoin for children and phenobarbital for adults
- Epileptic seizures first described in an Akkadian text from 2000 B.C.
- Early reports saw seizures and convulsions as the work of evil spirits.
- Ancient Greeks referred to epilepsy as the sacred disease.
Seizure Data Sources
| Reference | URL |
|---|---|
| Glossary | https://www.alternix.com/blogs/glossary-of-terms/seizure |
| Wikipedia | http://en.wikipedia.org/wiki/Seizure |
| Wikidata | https://www.wikidata.org/wiki/Q6279182 |
| Knowledge Graph | https://www.google.com/search?kgmid=/m/06rhk |
