Epilepsy and the seizures it causes affect people in various ways. Seizures often happen without warning and may happen for a few seconds to a few minutes. You likely experience similar symptoms with each seizure. 

Doctors identify seizures by how and where they begin in the brain. Understanding how seizures start helps us pinpoint the cause and plan your treatment with you.

Doctors identify seizures by how and where they begin in the brain. Understanding how seizures start helps us pinpoint the cause and plan your treatment with you.

Focal seizures start in one area and can spread throughout the brain. Types of focal seizures include:

• Focal aware: You remain awake and aware during a seizure, but you might not be able to talk or respond. This type was previously called simple partial seizures.
• Focal impaired awareness: You may be partially aware or completely lose awareness, and you may not be able to talk or respond. This type was previously called complex partial or psychomotor seizures.
• Focal to bilateral tonic-clonic: These seizures start as focal aware or focal impaired awareness seizure and spread to both sides of the brain.

Generalized seizures may involve the entire brain. Several types of generalized seizures exist, including:

• Absence: These seizures usually last less than 30 seconds and involve staring and a loss of awareness. You may look like you’re daydreaming. This type was previously called petit mal seizures.
• Atonic seizures: You suddenly lose muscle control, which may cause you to become limp and fall, or drop your head.
• Clonic: This type causes repeated, rhythmic jerking movements, usually in the arms, legs, or face.
• Myoclonic: Very short (two seconds or less) seizures that cause sudden, brief twitches or jerks, usually in the neck, shoulders, and upper arms.
• Tonic: Muscles suddenly stiffen in your back, arms, or legs, which may cause you to fall.
• Tonic-clonic: You experience symptoms of a tonic seizure first (muscle stiffness) and then a clonic seizure (rhythmic jerking). This type was previously called grand mal seizures.

Nonepileptic seizures (NES) resemble an epileptic seizure, with sudden changes in awareness, behavior, movement, or sensation. However, the event is not related to the brain’s electrical activity. Rather, it may result from psychological factors such as anxiety, depression, or post-traumatic stress disorder. Physical factors can also cause NES, such as sleep disorders, low blood pressure, or other medical conditions.

Our Comprehensive Epilepsy Program is internationally known for our research and expertise in diagnosing and treating people with NES.

People can develop epilepsy at any age. Certain factors can increase the risk of epilepsy, but the disorder may develop even if you don't have risk factors. About half of epilepsy cases have no identifiable cause. Epilepsy can be treated even when we can’t identify the cause.

 Some risk factors for epilepsy include:

• Brain blood vessel diseases, such as a previous stroke, hemorrhage, abnormal brain blood vessels (arteriovenous malformation or cavernous malformation), or structural problems
• Brain conditions such as dementia, brain tumors, or stroke
• Brain injury, such as brain damage at or before birth, or traumatic brain injuries due to a vehicle or other accident
• Congenital (present at birth) brain conditions, such as dysplasias, malformations, tuberous sclerosis
• Developmental disorders such as autism spectrum disorder, Down syndrome, or neurofibromatosis (NF)
• Family history of seizures or epilepsy
• Infections such as meningitis, HIV and AIDS, or viral encephalitis
• Inherited changes in specific genes

Making the correct diagnosis—including pinpointing the source of seizures—is important in choosing the right treatment for epilepsy and seizures. The care team at our Comprehensive Epilepsy Program has extensive experience recognizing signs and symptoms of seizures for an accurate diagnosis.

Our epilepsy specialists begin with a thorough evaluation, asking you about your medical history and conducting a physical exam. We work closely with you to understand the causes and types of seizures you have, discussing what you experience before, during, and right after a seizure.

Stanford Health Care offers a variety of diagnostic tests and imaging to determine the causes of seizures and epilepsy, and to rule out other conditions.

Diagnostic tests that you may need include:

• Blood tests, which check for signs of infections, genetic disorders, or other conditions that may be causing symptoms
• Neuropsychological testing, a process to assess thinking and behavioral functions such as language, concentration, and attention
• Electroencephalogram (EEG), a noninvasive test that records your brain’s electrical activity to identify seizure sources
• Stereoelectroencephalography (SEEG), which uses a robotic system to assist with a minimally invasive surgery. We place very small wires inside several parts of the brain to record and identify the source of seizures
• Functional mapping, a procedure in which neurosurgeons place electrodes in, or on, your brain to record electrical activity more precisely. Functional mapping identifies seizure sources and areas of critical brain function, such as language, sensation, and movement, to help plan surgery.
• Wada test (intracarotid amobarbital procedure), which identifies areas of the brain that control speech, memory, and other critical brain functions to inform surgical plans

We also use various imaging tests, including:

• Computed tomography scan (CT) to see the structure of the brain
• Magnetic resonance imaging (MRI) to see brain tissue
• High-density EEG to localize seizure origin, shown as a three-dimensional view of the brain
• Positron emission tomography scan (PET) to measure brain blood flow, oxygen use, and metabolism
• Single photon emission computed tomography (SPECT) to see imaging of the brain during a seizure and again 24 hours later

Most people come to our Comprehensive Epilepsy Program Outpatient Clinic for evaluation. People who have drug-resistant epilepsy, which does not respond to medication, may need inpatient care in our Epilepsy Monitoring Unit (EMU) for in-depth testing and 24/7 monitoring.