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A grand mal seizure — also known as a tonic-clonic seizure — is a type of seizure characterized by loss of consciousness, falling down, loss of bowel or bladder control, and rhythmic convulsions. Seizures result from an abnormal electrical discharge in the brain. Other types of seizures include petit mal seizure and temporal lobe seizure.

Repeated brain seizures characterize a seizure disorder known as epilepsy. Only a small percentage of people who experience at least a single seizure episode go on to develop epilepsy.

The causes of seizures can vary. Often, the cause is unknown. Sometimes seizures run in families. Finding the underlying cause can help stop seizures.

A typical grand mal seizure starts with a loss of consciousness and falling down. This is followed by a 15- to 20-second period with muscle rigidity (tonic phase) and then a one- to two-minute period of violent, rhythmic convulsions (clonic phase). During a grand mal seizure, you may take on a dusky appearance, resulting from decreased blood oxygen levels due to impaired breathing during the seizure.

Most grand mal seizures last from 30 seconds to five minutes. After the seizure, you may experience a headache and drowsiness or confusion. Seizures often occur randomly, though in rare cases, stimulation by light, sound or touch can trigger a seizure in susceptible people. Sleep deprivation and excessive alcohol use also may trigger seizures.

Sometimes the seizures involve only a few muscles, such as one side of the face or one arm or leg. This is called a focal seizure.

During normal waking and sleeping, your brain cells produce various electrical discharge patterns. If the electrical discharges by your brain cells become abnormally synchronized, a convulsion or seizure occurs. The abnormal firing of your brain cells can remain localized to a small area or can spread rapidly to involve your entire brain.

Often, the cause of a seizure is unknown. Some of the known causes of seizures include:

• Metabolic disturbances. Diseases of the kidney or liver can cause chemical disturbances in your body, as can very low levels of sodium, calcium or magnesium.
• Previous brain trauma. Traumatic head injuries, such as those sustained in automobile accidents or serious sports injuries, can cause seizures.
• Vascular system problems. Blood vessel disorders, such as arteriovenous malformation of the brain — in which an abnormal connection exists between arteries and veins, and strokes are common causes of seizures in older adults.
• Toxic substances. Using drugs or other chemicals or withdrawing from addicting substances, especially alcohol, can affect your brain's electrical activity and your nervous system.
• Infection. An inflammation of your brain, such as that caused by meningitis or encephalitis, may trigger a seizure.
• Birth defects. Congenital malformations in the brain can be responsible for seizures in infants and young children.
• Brain tumor. Although a brain tumor is an uncommon cause, a seizure may be an indication of a brain tumor.

Seek immediate medical care when any of the following occur:

• The seizure lasts more than five minutes.
• A second seizure immediately follows.
• The person having the seizure is pregnant.
• Signs of injury or illness are present.

If you see someone having a seizure, call for medical help immediately and then follow these tips:

• Gently roll the person onto one side and put something soft under his or her head.
• Loosen tight neckwear.
• Don't put anything in the mouth — the tongue can't be swallowed.
• Don't try to restrain the person.
• Look for a medical alert bracelet, which may indicate an emergency contact person and other information.

Although the signs and symptoms of a grand mal seizure may be easy to recognize, it may be difficult for a doctor to diagnose the underlying causes of seizure disorders.

Your doctor may use these diagnostic approaches:

