Finalizing Epilepsy Diagnosis Increases Seizure Freedom Likelihood

Krista Eschbach, MD

Finalizing the diagnosis of an epilepsy syndrome with mixed features was associated with a greater likelihood of seizure-free periods of at least 6 months than when diagnoses are changing to match new clinical presentations to conventional classifications in a new study.

Krista Eschbach, MD, Department of Pediatrics, Section of Neurology, Children's Hospital of Colorado, University of Colorado Anschutz Medical Campus, and colleagues recently reported on the first systematic evaluation of the relationship between initial and final epilepsy syndrome diagnosis, electroclinical traits, and outcomes in patients with features that overlap multiple epilepsy syndromes.

In examining the diagnoses and course of children with suspected epilepsy marked by myoclonic-atonic seizures (EMAS), Eschbach and colleagues characterized the switching of diagnoses when different clinical features manifest as "more reactive than predictive.”

They suggest that using a trait-based prognostication to distinguish between syndromes rather than fitting complex presentations into the conventional classifications could hasten accurate diagnosis and optimal management.

"Importantly, this study bring attention to the prognostic limitations of conventional epilepsy syndrome classification," Eschbach told MD Magazine®. "It supports the idea that Lennox-Gastaut Syndrome (LGS) and EMAS are both part of a spectrum of disease in which specific traits may better predict outcomes than the syndrome classification."

The investigators conducted a cross-sectional retrospective chart review of 72 children with onset of potential EMAS between May 2004 and April 2017 whose records extended over a sufficient period to allow at least 1 year of follow-up. The cohort consisted of 74% males with a mean age of epilepsy onset of 2.8 years and mean follow-up time of 4.6 years. The mean time from epilepsy onset to final diagnosis was 2.6 years. Most (65%) had some amount of diagnosis switching during the follow-up period.

Generalized tonic-clonic seizures was the initial presentation in 64.9% of the children, and fewer (14.3%) presented with myoclonic-atonic seizures. An initial, non-specific diagnosis of genetic generalized epilepsy was given to 35 (46%) of the patients, but this remained as a final diagnosis in only 7 patients (9.1%). An initial diagnosis of EMAS was applied to 30 patients (39%), and was the final diagnosis for 57 patients (74%), including 3 patients who were changed from an LGS diagnosis. Conversely, 8 of 9 patients initially diagnosed with EMAS were given a final diagnosis of LGS.

A seizure-free period of at least 6 months was attained in 27 (38%) of the cohort and 17 (24%) had normal development at time of last follow-up. Although the final diagnosis was not significantly associated with developmental outcome, it was associated with attaining the sustained period of seizure freedom (P= .03). The initial diagnosis, in contrast, was not predictive of outcome nor associated with either seizure freedom or developmental status.

The investigators indicated that the overlap between electroclinical features in EMAS and related disorders suggests that diagnosis switching is more than clinician 'misdiagnosis', but rather “a result of ambiguity in diagnostic criteria that does not adequately account for the diversity and evolution of features over time.”

"The next step is to develop a trait-based predictive model to stratify patients based on the presence of key electroclinical features," Eschbach said. "This type of diagnostic approach may improve prognostication, as well as potentially help guide treatment decisions."

The study, "Diagnosis Switching and Outcomes in a Cohort of Patients withPotential Epilepsy with Myoclonic-atonic Seizures," was published in Epilepsy Research.