title: Intraoperative monopolar mapping during 5-ALA-guided resections of glioblastomas adjacent to motor eloquent areas: evaluation of resection rates and neurological outcome.
abstract: OBJECTIVE
  Resection of glioblastoma adjacent to motor cortex or subcortical motor pathways carries a high risk of both incomplete resection and postoperative motor deficits. Although the strategy of maximum safe resection is widely accepted, the rates of complete resection of enhancing tumor (CRET) and the exact causes for motor deficits (mechanical vs vascular) are not always known. The authors report the results of their concept of combining monopolar mapping and 5-aminolevulinic acid (5-ALA)-guided surgery in patients with glioblastoma adjacent to eloquent tissue.
  
  
  METHODS
  The authors prospectively studied 72 consecutive patients who underwent 5-ALA-guided surgery for a glioblastoma adjacent to the corticospinal tract (CST; < 10 mm) with continuous dynamic monopolar motor mapping (short-train interstimulus interval 4.0 msec, pulse duration 500 μsec) coupled to an acoustic motor evoked potential (MEP) alarm. The extent of resection was determined based on early (< 48 hours) postoperative MRI findings. Motor function was assessed 1 day after surgery, at discharge, and at 3 months.
  
  
  RESULTS
  Five patients were excluded because of nonadherence to protocol; thus, 67 patients were evaluated. The lowest motor threshold reached during individual surgery was as follows (motor threshold, number of patients): > 20 mA, n = 8; 11-20 mA, n = 13; 6-10 mA, n = 10; 4-5 mA, n = 13; and 1-3 mA, n = 23. Motor deterioration at postsurgical Day 1 and at discharge occurred in 30% (n = 20) and 10% (n = 7) of patients, respectively. At 3 months, 3 patients (4%) had a persisting postoperative motor deficit, 2 caused by vascular injury and 1 by mechanical injury. The rates of intra- and postoperative seizures were 1% and 0%, respectively. Complete resection of enhancing tumor was achieved in 73% of patients (49/67) despite proximity to the CST.
  
  
  CONCLUSIONS
  A rather high rate of CRET can be achieved in glioblastomas in motor eloquent areas via a combination of 5-ALA for tumor identification and intraoperative mapping for distinguishing between presumed and actual motor eloquent tissues. Continuous dynamic mapping was found to be a very ergonomic technique that localizes the motor tissue early and reliably.
authors.affiliation: Departments of Neurosurgery and.
authors.forename: Philippe
authors.initials: P
authors.lastname: Schucht
authors.forename: Kathleen
authors.initials: K
authors.lastname: Seidel
authors.forename: Jürgen
authors.initials: J
authors.lastname: Beck
authors.forename: Michael
authors.initials: M
authors.lastname: Murek
authors.forename: Astrid
authors.initials: A
authors.lastname: Jilch
authors.forename: Roland
authors.initials: R
authors.lastname: Wiest
authors.forename: Christian
authors.initials: C
authors.lastname: Fung
authors.forename: Andreas
authors.initials: A
authors.lastname: Raabe
mesh_terms: D000161:Acoustic Stimulation; D000622:Aminolevulinic Acid; D001931:Brain Mapping; D001932:Brain Neoplasms / Q000503:physiopathology / Q000601:surgery*; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D005909:Glioblastoma / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods; D009044:Motor Cortex / Q000503:physiopathology*; D019635:Neurosurgical Procedures; D017319:Photosensitizing Agents; D011446:Prospective Studies; D011712:Pyramidal Tracts / Q000473:pathology
chemical_list: D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid
keywords: 5-ALA = 5-aminolevulinic acid; CRET = complete resection of enhancing tumor; CST = corticospinal tract; CUSA = Cavitron Ultrasonic Surgical Aspirator; DCS = direct cortical stimulation; EEG = electroencephalography; GTR = gross-total resection; KPS = Karnofsky Performance Scale; MEP = motor evoked potential; MRC = Medical Research Council; MT = motor threshold; SSEP = somatosensory evoked potential; STR = subtotal resection; TES = transcranial electrical stimulation; TOF = train of five; corticospinal tract; glioblastoma; intraoperative neuromonitoring; motor evoked potential; subcortical mapping; tumor surgery