title: Microsurgical management of hypoglossal schwannomas over 3 decades:  a modified grading scale to guide surgical approach.
abstract: BACKGROUND
  Schwannomas originating from the hypoglossal nerve are extremely rare. Microsurgical resection with the goal for cure has traditionally been associated with a high risk of postoperative deficits.
  
  
  OBJECTIVE
  To summarize our clinical experience using tailored cranial base approaches for these formidable lesions.
  
  
  METHODS
  The clinical records of 13 patients were retrospectively reviewed. In addition, all reported patients in the literature were reviewed. The extreme lateral infrajugular transcondylar-transtubercular exposure approach was used in all of our patients. Based on our experience and literature analysis, we propose the following modified grading scale to facilitate surgical planning: type A, intradural tumors; type B, dumbbell-shaped tumors; type C, extracranial tumors; and type D, peripheral tumors.
  
  
  RESULTS
  All 13 patients underwent total, near-total, or subtotal tumor resection. Eight patients were men, 5 were women (mean age, 41.7 years). Sural nerve graft reconstruction for the hypoglossal nerve was performed in 4 patients. Three of the 4 patients in whom nerve reconstruction was performed regained satisfactory movement of their tongue. In the review of the literature, the mean patient age was 45.8 years. Patients presented with tongue atrophy (91.6%), headache (60.9%), and dysphagia (31.8%). The tumors were categorized as type A in 31.7% of these patients, type B in 38.6%, type C in 6.2%, and type D in 23.4%.
  
  
  CONCLUSIONS
  The extreme lateral infrajugular transcondylar-transtubercular exposure approach, which is a modification of the extreme lateral suboccipital approach, provides sufficient exposure for most intracranial dumbbell-shaped hypoglossal schwannomas. Hypoglossal nerve reconstruction using a sural nerve graft improves tongue atrophy and movement for patients with resected nerves.
authors.affiliation: Division of Neurosurgery, Duke University Medical Center, Durham, North Carolina 27710, USA. ynonaka1971@yahoo.co.jp
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Nonaka
authors.forename: Peter M
authors.initials: PM
authors.lastname: Grossi
authors.forename: Ketan R
authors.initials: KR
authors.lastname: Bulsara
authors.forename: Raymond M
authors.initials: RM
authors.lastname: Taniguchi
authors.forename: Allan H
authors.initials: AH
authors.lastname: Friedman
authors.forename: Takanori
authors.initials: T
authors.lastname: Fukushima
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003390:Cranial Nerve Neoplasms / Q000601:surgery*; D005260:Female; D006801:Humans; D020437:Hypoglossal Nerve Diseases / Q000601:surgery*; D008297:Male; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D009442:Neurilemmoma / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000379:methods*; D055815:Young Adult