title: Evaluating the importance of the tentorial angle in the paramedian supracerebellar-transtentorial approach for selective amygdalohippocampectomy.
abstract: OBJECTIVE
  A challenging step of the paramedian supracerebellar-transtentorial approach is to expose the anterior portion of the mediobasal-temporal region (MTR), a step that seems most affected by the steepness of the tentorium. The objective of this study was to define magnetic resonance imaging measurements that can predict the level of challenge in exposing the anterior portion of the MTR.
  
  
  METHODS
  Cranial magnetic resonance imaging studies of 100 healthy individuals were examined. The tentorial and occipital angles were measured, and the amount of brain tissue that remained hidden on the microscopic view in front of the petrous apex was indirectly estimated. These measurements were statistically compared with the cephalic index of each person.
  
  
  RESULTS
  The mean values for the tentorial and occipital angles were 42° (range 25°-53°) and 98° (range 69°-122°), respectively. The results proved that the higher the tentorial angle, the higher the occipital angle and the greater the amount of hidden brain tissue. Of 100 persons, 3 (3%) were found to be dolichocephalic, 23 (23%) were mesocephalic, and 74 (74%) were brachycephalic. Statistical analysis proved that individuals with a dolichocephalic cranial shape have lower tentorial and occipital angles.
  
  
  CONCLUSIONS
  The results provide strong evidence proving that the lesser the tentorial and occipital angles, the easier the exposure of the anterior portion of the MTR during the paramedian supracerebellar-transtentorial approach. The tendency of the cranial shape toward dolichocephaly seems to have the same practical value in choosing the approach. It is easier to expose the anterior portion of the MTR in these individuals.
authors.affiliation: Department of Neurosurgery, Yeditepe University School of Medicine, İstanbul, Turkey.
authors.forename: Spyros
authors.initials: S
authors.lastname: Lafazanos
authors.affiliation: Department of Neurosurgery, Yeditepe University School of Medicine, İstanbul, Turkey. Electronic address: drture@yahoo.com.
authors.forename: Uğur
authors.initials: U
authors.lastname: Türe
authors.affiliation: Department of Neurosurgery, Yeditepe University School of Medicine, İstanbul, Turkey.
authors.forename: Mehmet Volkan
authors.initials: MV
authors.lastname: Harput
authors.affiliation: Department of Neurosurgery, Yeditepe University School of Medicine, İstanbul, Turkey.
authors.forename: Pablo
authors.initials: P
authors.lastname: Gonzalez Lopez
authors.affiliation: Department of Neurosurgery, Yeditepe University School of Medicine, İstanbul, Turkey.
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Fırat
authors.affiliation: Department of Anesthesiology, Yeditepe University School of Medicine, İstanbul, Turkey.
authors.forename: Hatice
authors.initials: H
authors.lastname: Türe
authors.affiliation: Department of Anatomy, Medical School, Democritus University of Thrace, Alexandroupolis, Greece.
authors.forename: Thespis
authors.initials: T
authors.lastname: Dimitriou
authors.affiliation: Department of Neurosurgery, Yeditepe University School of Medicine, İstanbul, Turkey.
authors.forename: M Gazi
authors.initials: MG
authors.lastname: Yaşargil
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000679:Amygdala / Q000033:anatomy & histology / Q000601:surgery*; D035301:Cranial Fossa, Middle / Q000033:anatomy & histology; D005260:Female; D006624:Hippocampus / Q000033:anatomy & histology / Q000601:surgery*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D010579:Petrous Bone / Q000033:anatomy & histology; D012016:Reference Values; D013702:Temporal Lobe / Q000033:anatomy & histology / Q000601:surgery*; D055815:Young Adult
keywords: Mediobasal temporal region; Paramedian supracerebellar-transtentorial approach; Selective amygdalohippocampectomy; Tentorial angle