Abstracts

Rationale: Patients with focal epilepsy often experience delayed diagnosis. It is unknown if structural changes on brain imaging are associated with pre-diagnostic seizure frequency, severity, or duration. Using retrospective data from The Human Epilepsy Project (HEP), which enrolled patients with newly treated focal epilepsy, we examined whether atrophy on brain MRI was associated with pre-diagnostic seizure burden.

Methods: We retrospectively analyzed data from HEP, which enrolled participants between 2012 and 2017 across 34 sites in the USA, Canada, Europe, and Australia, within 4 months of treatment for focal epilepsy. There were 447 total participants, all of whom underwent MRI brain upon enrollment, and completing detailed pre-treatment seizure histories including types, frequencies, and durations. Medical records pertaining to initial diagnosis and treatment were also collected and reviewed. Based on clinical descriptions from seizure diaries and the medical record, seizures were categorized as either non-motor or motor at epilepsy onset. The date of conversion to motor seizures (if applicable), date of diagnosis, total number of non-motor and motor seizures, and total number of bilateral tonic clonic seizures were recorded. All MRI brain findings were reviewed in detail in order to compare pre-diagnostic seizure burden to brain atrophy.

Results: Demographic characteristics were similar between the 246 (55%) participants with non-motor and 201 (45%) participants with motor seizures at epilepsy onset. There was no association between visual atrophy on brain MRI and delay to diagnosis of epilepsy (p = 0.687). Atrophic brains were not associated with the total number of pre-diagnostic bilateral tonic clonic seizures experienced by participants (p = 0.72). Among the 246 participants (55%) with non-motor seizures at epilepsy onset, there was no association between a more rapid time to conversion from non-motor to motor seizures and brain atrophy (p = 0.13). There was a significant relationship between the total number of pre-diagnostic non-motor seizures and brain atrophy (p = 0.03), but this appeared to be due to a single outlier who reported 42,120 seizures (based on seizure frequency and duration) prior to diagnosis. Excluding this participant, there was no relationship between total number of pre-diagnostic non-motor seizures and brain atrophy (p = 0.98). There was no relationship between total number of pre-diagnostic motor seizures and brain atrophy (p = 0.92).

Conclusions: This study shows that atrophy on brain MRI in patients with newly treated focal epilepsy is not directly related to pre-diagnostic seizure burden. While finding brain atrophy in this patient population likely has multifactorial contributions, ongoing investigation is needed to clarify the causes and consequences.

Funding: Please list any funding that was received in support of this abstract.: There were no sources of funding for this study. The development of the HEP database comes from a variety of funding sources in industry, philanthropy, and foundations including The Epilepsy Study Consortium, UCB pharmaceuticals, Finding a Cure for Epilepsy and Seizures (FACES), Pfizer, Eisai, Lundbeck, Sunovion, The Andrews Foundation, The Vogelstein Foundation, Friends of FACES, and others.