ABOUT LENNOX-GASTAUT SYNDROME

What is LGS?

Lennox-Gastaut Syndrome (LGS) is a rare and often debilitating form of childhood-onset epilepsy.

The syndrome is characterised by:

- Multiple seizure types

- Moderate to severe cognitive impairment

- Slow spike-and-wave on EEG

- Seizures starting in childhood

Any seizure type can be seen in LGS.

The most common seizure types are:

- Tonic

- Atonic drop seizures

- Generalised tonic-clonic

- Atypical absence

- Non-convulsive status epilepticus

- Myoclonic

Whilst developmental delay/ cognitive impairment occurs in the majority of people with LGS, it is not always present at the start of LGS and is not a requirement for diagnosis. [1]

LGS constitutes between 1-4% of paediatric epilepsies [2] and typically appears between the second and sixth year of life.

LGS Foundation Lennox-Gastaut Syndrome, About LGS

What causes LGS?

LGS occurs secondary to many different causes including injury, brain malformations, infections, and genetic factors.
Most with LGS may have abnormal brain imaging, but some have normal brain imaging prior to developing LGS.
LGS can also develop from other epilepsy syndromes such as West, Ohtahara, Hypothalamic Hamartoma, etc.
Many genes are associated with LGS and each gene is a risk factor for developing LGS if seizures remain uncontrolled.
Emerging evidence suggests that genetic factors account for most unknown causes of LGS.

Who has LGS?

LGS constitutes between 3-4% of all children with epilepsy and 1-2% of all people with epilepsy.
LGS typically appears between age 2-5 years of age, but can be seen in younger and older children. LGS is established in the majority of children by age 6 years of age.
Approximately 13,400 children under the age of 18 in the United States are estimated to have LGS.
Approximately 34,300 adults 18 years and older in the United States are estimated to have LGS.
This means approximately 48,000 children and adults in the United States currently have LGS.
Click here for more information on the epidemiology of LGS.

How does LGS change over time?

There is no cure for LGS. Seizures may go into remission, and may also recur.
30-50% of children with infantile spasms will develop LGS.
80-90% of children with LGS will continue to have seizures into adulthood.
Up to 70% with LGS will no longer show slow spike-and-wave (<3Hz) on EEG in adulthood.
Most with LGS show paroxysmal fast rhythms (10-20 Hz) on EEG, mainly during non-REM sleep, at some point in their life.
70% with LGS will show cognitive impairment at diagnosis and more than 50% suffer behavioral issues including hyperactivity, sleep disturbances, rage attacks, aggression, and autistic features.
The mortality rate is 5%. Those with LGS are 24 times more likely to die prematurely.
Premature death in LGS is often due to Sudden Unexpected Death in Epilepsy (SUDEP), seizures, injury, or the underlying brain disorder.

More about LGS:

Adults with LGS:

As children with Lennox-Gastaut Syndrome grow older, types of seizures may change. Nearly all adults with LGS have tonic seizures (GPFA on EEG).
Older children with LGS often experience acute psychotic episodes, forms of psychosis with aggressiveness, behavioral problems, and irritability.
Cognitive issues in adults include slowed reaction time and information processing.
More information on adults with Lennox-Gastaut Syndrome including the process of transitioning can be found on our adults page

School-age Children:

School-age children are usually placed into a special education classroom or will receive home tutoring.
Parents and caregivers may need to consider future options for their child, including legal guardianship, respite care, group home facilities, and/or day programs.
For those individuals with LGS who do not have adequate neurological services in their state of residency, an out-of-state facility is suggested.
Level 4 facilities (facilities which provide intensive neurological services, elaborate evaluations and treatment options) are typically recommended if the local neurologist or epileptologist does not have experience in treating Lennox-Gastaut Syndrome.
For a listing of epilepsy centers in the United States, visit the National Association of Epilepsy Centers

Treatment:

The prognosis of Lennox-Gastaut Syndrome can greatly vary from person to person. Complete recovery, with freedom of seizures and normal development, is unusual for a child with LGS. Although there is no cure, there are various treatment options available which can be further explored on our treatments page.

Many children are typically developing normal when first diagnosed, but then begin to lose skills, sometimes dramatically, in association with uncontrolled seizures. Young children with LGS may exhibit behavioral issues, personality disturbances, mood instability, and slowing of psychomotor development. Behavioral disturbances can include poor social skills and attention seeking behavior, which can be caused by the effects of the medication, difficulty interpreting information, or due to continued electrical disturbances in the brain. Some children with LGS are prone to develop non-convulsive status epilepticus (a continuous seizure state that is associated with a change in the child's level of awareness). This requires medical intervention to bring it to an end.

As children with Lennox-Gastaut Syndrome grow older, types of seizures may change. In most cases, the drop-seizures (atonic) are replaced by partial, complex partial, and secondarily generalized convulsions. The uncontrolled seizures may become less of an issue as children grow, but impaired intellectual functioning and behavioral problems persist. Older children with LGS experience acute psychotic episodes, forms of psychosis with aggressiveness, character problems, and irritability. Cognitive problems include slowed reaction time and information processing. The main characteristics of mental deterioration are reported as apathy, memory disorders, impaired visuomotor speed, and perseverance. More information on adults with Lennox-Gastaut Syndrome including the process of transitioning can be found on our adults page.

School-age children are usually placed into a special education classroom or will receive home tutoring. Parents and caregivers may need to consider future options for their child, including legal guardianship, respite care, group home facilities, and/or day programs. For those individuals with LGS who do not have adequate neurological services in their state of residency, an out-of-state facility is suggested. Level 4 facilities (facilities which provide intensive neurological services, elaborate evaluations and treatment options) are typically recommended if the local neurologist or epileptologist does not have experience in treating Lennox-Gastaut Syndrome. For a listing of epilepsy centers in the United States, visit the National Association of Epilepsy Centers.

The prognosis of Lennox-Gastaut Syndrome can greatly vary from person to person. Complete recovery, with freedom of seizures and normal development, is unusual for a child with LGS. Although there is no cure, there are various treatment options available which can be further explored on our treatments page.

1, 5. Brown, L. Disorder Information: LGS. Child Neuro Net. http://childneurochannel.org/disorders/lgs/. Accessed 2.23.15

2. Glauser, Tracey. Lennox-Gastaut Syndrome. Medscape. 2011. http://emedicine.medscape.com/article/1176735- overview. Last accessed 9/23/11

3. Trevathan et al. Prevalance and descriptive epidemiology of Lennox-Gastaut syndrome amont Atlanta children. Epilepsia. Dec 1997

4. Van Rijckevorsel, Kenou et al. Treatment of LennoxGastaut syndrome: overview and recent findings. Neuropsychiatric Disease and Treatment. 2008: 4(6) 1001-1019