title: Modified concentric craniotomy for the removal of a huge calvarial metastatic tumor: technical note.
abstract: BACKGROUND
  It is challenging for neurosurgeons to remove huge tumors involving the skull that may possibly invade the dura or intracranial neural tissue. In this situation, excision of the tumor may cause profound blood loss, unexpected opening of the dura, or neurological injury. We describe a technique of craniotomy in a pediatric patient to avoid surgical complications.
  
  
  METHODS
  A 15-year-old boy had a huge metastatic calvarial Ewing's sarcoma. We removed the tumor successfully with modified concentric craniotomy. First, two oval burr holes are made on both sides of the tumor. The inner craniotomy uses the internal margin of the oval holes, while the outer cut uses the outer margins. The skull bone in between the two craniotomies is removed easily in two pieces and the dura surrounding the tumor can be exposed early in the procedure. In this way, the huge skull tumor can be removed en bloc under direct vision to avoid unwanted complications. Minimal blood and bone loss can be achieved.
  
  
  RESULTS
  Blood transfusion was not necessary during the surgery. The patient did not have new neurological symptoms and signs after surgery.
  
  
  CONCLUSIONS
  The goal of the modified concentric craniotomy is to develop an accessible margin of the dura surrounding the bulky tumor in the early phase of surgery. Blood and bone loss can be reduced significantly.
authors.affiliation: Division of Neurosurgery, Department of Surgery, Cathay General Hospital, Taipei, Taiwan.
authors.forename: Ying
authors.initials: Y
authors.lastname: Kao
authors.affiliation: Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, 7 Chung-Shan S. Rd., Taipei, 10041, Taiwan.
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Yang
authors.affiliation: Division of Neurosurgery, Department of Surgery, National Taiwan University Hospital, National Taiwan University College of Medicine, 7 Chung-Shan S. Rd., Taipei, 10041, Taiwan. mfkenator@gmail.com.
authors.forename: Meng-Fai
authors.initials: MF
authors.lastname: Kuo
mesh_terms: D000293:Adolescent; D001859:Bone Neoplasms / Q000473:pathology; D003399:Craniotomy / Q000379:methods*; D006801:Humans; D008297:Male; D059146:Metastasectomy / Q000379:methods; D012272:Ribs; D012512:Sarcoma, Ewing / Q000556:secondary / Q000601:surgery*; D012888:Skull Neoplasms / Q000556:secondary / Q000601:surgery*
keywords: Calvarial tumors; Craniotomy techniques; Dural tumors