Abstracts

Rationale: Juvenile myoclonic epilepsy (JME) and epilepsy with generalized tonic-clonic seizures alone (GTCA) are forms of idiopathic generalized epilepsy (IGE) but exhibit differences in clinical characteristics. The brain microstructure analysis showed a possible explanation of clinical differences in IGE. This study compares cerebral cortex thickness between JME and GTCA patients to understand the underlying nature of distinct characteristics.

Methods: A total of 160 patients (124 with JME and 36 with GTCA) who presented with seizures and visited the epilepsy clinic of Severance Hospital between January 2000 and May 2021 were conducted. Clinical characteristics and initial T1-weighted brain MRIs were obtained, and the cortical thickness of 34 cerebral regions was assessed using FreeSurfer (version 6.0; Athinoula A. Martinos Center for Biomedical Imaging). The cortical thickness of each cerebral region was compared between the two patient groups.

Results: No statistically significant difference in patient characteristics was shown between JME and GTCA groups, except for specific anti-seizure medications (lamotrigine, P = 0.001; levetiracetam, P = 0.008) and the proportion of patients who were seizure-free for more than two years (P = 0.018) (Table 1). The left cerebral cortex from superior frontal gyrus (P= 0.016), caudal middle frontal gyrus (P = 0.022), post-central gyrus (P = 0.026), and superior temporal gyrus (P = 0.033) were thicker in JME patients compared with GTCA patients. Also, the right cerebral cortex from superior frontal gyrus (P = 0.007), caudal middle frontal gyrus (P = 0.019), pars orbitalis gyrus (P = 0.030), superior temporal gyrus (P = 0.031), superior parietal gyrus (P = 0.030), inferior parietal gyrus (P = 0.017), supramarginal gyrus (P = 0.007), and precuneus (P = 0.040) were thicker in JME patients than GTCA patients (Figure 1).

Conclusions: In conclusion, compared to JME patients, GTCA patients had thinner regions in parts of the frontal lobe and temporal lobe from both hemispheres and portions of the parietal lobe and precuneus from the right hemisphere. The thickness variation of the neocortex could be a potential radiologic biomarker for distinguishing JME and GTCA and could provide an explanation of the clinical differences. Limitations are small patient size, not considering left-right dominance, and subcortical and cerebellar structures.

Funding: None