A longitudinal quantitative MRI study of community-based patients with chronic epilepsy and newly diagnosed seizures: methodology and preliminary findings.

Experimental and human data suggest that progressive cerebral damage may result from the cumulative effect of brief recurrent seizures. Longitudinal studies addressing this fundamental question, however, are lacking. We have addressed this need with a large prospective community-based observational study, which aims to rescan 154 patients with chronic active epilepsy and 90 patients with newly diagnosed seizures, after an interval of 3.5 years. Here, we describe the quantitative magnetic resonance methods used to identify subtle volume changes in hippocampal, cerebellar, and neocortical structures over time and report preliminary findings. Using this methodology, we have previously shown that we can reliably detect individual hippocampal volume (HV) and cerebellar volume (CBV) changes greater than 3.1 and 3.0%, respectively (Lemieux et al, 2000). Analysis of the first 53 subjects (24 patients with chronic active epilepsy, 9 patients with newly diagnosed seizures, and 20 controls) has demonstrated significant HV losses in 4 individuals. Automated and semiautomated calculation has detected significant reductions in CBV, total brain volume, and gray matter volume in 2, 3, and 1 subject, respectively. There were no significant white matter volume losses detected. Data collected from rescanning the entire cohorts will help to provide further information on the relationship between recurrent seizures and secondary brain damage.