FACTS AND FIGURES

  1. What is a seizure?
  2. What is epilepsy?
  3. Are all seizures epilepsy?
  4. How are types of seizures classified?
  5. How are seizure etiologies classified?
  6. What causes epilepsy?
  7. What are the symptoms and signs of a seizure?
  8. How often does epilepsy occur in the United States?
  9. How is epilepsy diagnosed?
  10. How is epilepsy treated?
  11. What is the prognosis of epilepsy?
  12. What contributes to recurrent seizure or treatment failure?
  13. What are the most recent evidence-based recommendations for managing AEDs (Anti-seizure Drugs) for women of childbearing potential and pregnant women therapy to minimize teratogenesis?
  14. How should providers counsel women with epilepsy who are pregnant or planning to become pregnant about their risk of increased seizure frequency and obstetrical complications?

1. What is a seizure?

  • A seizure is a transient disruption of brain function due to abnormal and excessive electrical discharges in brain cells.
  • This disruptive event must be distinguished from events that may mimic seizures but are not due to abnormal and excessive electrical discharges in brain cells, such as syncope, cardiac disturbances, or psychologically based events (events mimicking seizures that have an emotional basis, or Psychogenic, Non-epileptic Seizures (PNES)).
  • Non-epileptic events may require further neurological investigations that may include 24-hour video-EEG monitoring. Events with an emotional causality should be addressed with psychological counseling, patient and family education and psychiatric treatment as indicated.

2. What is epilepsy?

  • Epilepsy is a disease of the brain that predisposes a person to recurrent unprovoked seizures.
  • It is diagnosed when two or more unprovoked seizures have occurred. Unprovoked means that the seizures occur when an acute brain disturbance cannot be identified as the cause of seizure, in spite of neurological evaluation.
  • Historically, the occurrence of only one seizure has not been considered epilepsy except in specific situations. The International League against Epilepsy (Fisher et al, 2013, ILAE) is considering a new definition to clarify these situations. Specifically, epilepsy will be considered present if:
    • At least two unprovoked seizures occur more than 24 hours apart
    • One unprovoked seizure occurs but there is a probability of further seizures (approximately 75% or more) based on interictal EEG and epilepsy syndrome
    • At least two seizures occur in a setting of reflex epilepsy

3. Are all seizures epilepsy?

  • Some seizures may be provoked by another medical problem and would not recur on their own. In these situations, the seizures are not consideredepilepsy.
  • These may includeseizures provoked by acute brain disturbance such as head trauma, drug or alcohol intoxication, metabolic disturbance, stroke, fever, hyperglycemia, or hypoglycemia.
  • Many acute brain disturbances are treatable or reversible, so that the risk of seizure recurrence can be satisfactorily reduced by appropriate treatment of the brain disturbance.

4. How are types of seizures classified?

Seizures are commonly characterized into two groups, partial and generalized, according to the clinical characteristics and EEG findings (interictal and ictal).

  • Partial seizures begin in one area of the brain:
    • Simple Partial Seizure - no mental confusion or loss of awareness during or after the seizure. About 14% of 
persons with epilepsy have this type of seizure and may involve simple motor movement or a sensation in one part of the body (e.g., a brief arm tremor), sensory changes (ie, paresthesias), visual changes, or aphasia. Sometimes only sensory symptoms are called an ‘aura’.
    • Complex Partial Seizure - brief mental confusion or loss of awareness which sometimes goes unnoticed or is misdiagnosed; loss of posture and falling are rare. After the seizure has ended, confusion steadily reduces over a few 
seconds to a few minutes. About 36% of persons with epilepsy have this type of seizure. These 
seizures by themselves do not involve full body convulsions but unilateral tonic or clonic movements may be seen. These seizures can involve odd motor movements, 
lip smacking, (called automatisms) or odd sensations.
  • Generalized Seizures involve generalized epileptiform activity and are further divided into:
    • Primary Generalized Seizure - seizure begins diffusely from both cerebral hemispheres without
any clear area of onset. Examples are generalized tonic-clonic seizures (formerly called
"grand mal"), absence seizures (formerly called ‘petit mal’, myoclonic seizures, and atonic seizures. About 25% of persons with epilepsy have generalized tonic-clonic or "grand mal" seizures, 5% or less have either absence ("petit mal") seizures or myoclonic seizures, with less than 1% for atonic seizures. Falls may occur with many seizure types, especially with generalized tonic-clonic and atonic seizures.
    • Secondarily Generalized Tonic Clonic Seizure - seizure begins as either simple or complex partial 
seizure, which then spreads to involve both hemispheres and results in convulsive activity.
  • The ILAE in 2010 proposed a new seizure classification dividing seizure types into the following: 1) generalized, 2) focal, or 3) unknown.
    • The terms “simple” and “complex” would be replaced with descriptors such as “with or without loss of consciousness” or “dyscognitive”.
    • The term “secondarily generalized” would be replaced with “evolving to a bilateral convulsive seizure”.
    • An overview of revised terminology and concepts can be found at here.

5. How are seizure etiologies classified?

The following terms are used to classify the cause or etiology of seizures and epilepsy.

  • Symptomatic – cause of seizure is known and is not genetic
  • Idiopathic- cause of seizure is unknown, or genetic factors are present or suspected.
  • Cryptogenic - probably a symptomatic seizure, but the exact cause could not be definitely 
established.
  • The 2010 ILAE classification scheme proposed different terminology in which epilepsies may be genetic, structural-metabolic or unknown, depending on the etiology.

