The International Lennox–Gastaut syndrome Awareness day is celebrated annually on Novemrt 1. Lennox-gastaut Syndrome LGS) is a complex, rare, and severe childhood-onset epilepsy. It is characterized by multiple and concurrent seizure types, cognitive dysfunction, and slow spike waves on electroencephalogram (EEG). Typically, it presents in children aged 3-5 years and can persist into adulthood. It has been associated with several gene mutations, perinatal insults, congenital infections, brain tumors/malformations, and genetic disorders such as tuberous sclerosis and West syndrome. The prognosis for LGS is poor with a 5% mortality in childhood and persistent seizures into adulthood (80%-90%). LGS was named for neurologists William G. Lennox (Boston, USA) and Henri Gastaut (Marseille, France). The international LGS Awareness Day is on November 1st.
The symptoms og Lennox Gastaut Syndrome vary and progress with age. The symptoms are characterized by a triad of seizures, cognitive dysfunction, and EEG findings. Symptoms may not fully emerge until 1-2 years after first seizure episode. LGS can also cause seizures which begin between between 3 and 5 years of age. The mainstay symptoms is seizures that are frequent — occurring daily — and difficult to treat with antiseizure medications. An estimated 30% of patients with infantile spasms (West syndrome) have been reported to progress to LGS. The seizures are most commonly tonic seizures. They occur most frequently during non-REM sleep (90%). The seizures initially last only a few seconds and are activated by sleep. The presentation can be subtle The present often as tonic eyelid opening with some changes in breathing coupled with pupillary dilation, urinary incontinence, increased heart rate, and flushing can occur
Nonconvulsive status epilepticus occurs in about 50% of patients. The seizures can cause sudden falling often leading to injury. These “drop attacks” are typically first manifestation of LGS. These drop attacks are characterized by single, generalized monoclonic jerk that precedes tonic contraction of axial muscles.
Slow spike EEG Findings strongly suggest LGS include consistent slow spike-wave (< 3 hertz [Hz]) on awake EEG. The complexes typically consist of a spike (duration < 70 milliseconds) or a sharp wave (70-200 milliseconds), followed first by a positive deep trough, then a negative wave (350-400 milliseconds). Not every wave is preceded by a spike. Bursts increase and decrease without clear onset and offset. Slow spike waves may occur during seizure or between seizures, or may occur in absence of any observable clinical changes which helps distinguish pattern from extended 3-Hz spike-wave discharges. Another symptom of Lennox Gastaut Syndrome is Occular abnormalities which affect 90% of children. They can present as refractive error, strabismus, cortical visual impairment, and premature retinopathy.
The exact causes of Lennox Gastaut Syndrome Are unknown however,evidence implicates cortical hyperexcitability occurring at critical periods of brain development. There are two types of LGS: idiopathic LGS and secondary LGS. Idiopathic is unknown origin. Secondary is when an identifiable underlying pathology is responsible. The most common type of LGS (70–78%) is secondary. These patients tend to have a worse prognosis than those with idiopathic LGS. In up to one-third of cases no cause can be found. Secondary Lennox Gastaut syndrome can occur following brain damage. The brain damage can occur from perinatal insults, encephalitis, meningitis, tumor, and brain malformation.
Other identified disorders include genetic disorders such as tuberous sclerosis and inherited deficiency of methylene tetrahydrofolate reductase. Some of these cases once thought to be of unknown cause may have definitive etiology by modern genetic testing. Progress in genome and exome sequencing is revealing that some individuals diagnosed with Lennox Gastaut Syndrome have de novo mutations in a variety of genes, including CHD2, GABRB3, ALG13 and SCN2A The Epi4K study consortium observed de novo mutations in at least 15% of a study cohort of 165 patients with LGS and infantile spasms using whole exome sequencing.,A 2013 study found a high frequency of rare copy-number variation (CNV’s) in adult patients with LGS or LGS-like epilepsy