An atypical case of Lennox-Gastaut syndrome not associated with mental retardation: a nosological issue

Treatment with Cenobamate in Adult Patients with Lennox-Gastaut Syndrome: A Case Series

Background. Lennox-Gastaut syndrome (LGS) is a developmental and epileptic encephalopathy (DEE) in which drug resistance to antiepileptic drugs (AEDs) is common. Focal-onset seizures (FOS) are among the seizure types characterizing LGS. Cenobamate (CNB) is a new AED indicated for the treatment of FOS and it has shown promising results in terms of seizure frequency reduction in both clinical trials and real-world experience. To date, the use of CNB in patients with DEEs is limited to Dravet syndrome. Methods: This was a retrospective study aimed to determine the 12-month effectiveness and tolerability of CNB in patients with LGS following real-world practice. Results: Four patients with LGS receiving CNB treatment were identified. At 12 months from starting CNB, the reduction in baseline seizure frequency ranged from 25 to 74%, with two patients achieving ≥50% seizure reduction. CNB was generally well tolerated and adjustments in doses of concomitant AEDs were required. Conclusions: CNB may represent a promising therapeutic option in patients with drug-resistant epilepsy associated with LGS. Further research is needed to confirm this preliminary evidence.

Age at onset in patients with Lennox-Gastaut syndrome: Correlations with clinical manifestations

The aim of the current study was to investigate the age at onset in patients with Lennox-Gastaut Syndrome (LGS). We also investigated the clinical and EEG characteristics of these patients in different age groups. This was a retrospective study. All patients with a diagnosis of LGS were recruited at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 through 2020. 300 patients had LGS. Age at onset was 3.3 ± 4.1 years (minimum = 0 and maximum = 21 years). In 10 patients (3%) LGS started at age 14 years or above. Epileptic spasms were more often observed in those with an age at onset below one year (8%) compared with those with an age at onset of 1 to 8 years (0.7%) [Odds Ratio (OR) = 10.32]. Intellectual disability was less frequently observed in those with an age at onset of 8 years and above (68%) compared with those with an age at onset of 1 to 8 years (90%) (OR = 0.33). Tonic-clonic seizures were more often observed in those with an age at onset of 8 years and above (83%) compared with those with an age at onset of 1 to 8 years (55%) (OR = 2.87). While age at onset of LGS in the majority of patients is below 8 years, in some patients the syndrome begins in their late childhood or even during adolescence. Age at onset of LGS has significant correlations with the clinical manifestations of the syndrome.

Cognitive and functional status in late-onset Lennox-Gastaut syndrome: Variation on a classic phenotype

Lennox-Gastaut syndrome (LGS) denotes a refractory epileptic encephalopathy of childhood onset with the triad of generalized slow spike-wave (GSSW) on interictal scalp electroencephalogram (EEG), multiple seizure types, and intellectual impairment. The neurobiology of LGS is said to sustain abnormal patterns of brain activity and connectivity that ultimately impair normal cerebral developmental mechanisms. However, we describe eight patients from our combined practice who presented with electroclinical findings consistent with LGS but without significant cognitive impairment. All patients fulfilled the other criteria of LGS with multiple seizure types (three or more of generalized tonic-clonic, atonic, tonic, myoclonic, and atypical absence) and GSSW activity on EEG. Four subjects completed high school, two completed some college, two acquired college degrees, and all performed basic and instrumental activities of daily living (ADL) independently. Magnetic resonance imaging (MRI) was normal in all patients. We speculate that a variation of the classic phenotype of LGS can present with preserved cognitive and functional status, often with onset in the second decade of life, and associated with normal brain imaging.

