title: Stereological and Morphometric Analysis of MRI Chiari Malformation Type-1.
abstract: OBJECTIVE
  In this study, we aimed to investigate the underlying ethiological factors in chiari malformation (CM) type-I (CMI) via performing volumetric and morphometric length-angle measurements.
  
  
  METHODS
  A total of 66 individuals [33 patients (20-65 years) with CMI and 33 control subjects] were included in this study. In sagittal MR images, tonsillar herniation length and concurrent anomalies were evaluated. Supratentorial, infratentorial, and total intracranial volumes were measured using Cavalieri method. Various cranial distances and angles were used to evaluate the platybasia and posterior cranial fossa (PCF) development.
  
  
  RESULTS
  Tonsillar herniation length was measured 9.09±3.39 mm below foramen magnum in CM group. Tonsillar herniation/concurrent syringomyelia, concavity/defect of clivus, herniation of bulbus and fourth ventricle, basilar invagination and craniovertebral junction abnormality rates were 30.3, 27, 18, 2, 3, and 3 percent, respectively. Absence of cisterna magna was encountered in 87.9% of the patients. Total, IT and ST volumes and distance between Chamberlain line and tip of dens axis, Klaus index, clivus length, distance between internal occipital protuberance and opisthion were significantly decreased in patient group. Also in patient group, it was found that Welcher basal angle/Boogard angle increased and tentorial slope angle decreased.
  
  
  CONCLUSIONS
  Mean cranial volume and length-angle measurement values significantly decreased and there was a congenital abnormality association in nearly 81.5 percent of the CM cases. As a result, it was concluded that CM ethiology can be attributed to multifactorial causes. Moreover, congenital defects can also give rise to this condition.
authors.affiliation: Department of Anatomy, Faculty of Medicine, Istanbul Medeniyet University, Istanbul, Turkey.
authors.forename: Ozan Alper
authors.initials: OA
authors.lastname: Alkoç
authors.affiliation: Department of Anatomy, Faculty of Medicine, Afyon Kocatepe University, Afyon, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Songur
authors.affiliation: Department of Neurological Surgery, Faculty of Medicine, Balıkesir University, Balıkesir, Turkey.
authors.forename: Olcay
authors.initials: O
authors.lastname: Eser
authors.affiliation: Department of Anatomy, Faculty of Medicine, Turgut Özal University, Ankara, Turkey.
authors.forename: Muhsin
authors.initials: M
authors.lastname: Toktas
authors.affiliation: Department of Anatomy, Faculty of Medicine, Afyon Kocatepe University, Afyon, Turkey.
authors.forename: Yücel
authors.initials: Y
authors.lastname: Gönül
authors.affiliation: Department of Radiology, Afyonkarahisar State Hospital, Afyon, Turkey.
authors.forename: Ertap
authors.initials: E
authors.lastname: Esi
authors.affiliation: Department of Radiology, Faculty of Medicine, Ordu University, Ordu, Turkey.
authors.forename: Alpay
authors.initials: A
authors.lastname: Haktanir
keywords: Cavalieri method; Chiari malformation; MRI; Morphometry