Extradural Anterior Clinoidectomy and Optic Canal Unroofing for Paraclinoid and Basilar Aneurysms: Usefulness of a No-Drill Instrumental Method

  • Koichi Iwasaki
  • Hiroki Toda
  • Hirokuni Hashikata
  • Masanori Goto
  • Hitoshi Fukuda
Conference paper
Part of the Acta Neurochirurgica Supplement book series (NEUROCHIRURGICA, volume 129)


The authors describe extradural anterior clinoidectomy without the use of a high-speed drill or ultrasonic device to clip paraclinoid and basilar aneurysms, which can eliminate potential complications related to traditional power drilling or ultrasonic device use. This method involves four steps: (1) partial osteotomy of the sphenoid wing at the superior orbital fissure (SOF); (2) peeling of the dura propria of the temporal lobe from the inner cavernous membrane of the SOF; (3) isolation and resection of the exposed meningo-orbital band to expose the superolateral aspect of the anterior clinoid process (ACP); and (4) piecemeal rongeuring of ACP and the roof of the optic canal. The entire procedure was performed using surgical instruments, including micro-rongeurs, a fine Kerrison punch, and micro-dissectors. Subsequently, intradural neck clipping was performed. Twenty consecutive patients with paraclinoid and basilar aneurysms successfully underwent clipping after this non-drill extradural clinoidectomy. Minor morbidity was noted in two patients (cerebrospinal fluid leakage in one and transient oculomotor palsy in the other). The non-drill method is a simple, easy, safe, and quick alternative to traditional power drilling in extradural clinoidectomy, and this method can avoid morbidity related to direct mechanical/thermal injury of important neurovascular structures.


Skull base surgery Paraclinoid aneurysm Extradural anterior clinoidectomy No-drill method Surgical complication 


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Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  • Koichi Iwasaki
    • 1
  • Hiroki Toda
    • 1
  • Hirokuni Hashikata
    • 1
  • Masanori Goto
    • 1
  • Hitoshi Fukuda
    • 2
  1. 1.Department of NeurosurgeryKitano Medical Research Institute and HospitalOsakaJapan
  2. 2.Department of NeurosurgeryAmagasaki General Medical CenterAmagasakiJapan

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