Epilepsy is a brain disease in which nerve cells fire in abnormal, synchronized bursts, producing seizures. Around 50 million people worldwide live with it, making it one of the most common neurological conditions. A diagnosis typically requires at least two unprovoked seizures more than 24 hours apart, though a single seizure can qualify if the estimated risk of another within ten years is 60% or higher. About 70% of people with epilepsy can become seizure-free with proper treatment.
What Happens in the Brain During a Seizure
Your brain cells communicate through a balance of excitatory and inhibitory chemical signals. The main excitatory signal comes from glutamate, which prompts neurons to fire. The main inhibitory signal comes from GABA, which quiets them down. In epilepsy, this balance tips toward excitation. That can happen because of increased glutamate activity, reduced GABA activity, changes in the ion channels that control electrical charge across cell membranes, or shifts in the concentration of charged particles like sodium and calcium around neurons.
When a seizure starts, two things happen at once: a group of neurons begins firing in rapid, high-frequency bursts, and those neurons synchronize with each other. Calcium floods into the cells, which triggers sodium channels to open, which generates more electrical impulses in a self-reinforcing loop. In some forms of epilepsy, the brain loses certain cells that normally act as brakes on this process. In others, injured neurons sprout new connections to their neighbors, creating circuits that amplify excitation rather than contain it.
Types of Seizures
Seizures are classified into four main categories: focal, generalized, unknown, and unclassified. The distinction matters because it shapes which treatments are most likely to work.
Focal seizures start in one specific area of the brain. Depending on where that area is and how far the activity spreads, you might experience a strange sensation, involuntary movement on one side of the body, a change in awareness, or a combination. Some focal seizures feel like a sudden wave of déjà vu or an unexplained emotion. Others cause repetitive movements like lip smacking or hand rubbing.
Generalized seizures involve both sides of the brain from the start. The most widely recognized type is the tonic-clonic seizure (formerly called grand mal), where the body stiffens and then jerks rhythmically. But generalized seizures also include absence seizures, which look like brief staring spells lasting just a few seconds, and myoclonic seizures, which cause sudden, shock-like muscle jerks. A person can have more than one seizure type.
Known Causes
Epilepsy has five recognized categories of cause: structural, genetic, infectious, metabolic, and autoimmune. Many people have epilepsy that doesn’t fit neatly into any of them, and in a significant number of cases the cause remains unknown.
Structural causes include brain injuries from trauma, stroke, tumors, or abnormalities in how the brain developed before birth. Genetic causes range from single-gene mutations to complex patterns involving multiple genes. Some childhood epilepsy syndromes are strongly hereditary, while others involve new genetic changes not present in either parent. Infections like meningitis, encephalitis, and in some regions neurocysticercosis can damage brain tissue and trigger epilepsy. Metabolic disorders that disrupt the brain’s chemical environment and autoimmune conditions where the immune system attacks brain cells round out the list.
Nearly 80% of people with epilepsy live in low- and middle-income countries, partly because risk factors like birth complications, infections, and limited access to emergency care for head injuries are more common in those settings.
How Epilepsy Is Diagnosed
Diagnosis starts with a detailed account of what happened during the suspected seizure, ideally from someone who witnessed it. Two tests form the backbone of the workup. An EEG (electroencephalogram) records electrical activity in the brain through small electrodes placed on the scalp. In people with epilepsy, the EEG often shows characteristic abnormal wave patterns, even between seizures. An MRI scans the brain’s structure to look for anything that might be causing seizures, such as scar tissue, a tumor, or a developmental abnormality.
If the EEG and MRI don’t pinpoint where seizures originate, more specialized imaging can help. One option is a SPECT scan, which captures blood flow in the brain during a seizure to identify the active zone. Some people undergo prolonged video-EEG monitoring in a hospital, where they’re recorded continuously until a seizure occurs so doctors can see exactly what the brain is doing at the moment symptoms start.
Treatment With Medication
Anti-seizure medications are the first line of treatment. These drugs work through several mechanisms: some reduce the activity of excitatory signals, some enhance inhibitory signals, and some stabilize the electrical properties of nerve cell membranes to make them less likely to fire inappropriately. Finding the right medication, or combination, often takes time. The goal is full seizure control with tolerable side effects.
For roughly 70% of people, medication can effectively eliminate seizures. The remaining 30% have what’s called drug-resistant or refractory epilepsy, meaning seizures continue despite trying two or more appropriate medications at adequate doses.
Options When Medication Doesn’t Work
Surgery is the most established alternative for drug-resistant epilepsy. The most common type is resective surgery, where the surgeon removes the specific area of brain tissue where seizures originate. This is most often performed on the temporal lobe and can be highly effective when the seizure focus is clearly defined and located in a region that can be safely removed.
For people who aren’t candidates for resective surgery, device-based therapies offer another path. Deep brain stimulation involves implanting electrodes in the brain connected to a pacemaker-like device in the chest. The device sends electrical impulses that disrupt seizure activity before it spreads. Other implanted devices work on similar principles, targeting different parts of the brain or the vagus nerve in the neck.
Dietary therapy also plays a role. The ketogenic diet, a high-fat, very low-carbohydrate eating plan, has been used for epilepsy since the 1920s and has solid evidence behind it. After six months on the diet, about half of children experience at least a 50% reduction in seizures, and roughly a third achieve a 90% or greater reduction. The diet requires medical supervision and careful monitoring, but it can be a meaningful option for people whose seizures resist medication.
What to Do if Someone Has a Seizure
If you witness a tonic-clonic seizure, the CDC recommends these steps: stay calm and stay with the person. Ease them to the ground if they’re falling. Clear hard or sharp objects from the area around them and place something soft under their head. Gently turn them onto one side with their mouth pointing toward the ground to keep the airway clear. Loosen anything around the neck, remove eyeglasses, and time the seizure.
Do not put anything in their mouth, do not try to hold them down, and do not attempt to give them water or food until they are fully alert. Most seizures end on their own within one to three minutes.
Call 911 if the seizure lasts longer than five minutes, if a second seizure follows shortly after, if the person has difficulty breathing or doesn’t wake up afterward, if they were injured during the seizure, or if the seizure happens in water. You should also call if this is the person’s first seizure, if they’re pregnant, or if they have diabetes and lose consciousness.
Living With Epilepsy
Epilepsy’s impact extends well beyond seizures themselves. Sleep deprivation, stress, and alcohol are common seizure triggers, so managing these becomes part of daily life. Many people with epilepsy face restrictions on driving until they’ve been seizure-free for a period set by their state or country, which can range from three months to over a year. Employment, swimming, and certain activities at height may require extra precautions.
The social and psychological toll is significant. Stigma remains a barrier in many communities, and rates of depression and anxiety are higher among people with epilepsy than in the general population. Despite this, the majority of people with epilepsy lead full, active lives, particularly when seizures are well controlled. The treatment gap is not a scientific problem but an access problem: three quarters of people with epilepsy in low-income countries don’t receive the treatment they need, even though effective medications exist and are relatively inexpensive.