title: The safety and efficacy of chronically implanted subdural electrodes: a prospective study.
abstract: BACKGROUND
  The popularity of subdural electrodes for the presurgical evaluation of patients with intractable seizures is increasing. However, few reports have prospectively dealt with their efficacy and safety.
  
  
  METHODS
  We conducted a 5-year prospective study of patients evaluated by the California Comprehensive Epilepsy Program, who subsequently underwent subdural electrode implantation at one of two institutions. Efficacy was examined by ultimate outcome with regards to postsurgery resection seizure frequency. Fifty-five patients underwent 58 implant procedures and postresection outcomes were available in 47 patients. Safety was defined by the incidence of expected and unexpected complications, and neuropathologic examination of tissue specimens.
  
  
  RESULTS
  The most common expected adverse effects during implant were fever < or = 102 degrees (41%), cerebrospinal fluid leakage (19%), headache (15%), and nausea (4%). There were no infections. Unexpected adverse events included fever > 102 degrees F (5%), migraine (5%), iatrogenic electrode dysfunction (5%), and temporalis muscle fibrosis (5%). The incidence of pathologic findings suggestive of foreign body reaction was 10%. There were no permanent sequelae. Surgical outcomes were excellent in all (> or = 75% seizure reduction) with 50% seizure free regardless of the focus.
  
  
  CONCLUSIONS
  Subdural electrodes are a safe, easy, and efficacious tool for evaluating seizure foci prior to resective surgery. They should no longer be considered investigational devices.
authors.affiliation: Veterans Administration Medical Center, West Los Angeles, California, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Swartz
authors.forename: J R
authors.initials: JR
authors.lastname: Rich
authors.forename: P S
authors.initials: PS
authors.lastname: Dwan
authors.forename: A
authors.initials: A
authors.lastname: DeSalles
authors.forename: M H
authors.initials: MH
authors.lastname: Kaufman
authors.forename: G O
authors.initials: GO
authors.lastname: Walsh
authors.forename: A V
authors.initials: AV
authors.lastname: Delgado-Escueta
mesh_terms: D000927:Anticonvulsants / Q000008:administration & dosage / Q000627:therapeutic use; D001921:Brain / Q000601:surgery; D004558:Electric Stimulation; D004567:Electrodes, Implanted / Q000009:adverse effects; D004569:Electroencephalography; D004827:Epilepsy / Q000188:drug therapy / Q000601:surgery; D006801:Humans; D007275:Injections, Intravenous; D008140:Lorazepam / Q000008:administration & dosage / Q000627:therapeutic use; D008279:Magnetic Resonance Imaging; D011182:Postoperative Care; D011446:Prospective Studies; D012449:Safety
chemical_list: D000927:Anticonvulsants; D008140:Lorazepam