Authors :
Presenting Author: Ribal Bitar, MD,MSc – Massachussets General Hospital
Ahmad Beydoun, MD – Professor, Neurology, American University of Beirut; Zein El Abdine Fawaz, MD – Clinical Research Fellow, Neurology, American University of Beirut; Nawal Koleilat, MBA – Clinical Research Assistant, Neurology, American University of Beirut; Wassim Nasreddine, MD – Assistant Professor, Neurology, American University of Beirut; Omar Nawfal, MD – Clinical Fellow, Neurology, American University of Beirut
Rationale: Despite the availability of multiple antiseizure medications (ASMs), one-third of patients with focal seizures will be refractory to medical treatment. Few studies suggested that the nature of the pathological substrate identified on brain MRI is an important determinant of medical refractoriness. This study aimed to evaluate the 12-month terminal seizure freedom in adult patients with new-onset focal epilepsy according to the underlying pathological substrate.
Methods: Patients included in this study were enrolled in a prospective multicenter centralized study that evaluates patients with new-onset seizures. All patients underwent a detailed history assessment, a three hour video-EEG study, an epilepsy protocol MRI, and were regularly followed up. For this study, we included all consecutive adult patients diagnosed with focal epilepsy and with a follow-up of at least two years.
Demographic data, numbers and doses of ASMs, MRI findings, and terminal 12-month seizure freedom were recorded. Epileptogenic lesions on brain MRI were classified into cerebral infarction, cerebrovascular anomalies, cortical gliosis, hippocampal sclerosis, malformation of cortical development, and tumors. Patients who had normal, incidental, or non-specific neuroanatomy findings on MRI were classified as cryptogenic. Univariate analyses were conducted, and a logistic regression analysis was performed to assess whether the type of epileptogenic lesion is predictive of terminal seizure freedom. The study was Institutional Review Board approved, and all participants provided informed consent.
Results: A total of 356 patients (55.9% males; mean age: 42.1±18.8) were enrolled in this study. Among them, 258 (72.5%) achieved a 12-month terminal seizure freedom. Table 1 shows the demographic and clinical characteristics of the patients stratified based on whether they achieved terminal seizure freedom. A total of 217 patients (61.0%) had an associated cryptogenic brain MRI. Those with an epileptogenic lesion on MRI were significantly less likely to achieve terminal seizure freedom (56.8%) compared to those with cryptogenic MRI (82.5%, P < 0.001). The type of epileptogenic lesion was significantly associated with the likelihood of achieving a terminal seizure remission (Figure 1). When compared to patients with no epileptogenic lesion, seizure freedom was significantly less in patients with hippocampal sclerosis (OR = 0.066), followed by cerebrovascular anomalies (OR = 0.177), tumors (OR = 0.212), malformations of cortical development (OR = 0.239) and cortical gliosis (OR = 0.405).
Conclusions: This study highlights the significant impact of etiology on the response to ASMs in patients with focal epilepsy. The findings demonstrate that cryptogenic etiology is associated with the highest rates of terminal seizure freedom, while patients with hippocampal sclerosis exhibit the poorest response to treatment. These results emphasize the importance of considering etiology when determining the treatment approach for patients with focal epilepsy.
Funding: None