LGS is a syndrome, not a single-gene disorder. Multiple underlying etiologies are recognized: structural brain abnormalities such as cortical dysplasia, tuberous sclerosis complex, perinatal hypoxic-ischemic injury, and brain malformations are among the most commonly identified causes. Metabolic disorders, immune-mediated encephalopathies, and pathogenic variants in genes involved in neuronal development and synaptic function are additional recognized etiologies. In a substantial proportion of affected individuals, the underlying etiology remains undetermined after comprehensive evaluation. The packet for this disease does not enumerate causative genes, consistent with LGS being a polygenic and polyetiologic syndrome rather than a disorder traceable to a single genetic cause.

Diagnosis of LGS rests on recognition of the defining clinical triad: multiple seizure types (particularly tonic and atonic), slow spike-and-wave electroencephalographic abnormality, and intellectual disability or developmental delay. Electroencephalography—both routine interictal recordings and prolonged monitoring—is central to confirming the characteristic EEG pattern and documenting seizure type diversity. Neuroimaging (MRI) is indicated to identify structural causes. Per clinical guidelines derived from expert review of early-onset epileptic encephalopathies, the evaluation following an initial diagnosis typically encompasses neuroimaging, metabolic workup for treatable causes, and genetic testing to identify an underlying etiology when feasible. A comprehensive developmental assessment characterizes cognitive and adaptive function at baseline and guides educational and therapeutic planning. The severity and frequency of drop attacks warrant fall-risk assessment and protective measures.

Multiple antiseizure medications carry FDA approval for seizure management in Lennox-Gastaut syndrome. Lamotrigine, topiramate, and rufinamide (BANZEL) are established antiseizure agents with regulatory approval specifically for LGS. Clobazam (ONFI, SYMPAZAN), a benzodiazepine, is approved for adjunctive seizure treatment in LGS. Cannabidiol (EPIDIOLEX) and fenfluramine (FINTEPLA) represent more recently approved options, each with demonstrated efficacy in reducing seizure frequency in LGS clinical trials. Felbamate and clonazepam (KLONOPIN) are additional pharmacological agents with established use in this condition. Polypharmacy is common in LGS given the refractory nature of the seizure disorder and the multiple seizure types requiring control. Per clinical guidelines for epileptic encephalopathies, non-pharmacological approaches—including the ketogenic diet, vagus nerve stimulation, and corpus callosotomy—are established adjuncts for individuals with inadequate response to medication. Per expert review, individuals with photosensitivity may experience seizure provocation from rapidly flickering lights, a recognized precipitant in epileptic encephalopathies of this type.

LGS carries a guarded long-term prognosis, with persistent seizures and intellectual disability in the majority of affected individuals. Complete seizure freedom is achieved in a minority. The ongoing seizure burden—particularly drop attacks—creates substantial injury risk and often necessitates protective headgear and supervised environments. Cognitive and adaptive function may plateau or undergo further decline with sustained seizure burden and associated developmental impairment. Mortality is elevated relative to the general population, with sudden unexpected death in epilepsy (SUDEP), aspiration events, and injury from seizure-related falls as recognized causes. Long-term outcomes are influenced by the severity of the underlying etiology, age at onset, severity of the initial epileptic encephalopathy, and response to antiseizure treatment.

Active clinical trial records are present for Lennox-Gastaut syndrome, with current investigations encompassing studies on cannabidiol dosing optimization in adults with LGS, a study examining the transition from artisanal cannabidiol preparations to pharmaceutical-grade formulations, a feasibility study of responsive neurostimulation systems in LGS, and investigations of transdermal cannabidiol delivery. Per expert review, clinical trial registries in the United States and Europe serve as the principal resources for identifying current study opportunities for individuals with LGS and related epileptic encephalopathies.