title: Utility of tubular retractors to minimize surgical brain injury in the removal of deep intraparenchymal lesions: a quantitative analysis of FLAIR hyperintensity and apparent diffusion coefficient maps.
abstract: OBJECTIVE
  Brain retraction systems are frequently required to achieve surgical exposure of deep-seated brain lesions. Spatula-based systems can be associated with injury to the cortex and deep white matter, particularly adjacent to the sharp edges, which can result in uneven pressure on the parenchyma over the course of a long operation. The use of tubular retractor systems has been proposed as a method to overcome these limitations. There have been no studies assessing the degree of brain injury associated with the use of tubular retractors. METHODS :Twenty patients were retrospectively identified at Weill Cornell Medical College who underwent resection of deep-seated brain lesions between 2005 and 2014 with the aid of a METRx tubular retractor system. Using the Brainlab software, pre- and postoperative images were analyzed to assess volume, depth, extent of resection, and change in postoperative MR FLAIR hyperintensity and restricted diffusion on diffusion-weighted imaging (DWI).
  
  
  RESULTS
  The mean preoperative tumor volume was 16.25 ± 17.6 cm(3). Gross-total resection was achieved in 75%, near-total resection in 10%, and subtotal resection in 15% of patients. There was a small but not statistically significant increase in average FLAIR hyperintensity volume by 3.25 ± 10.51 cm(3) (p = 0.16). The average postoperative volume of DWI high signal area with restricted diffusion on apparent diffusion coefficient maps was 8.35 ± 3.05 cm(3). Assuming that the volume of restricted diffusion on DWI around tumor was 0 preoperatively, this represented a statistically significant increase on DWI (p < 0.001).
  
  
  CONCLUSIONS
  Although tubular retractors do not appear to significantly increase FLAIR signal in the brain, DWI intensity around the retractors can be identified. These data indicate that although tubular retractors may minimize damage to surrounding tissues, they still cause cytotoxic edema and cellular damage. Objective comparison against other retraction methods, as compared by 3D volumetric analysis or similar methods, will be important in determining the true advantage of tubular retractor systems.
authors.affiliation: Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York.
authors.forename: Evan D
authors.initials: ED
authors.lastname: Bander
authors.affiliation: Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Jones
authors.affiliation: Radiology.
authors.forename: Ilhami
authors.initials: I
authors.lastname: Kovanlikaya
authors.affiliation: Departments of 1 Neurosurgery.|Otolaryngology.|Neuroscience, and.
authors.forename: Theodore H
authors.initials: TH
authors.lastname: Schwartz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001929:Brain Edema / Q000209:etiology; D001930:Brain Injuries / Q000517:prevention & control*; D001932:Brain Neoplasms / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D005909:Glioblastoma / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007431:Intraoperative Complications / Q000517:prevention & control*; D008297:Male; D008579:Meningioma / Q000601:surgery; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000009:adverse effects / Q000295:instrumentation*; D011183:Postoperative Complications / Q000517:prevention & control*; D012189:Retrospective Studies; D013525:Surgical Instruments; D055815:Young Adult
keywords: ADC = apparent diffusion coefficient; DWI = diffusion-weighted imaging; FLAIR; GTR = gross-total resection; NTR = near-total resection; STR = subtotal resection; brain injury; diffusion-weighted imaging; magnetic resonance imaging; neurosurgery retractor; surgical technique; tube; tubular