The preoperative evaluation of epilepsy is an important step in the surgical treatment of epilepsy and is the basis for deciding whether to use surgery or what type of surgery to use. What does the preoperative evaluation of epilepsy involve? Electrophysiological examination is still the gold standard for localization of the epileptogenic focus, and the localization is most reliable only when the imaging results are consistent with the electrophysiological examination results. There is a consensus among domestic and international scholars that it is preferable to utilize a comprehensive diagnostic procedure rather than a single method for preoperative testing. The most commonly used and better method to determine the location of the epileptogenic focus is to use staging (phase) estimation. 1. Initial evaluation (phase-1) – non-invasive examination (1) Clinical evaluation: detailed patient history, direct observation of seizure symptoms (reduction or discontinuation of antiepileptic drugs if necessary), neurological examination and visual field examination. (2) Preoperative EEG evaluation Scalp EEG (including routine, hyperventilation, flash stimulation, nonstop antiepileptic drug and discontinuation examinations) Pterygoid and nasopharyngeal electrode EEG Orbital parietal electrode EEG (suspected frontal foci) Sleep EEG Sleep deprivation EEG Long-range scalp EEG Video EEG monitoring (3) Neuropsychological evaluation Wechsler intelligence test (WAIS) H-R (Halstead- Reitan) set of experiments Clinical memory scale assessment Carotid Amytal test (Wada test), assessment of language dominant hemisphere and estimation of memory function, performed before temporal lobectomy or cerebral hemispherectomy (4) CT: a routine preoperative test in patients with epilepsy, less disturbed by intracranial foreign bodies, more sensitive than MRI in detecting intracranial calcified foci, inferior to MRI in the sensitivity of detecting structural lesions. the CT abnormality rate in epilepsy is 30% to 50%. (5) MRI: It can show various types of structural abnormalities with high resolution, and is the most important diagnostic method for MTS (medial temporal lobe sclerosis). It can measure temporal lobe size and hippocampal volume, and can correctly identify 95% of tumors and vascular malformations. fMRI (functional magnetic resonance) can accurately show the relationship between epileptic foci and adjacent functional cortical areas. MRS (magnetic resonance spectroscopy) is particularly helpful in the diagnosis of patients with temporal lobe epilepsy without hippocampal atrophy; the lesion is usually on the low-signal side, and the identification of MTS is more sensitive than MRI. (6) SPECT: a functional imaging technique that determines changes in blood concentrations of radiotracer in the epileptogenic zone during seizures and interictal periods to determine It is particularly useful for patients with normal MRI and inconsistent MRI and EEG localization results, and has a high positive localization rate. (7) PET: It is also a functional imaging technique, which is very helpful for the localization of intracranial epileptogenic areas, with a localization accuracy of 86%. By using tracers to localize the epileptogenic zone, the metabolism of the epileptogenic zone is enhanced during seizures and decreased during interictal periods. It is especially indicated in patients with inconsistent localization of the epileptogenic zone by structural imaging (CT, MRI) and or EEG. If MRI does not reveal structural abnormalities, the sensitivity of PET localization is significantly reduced, and PET can detect local hypometabolic abnormalities in only 56% of patients with temporal lobe epilepsy and 9% of patients with extratemporal lobe epilepsy. absorption on the side of the epilepsy. PET and extratemporal lobe epilepsy: PET has an accuracy rate of 33% to 65% for extratemporal lobe epilepsy localization with positive findings, then there is a high rate of agreement with EEG localization. (8) Cerebral angiography: It is mainly used to examine patients suspected of having intracranial occupying lesions or epilepsy due to cerebrovascular malformations. (9) MEG (magnetoencephalography): a non-invasive and safe examination method, when video EEG monitoring, PET or SPECT cannot accurately locate the epileptogenic zone, MEG should be considered. 2. Phase 2 evaluation (phase-2) – invasive monitoring Subdural strip electrode implantation for EEG monitoring: this test is used when the EEG fixation side is unreliable or the localization is unclear. Deep electrode EEG: EEG with dual temporal lobe release, which is used when a more accurate location of the epileptic foci within one hemisphere needs to be identified. Cortical electroencephalography (ECoG): should be performed routinely in patients who have undergone craniotomy to verify the site of the epileptogenic focus and to determine the extent of distribution, to help determine the extent of resection and to evaluate residual distribution activity after resection.