When seizures strike

You're sitting on a park bench sipping coffee when someone passing by suddenly drops to the ground in convulsions, face contorted, limbs jerking rhythmically.

What's happening? It's likely a seizure — "an electrical abnormality where the brain essentially goes haywire," in the words of neurologist Dr. Andrew Cole, founding director of the Epilepsy Service at Harvard-affiliated Massachusetts General Hospital.

"It's an electrical storm, if you will, where the usual mechanisms that keep our brains working properly fall apart," says Dr. Cole.

The vast majority of seizures are due to epilepsy, a neurological disorder affecting about three million Americans 18 and older — about 1% of all adults, according to the CDC. But far more people will have a seizure at some point that strikes for another reason — with the odds growing as we get older.

"Everyone has a seizure threshold, though most of us never cross it," Dr. Cole says. "But there are circumstances where the likelihood is higher."

Long list of triggers

As brain science advances, the definition of epilepsy has become something of a moving target, Dr. Cole notes. Currently, someone is said to have epilepsy if they have "unprovoked seizures or a tendency toward them," he says. "If they've experienced a single seizure, they're considered to have epilepsy if doctors believe there's a 60% or greater chance they'll have a second one."

But a variety of factors — some of them seemingly harmless — can trigger a seizure, including

• high fever
• head injury
• extreme lack of sleep
• blood sugar fluctuations
• alcohol or drug misuse, including withdrawal
• certain medications
• brain infections such as meningitis or encephalitis
• stroke
• eclampsia, a pregnancy complication involving high blood pressure and organ problems.

Age also plays a role. While epilepsy can arise at any age, new cases are most common in childhood. Incidence rises again in adults 60 and up. In this group, seizures are often linked to stroke, head trauma, Alzheimer's disease, and brain tumors, among other causes. "It's due to what I call the accumulation of insults our brains suffer over the course of our lives," Dr. Cole says.

How to respond

Seizures can look different depending on the type. Classic "tonic-clonic" seizures (previously termed grand mal) "start everywhere all at once and look like convulsions," Dr. Cole explains. "People shake and jerk, and afterwards they're pretty sleepy or maybe unarousable for a few moments."

But there are wide variations. Someone seizing may display unusual, repetitive behaviors, such as smacking their lips or picking at their clothes; stare into space; or stiffen suddenly, then jerk. Other types of seizures cause a sudden loss of muscle strength, leading someone to lose consciousness and collapse.

These effects can place the person in more danger than the seizure itself, leaving them vulnerable to falls, head injuries, burns, drowning, and other types of accidents.

But you can help. If you witness someone having a seizure, Dr. Cole recommends these steps:

Keep them safe. "Move them away from sharp, hot, or icy cold objects — things that would hurt someone who's not conscious and can't protect themselves," he says.

Prevent choking. If they're lying down, position them on their side to keep their airway clear. "You may notice gurgling or froth coming out of their mouth, but don't stick anything in there, such as your fingers," he cautions. "They may bite them."

Track details. Note how long the seizure lasts, as well specific movements or behaviors to fill in doctors later, if necessary.

Don't, however, rush to call 911. Most people who have seizures are coping with a lifelong issue and don't need urgent treatment.

"Typically, a seizure will last only a minute or two, so don't panic," Dr. Cole says. "The vast majority of people you might see have a seizure are likely under medical care." But if it's not stopping and goes on for longer than three minutes, then it's time to call 911.

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