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Lennox-Gastaut syndrome

Lennox-Gastaut syndrome (LGS), also known as Lennox syndrome, is a difficult to treat form of childhood-onset epilepsy, that most often appears between the second and sixth year of life and is characterized by frequent seizures and different seizure types and is often accompanied by mental retardation and behavior problems. more...

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As a rule, the age of seizure onset in LGS is between two and six years old. However, some patients get their first seizure within the first two years of life or after the first eight. The syndrome shows clear parallels to West syndrome, enough to suggest a connection.

Daily multiple seizures are typical in LGS. Also typical is the broad range of seizures that can occur, larger than that of any other epileptic syndrome. The most frequently occurring seizure types are: tonic, which are often nocturnal (90%); the second most frequent are myoclonic seizures, which often occur when the patient is over-tired.

Atonic, atypical absence, complex partial, focalized and tonic-clonic seizures are also common. Additionally, about half of patients will suffer from status epilepticus, usually the nonconvulsive type, which is characterized by dizziness, apathy, and unresponsiveness. The seizures can cause sudden falling (or spasms in tonic, atonic and myoclonic episodes) and/or loss of balance, which is why patients often wear a helmet to prevent head injury.

In addition to daily multiple seizures of various types, children with LGS frequently have have arrested/slowed psychomotor development and behavior disorders. The most common type

The syndrome is also characterized by an interictal (between-seizures) EEG featuring slow spike-wave complexes.

Incidence and Prevalence

Approximately 5% of children with epilepsy have LGS, and is more common in males than females. Whereas some children seem perfectly normal prior to the development of seizures, others already had some form of epilepsy, such as West syndrome, which is seen in 20% of patients before (symptomatic) LGS. West syndrome is characterized by Blitz Nick Salaam seizures, and typically evolves into LGS in the second year of life.


According to a 1997 community-based retrospective study in the Helsinki metropolitan area and the province of Uusimaa, the annual incidence of both Lennox-Gastaut was 2 in 100,000 (0.002%) from 1975-1985.

United States

0.026% of all children in the Atlanta, Georgia metropolitan area were estimated to have LGS in 1997, which was defined as, "onset of multiple seizure types before age 11 years, with at least one seizure type resulting in falls, and an EEG demonstrating slow spike-wave complexes (<2.5 Hz)." The study concluded that LGS accounts for 4% of childhood epilepsies.


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From Gale Encyclopedia of Childhood and Adolescence, 4/6/01

Epilepsy, from the Greek word for seizure , is a recurrent demonstration of a brain malfunction. The outward signs of epilepsy may range from only a slight smacking of the lips or staring into space to a generalized convulsion. It is a condition that can affect anyone of any age, sex, or race.

The number of people with epilepsy is not known. Some authorities say that up to 0.5% of the population are epileptic, but others believe this estimate is too low. Many cases of epilepsy, particularly those with very subtle symptoms, are not reported. The most serious form of epilepsy is not considered an inherited condition, though parents with epilepsy are more prone to have children with the disease. On the other hand, an epileptic child may have parents who show no sign of the condition, though they will have some abnormal brain waves.

Though the cause of epilepsy remains unknown, the manner in which the condition is demonstrated indicates the area of the brain that is affected. Jacksonian seizures, for example, which are localized twitching of muscles, originate in the frontal lobe of the brain in the motor cortex. A localized numbness or tingling indicates an origin in the parietal lobe on the side of the brain in the sensory cortex.

The recurrent symptoms, then, are the result of localized, excessive activity of brain cells or neurons. These can be seen on the standard brain test called the electroencephalogram (EEG). For this test electrodes are applied to specific areas of the head to pick up the electrical waves generated by the brain. If the patient experiences an epileptic episode while wired to the EEG, the abnormal brain waves can easily be seen and the determination made as to their origin in the brain. Usually the patient does not experience a seizure and no abnormalities are found.

