Topline summary
- Lennox-Gastaut Syndrome (LGS) is a severe childhood onset epileptic encephalopathy featuring multiple treatment resistant seizures, developmental impairment, and characteristic EEG abnormalities.
- It has diverse structural, genetic, and metabolic causes, leads to significant behavioral and cognitive challenges, and often persists into adulthood with substantial long-term impact.
- Management is complex and lifelong, requiring multidisciplinary care and multiple therapies, as only a small minority achieve seizure freedom.
What is Lennox-Gastaut Syndrome (LGS)?
LGS is a rare developmental and epileptic encephalopathy, characterized by frequent treatment-resistant seizures (atonic, tonic, and atypical absence seizures), varying levels of developmental delay and/or intellectual disability, and a range of social, behavioral, and communication problems.
What are the key clinical characteristics of LGS?
LGS is defined by a triad of features: multiple treatment‑resistant seizure types, developmental and cognitive impairment, and characteristic EEG patterns such as generalized slow spike-waves (SSW) and generalized paroxysmal fast activity (GPFA).
See Episode 1: When the Seizures Don’t Stop: Recognizing Lennox-Gastaut Syndrome
What causes LGS?
LGS is caused by a wide range of underlying brain abnormalities, genetic mutations, and metabolic disorders, making its origins highly multifactorial. It can arise from structural brain injuries, genetic etiologies (including recently identified mutations not yet widely recognized in practice), or metabolic conditions, and many patients present with multiple comorbidities that further complicate the underlying cause.
See Episode 1: When the Seizures Don’t Stop: Recognizing Lennox-Gastaut Syndrome
What types of seizures occur in LGS?
LGS is associated with multiple seizure types, most notably:
- Tonic seizures, which are required under the updated ILAE definition of LGS
- Atonic seizures (also known as “drop attacks”)
- Atypical absence seizures. These seizure types are typically frequent and treatment resistant, contributing to the clinical complexity of the syndrome.
See Episode 1: When the Seizures Don’t Stop: Recognizing Lennox-Gastaut Syndrome
How is LGS diagnosed?
LGS is diagnosed through a combination of clinical features, seizure types, and characteristic EEG findings, along with an understanding of the patient’s developmental history. Diagnosis is often challenging and delayed because symptoms evolve over time, EEG patterns can overlap with other epilepsies, and clinicians may struggle to integrate EEG, MRI, and genetic testing—especially since the full triad of features may not be present at onset. The updated ILAE criteria require onset before 18 years, the presence of tonic seizures, and generalized SSW (≤ 2.5 Hz) during wakefulness and/or paroxysmal fast activity (³ 10.0 Hz) during sleep on EEG. Yet, applying these criteria consistently remains difficult in real-world practice.
See Episode 3: The Diagnostic Puzzle: Tools for Timely and Accurate LGS Identification
What treatment options are available for LGS?
Treatment for LGS typically involves multiple antiseizure medications and adjunctive nonpharmacologic therapies, as seizures are often highly drug-resistant. First-tier pharmacologic options include valproate, lamotrigine, clobazam, rufinamide, topiramate, and most recently, purified cannabidiol. Pragmatically, therapy is matched to the most injurious seizure type and the comorbidity profile, increasing the complexity of LGS management. As such, LGS care often requires multidisciplinary, long-term management, incorporating neurologists, dietitians, therapists, and caregivers to address not only seizures but also developmental, behavioral, and psychosocial needs.
See Episode 5: Managing the Storm: Evidence-Based Strategies for Treating LGS
Does LGS continue into adulthood?
LGS typically persists into adulthood, and many individuals continue to face ongoing seizures and developmental or behavioral challenges over time. While seizure semiology and frequency may change over time, most adults with a history of LGS continue to have active epilepsy and enduring intellectual, behavioral, and functional impairment. Accordingly, transition to adulthood should include thoughtful, sustained support and coordinated care for both individuals living with LGS and their caregivers as they navigate adulthood.
See Episode 2: More Than Seizures: Understanding the Full Burden of LGS
What behavioral or cognitive challenges are associated with LGS?
LGS is associated with significant behavioral and cognitive challenges. These may include developmental delay, intellectual disability, and a range of behavioral, social, and communication difficulties, all of which can evolve over time. Many individuals also experience comorbid conditions that further affect daily functioning, contributing to challenges with learning, emotional regulation, and social interaction.
See Episode 2: More Than Seizures: Understanding the Full Burden of LGS
What is the long-term prognosis for patients with LGS?
LGS generally has a challenging long-term prognosis, with most individuals continuing to experience pharmacoresistant seizures and persistent neurodevelopmental, cognitive, and behavioral impairments that extend well beyond childhood. Only a small minority (around one in six) achieve seizure freedom later in life. Long-term outcomes are further complicated by substantial functional dependence, psychiatric and psychosocial comorbidities, and impaired quality of life. Because these difficulties often persist and evolve over time, individuals with LGS require lifelong, multidisciplinary care to support their development, daily functioning, and quality of life.
See Episode 2: More Than Seizures: Understanding the Full Burden of LGS
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