title: Motor evoked potential monitoring with supratentorial surgery.
abstract: OBJECTIVE
  To assess feasibility and clinical value of motor evoked potential (MEP) monitoring with surgery close to supratentorial motor areas and pathways.
  
  
  METHODS
  Functional mapping by somatosensory evoked potential phase reversal and continuous MEP recording after high-frequency repetitive electrical cortex stimulation was performed during 182 operations in 177 patients. Significant MEP changes were reported to trigger surgical reaction. Intraoperative surgical and electrophysiological findings were documented prospectively. Patient files were reviewed for clinical data. MEP monitoring results were correlated with motor outcome.
  
  
  RESULTS
  MEP recording was successful in 167 cases (91.8%). Inadequate electrode placement was an important reason for failed recording in the remaining patients, whereas preoperative paresis and anesthesia had no significant effect. Permanently disabling new motor deficit occurred in 8 cases (4.9%), whereas transient and nondisabling weakness was frequent (27.4%). Significant MEP changes occurred during 64 operations (39%). Irreversible MEP loss always predicted new, usually permanent, paresis. Unaltered MEP recordings indicated unimpaired motor function in the monitored muscle groups, except for rare transient deficit because of late edema and rebleeding. Irreversible MEP deterioration without loss and reversible changes could be associated with new paresis, which was transient in most patients. No major complications were observed, except for intraoperative generalized seizure in one epilepsy patient under insufficient anticonvulsant therapy.
  
  
  CONCLUSIONS
  MEP monitoring with supratentorial surgery is feasible and safe. It may help to maximize resection within the limits of preserved motor function. Further evidence is needed to confirm these results.
authors.affiliation: Department of Neurosurgery, University of Bonn, Bonn, Germany. neuloh@ukb.uni-bonn.de
authors.forename: Georg
authors.initials: G
authors.lastname: Neuloh
authors.forename: Ulrich
authors.initials: U
authors.lastname: Pechstein
authors.forename: Cornelia
authors.initials: C
authors.lastname: Cedzich
authors.forename: Johannes
authors.initials: J
authors.lastname: Schramm
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001931:Brain Mapping; D002648:Child; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009044:Motor Cortex / Q000503:physiopathology*; D011446:Prospective Studies; D011712:Pyramidal Tracts / Q000503:physiopathology*; D011930:Reaction Time; D015173:Supratentorial Neoplasms / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome