Seizures are episodes of altered brain function that cause motor, cognitive, and sensory changes thought to result from changes in excitability in neurons.
A Seizure Disorder (also called Epileptic Disorder) is a tendency toward recurrent seizure activity without evidence of a reversible metabolic cause. Seizures occur when brain cells - which communicate through electrical signals - send out abnormal signals. An individual who has recurrent seizures is considered to have epilepsy.
However, seizures are not considered epilepsy if they occur only once or are treatable. Children, for example, often grow out of the condition.
Seizure disorders are chronic conditions that occur most frequently in the elderly.
Causes of Seizures:
A seizure is not a disease but a symptom of underlying central nervous system dysfunction.
Seizures can be caused by:
- A major illness
- Vascular lesions
- Congenital deformities
Provoked And Unprovoked Seizures:
Unprovoked Seizures (also known as Primary Seizures or Idiopathic Seizures) are those seizures that have no determined cause.
Multiple episodes of unprovoked seizures are considered a seizure disorder.
Provoked Seizures (also known as Secondary Seizures) are those that are caused by direct insult to the Central Nervous System.
These include Febrile Seizures (the most common, usually occuring in children, usually with a high fever over 104 degrees), metabolic conditions (hypoglycemia, hypoxia, toxemia of pregnancy) and those that involve CNS insult (brain injury).
Classification of Seizures:
In order to categorize a particular seizure disorder, several factors have to be taken into consideration like type of seizure, EEG recordings, behavior, genetic factors and response to treatment.
1) Partial (focal) Seizures - the most common seizure diagnosis in people over ten.
- Simple Partial Seizures - seizures that originate from one focal (or area) of the brain. These do not involve consciousness impairment. The symptoms depend upon which area of the brain is misfiring neurons.
- Complex Partial Seizures - involve impairment of consciousness and often arise from the temporal lobe of the brain. These seizures may involve automatisms like lip smacking, grimacing, or rubbing clothing. Hallucinations, deja vu, and jamais vu.
- Secondarily Generalized Partial Seizures - Seizures that begin at one focal part of the brain and become generalized, spreading to both hemispheres of the brain.
2) Generalized Onset Seizures: most common in young children.
- Absence (petit mal) Seizures - generalized, non-convulsive epileptic events expressed as disturbances in consciousness. Generally start in childhood and characterized by a blank stare, lip smacking, motionless and unresponsiveness.
- Atonic Seizures - Sudden, split-second loss of muscle tone, leading to slack jaw, drooping of the limbs or falling on the floor.
- Myoclonic Seizures - brief, involuntary muscle contractions induced by stimuli of cerebral origin. Involves bilateral jerking of muscles.
- Tonic-Clonic (grand mal) Seizures - sharp tonic contraction of the muscles with extension of extremities followed by an immediate lack of consciousness. Incontinence is common. Cyanosis (blue tinge of lips and fingers) is common from constriction of airways. Clonic phase involves rhythmic, bilateral contraction and relaxation of the arms and legs. Tonic-Clonic Phase lasts 60-90 seconds and person remains unconscious afterward.
3) Unclassified Seizures: Observed in the neonatal and infancy period and cannot be placed in the previous categories. Typically hard to control with medications.
Diagnosis of Seizures:
The diagnosis of a seizure disorder is based upon a thorough medical history and neurologic examination including a full description of the seizures.
Physical and laboratory studies are performed to rule out metabolic disease.
Skull radiology, CT Scans and MRIs are performed to detect structural defects.
An Electroencephalogram (EEG) is the most useful diagnostic tool as it records changes in the electrical activity of the brain.
Treatment of Seizure Disorders:
Once the underlying disease is treated, the aim is to bring the seizures under control.
There are over twenty types of anti-convulsant medications available.
Surgery is indicated in cases where the seizure disorder is resistant to medications.
Helpful Seizure Disorder Resources:
The leading resource for Epilepsy is the Epilepsy Foundation's website. They offer local support, eCommunities and first aid help. There are areas for children, adults and seniors.
Epilepsy.com is a website devoted to bringing accessible information, community, and resources to those dealing with epilepsy.
Epilepsy Advocate - A community of caregivers, advocates, and other individuals affected by epilepsy or seizure disorder. This website provides information about the disorder, bios on epilepsy advocates, community resources, coping strategies, and the option to sign up for the free "Epilepsy Advocate" magazine.
Epilepsy Society - A UK-based support community full of information, with helplines, info for health professionals, and fundraising opportunities.