Epilepsy causes, types and triggers

What causes epilepsy?

In approximately 50% of cases, the cause of epilepsy is unknown. In some instances, the condition may occur as a result of:

• A head injury (during birth or an accident) and scarring on the brain
• Low oxygen levels during birth
• Tumours (or cysts) in the brain
• A genetic condition, such as tuberous sclerosis that causes damage to the brain
• Developmental disorders such as autism or neurofibromatosis
• Injury as a result of stroke
• Infections affecting the brain such as meningitis, viral encephalitis or AIDS
• Abnormal levels of sodium or blood sugar
• Dementia or Alzheimer’s disease
• Brain malformation as a result of maternal drug use

Sometimes a cause can relate to a genetic influence, where the condition appears to run in families. Researchers have established that up to 500 genes, however, are linked to the condition, but not all can be definitively determined as a direct cause of epilepsy. Some genes merely make a person more sensitive to certain seizure triggers such as environmental factors.

Types of epilepsy

Types of epilepsy will typically be categorised and treated according to the condition’s causes (if known) and overall symptoms. The main classification types are known as⁷:

• Idiopathic (no apparent cause)
• Cryptogenic (there is likely a cause but it is still unknown)
• Symptomatic (an underlying cause has been identified)

From there, epilepsy may be sub-categorised as generalised or partial (focal):

• Idiopathic generalised epilepsy: Typically diagnosed during childhood or adolescence, this type often shows little or no nervous system abnormalities, other than seizures. Tests may involve EEG (electroencephalogram which measures electrical impulses in the brain) or MRI (magnetic resonance imaging) scan. Scans will show a structurally normal brain, but a specialist may be able to determine subtle changes which may have been present since birth, such as epileptic discharges affecting one or more areas of the brain. A person with this type has normal intelligence, but will experience myoclonic seizures, absence seizures or generalised tonic-clonic seizures (grand mal seizures). Some youngsters may ‘grow out’ of this type of epilepsy and stop having seizures.
• Idiopathic partial (focal) epilepsy (sometimes known as BFEC – Benign focal epilepsy of childhood): This mild type is often diagnosed in early childhood (between the ages of 5 and 8) and almost always is outgrown by puberty (sexual maturation). Seizures are typical during a person’s sleep state. A child will experience partial motor seizures (affecting the face) and grand mal seizures. Diagnosis is typically made with an EEG.
• Symptomatic / Cryptogenic generalised epilepsy: With a symptomatic type, a cause has been determined and often relates to widespread brain damage. A sufferer may also have other neurological problems, such as cerebral palsy or mental retardation. Where a cause has not been determined, a diagnosis will be made as cryptogenic epilepsy. Both experience multiple types of seizures – namely, generalised tonic-clonic, tonic, myoclonic, atonic, tonic and absence). This is often difficult to control. Sub-types include Lennox-Gastaut syndrome.
• Symptomatic partial (focal) epilepsy: Commonly diagnosed in adulthood, this type is also frequently seen in childhood. A localised abnormality in the brain (due to stroke, tumours, congenital brain abnormalities, trauma, scarring or ‘sclerosis’, infections or cysts) typically causes this type of epilepsy. Some abnormalities may be microscopic and difficult to pick up on an MRI scan, however some abnormalities can be seen and identified. In many cases, surgery may be able to correct these abnormalities without compromising the rest of the brain’s normal function.

Common triggers for epileptic seizures

Commonly noted triggers that bring on seizures among epilepsy sufferers include:

• A fever or illness
• Stress
• Lack of sleep or poor sleep
• Stimulants such as caffeine, alcohol and medications or illicit drugs
• Bright or flashing lights
• Overeating, skipping meals or specific foods / ingredients
• Missing medication doses

Identifying triggers is often tricky. Sometimes a seizure incident is brought on by a trigger, other times not. For others, a combination of factors may trigger a seizure.

An example of triggers that lead to an epileptic seizure are flashing lights or specific visual patterns in people with photosensitive epilepsy (although this is relatively rare and only occurs in around 3% of all epilepsy cases).

Women may also note that seizures are more commonly experienced around their menstrual periods⁸. A doctor will be able to change or prescribe other medications for a woman to take before she has her menstrual period each month.

Often a newly diagnosed epilepsy sufferer may be advised to keep a record of possible triggers. In their record-keeping, they can note details such as the day and time of the incident, what they were busy with when the seizure happened, what was happening around them at the time, if there were any particular smells, sounds, sights or unusual stressors. It may also be useful to note if the person was eating or how long it had been between the last meal and the seizure, whether the person was feeling tired or fatigued and if they had a poor night’s sleep the previous day.

Details about medications can also be included in the journal as an easy way to track whether treatment is working or not. If possible, it will be helpful to a doctor if a person can note how they felt just before and after experiencing a seizure, and whether they experience any side-effects on their medication.

A journal may also prove useful to a sufferer as many find it difficult to recall information once they have experienced a seizure or lost consciousness. If a person can train themselves to pay attention to details and take note of them as far as possible, this can be very useful for effective management of the condition.

 

References

^{7. Chang R, Leung C, Ho C, Yung A. Classifications of seizures and epilepsies, where are we? – A brief historical review and update. Journal of the Formosan Medical Association. 2017;116(10):736-741. doi:10.1016/j.jfma.2017.06.001}

^{8. Shorvon S. The etiologic classification of epilepsy. Epilepsia. 2011;52(6):1052-1057. doi:10.1111/j.1528-1167.2011.03041.x}