Table 3.
Tabular summary for defi nition of DRE, investigative procedures, indications for surgery and guidelines for classifying the level of experise of a center performing epilepsy surgery
| Level of evidence | Definition of drug resistant epilepsy (all should be worked-up for epilepsy surgery) |
|---|---|
| B, C, D | Having failed two AEDs or more, tried on adequate dose: mono followed by rational polytherapy, appropriately for the epilepsy syndrome |
| Mostly D | Duration of 2 years; more than one seizure per month |
| Earlier, if the seizures were "disabling" and prevented the person from having a normal life appropriate for his age and profession | |
| B, C, D | Earlier duration considered for pediatric epilepsy, particularly with epilepsia partialis continua, catastrophic onset, epileptic encephalopathy, disabling seizures, infantile spasms (lesional, e.g. Tuberous sclerosis) |
| Investigative procedures | |
| B, C, D | Standard |
| Interictal EEG: At least three incterictal EEG, both awake and sleep recordings: see guidelines for EEG | |
| VEEG: At least 3 events if concordant and many more events if discordant/inconclusive. | |
| MRI: standard sequences: MRI thin slices perpendicular to the hippocampus with at least 1.5 Tesla, closed magnet; T1 and T2 sequences. Special: FLAIR, gradient ECHO, SPGR, MRS, hippocampal volumetry | |
| Electrocorticography: has been included in standard as inmandatory for neocortical resections | |
| Special investigations | |
| Indications: When standard investigations are discordant for substrate-negative pathologies and dual pathologies | |
| SPECT: Interictal SPECT, ictal SPECT, ictal–interictal subtraction [SISCOS], ictal–interictal subtraction with coregistration on MRI [SISCOM] | |
| PET: Fdg–PET, other ligands like flumazenil, tryptophan, etc. | |
| Invasive: depths, grids and strips | |
| Indications for surgery | |
| B, C, D | Surgical substrate with concordance with medical intractability, as defined in I |
| B, C, D | Substrate negative with pre-electrical (VEEG, EEG), functional imaging (PET, SPECT interictal, ictal SPECT) and intraoperative electrical (invasive VEEG or electrocorticographic) concordance with medical intractability, as defined in I |
| Guidelines for an epilepsy surgery center | |
| GPP | Level I center: |
| Capable of performing "simple*" epilepsy surgeries and emergencies | |
| 1. Electrodiagnostic | |
| (a) A >24 h VEEG and EEG with surface/sphenoidal recording with supervision by EEG technologist and assistance by epilepsy staff nurse or monitoring technician if necessary | |
| 2. Epilepsy surgery | |
| (a) Emergency or elective neurosurgery | |
| (b) Mesial temporal sclerosis | |
| (c) An established referral agreement with a Level II epilepsy surgical center for surgical procedures for epilepsy, when indicated | |
| 3. Imaging | |
| (a) MRI with fMRI for language and memory | |
| 4. Pharmacological expertise | |
| (a) Quality-assured antiepileptic drug levels and 24-h antiepileptic drug level service | |
| 5. Neuropsychological/psychosocial services | |
| 6. Rehabilitation (inpatient and outpatient) | |
| 7. Mandatory expertise | |
| (a) Neurosurgery | |
| (b) Neurology | |
| (c) Internal medicine, pediatrics and general surgery | |
| *Simple epilepsy surgery: emergency, mesial temporal sclerosis with concordance | |
| Level II center: | |
| Capable of performing "complex*" epilepsy surgeries and emergencies | |
| Includes all capabilities of Level I and, in addition, should be capable of the following: | |
| 1. Electrodiagnostic | |
| (a) 24-h video/EEG with surface and sphenoidal electrodes | |
| (b) Invasive VEEG with 24-h recording | |
| (c) Evoked potential recording | |
| (d) Electrocorticography | |
| 2. Epilepsy surgery | |
| Clinical experience of >25 cases per year | |
| 3. Imaging: both standard and special investigations | |
| 4. Team experts | |
| In addition to those mentioned in Level I, (a) neuroradiologist (b) nuclear medicine specialist (c) psychiatrist | |
| *Complex epilepsy surgery: includes simple surgeries and all surgeries mentioned in Level II center | |
| Surgical strategies | |
| A, B, C, D | Temporal surgeries |
| Anteromedial temporal resection and amygdalohippoacampectomy*,selective amygdalohippocampectomy, lesional resection and lateral temporal resections | |
| Extratemporal surgeries | |
| Lesional resections, single-lobe resections, multi-loberesections, hemispherotomy, corpus callosotomy and multiple subpial transaction | |
| Phase II: grid and depth placement | |
| Neuromodulatory surgery: vagal nerve stimulation | |
| Electrocorticography, evoked potentials, neuronavigation andinvasive VEEG required for Level II | |
| *Level I center, all surgical strategy: Level II | |