Grand mal seizures are those that are most characteristic of epilepsy. Immediately prior to the seizure, the patient may have some indication that a seizure is imminent. This feeling is called an aura. Very soon after experiencing the aura the patient will lapse into unconsciousness and experience clonic seizures, which are generalized muscle contractions that may distort the body position. Thrashing movements of the limbs shortly ensue and are caused by opposing sets of muscles alternating in contractions (hence, the other name for grand mal seizures: tonic-clonic seizures). The patient may also lose bladder control. When the seizures cease, usually after three to five minutes, the patient may remain unconscious for up to half an hour. Upon waking, he or she may not remember having had a seizure and may be confused for a time.

In contrast to the drama of the grand mal seizure, the petit mal may seem inconsequential. The patient interrupts whatever he or she is doing and for up to about 30 seconds may show subtle outward signs such as blinking eyes, staring into space, or pausing in conversation. After the seizure previous activities are resumed. Petit mal seizures are associated with heredity, and they never occur in people over the age of 20 years. Oddly, though the seizures may occur several times a day, they do so usually when the patient is quiet and not during periods of activity. After puberty these seizures may disappear or they may be replaced by the grand mal type of seizure.

A serious form of seizure, status epilepticus, indicates a state in which grand mal seizures occur in rapid succession with no period of recovery between them. This can be a life-threatening event because the patient has difficulty breathing and may experience a dangerous rise in blood pressure. This form of seizure is very rare, but it can be brought on if someone abruptly stops taking medication prescribed for the epilepsy. It may also occur during alcohol withdrawal.

Most children who experience seizures are not epileptic because the seizures occur only once. Epileptic children frequently suffer more from the misconceptions that accompany the condition than from the seizures themselves. While medication can control most of the symptoms, it cannot educate other children and adults who mistakenly believe epilepsy is a sign of below-average intelligence or even mental retardation . Over-protective parents often attempt to hide their child's condition from others or limit their activities unnecessarily.

Some types of epilepsy are characteristic of children. Benign rolandic epilepsy, which involves seizures that commonly occur at night or during sleep, usually starts after three years of age and disappears, with or without treatment, by adolescence. Juvenile myoclonic epilepsy, or epilepsy of Janz, begins in late childhood or adolescence and is characterized by jerking of the arms or legs that occurs while drifting off to sleep or upon awakening. It is easily controlled by medication and is believed to be genetic in origin.

Infantile spasms, sometimes incorrectly diagnosed as colic , usually begin between four and eight months of age and disappear by the age of four years. Most children with infantile spasms have impaired mental capabilities and subsequently develop Lennox-Gastaut syndrome, another form of epilepsy that includes falling down and multiple seizures.

A number of drugs are available for the treatment of epilepsy. The oldest is phenobarbital, which has the unfortunate side effect of being addictive. Other commonly used drugs include phenytoin, carbamazepine, and sodium valproate. All have the possibility of causing such undesirable side effects as drowsiness, nausea, or dizziness. Several new drugs are being studied to determine their efficacy and safety.

The epileptic patient needs to be protected from self-injury during an attack. Usually for the patient having a petit mal seizure, little needs to be done. Occasionally these individuals may lose their balance and need to be helped to the ground to avoid hitting their heads, but otherwise need little attention. The individual in a grand mal seizure should not be restrained, but may need some help to avoid striking his limbs or head on the floor or nearby obstruction. If possible, the patient should be rolled onto his side. This will maintain an open airway for breathing by allowing the tongue to fall to one side.

Epilepsy can be a recurrent, lifelong condition. Medication can control seizures in a substantial percentage of patients, perhaps up to 85% of those with grand mal manifestations. Some patients will experience seizures even with maximum dosages of medication, and these individuals need to wear an identification bracelet to let others know of their condition.

Further Reading

For Your Information


  • Freeman, John M., et al. Seizures and Epilepsy in Childhood: A Guide for Parents . Baltimore: The Johns Hopkins University Press, 1990.


  • Glanz, J. "Do Chaos-Control Techniques Offer Hope for Epilepsy?" Science 265, August 26, 1994, p. 1174.
  • Hahn, Jin S. "New Antiepileptic Drugs for the Treatment of Childhood Epilepsies." The Western Journal of Medicine 162, April 1995, p. 353.

Gale Encyclopedia of Childhood & Adolescence. Gale Research, 1998.

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