Dipole Source Localization of Periodic Sharp Wave Complexes in Creutzfeldt-Jakob Disease

BACKGROUND: Patients with Creutzfeldt-Jakob disease (CJD) show periodic sharp wave complexes (PSWCs) on electroencephalography (EEG) during the course of their illness. However, the source location of PSWCs and the pathophysiological mechanism remains unclear. METHODS: Ten patients with sporadic CJD who showed typical PSWCs on EEG underwent brain magnetic resonance imaging (MRI) and positron emission tomography (PET, n=8) or single-photon emission computed tomography (SPECT, n=2) scans. A 30-second epoch from the EEG was selected for analysis. The recording was separated blindly using independent component analysis. The separate independent components were subjected to dipole source localization using a single dipole model. The source locations were compared with neuroimaging findings in each patient. RESULTS: Two to three independent components responsible for the PSWCs seen in CJD were identified. The EEG recording reconstructed from the selected independent components accounted for about 70% of the variance in the original recording. All but one patient had dipole sources localized in both cortical and subcortical areas. One patient had only subcortical dipole sources in both caudate nuclei. The cortical locations included the cingulate, insula, frontal, temporal, and occipital areas. The subcortical sources were located in the striate, thalamic, and subthalamic nuclei. All the dipole sources were localized within lesions seen as neuroimaging abnormalities. CONCLUSIONS: These results suggest that a subcortical mechanism, in addition to cortical structures, is involved in producing the generalized periodic discharges in CJD.

Dipole Source Localization and Low Resolution Electromagnetic Tomography(LORETA) of Interictal Spikes in Mesial and Lateral Temporal Lobe Epilepsy / 대한간질학회지

PURPOSE: To investigate the usefulness of dipole source localization (DSL) and low resolution electromagnetic tomography (LORETA) in localizing epileptic focus, we performed DSL and LORETA of interictal spikes in patients with mesial and lateral temporal lobe epilepsy (TLE). METHOD: We analyzed representative interictal spikes in 17 patients with TLE (9:mesial TLE; 8:lateral TLE). We used ASA3 (Advanced Neuro Technology, Netherlands) for DSL, voltage topography (VT) and LORETA of interictal spikes. RESULT: Most interictal spikes for analysis have their maximum amplitudes at electrode F7, 8 or T7, 8 except one patient with lateral TLE (P7). In mesial TLE, VT showed a maximum negative electrical field in ipsilateral fronto-temporal region. DSL showed dipole sources in ipsilateral anterior mesial temporal lobe (33.3%, 3/9), temporal pole (44.5%, 4/9), orbitofrontal (11.1%, 1/9) and anterior inferior frontal (11.1%, 1/9) regions. LORETA showed maximum current density in ipsilateral fronto-temporal or anterior-mid temporal areas with lateral temporal maximum. In lateral TLE, dipole sources were in ipsilateral temporal pole (62.5%, 5/8), thalamus (12.5%, 1/8) and in posterosuperior temporal area (2/8, 25%). VT of spikes at F7 or F8 showed similar results as those of mesial TLE while that of spikes at T7, T8 and P7 had a tendency of electrical fields more extending to the mid- and posterior temporal regions. LORETA showed more diffuse current distribution in whole temporal lobe (anterior to posterior) with lateral temporal maximum. CONCLUSION: The patterns of DSL and LORETA were somewhat helpful to differentiate mesial from lateral TLE. LORETA usually showed more diffuse activity beyond the epileptic focus.