The symptoms vary and progress with age. The symptoms are characterized by a triad of seizures, cognitive dysfunction, and EEG findings. The triad may not fully emerge until 1–2 years after first seizure episode. Seizures The peak age of onset of seizures is typically 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%). They initially last only a few seconds and are activated by sleep. The presentation can be subtle. They 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 the first manifestation of LGS. The attacks are characterized by a single, generalized monoclonic jerk that precedes tonic contraction of axial muscles. EEG findings Findings that 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. Ocular abnormality Ocular abnormalities affect around 90% of children. They can present as refractive error, strabismus, cortical visual impairment, and premature retinopathy.
Lennox–Gastaut syndrome
Goldenhar syndrome
Joubert syndrome
Bardet–Biedl syndrome
Shprintzen–Goldberg syndrome
Benjamin syndrome
Christianson syndrome
Laron syndrome