ABSTRACT
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.
Subject(s)
Humans , Electrodes , Epilepsy, Temporal Lobe , Magnets , Temporal Lobe , ThalamusABSTRACT
BACKGROUND: The clinical differentiation of hippocampal and neocortical temporal lobe epilepsy has practical value. And there seems no report concerning the clinical difference between anterior and posterior neocortical TLE. This study aims to determine whether there are important clinico-electrical differences between patients with hippocampal sclerosis(medTLE; MTLE) and those with anterior lateral temporal epileptogenic zone(anterior lateral TLE; ALTLE) and posterior lateral temporal one(posterior lateral TLE; PLTLE). METHODS: The case histories, interictal EEG, ictal semiology, ictal EEG, and memory lateralization in Wada test were compared statistically in the three groups (30 MTLE, 16 ALTLE, and 11 PLTLE). Lateral TLE(LTLE) was diagnosed when the radiologic studies showed discrete lesions lateral to collateral sulcus or the results of invasive study confirmed massive epileptogenic zones in the lateral temporal lobe. Whether the epileptogenic zone was located on the anterior or posterior to the line across the interpeduncular fossa of the midbrain made the differentiation between ALTLE and PLTLE. RESULTS: A history of febrile convulsion was more common in MTLE patients(p<0.001). An aura with auditory or visual components was unique in ALTLE and PLTLE. Oroalimentary and hand automatisms occurred more frequently in MTLE, while secondary GTCS and version were more frequent in PLTLE(p<0.01). Onset of secondary GTCS and version occurred later in seizures of MTLE(p<0.05). Memory lateralization in Wada test was highly possible in MTLE and PLTLE(p<0.01). Irritative zone was located on the posterior temporal electrode in 4 of 11 patients with PLTLE. Ictal onset with rhythmic beta activity was not observed in MTLE. CONCLUSION: There are a number of clinico-electrical differences among MTLE, ALTLE, and PLTLE.