• Medical history. Descriptions of your past seizures from you and from family members can help your doctor identify the type and causes of your seizures.
• Physical and neurological examination. Aside from a routine physical examination, your doctor may perform a neurological examination — testing your reflexes, muscle tone and strength, function of your senses, gait, posture, coordination, and balance. Your doctor may also ask questions to test your thinking, judgment and memory.
• Electroencephalography (EEG). This procedure measures the waves of electrical activity your brain produces. Small electrodes are attached to your scalp with paste or an elastic cap as you lie still. You remain still during the test, but at times you may be asked to breathe deeply and steadily for several minutes or to stare at a patterned board. At times, a light may be flashed in your eyes. Typically, a recording during a brief period of sleep is obtained as well. These actions are meant to stimulate your brain. The electrodes pick up the electrical impulses from your brain and send them to the EEG machine, which records your brain waves on a moving sheet of paper or digitally on a computer screen.
• Magnetic resonance imaging (MRI). Images taken of your brain may help determine what's causing your seizures and can rule out other disorders such as a stroke or a brain tumor.
• Blood tests. These tests may reveal a chemical imbalance in your blood or presence of toxic substances. Blood tests may also exclude other causes of seizures.
• Spinal tap (lumbar puncture). Removing a small sample of fluid from your spinal canal for laboratory analysis may reveal evidence of a brain infection or inflammation that may be causing your seizures.

Recurrent seizures may put you and others at risk of physical harm. A seizure that produces either loss of awareness or control can be dangerous if you're driving a car or operating other equipment. Many states have licensing restrictions related to your ability to control seizures. For children, seizure disorders may result in limitations on the physical activities in which they can participate in school. In addition, for both children and adults, seizures can produce injuries associated with falling, such as a head injury.

If an underlying cause can be found, correcting it may stop the seizures. If you have infrequent seizures, you can lead an active, productive lifestyle. Several types of treatments are available for both frequent and infrequent seizures:

• Medications. Many medications can effectively reduce or eliminate the number of seizures for some people. Finding the right medication and dosage can be complex. Medications available for the treatment of seizures include phenytoin (Dilantin), carbamazepine (Carbatrol, Tegretol), valproic acid (Depakene), divalproex (Depakote), gabapentin (Neurontin), phenobarbital, clonazepam (Klonopin), lorazepam (Ativan), diazepam (Valium), primidone (Mysoline), oxcarbazepine (Trileptal), lamotrigine (Lamictal), topiramate (Topamax), felbamate (Felbatol), tiagabine (Gabitril), zonisamide (Zonegran) and levetiracetam (Keppra). Seizure medications are associated with birth defects. However, if you're pregnant, continued seizures can be harmful to you and your baby. If you have epilepsy and you're thinking about becoming pregnant, talk to your doctor.
• Surgery. For seizure disorders that don't respond well to medications, surgery may be an option if the seizures are localized to a particular part of the brain and that part of the brain can be removed without serious consequences. Surgery may also be effective if the cause of seizures is a tumor or malformation of the brain. In children who don't seem to have a focal point to their seizures and who regularly fall to the ground during their seizures, surgery to split the tissue that connects the brain's two hemispheres — called the corpus callosum — may dramatically reduce "drop seizures" without adversely affecting the brain's other functions.
• Ketogenic diet. This complicated, rigid approach involves a high-fat, low-carbohydrate, low-protein diet. The diet's name comes from ketones, chemicals produced during starvation when your body uses more fat for energy than it normally does. Exact amounts of specific foods and beverages are prescribed for each meal. The diet is so sensitive that even a tiny intake of sugar can significantly reduce the amount of ketones produced. It's not clear how the diet works to reduce seizures. But in children, a third of those on the diet gain complete control over their seizures, another third have fewer seizures and the final third are unaffected by the diet. Close medical supervision is necessary for this diet to succeed. It's definitely not something you can undertake on your own.
• Vagus nerve stimulation. A device called a vagus nerve stimulator may be an option if medications are ineffective or cause serious side effects. The stimulator is implanted into your chest under the collarbone. Wires from the stimulator are wrapped around the vagus nerve in your neck. The vagus nerve connects the lower part of your brain to your heart, lungs and gastrointestinal tract. The device turns on and off according to an adjustable program, stimulating your brain. It's not clear how brain stimulation via the vagus nerve inhibits seizures.

If you have a seizure disorder, wear a medical bracelet to help emergency medical personnel. The bracelet should state whom to contact in an emergency and what medications you use.

You may also have to limit activities such as driving, swimming, skiing, working at heights and operating other equipment. Doing so may prevent physical harm. Some states have laws requiring such restrictions depending upon how well you're able to control your seizures.