6. What causes epilepsy?

  • When the cause is determined, the four most common are head trauma, stroke, brain tumor, and brain infection.
  • Other causes include drug effects or intoxication, genetics, metabolic disturbances.
  • The causes may vary by age with genetic, congenital malformations or metabolic disturbances more common in young children, trauma and tumors more common in young adults, and stoke most common in older adults.
  • The cause is "unknown" in 60 to 70% of cases (i.e. idiopathic / cryptogenic).

7. What are the symptoms and signs of a seizure?

  • Symptoms and signs may vary from person to person, but are usually consistent and predictable for each individual.
  • Examples of symptoms are loss of awareness, mental confusion, speech impairment, paresthesias (abnormal sensations such as numbness or tingling),olfactory, gustatory or visual hallucinations, and/or abdominal discomfort.

Examples of external signs are mental confusion, staring, changes in muscle tone, muscle twitches or jerking movements, oral or manual automatic 
behavior (automatisms), unsteadiness, and convulsions. 

8. How often does epilepsy occur in the United States?

  • 1 in 26 people will develop epilepsy or recurring seizures in their lifetime.
  • The incidence of epilepsy in the US population is between 35.5-71/100,000 persons per year.
  • The prevalence of epilepsy in the US population is between 5-8.4/1000 persons per year or approximately 1% of the population.
  • Approximately 2.2 to 3 million persons in the U.S. have epilepsy.
  • It affects all ages, socioeconomic and racial groups.
  • Epilepsy incidence however, is highest in children and older adults.  

9. How is epilepsy diagnosed?

There is no single test to diagnose seizures or epilepsy. Common tests performed include:

  • Accurate history and seizure description are most important
  • Blood tests: Complete Blood Count (CBC), electrolytes, liver and renal function tests 
are sometimes utilized
  • Computerized Tomography Scanning (CT) is preferred for evaluation of acute 
seizure
  • Magnetic Resonance Imaging (MRI) is preferred for further evaluation or in non-emergent
situations
  • Electroencephalograms (EEG), preferably wake and sleep (in order not to miss aberrant activity)
  • When seizures are difficult to diagnose or control, continuous video-EEG monitoring can be utilized to confirm the diagnosis and determine appropriateness for different treatment options.

10. How is epilepsy treated?

  • Anti-seizure medication (AED) is the primary treatment to control seizures.
  • Some forms of epilepsy, because of their benign nature and prognosis, may not require AED treatment
  • Epilepsy surgery should be considered when 2 or more medications fail to satisfactorily control seizures 
and the seizure origin in the brain can be well localized and safely removed.
  • When epilepsy surgery is not an option, dietary therapies, vagus nerve stimulation, responsive neurostimulation and investigational drug trials may help control seizures but are not considered curative at this point. Other devices and types of treatment are being studied.

11. What is the prognosis of epilepsy?

  • 60% to 70% of people with epilepsy will respond satisfactorily to the first AED used.
  • Prognosis is highly dependent on the cause of epilepsy and seizure type.
  • Satisfactory response within a few months to the first AED used is predictive of favorable 
long-term seizure control.
  • In the long-term, most patients achieve satisfactory seizure control, about 50% of whom 
can successfully discontinue AED treatment, usually after being seizure free for at least 2 to 5 years.

12. What contributes to recurrent seizure or treatment failure?

  • Poor adherence to medications or other therapies
  • Sleep deprivation
  • Active medical illness
  • Major emotional stress
  • Medication adjustments
  • Fever related to flu / other sickness
  • Substance abuse

13. What are the most recent evidence-based recommendations for managing AEDs (Anti-seizure Drugs) for women of childbearing potential and pregnant women therapy to minimize teratogenesis?

The American Academy of Neurology (AAN) and the American Epilepsy Society (AES) published guidelines in July 2009 addressing management issues for women with epilepsy with a focus on pregnancy. Here are a few key points for clinicians.

  • There is strong evidence to avoid valproate in the first trimester to avoid major congenital malformations in comparison to carbamazepine, and good evidence to avoid the use of valproate in polytherapy to avoid major congenital malformations.
  • There is good evidence to limit the doses of valproate and lamotrigine in the first trimester to avoid major congenital malformations.
  • There is also good evidence to support monotherapy in favor of polytherapy to avoid major congenital malformations.
  • While there is good evidence to avoid valproate in pregnancy to avoid poor cognitive outcomes, carbamazepine probably does not contribute to poor cognitive outcomes when used in pregnancy.
  • Please see the clinician summary published by the AAN for more details, or the full guidelines on https://www.aan.com. Pregnant women with epilepsy may be referred to an Epilepsy Pregnancy Registry.
  • For additional information, visit the Women and Epilepsy section of the website.

14. How should providers counsel women with epilepsy who are pregnant or planning to become pregnant about their risk of increased seizure frequency and obstetrical complications?

For a framework to counsel women with epilepsy, please review the AES Checklist for Women. The AAN published recent guidelines in July 2009. Important points to consider include:

  • There is good evidence that being seizure-free for 9 months or more means there is a very high likelihood of seizure freedom during pregnancy, and not enough information to inform whether pregnancy results in higher seizure frequency or status epilepticus.
  • There is good evidence to show that there is not a significantly higher risk of C-section, meaning greater than 2 times the risk expected.
  • Please see the clinician summary published by the AAN for more details, or the full guidelines on https://www.aan.com.