title: Quantitative analysis of the Kawase versus the modified Dolenc-Kawase approach for middle cranial fossa lesions with variable anteroposterior extension.
abstract: OBJECTIVE
  The surgical corridor to the upper third of the clivus and ventral brainstem is hindered by critical neurovascular structures, such as the cavernous sinus, petrous apex, and tentorium. The traditional Kawase approach provides a 10 × 5-mm fenestration at the petrous apex of the temporal bone between the 5th cranial nerve and internal auditory canal. Due to interindividual variability, sometimes this area proves to be insufficient as a corridor to the posterior cranial fossa. The authors describe a modification to the technique of the extradural anterior petrosectomy consisting of additional transcavernous exploration and medial mobilization of the cisternal component of the trigeminal nerve. This approach is termed the modified Dolenc-Kawase (MDK) approach.
  
  
  METHODS
  The authors describe a volumetric analysis of temporal bones with 3D laser scanning of dry and drilled bones for respective triangles and rhomboid areas, and they compare the difference of exposure with traditional versus modified approaches on cadaver dissection. Twelve dry temporal bones were laser scanned, and mesh-based volumetric analysis was done followed by drilling of the Kawase triangle and MDK rhomboid. Five cadaveric heads were drilled on alternate sides with both approaches for evaluation of the area exposed, surgical freedom, and angle of approach.
  
  
  RESULTS
  The MDK approach provides an approximately 1.5 times larger area and 2.0 times greater volume of bone at the anterior petrous apex compared with the Kawase's approach. Cadaver dissection objectified the technical feasibility of the MDK approach, providing nearly 1.5-2 times larger fenestration with improved view and angulation to the posterior cranial fossa. Practical application in 6 patients with different lesions proves clinical applicability of the MDK approach.
  
  
  CONCLUSIONS
  The larger fenestration at the petrous apex achieved with the MDK approach provides greater surgical freedom at the Dorello canal, gasserian ganglion, and prepontine area and better anteroposterior angulation than the traditional Kawase approach. Additional anterior clinoidectomy and transcavernous exposure helps in dealing with basilar artery aneurysms.
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Manjul
authors.initials: M
authors.lastname: Tripathi
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Rama Chandra
authors.initials: RC
authors.lastname: Deo
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Ashish
authors.initials: A
authors.lastname: Suri
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Vinkle
authors.initials: V
authors.lastname: Srivastav
authors.affiliation: Departments of 1 Neurosurgery.
authors.forename: Britty
authors.initials: B
authors.lastname: Baby
authors.affiliation: Department of Computer Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.
authors.forename: Subodh
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Computer Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.
authors.forename: Prem
authors.initials: P
authors.lastname: Kalra
authors.affiliation: Department of Computer Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.
authors.forename: Subhashis
authors.initials: S
authors.lastname: Banerjee
authors.affiliation: Department of Computer Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.
authors.forename: Sanjiva
authors.initials: S
authors.lastname: Prasad
authors.affiliation: Department of Computer Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.
authors.forename: Kolin
authors.initials: K
authors.lastname: Paul
authors.affiliation: Anatomy, and.
authors.forename: Tara Sankar
authors.initials: TS
authors.lastname: Roy
authors.affiliation: Forensic Science and Toxicology, All India Institute of Medical Sciences; and.
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Lalwani
mesh_terms: D002102:Cadaver; D035301:Cranial Fossa, Middle / Q000601:surgery*; D003388:Cranial Fossa, Posterior / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D019635:Neurosurgical Procedures / Q000379:methods*; D010579:Petrous Bone / Q000601:surgery*; D019292:Skull Base Neoplasms / Q000601:surgery*; D013701:Temporal Bone / Q000601:surgery
keywords: CN = cranial nerve; Dolenc; GSPN = greater superficial petrosal nerve; Kawase; MDK = modified Dolenc-Kawase; MMA = middle meningeal artery; cadaver; petrosectomy; petrous; quantitative; skull base