title: Various patterns of the middle cerebral vein and preservation of venous drainage during the anterior transpetrosal approach.
abstract: OBJECTIVE
  The drainage of the superficial middle cerebral vein (SMCV) has previously been classified into 4 subtypes. Extradural procedures and dural incisions during the anterior transpetrosal approach (ATPA) may interrupt the route of drainage from the SMCV. In this study, the authors examined the relationship between anatomical variations in the SMCV and the corresponding surgical modifications to the ATPA that are necessary for venous preservation.
  
  
  METHODS
  This study included 48 patients treated via the ATPA in whom the SMCV was examined using 3D CT venography. The drainage patterns of the SMCV were classified into 3 types: cavernous or absent (Type 1), sphenobasal (Type 2), and sphenopetrosal (Type 3). Type 2 was subdivided into medial (Type 2a) and lateral (Type 2b), and Type 3 was subdivided into vein (Type 3a), vein and sinus (Type 3b), and sinus (Type 3c). The authors performed 3 ATPA modifications to preserve the SMCV: epidural anterior petrosectomy with subdural visualization of the sphenobasal vein (SBV), modification of the dural incision, and subdural anterior petrosectomy. Standard ATPA can be performed with Type 1, Type 2a, and Type 3a drainage. With Type 2b drainage, an epidural anterior petrosectomy with subdural SBV visualization is appropriate. The dural incision should be modified in Type 3b. With Type 3c, a subdural anterior petrosectomy is required.
  
  
  RESULTS
  The frequency of each type was 68.7% (33/48) in Type 1, 8.3% (4/48) in Type 2a, 4.2% (2/48) in Type 2b, 14.6% (7/48) in Type 3a, 2.1% (1/48) in Type 3b, and 2.1% (1/48) in Type 3c. No venous complications were found.
  
  
  CONCLUSIONS
  The authors propose an SMCV modified classification based on ATPA modifications required for venous preservation.
authors: Department of Neurosurgery, Keio University School of Medicine; and.
authors: Shunsuke
authors: S
authors: Shibao
authors: Department of Neurosurgery, Keio University School of Medicine; and.
authors: Masahiro
authors: M
authors: Toda
authors: Department of Neurosurgery, Keio University School of Medicine; and.
authors: Maaya
authors: M
authors: Orii
authors: Department of Diagnostic Radiology, Keio University Graduate School of Medicine, Tokyo, Japan.
authors: Hirokazu
authors: H
authors: Fujiwara
authors: Department of Neurosurgery, Keio University School of Medicine; and.
authors: Kazunari
authors: K
authors: Yoshida
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology / Q000601:surgery; D002550:Cerebral Veins / Q000033:anatomy & histology / Q000473:pathology / Q000601:surgery*; D002560:Cerebrovascular Circulation; D002648:Child; D004388:Dura Mater / Q000033:anatomy & histology / Q000601:surgery; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D010579:Petrous Bone / Q000033:anatomy & histology* / Q000601:surgery*; D013355:Subdural Space / Q000033:anatomy & histology / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014656:Vascular Surgical Procedures / Q000379:methods*; D055815:Young Adult
keywords: ATPA = anterior transpetrosal approach; CS = cavernous sinus; CTV = CT venography; DSA = digital subtraction angiography; GPN = greater petrosal nerve; Hacker’s classification; SBV = sphenobasal vein; SMCV = superficial middle cerebral vein; SPS = superior petrosal sinus; anatomy; anterior transpetrosal approach; superficial middle cerebral vein; venous preservation