title: Endoscopic-assisted resection of intracranial epidermoid tumors.
abstract: OBJECTIVE
  Intracranial epidermoid tumors are epithelially derived lesions that may present particular challenges to neurosurgeons, often encasing critical neurovascular structures and extending into multiple subarachnoid cisterns. We aimed to evaluate our recent experience with endoscopic assistance to craniotomy with microsurgical resection of these lesions.
  
  
  METHODS
  A retrospective review of patients undergoing endoscopic-assisted craniotomy for resection of an epidermoid tumor at the Keck School of Medicine of University of Southern California between 2009 and 2012 was conducted. In all patients, the surgical approach and tumor resection were first performed microscopically. This was followed by use of an angled endoscope to facilitate further inspection and additional resection of tumor using a two-surgeon technique.
  
  
  RESULTS
  Twelve patients undergoing 13 consecutive endoscopic-assisted craniotomies were included in the analysis. The mean patient age was 45 years. The mean maximal tumor diameter was 4.0 cm (range, 2.4-5.8 cm). Surgery was for recurrent epidermoid in 6 of 13 cases (46%). Epidermoid tumor location included the cerebellopontine angle (9 patients, 75%), fourth ventricle (2 patients, 17%), and third ventricle (1 patient, 8%). Surgical approaches included retrosigmoid craniotomy (8 patients), suboccipital craniotomy (1 patient), suboccipital craniotomy with supracerebellar approach (1 patient), extradural temporopolar approach (1 patient), and subtemporal approach (1 patient). In 11 of 13 cases (85%), additional tumor was identified upon inspection with an angled endoscope, facilitating additional tumor resection in each case. Gross or deliberate near total resection was achieved in 7 of 13 cases (54%). Four patients (31%) had improvement of cranial nerve function. Postoperative neurological deficits included transient abducens and oculomotor nerve paresis in one patient each.
  
  
  CONCLUSIONS
  The endoscope is a safe and effective adjunct to the microscope in facilitating additional inspection and further resection of epidermoid tumors. Endoscopic-assisted surgery is particularly useful for identifying and removing additional tumor located around surgical corners.
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, Los Angeles County-University of Southern California Medical Center, Los Angeles, California, USA. Electronic address: alexandertuchman@gmail.com.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tuchman
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, Los Angeles County-University of Southern California Medical Center, Los Angeles, California, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Platt
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, Los Angeles County-University of Southern California Medical Center, Los Angeles, California, USA.
authors.forename: Jesse
authors.initials: J
authors.lastname: Winer
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, Los Angeles County-University of Southern California Medical Center, Los Angeles, California, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Pham
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, Los Angeles County-University of Southern California Medical Center, Los Angeles, California, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Giannotta
authors.affiliation: Department of Neurosurgery, Keck School of Medicine, Los Angeles County-University of Southern California Medical Center, Los Angeles, California, USA.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Zada
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000601:surgery*; D002294:Carcinoma, Squamous Cell / Q000601:surgery*; D003399:Craniotomy / Q000379:methods; D004724:Endoscopy / Q000379:methods*; D057510:Endovascular Procedures / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: Craniotomy; Endoscopy; Epidermoid tumor; Skull base surgery