Operative Technique Endoscopic extradural anterior clinoidectomy and optic nerve decompression through a pterional port André Beer-Furlan a,b , Alexander I. Evins a , Luigi Rigante a , Justin C. Burrell a , Giulio Anichini a , Philip E. Stieg a , Antonio Bernardo a,⇑ a Department of Neurological Surgery, Weill Cornell Medical College, Cornell University, New York, NY, USA b Department of Neurosurgery, University of São Paulo Medical School (FMUSP), São Paulo, Brazil article info Article history: Received 7 October 2013 Accepted 13 October 2013 Keywords: Anterior clinoidectomy Decompression Endoscopy Keyhole Optic nerve Pterional abstract Since the first description of the intradural removal of the anterior clinoid process, numerous refinements and modifications have been proposed to simplify and enhance the safety of the technique. The growing use of endoscopes in endonasal and transcranial approaches has changed the traditional management of many skull base lesions. We describe an endoscopic extradural anterior clinoidectomy and optic nerve decompression through a minimally invasive pterional port. Minimally invasive optic nerve decompres- sion, with endoscopic extradural anterior clinoidectomy, through a pterional keyhole craniotomy was performed on five preserved cadaveric heads. The endoscopic pterional port provided a shorter and more direct route to the anterior clinoid region, and helped avoid unnecessary and extensive bone removal. An extradural approach helped minimize complications associated with infraction of the subdural space and allowed for the maintenance of visibility while drilling with continuous irrigation. Adequate 270° bone decompression of the optic canal was achieved in all specimens. Endoscopic extradural anterior clinoi- dectomy and optic nerve decompression is feasible through a single minimally invasive pterional port. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Since the first description of the intradural removal of the ante- rior clinoid process (ACP), numerous refinements and modifica- tions have been proposed to simplify and enhance the safety of the technique [1–11]. Dolenc pioneered the extradural technique for anterior clinoidectomies which provided a safe approach to the cavernous sinus and helped avoid infraction of the subdural space and its associated complications. The extradural anterior cli- noidectomy was initially proposed for use in the management of carotid-cavernous fistulas and intracavernous aneurysms [12]. Over the following decades, the application of this technique was extended for use in the treatment of basilar tip aneurysms, le- sions of the cavernous sinus, craniopharyngiomas, peri- and supra- sellar meningiomas, and select giant pituitary adenomas [4,13–19]. Extradural anterior clinoidectomies have also been shown to be effective for optic nerve decompression [20]. This is consistent with the fact that the optic strut forms the floor of the optic canal and the base of the anterior clinoid forms its lateral margin [21]. The growing use of endoscopes in endonasal and transcranial approaches has changed the traditional management of many skull base lesions. Use of the endoscope has been shown to improve ana- tomic visualization, reduce exposure and brain retraction, and minimize surgical morbidity [22]. Endoscopic neurosurgery is well established and widely accepted as a means of treatment for le- sions of the cranial base [22–28]. In this study, we investigated the use of a minimally invasive pterional port with an endoscopic extradural anterior clinoidecto- my for optic nerve decompression. 2. Methods Minimally invasive optic nerve decompression, with endoscopic extradural anterior clinoidectomy, through a pterional keyhole cra- niotomy was performed on five preserved cadaveric heads injected with colored latex (red for arteries and blue for veins). Three-point fixation was achieved using a Mayfield head holder. The head was positioned with 5° extension and 10–15° of lateralization contra- lateral to the side of the approach. Dissections were performed using 0° and 30° endoscopes with two dimensional optics (4 mm diameter, 18 cm length; Karl Storz, Tuttlingen, Germany) and a 0° endoscopes with three dimensional optics (4.9 mm diameter, 30 cm length; Visionsense, New York, NY, USA). Images were recorded and stored using the Karl Storz AIDA system and the Visionsense software, respectively. An endoscope holder and a Greenberg retractor system were used to perform bimanual dissection and drilling. An Anspach eMax 2 Plus (DePuy 0967-5868/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jocn.2013.10.006 ⇑ Corresponding author. Tel.: +1 212 746 1468; fax: +1 212 746 7007. E-mail address: anb2029@med.cornell.edu (A. Bernardo). Journal of Clinical Neuroscience 21 (2014) 836–840 Contents lists available at ScienceDirect Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn