Myoclonic-Atonic Seizures and Lennox-Gastaut Syndrome Present With Overlapping Features, Difficulty in Diagnosis

Patients with a higher number of Lennox-Gastaut syndrome traits had a greater likelihood of ongoing seizures, and each additionally observed Lennox-Gastaut syndrome trait was associated with half the likelihood of achieving seizure freedom.

Children with epilepsy with myoclonic-atonic seizures (EMAS) and Lennox-Gastaut syndrome (LGS) often present with overlapping features; attaining a 6-month freedom from seizures in this patient population is greatest only after multiple epilepsy diagnoses, according to a study in Epilepsy Research.

Researchers from Colorado performed a cross-sectional, retrospective medical chart review of pediatric patients with epilepsy from the Children’s Hospital of Colorado (n=77). A total of 57 patients from this cohort had a final diagnosis of EMAS. The study investigators reviewed medical records for patient demographics, age at seizure and epilepsy onset, types of seizures, treatment, developmental milestones, seizure freedom, epilepsy diagnoses, family history, and electroencephalogram features. Seizure freedom for this study was defined as freedom from seizure by 6 months.

A total of 65% of patients had received more than 1 epilepsy diagnosis, and the first, second, and third of these diagnoses occurred within 1-year, 3-year, and 10-year periods after the onset of epilepsy, respectively. Seizure freedom, as defined in this study, was associated with the final epilepsy diagnosis (P=.03). Half the cohort (50%) had recorded LGS traits such as paroxysmal fast activity, slow spike-and-wave, and tonic seizures. Patients with a higher number of LGS traits had a greater likelihood of ongoing seizures (log rank test, P=.018). In an analysis adjusted for age of epilepsy onset, each additionally observed LGS trait was associated with half the likelihood of achieving seizure freedom (0.49; 95% CI, 0.31-0.77; P=.002).

Limitations of the study were the inclusion of patients from a single center in Colorado, as well as the small number of participants in the final analysis.

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“Future research should attempt to stratify patients based not only on epilepsy syndrome diagnosis, but also on the presence of various electroclinical traits to more accurately predict outcome and guide treatment decisions,” the researchers concluded. “Ultimately, this could suggest the need to group these diagnoses and use trait based predictive models to further stratify patients.”


Eschbacha K, Mossb A, Joshi C, et al. Diagnosis switching and outcomes in a cohort of patients with potential T epilepsy with myoclonic-atonic seizures. Epilepsy Res. 2018;147:95-101.