title: Invasive EEG in refractory epilepsy: insertion of subdural grids through linear craniectomy reduces complications and remains effective.
abstract: OBJECTIVE
  To evaluate our technique of implanting subdural grids by linear craniectomy under computer-assisted navigation for invasive electroencephalography in medically refractory epilepsy.
  
  
  METHODS
  We report results from our first 38 consecutive patients with medically refractory epilepsy who underwent subdural grids implantation by linear craniectomy. For each case, a preoperative MRI was performed for navigation followed by a postoperative MRI for localization control of the intracranial electrode contacts. A linear skin incision, adapted to the depth and type of subdural electrode (strip or grid) and compatible with possible subsequent therapeutic surgery, was carried out. One or two linear craniectomies (maximal length 6cm, width 1cm) were then drilled with a bevel. The dura mater was incised under microscopic guidance to avoid opening the arachnoid. The required subdural electrodes were then slipped subdurally through each linear craniectomy (letter-box technique).
  
  
  RESULTS
  Forty-one invasive electroencephalographies were performed with 28 (68%) bilateral. For all invasive electroencephalographies, at least one subdural grid was implanted. Sixty-one subdural grids were implanted in total, 52 with 20 contacts and nine with 32 contacts. No cerebrospinal fluid leakage, no infection, no neurological deficit and no permanent complications were observed. Three subdural grids (5%) were not positioned exactly as planned but this had no consequence for the invasive electroencephalography analysis.
  
  
  CONCLUSIONS
  The implantation of 61 consecutive subdural grids for invasive electroencephalography through linear craniectomies was associated with no transient or permanent complications in this population. This letter-box technique appears to be practical and safe without limiting explorative efficacy.
authors.affiliation: Department of Neurosurgery, University Hospital St-Luc, Université Catholique de Louvain, 10, Avenue Hippocrate, 1200 Brussels, Belgium. Electronic address: christian.raftopoulos@uclouvain.be.
authors.forename: C
authors.initials: C
authors.lastname: Raftopoulos
authors.affiliation: Department of Neurosurgery, University Hospital St-Luc, Université Catholique de Louvain, 10, Avenue Hippocrate, 1200 Brussels, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Vaz
authors.affiliation: Department of Neurosurgery, University Hospital St-Luc, Université Catholique de Louvain, 10, Avenue Hippocrate, 1200 Brussels, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Tassigny
authors.affiliation: Department of Neurology, UCL Center for Refractory Epilepsy, University Hospital St-Luc, Université Catholique de Louvain, 10, Avenue Hippocrate, 1200 Brussels, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Van Rijckevorsel
mesh_terms: D000293:Adolescent; D000328:Adult; D065634:Cerebrospinal Fluid Leak / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D003399:Craniotomy; D004351:Drug Resistance; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000295:instrumentation / Q000379:methods*; D004827:Epilepsy / Q000601:surgery*; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation; D011183:Postoperative Complications / Q000453:epidemiology; D013355:Subdural Space / Q000601:surgery*; D055815:Young Adult
keywords: Craniectomie; Craniectomie linéaire; Craniotomy; EEG invasif; Electroencephalography; Invasive EEG; Linear craniectomy; Minimal invasive; Subdural grid; Technique « minimal invasive »; Électrode sous-durale; Électroencéphalographie