title: Safety of drilling for clinoidectomy and optic canal unroofing in anterior skull base surgery.
abstract: BACKGROUND
  Skull base drilling is a necessary and important element of skull base surgery; however, drilling around vulnerable neurovascular structures has certain risks. We aimed to assess the frequency of complications related to drilling the anterior skull base in the area of the optic nerve (ON) and internal carotid artery (ICA), in a large series of patients.
  
  
  METHODS
  We included anterior skull base surgeries performed from 2000 to 2012 that demanded unroofing of the optic canal, with extra- or intradural clinoidectomy and/or drilling of the clinoidal process and lateral aspect of the tuberculum sella. Data was retrieved from a prospective database and supplementary retrospective file review. Our IRB waived the requirement for informed consent. The nature and location of pathology, clinical presentation, surgical techniques, surgical morbidity and mortality, pre- and postoperative vision, and neurological outcomes were reviewed.
  
  
  RESULTS
  There were 205 surgeries, including 22 procedures with bilateral optic canal unroofing (227 optic canals unroofed). There was no mortality, drilling-related vascular damage, or brain trauma. Complications possibly related to drilling included CSF leak (6 patients, 2.9 %), new ipsilateral blindness (3 patients, 1.5 %), visual deterioration (3 patients, 1.5 %), and transient oculomotor palsy (5 patients, 2.4 %). In all patients with new neuropathies, the optic and oculomotor nerves were manipulated during tumor removal; thus, new deficits could have resulted from drilling, or tumor dissection, or both.
  
  
  CONCLUSIONS
  Drilling of the clinoid process and tuberculum sella, and optic canal unroofing are important surgical techniques, which may be performed relatively safely by a skilled neurosurgeon.
authors.affiliation: Department of Neurosurgery, Hadassah-Hebrew University Medical Center, P.O. Box 12000, Jerusalem, 91120, Israel. spektor@hadassah.org.il
authors.forename: Sergey
authors.initials: S
authors.lastname: Spektor
authors.forename: Shlomo
authors.initials: S
authors.lastname: Dotan
authors.forename: Cezar José
authors.initials: CJ
authors.lastname: Mizrahi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003399:Craniotomy / Q000009:adverse effects / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008579:Meningioma / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D009900:Optic Nerve / Q000601:surgery; D011446:Prospective Studies; D012189:Retrospective Studies; D019291:Skull Base / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult