User:Karmattol/Lennox-Gastaut Syndrome

Lennox-Gastaut syndrome (LGS) is a syndrome of often difficult-to-treat epilepsy that starts in childhood and consists of cognitive impairment (mental retardation or childhood-onset dementia), various forms of generalized seizures, and characteristic EEG findings usually termed "slow spike-and-wave".

Incidence and prevalence
Estimates of the incidence/prevalence of LGS range from 0.002% to 4% of all epilepsies.

Clinical Characteristics
As a general rule, the age of seizure onset in LGS patients is between the ages of 1-8 with peak onset between 3-5 years. Morbidity and mortality depend to some extent on the underlying cause of LGS.

Cognitive impairment can take the form of static mental retardation in a child with previously known neurological abnormalities or can present with new-onset dementia.

The epileptic seizures of LGS usually consist of generalized seizures that respond incompletely to anticonvulsant medications. These are tonic seizures, atypical absence seizures, and epileptic drop attacks, which usually result from tonic seizures but may occur with atonic seizures, myoclonic seizures, or secondarily generalized partial seizures. Patients with LGS also have high rates of status epilepticus.

The EEG findings of LGS can be divided into interictal (between-seizures) and ictal (during seizures) abnormalities. Interictal abnormalities include the replacement of normal waking activities with diffuse slowing (predominantly theta activity), runs of slow spike-wave complexes, and bursts of generalized fast (~10cps) activities, the last of which are most often present during sleep.

Causes
LGS can be classified as a symptomatic or a cryptogenic generalized epilepsy syndrome depending on whether the underlying cause is known or unknown. Between 30-40% of patients have West syndrome, leading many authorities to the conclusion that Ohtahara syndrome, West syndrome, and LGS form a series of age-dependent epileptic encephalopathies. [Wienmann HM. Lennox-Gastaut syndrome and its relationship to infantile spams. In Niedermeyer R, Degen R, eds. The Lennox-Gastaut Syndrome NY, NY, Alan Liss In 1988 301-316.

Treatment
Pharmacological-

Surgical- Since most patients with LGS do not have an identifiable location in the brain from which seizures emanate (a seizure focus), epilepsy surgery is usually not an option. However, some pallitive procedures can reduce the severity of generalized seizures to prevent injury and to facilitate care. Vagus nerve stimulation can help reduce the number of epileptic drop attacks and other generalized seizures. Corpus callosotomy can reduce the severity of drop attacks by impeding the generalization of seizures.

Other treatments- The ketogenic diet is a viable addition to therapy in some patients with LGS. The use of helmets to prevent head injury is important in those with frequent or severe drop attacks.

History
LGS was named for neurologist William G. Lennox (Boston, USA) and Henri Gastaut (Marseille, France). Gibbs originally reported the distinction between slow spike-and-wave in what would be called LGS and typical 3cps spike-and-wave usually seen in childhood absence epilepsy.