title: Proposed grading system to predict the extent of resection and outcomes for cranial base meningiomas.
abstract: OBJECTIVE
  This investigation was performed to construct a grading system for cranial base meningiomas that augments the current system of topographic labeling. This new system classifies cranial base meningiomas based on predicted surgical resection and patient outcomes.
  
  
  METHODS
  Two hundred thirty-two consecutive patients with cranial base meningiomas were surgically treated by the two senior authors between April 1993 and August 1997. Using standard statistical tests, a large number of preoperative, intraoperative, and follow-up findings were analyzed for correlation with the extent of resection. These included the presence of previous radiotherapy, Cranial Nerve III, V, and VI palsies, multiple fossa involvement, and vessel encasement.
  
  
  RESULTS
  Analysis revealed that each variable tested was independently and inversely correlated with total tumor resection (P < 0.002). We were able to construct a grading system based on these variables; when more variables are present, the grade is higher. With the grading system, lower-grade tumors were correlated with increased probabilities of total resection (r2 = 0.9947) and better patient outcomes, as measured by Karnofsky performance scale scores (r = 0.9291). We also found that, as a group, patients who underwent subtotal resection exhibited worse Karnofsky performance scale scores and had longer hospital stays.
  
  
  CONCLUSIONS
  The current system of classifying cranial base meningiomas provides no information regarding the tumor except location and no information concerning patient prognosis. We present a more useful system to categorize these tumors. Our scheme must be tested at other centers to corroborate our findings. This new grading system should serve to guide surgical treatment, inform patients, and improve communication among surgeons.
authors.affiliation: Department of Neurological Surgery, George Washington University Medical Center, Washington, District of Columbia, USA.
authors.forename: Z T
authors.initials: ZT
authors.lastname: Levine
authors.forename: R I
authors.initials: RI
authors.lastname: Buchanan
authors.forename: L N
authors.initials: LN
authors.lastname: Sekhar
authors.forename: C L
authors.initials: CL
authors.lastname: Rosen
authors.forename: D C
authors.initials: DC
authors.lastname: Wright
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D015331:Cohort Studies; D005260:Female; D005544:Forecasting; D006801:Humans; D017567:Karnofsky Performance Status; D007902:Length of Stay; D008297:Male; D008499:Medical Records; D008577:Meningeal Neoplasms / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D008579:Meningioma / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D008875:Middle Aged; D009493:Neurosurgery / Q000379:methods; D019291:Skull Base / Q000601:surgery*; D016896:Treatment Outcome