title: Selection of surgical approaches based on semi-quantifying the skull-base invasion by petroclival meningiomas: a review of 66 cases.
abstract: BACKGROUND
  Petroclival meningiomas are still challenging for neurosurgeons. In the present study, we reviewed 66 petroclival meningiomas that underwent craniotomy to assess the surgical approaches for petroclival meningiomas based on semi-quantifying tumor extension to skull base and to evaluate the outcomes.
  
  
  METHODS
  According to invasion characteristics, skull base related to petroclival meningiomas was semi-quantitatively divided into five regions: upper, middle, and lower petroclival regions (region A, B, and C, respectively), cerebellopontine angle region (region D), and parasellar and cavernous sinus region (region E). Appropriate surgical approaches were adopted for petroclival meningiomas with varying degrees of invasion, including the subtemporal (11/66), retrosigmoid (15/66), presigmoid (32/66), combined retrosigmoid and far-lateral (2/66), supra-infratentorial (4/66), and extended middle cranial fossa (2/66) approaches.
  
  
  RESULTS
  The results showed that involvement of region A, B, and C was in 64, 50, and eight patients, respectively. Invasion to region D and E occurred in 13 and 39 cases, respectively. The ratio of single region involvement was only 7.6 %, whereas most petroclival meningiomas tended to invade more regions (39.4 % for two, 37.9 % for three, 12.1 % for four, and 3.0 % for five regions, respectively). Gross total resection was achieved in 29 cases (43.9 %), near total resection in 27 cases (40.9 %), and subtotal resection in ten cases (15.2 %). After a mean follow-up period of 32.21 months, obvious cranial nerve deficits existed in seven patients, and recurrence occurred in eight patients.
  
  
  CONCLUSIONS
  We introduced a simple and practicable method for classification of petroclival meningiomas, which could semi-quantify tumor invasion and help to select surgical approaches. With careful preoperative evaluation, a cautiously selected approach would improve the prognosis.
authors.affiliation: Department of Neurosurgery, First Hospital of China Medical University, No. 155, North Nanjing Street, Heping District, Shenyang, Liaoning, China, 110001.
authors.forename: Jun
authors.initials: J
authors.lastname: Tao
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Wang
authors.forename: Bo
authors.initials: B
authors.lastname: Qiu
authors.forename: Shaowu
authors.initials: S
authors.lastname: Ou
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Pengfei
authors.initials: P
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D003388:Cranial Fossa, Posterior / Q000473:pathology / Q000601:surgery; D003399:Craniotomy / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000145:classification / Q000473:pathology / Q000601:surgery; D008579:Meningioma / Q000145:classification / Q000473:pathology / Q000601:surgery; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D019292:Skull Base Neoplasms / Q000145:classification / Q000473:pathology / Q000601:surgery