Lennox-Gastaut Syndrome (LGS)

Lennox-Gastaut syndrome (LGS) is a rare and severe form of childhood-onset epileptic encephalopathy. It is characterized by multiple types of treatment-resistant seizures (tonic, atypical absence, myoclonic, tonic/atonic drop, generalized tonic-clonic, and focal seizures), cognitive impairment, and generalized (2.5 Hz) slow spike-wave discharges on electroencephalography (EEG). Disease onset typically occurs before the age of 8 years, with a peak between 3 and 5 years. Patients usually experience seizures throughout life.1-3

General Prognosis of LGS

The long-term prognosis of LGS is generally poor, with unfavorable outcomes due to cognitive and behavioral challenges, poor response to seizure medications, increased risk of injuries, physical disability, social disability, dependence on others, reduced quality of life, and early mortality. These challenges also have a significant impact on patients’ family members and caregivers.4-6

Around 80% to 90% of patients have recurrent seizures, and the mortality rate is 14 times higher than that reported in the general population. The main cause of death is epilepsy-related events (eg, status epilepticus and sudden unexpected death in epilepsy). Because patients with LGS generally have uncontrolled seizures, they are more likely to experience sudden unexpected death in epilepsy.4-6

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Studies on LGS Prognosis

A retrospective study of 68 patients with LGS (aged 18 years and above), with a mean follow-up duration of 19.3 years, showed that a patient’s type of seizures and EEG characteristics changed as their age increased. The study found that patients’ seizure frequency rate and intensity progressively decreased but that treatment did not eliminate seizures. A majority of patients (76.5%) still experienced seizures (predominantly tonic, atonic, or tonic-clonic seizures) despite the administration of available treatments. In neuropsychological tests, 94.7% of the patients were found to have moderate to profound intellectual disability. Many patients (60.3%) could not maintain independent daily living skills (eating, bathing, toileting, and functional mobility).7

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Prognosis Associated With Treatment

The same retrospective study by Kim et al in 68 patients with LGS (aged 18 years to 35 years) also assessed seizure outcomes for a range of therapies, including antiseizure medications (ASMs), ketogenic diet (KD), focal resective surgery, corpus callosotomy (CC), and vagus nerve stimulation (VNS). Of the 68 patients studied, 16 patients (23.5%) were seizure-free for a mean follow-up duration of 19.3 years. Various other therapies, particularly the KD and focal resective surgery, provided effective seizure control for 2 to 3 years. However, most patients experienced seizure recurrence and needed additional treatment.7

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When ASMs were given as a sole treatment, 6 patients out of 26 became seizure free. Administration of the KD resulted in a seizure-free state in 5 patients out of 19 during the diet therapy, but seizures relapsed after discontinuation of the KD. However, one patient was able to maintain a seizure-free state by continuing on a modified Atkins diet (MAD). Seizure-free state was achieved in 3 out of 15 patients who received focal resective surgery.7 

Palliative procedures, corpus callosotomy (performed in 17 patients) and VNS (performed in 14 patients) were partially effective, but patients could not achieve seizure freedom.7

Prognosis Associated With Subtype

Patients with idiopathic LGS often have less severe symptoms than patients with secondary LGS. Outcomes are usually worse in patients with secondary LGS who have a history of infantile spasms or West syndrome.1-3

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Burden of Illness in LGS

In a lifetime with LGS, patients may find it expensive to manage their symptoms and condition. A study by Piña-Garza et al showed that total healthcare utilization and medical costs were much higher for patients with probable LGS than for other epilepsy patients in all age groups, suggesting that LGS is associated with a considerable lifelong cost burden that extends beyond childhood.7-9

Another similar study by Reaven et al demonstrated significantly higher healthcare utilization and costs for patients with probable LGS than for patients without epilepsy or seizures.10 Further, a recent study in the United Kingdom demonstrated that patients with LGS had higher healthcare resource usage, consisting of primary care general practitioner consultations, outpatient visits, inpatient admissions, and accident and emergency visits.11 Experts suggest that timely diagnosis and appropriate treatment are likely to result in improved prognosis and less costly management for patients with LGS.7-9

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  1. Ohtsuka Y, Amano R, Mizukawa M, Ohtahara S. Long-term prognosis of the Lennox-Gastaut syndrome. Jpn J Psychiatry Neurol. 1990;44(2):257-264. doi:10.1111/j.1440-1819.1990.tb01404.x
  2. Oguni H, Hayashi K, Osawa M. Long-term prognosis of Lennox-Gastaut syndrome. Epilepsia. 1996;37(s3):44-47. doi:10.1111/j.1528-1157.1996.tb01820.x
  3. Samanta D. Management of Lennox-Gastaut syndrome beyond childhood: a comprehensive review. Epilepsy Behav. 2021;114:107612. doi:10.1016/j.yebeh.2020.107612
  4. Kiriakopoulos E, Wirrell E, Sirven JI, Shafer PO. Lennox-Gastaut syndrome LGS. Epilepsy Foundation. September 3, 2019. Accessed February 22, 2023.
  5. Lennox-Gastaut syndrome. Orphanet. Updated April 2021. Accessed February 22, 2023.
  6. Amrutkar C, Riel-Romero RM. Lennox Gastaut syndrome. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2022. Updated August 1, 2022. Accessed February 22, 2023.
  7. Kim HJ, Kim HD, Lee JS, Heo K, Kim DS, Kang HC. Long-term prognosis of patients with Lennox-Gastaut syndrome in recent decades. Epilepsy Res. 2015;110:10-19. doi:10.1016/j.eplepsyres.2014.11.004
  8. Piña-Garza JE, Montouris GD, Vekeman F, et al. Assessment of treatment patterns and healthcare costs associated with probable Lennox-Gastaut syndrome. Epilepsy Behav. 2017;73:46-50. doi:10.1016/j.yebeh.2017.05.021
  9. Asadi-Pooya AA. Lennox-Gastaut syndrome: a comprehensive review. Neurol Sci. 2018;39(3):403-414. doi:10.1007/s10072-017-3188-y
  10. Reaven NL, Funk SE, Montouris GD, Saurer TB, Story TJ. Burden of illness in patients with possible Lennox-Gastaut syndrome: a retrospective claims-based study. Epilepsy Behav. 2018;88:66-73. doi:10.1016/j.yebeh.2018.08.032
  11. Chin RFM, Pickrell WO, Guelfucci F, Martin M, Holland R. Prevalence, healthcare resource utilization and mortality of Lennox-Gastaut syndrome: retrospective linkage cohort study. Seizure. 2021;91:159-166. doi:10.1016/j.seizure.2021.05.025

Reviewed by Hasan Avcu, MD, on 2/24/2023.