This technique suffers two main drawbacks, a relatively poor spatial resolution (though the later has increased from 8 cm3 voxels in the earlier studies to 1 cm3 voxels at present), and a limited spatial Selleckchem AZD1480 sampling of the brain that requires an a. priori hypothesis regarding the localization of the epileptogenic zone. In TLE, 1H MRS typically demonstrates reduced N-acetyl aspartate (NAA)/choline and creatine ratio in the epileptogenic
temporal lobe, often associated with less marked contralateral abnormalities.97-99 Inhibitors,research,lifescience,medical This finding was also observed in patients with MRI-ncgativc TLE.97,99-101. The few studies performed in extratemporal epilepsies have also reported reduced NAA/choline and creatine ratio in the epileptogenic zone, as well as in the irritative zone.102-104 According to all above findings, and the technical limitations of 1H MRS, it appears that the primary clinical utility of this investigation Inhibitors,research,lifescience,medical would be the prediction of postoperative seizure outcome in TLE patients, especially those with a normal Inhibitors,research,lifescience,medical MRI or bilateral hippocampal atrophy.100,105-107 However,
it. still needs to be demonstrated whether HI MRS is an independent predictor of surgical outcome, taking into account all other relevant clinical and imaging data. Magnetoencephalography The technology of multichannel magnetoencephalography (MEG) has considerably improved over the last. 10 years, with a dramatic increase in the number of recording channels, up to 300 sensors,108 and the development of more efficient, data analysis using magnetic source imaging (MSI) and spatial filtering by means of synthetic aperture magnetometry (SAM).109 This development necessitates revisiting the clinical
utility of MEG in the presurgical Inhibitors,research,lifescience,medical evaluation of patients with epilepsy,110 though the main limitation of MEG remains its lack of availability Inhibitors,research,lifescience,medical in the majority of epilepsy surgery centers. MEG primarily detects interictal epileptiform discharges, though in rare instances ictal recordings could be performed.111 It. was found to be more sensitive than scalp EEG, in particular for the detection of neocortical spikes, but also more potent for delineating the maximal source of interictal epileptiform discharges.112 MSI was compared with intracranial EEG recordings in 49 patients and demonstrated a predictive positive value for seizure localization of 82 %.113 Like FDG-PET, ictal SPECT, and 1H isothipendyl MRS, MSI might also help to disclose a brain lesion not. readily detectable on MRI and to better predict postoperative seizure outcome.110,114,115 The only study that has compared MEG and FDG-PET demonstrated congruent findings in the majority of patients.116 MEG appears to have a more specific impact than the above investigations on the localization of epileptogenic tuber,117 and of spiking cortex underlying Landau-Kleffner syndrome.