title: The combined microscopic-endoscopic technique for radical resection of cerebellopontine angle tumors.
abstract: OBJECTIVE
  The combined microscopic and endoscopic technique has shown significant advantages in the management of various lesions through different approaches. Endoscopic-assisted techniques have frequently been applied to cerebellopontine angle (CPA) surgery in the context of minimally invasive craniotomies. In this paper the authors report on the use of the endoscope in the CPA as a tool to increase the extent of resection, minimize complications, and preserve the function of the delicate CPA structures. They also describe a technique of the simultaneous use of the microscope and endoscope in the CPA and dissection of CPA tumors under tandem endoscopic and microscopic vision to overcome the shortcomings of introducing the endoscope alone in the CPA. The reliability of using the microscope alone in dissecting CPA tumors is evaluated, as is the effectiveness of the combined technique in increasing the resectability of various types of CPA tumors.
  
  
  METHODS
  The authors conducted a retrospective analysis of 50 patients who underwent combined microscopic-endoscopic resection of CPA tumors by the senior author over a period of 3 years (February 2011 to February 2014) at Brigham and Women's Hospital, Harvard Medical School. The reliability of the extent of microscopic removal was evaluated with endoscopic exploration. Additional resection was performed with both microscopic and the combined microscopic-endoscopic technique. Endoscopically verified total resection was validated by intraoperative or postoperative MRI. The function of the cranial nerves was evaluated to assess the impact of the combined technique on their function.
  
  
  RESULTS
  A tumor remnant was endoscopically identified in 69% of the 26 patients who were believed to have microscopic total resection. The utilization of the endoscopic visualization and dissection increased endoscopically verified total removal to 38 patients, and 82% of these patients had no sign of residual tumor on postoperative imaging. The technique was most effective with epidermoid tumors. There were a total of 17 new cranial nerve deficits in 10 patients. Preoperative fifth cranial nerve deficits improved in 52% and hearing improved in 29% of patients after surgery.
  
  
  CONCLUSIONS
  This method provides simultaneous microscopic and endoscopic visualization and dissection techniques through skull-base approaches to CPA tumors. It overcomes some of the shortcomings of endoscopic-assisted surgery, further extends the surgical field, and increases the radicality of tumor resection with good functional outcomes.
authors.affiliation: Department of Neurosurgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts;|Department of Neurosurgery, Ain Shams University, Cairo, Egypt;
authors.forename: Mohammad
authors.initials: M
authors.lastname: Abolfotoh
authors.affiliation: Department of Neurosurgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: Wenya Linda
authors.initials: WL
authors.lastname: Bi
authors.affiliation: Department of Neurosurgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts;|Department of Neurosurgery, Gangnam Severance Hospital, Yonsei University, College of Medicine, Seoul, Korea; and.
authors.forename: Chang-Ki
authors.initials: CK
authors.lastname: Hong
authors.affiliation: Department of Neurosurgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts;|Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona.
authors.forename: Kaith K
authors.initials: KK
authors.lastname: Almefty
authors.affiliation: Department of Neurosurgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: Abraham
authors.initials: A
authors.lastname: Boskovitz
authors.affiliation: Department of Neurosurgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: Ian F
authors.initials: IF
authors.lastname: Dunn
authors.affiliation: Department of Neurosurgery, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts;
authors.forename: Ossama
authors.initials: O
authors.lastname: Al-Mefty
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000601:surgery; D002528:Cerebellar Neoplasms / Q000601:surgery*; D002530:Cerebellopontine Angle / Q000601:surgery*; D003131:Combined Modality Therapy; D020209:Cranial Nerve Injuries / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology; D003399:Craniotomy; D004724:Endoscopy / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006309:Hearing; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008866:Microsurgery / Q000295:instrumentation / Q000379:methods*; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods*; D011183:Postoperative Complications / Q000453:epidemiology; D012189:Retrospective Studies; D013525:Surgical Instruments; D016896:Treatment Outcome; D020433:Trigeminal Nerve Diseases / Q000601:surgery; D055815:Young Adult
keywords: CPA = cerebellopontine angle; EVTR = endoscopically verified total resection; cerebellopontine angle; combined technique; endoscopic skull-base surgery; endoscopy; radical resection; skull-base approach; tumor