Types of Seizures
Different people can experience seizures in different ways and sometimes one person can even have multiple types of seizures. Epileptic seizures, or events caused by bursts of abnormal, excessive electrical activity within the brain, are generally classified into two major groups. The difference between them is how much of the brain is affected during a seizure.
- Focal Seizures – limited to one area of the brain
- Generalized Seizures – involves both sides of the brain
Within these two categories of seizures, there are some common subsets of seizures. These subgroups are classified based upon a person’s level of awareness and movements or motor symptoms while experiencing a seizure. The terms for these categories were updated a few years ago, so below we list the current (along with the previous) names. A person can be aware or unconscious during a focal seizure, but with generalized seizures, a person is almost always unconscious or unaware of what is happening.
- Focal Onset Seizures (previously known as partial seizures)
- Aware Seizures (previously known as simple partial seizures) – Person is conscious and experiences small symptoms such as a twitch, smell, or taste
- Impaired Awareness Seizures (previously known as complex partial seizures) – Person may lose consciousness, feel dizzy, or act confused, and is generally unable to respond for a few minutes
- Generalized Onset Seizures
- Non-motor or Absence Seizures (previously known as Petit Mal) – Person is unaware and appears to be “blanking out” or staring
- Tonic-Clonic (previously known as Grand Mal) – Person loses consciousness, muscles stiffen, and jerking movements are seen
- Atonic – Person loses consciousness and muscle tone, meaning that their head or body may go limp
The type of seizures can be determined by a doctor based on a description of the seizure from a witness or with testing, such as video EEG. Seizures with an unknown origin are simply called “unknown onset.” For more information on other types of seizures, check out the Epilepsy Foundation’s information on seizure types here.
What If the Seizures Are Not Epilepsy?
Not all people who have seizures or spells have epilepsy. Some seizures can be provoked, or brought about, as a direct result of a known physical cause such as illness, traumatic brain injury, or withdrawal from alcohol or drugs. Provoked seizures usually stop once the underlying illness is treated. Therefore, by definition, a provoked seizure is not epilepsy.
Some seizures may not even be caused by irregular brain activity. Unlike epileptic seizures, where the brain’s electrical activity is disrupted, psychogenic nonepileptic seizures (PNES) are thought to be caused by psychological distress or an underlying psychiatric disorder like PTSD. PNES will not show any irregular brain activity during an EEG test. Doctors can use the results of an EEG test to determine whether seizures are epileptic or nonepileptic.
There are a number of other seizure-like disorders that may mimic symptoms of seizures but have no epileptic causes. Examples include:
- Cardiac syncope
- Sleep disorders such as narcolepsy
- Movement disorders like a tic
For a more comprehensive list of seizure-like disorders, check out WebMD’s list.
Diagnosis & Treatment
Only a neurologist will be able to confirm if you are actually experiencing seizures. If you suspect you are suffering from seizures, talk to your doctor about seeing a specialist and the possible need for a video-EEG test. Neurologists may order one or more EEG tests to aid them in proper diagnosis and treatment.
Most seizure disorders and epilepsy are treated with anti-seizure medications (ASMs). Other treatments available include diet and vagus nerve stimulation. In some instances, focal seizures can be reduced or resolved by surgical intervention.