Lennox-Gastaut syndrome: a comprehensive review

Lennox-Gastaut syndrome (LGS) is considered an epileptic encephalopathy and is defined by a triad of multiple drug-resistant seizure types, a specific EEG pattern showing bursts of slow spike-wave complexes or generalized paroxysmal fast activity, and intellectual disability. The prevalence of LGS is estimated between 1 and 2% of all patients with epilepsy. The etiology of LGS is often divided into two groups: identifiable (genetic-structural-metabolic) in 65 to 75% of the patients and LGS of unknown cause in others. Lennox-Gastaut syndrome may be considered as secondary network epilepsy. The seizures in LGS are usually drug-resistant, and complete seizure control with resolution of intellectual and psychosocial dysfunction is often not achievable. Reduction in frequency of the most incapacitating seizures (e.g., drop attacks and tonic-clonic seizures) should be the major objective. Valproate, lamotrigine, and topiramate are considered to be the first-line drugs by many experts. Other effective antiepileptic drugs include levetiracetam, clobazam, rufinamide, and zonisamide. The ketogenic diet is an effective and well-tolerated treatment option. For patients with drug resistance, a further therapeutic option is surgical intervention. Corpus callosotomy is a palliative surgical procedure that aims at controlling the most injurious seizures. Finally, vagus nerve stimulation offers reasonable seizure improvement. The long-term outcome for patients with LGS is generally poor. This syndrome is often associated with long-term adverse effects on intellectual development, social functioning, and independent living.

Brainstem dysfunction in patients with late-onset Lennox-Gastaut syndrome: Voxel-based morphometry and tract-based spatial statistics study

Background:

There have been a few reports of patients who developed Lennox–Gastaut syndrome (LGS) in the second decades of their life.

Objectives:

The aim of this study was to investigate electroclinical presentation in patients with late-onset LGS. In addition, we evaluated structural abnormalities of the brain, which may give some clue about the common pathogenic pathway in LGS.

Materials and Methods:

We enrolled the patients with late-onset LGS. We collected electroclinical characteristics of the patients and evaluated structural abnormalities using voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) analysis.

Results:

The three subjects were diagnosed with late-onset LGS. The patients have no mental retardation and normal background activities on electroencephalography (EEG), and they had generalized paroxysmal fast activities on EEG, especially during sleep. The TBSS analysis revealed that fractional anisotropy values in the patients were significantly reduced in the white matter of brainstem compared with normal controls. However, VBM analysis did not show any significant difference between the patients and normal controls.

Conclusions:

Patients with late-onset LGS have different clinical and EEG characteristics from those with early-onset LGS. In addition, we demonstrated that brainstem dysfunction might contribute to the pathogenesis of late-onset LGS.

Conceptualizing lennox-gastaut syndrome as a secondary network epilepsy

Lennox–Gastaut Syndrome (LGS) is a category of severe, disabling epilepsy, characterized by frequent, treatment-resistant seizures, and cognitive impairment. Electroencephalography (EEG) shows characteristic generalized epileptic activity that is similar in those with lesional, genetic, or unknown causes, suggesting a common underlying mechanism. The condition typically begins in young children, leaving many severely disabled with recurring seizures throughout their adult life. Scalp EEG of the tonic seizures of LGS is characterized by a diffuse high-voltage slow transient evolving into generalized low-voltage fast activity, likely reflecting sustained fast neuronal firing over a wide cortical area. The typical interictal discharges (runs of slow spike-and-wave and bursts of generalized paroxysmal fast activity) also have a “generalized” electrical field, suggesting widespread cortical involvement. Recent brain mapping studies have begun to reveal which cortical and subcortical regions are active during these “generalized” discharges. In this critical review, we examine findings from neuroimaging studies of LGS and place these in the context of the electrical and clinical features of the syndrome. We suggest that LGS can be conceptualized as “secondary network epilepsy,” where the epileptic activity is expressed through large-scale brain networks, particularly the attention and default-mode networks. Cortical lesions, when present, appear to chronically interact with these networks to produce network instability rather than triggering each individual epileptic discharge. LGS can be considered as “secondary” network epilepsy because the epileptic manifestations of the disorder reflect the networks being driven, rather than the specific initiating process. In this review, we begin with a summation of the clinical manifestations of LGS and what this has revealed about the underlying etiology of the condition. We then undertake a systematic review of the functional neuroimaging literature in LGS, which leads us to conclude that LGS can best be conceptualized as “secondary network epilepsy.”