Lennox-Gastaut syndrome diagnosis
Even if your child is diagnosed early with epilepsy, it may take more time to diagnose
Lennox-Gastaut syndrome (LGS). Many of the features occur with other seizure conditions,28
which makes diagnosing LGS difficult.
Finding a cause
Diagnosing LGS begins with an initial evaluation that will look at your child's
medical history for seizures. Typically, your doctor may look for evidence of
infantile spasms. An estimated 20-60% of children with LGS have
a prior history of infantile spasms (often referred to as West syndrome).29
There are no biologic markers for LGS,30 so doctors must look for evidence
of other causes. LGS can be caused by:
- Brain malformations
- Perinatal asphyxia (a lack of oxygen around the time of birth)
- Severe head injury
- Central nervous system infection
- Inherited conditions
But in as many as 35% of cases, no cause can be found.31 In children
for whom there is no apparent cause for seizures, diagnosis can be difficult.
Additionally, your doctor may look for telltale conditions such as mental retardation,
hearing and sight impairment, and tuberous sclerosis. These conditions are sometimes
present in children with LGS.32
Characteristics of LGS
- Multiple seizure types, including tonic, atonic or drop attacks, atypical absence,
myoclonic, and generalized tonic-clonic seizures starting in childhood.
- A specific type of EEG (electroencephalography) pattern called slow spike-wave,
seen between seizures.
- Cognitive impairment or developmental delay seen over time.33
In children for whom there is no apparent cause for seizures, diagnosis can be difficult.
EEG tests
Electroencephalography (EEG) records the electrical activity of the brain. It is
an important test for diagnosing epilepsy because it shows patterns of normal or
abnormal brain activity.34
An EEG during sleep may be necessary to detect tonic seizures or generalized polyspike
bursts. Close follow-up, with repeat EEG may be necessary to establish the diagnosis.
A specific type of EEG pattern called a slow spike-and-wave is a characteristic
of LGS.35
LGS prognosis
Once a child is diagnosed with LGS, the prognosis varies by individual. The cause
associated with the syndrome will likely affect the prognosis, and sometimes the
therapeutic strategies. Patients with a prior history of infantile spasms have a
significantly worse prognosis.
Risk factors for a less favorable LGS prognosis include:
- Symptomatic cause
- Prior history of infantile spasms
- Onset before the age of 3
- High frequency of seizures
- Worsening periods of long duration
- Repeated episodes of status epilepticus37
Unfortunately, LGS usually persists through childhood and adolescence into adulthood.
The types of seizures may change as the child gets older , but freedom from seizures
and normal development is very unusual.39
Although there is no cure,40
seizure medications exist that may help with seizure control. Because LGS is marked
by multiple seizures, your doctor may recommend more than one medication to help
provide the right level of control.
References
28 Epilepsy Foundation. "Epilepsy Syndromes: Lennox-Gastaut Syndrome."
Web. Accessed August 20, 2009. http://www.epilepsyfoundation.org/about/types/syndromes/lg.cfm
29 Epilepsy Foundation. "Epilepsy Syndromes: Lennox-Gastaut Syndrome."
Web. Accessed August 20, 2009. http://www.epilepsyfoundation.org/about/types/syndromes/lg.cfm
30 Wheless, James MD. "Lennox-Gastaut Syndrome: Diagnosis," Epilepsy.com,
August 7, 2009. Web. Accessed August 26, 2009. http://www.epilepsy.com/epilepsy/epilepsy_LGS/diagnosis
31 National Institute of Neurological Disorders and Stroke. "NINDS
Lennox-Gastaut Syndrome Information Page," Accessed August 07, 2009. Web. August
20, 2009. http://www.ninds.nih.gov/disorders/lennoxgastautsyndrome/lennoxgastautsyndrome.htm
32 Epilepsy Foundation. "Epilepsy Syndromes: Lennox-Gastaut Syndrome."
Web. Accessed August 20, 2009. http://www.epilepsyfoundation.org/about/types/syndromes/lg.cfm
33 Wheless, James MD. "Lennox-Gastaut Syndrome: Diagnosis," Epilepsy.com,
August 7, 2009. Web. Accessed August 26, 2009. http://www.epilepsy.com/epilepsy/epilepsy_LGS/characteristics
34 Schachter, Steven C. M.D. "EEG" Epilepsy.com. December 15, 2006.
Web. Accessed on August 26, 2009. http://www.epilepsy.com/EPILEPSY/testing_eeg
35 Wheless, James MD. "Lennox-Gastaut Syndrome: Diagnosis," Epilepsy.com,
August 7, 2009. Web. Accessed August 26, 2009. http://www.epilepsy.com/epilepsy/epilepsy_LGS/diagnosis
36 Wheless, James MD. "Lennox-Gastaut Syndrome: Etiology/Causes," Epilepsy.com,
August 7, 2009. Web. Accessed August 26, 2009. http://www.epilepsy.com/epilepsy/epilepsy_LGS/etiology
37 Epilepsy Foundation. "Epilepsy Syndromes: Lennox-Gastaut Syndrome."
Web. Accessed August 20, 2009. http://www.epilepsyfoundation.org/about/types/syndromes/lg.cfm
38 Epilepsy Foundation. "Syndromes: Lennox-Gastaut Syndrome." Web.
Accessed August 20, 2009. http://www.epilepsyfoundation.org/answerplace/Medical/seizures/syndromes/lennoxgastaut.cfm
39 National Institute of Neurological Disorders and Stroke. "NINDS
Lennox-Gastaut Syndrome Information Page," Accessed August 07, 2009. Web. August
20, 2009. http://www.ninds.nih.gov/disorders/lennoxgastautsyndrome/lennoxgastautsyndrome.htm
40 National Institute of Neurological Disorders and Stroke. "NINDS
Lennox-Gastaut Syndrome Information Page," Accessed August 07, 2009. Web. August
20, 2009. http://www.ninds.nih.gov/disorders/lennoxgastautsyndrome/lennoxgastautsyndrome.htm