1 / 26

Posterior Fossa Volume and Skull Base Geometry in Children with Chiari I Malformation

Posterior Fossa Volume and Skull Base Geometry in Children with Chiari I Malformation. S.Sgouros Birmingham Children’s Hospital Birmingham, U.K. Acknowledgements. Kal Natarajan, Computer Scientist at the Neuroscience Informatics Laboratory Menia Kountouri, Research Fellow

kat
Download Presentation

Posterior Fossa Volume and Skull Base Geometry in Children with Chiari I Malformation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Posterior Fossa Volume and Skull Base Geometry in Children with Chiari I Malformation S.Sgouros Birmingham Children’s Hospital Birmingham, U.K.

  2. Acknowledgements • Kal Natarajan, Computer Scientist at the Neuroscience Informatics Laboratory • Menia Kountouri, Research Fellow • The Neuroscience Informatics Laboratory at ICH/BCH is supported by the Bernard Williams Syringomyelia Research Fund

  3. Hindbrain Hernia – Chiari I • Hindbrain hernia is considered to be due to maldevelopment of the posterior cranial fossa leading to small volume • Geometrical studies of 2D sagittal projections and quasi 3D studies • Lack of systematic analysis in paediatric age group

  4. 1998-2007 a total of 82 children with isolated Chiari I, 61 operated, 21 asymptomatic Normal control group 70 children (1m-15y) Extensive range of 3D image analysis tools Included: Children with symptomatic Chiari I Complete set of MR scans Excluded: Craniosynostosis-related hindbrain hernia e.g. Crouzon’s Shunt prior to craniovertebral decompression 3D Morphometric Analysis of Chiari I

  5. Posterior Fossa Volume

  6. Aim of the Study • To establish whether the volume of the posterior fossa in children with Chiari I is smaller than normal controls, as has been previously postulated • To establish the correlation between posterior fossa volume and the development of syringomyelia

  7. Patients • 42 children (24 Male, 57%) • Mean age: 127 m (range: 36-204 m) • Syrinx present pre-op: 25 patients (59%) • Comparison with 51 normal children of similar age

  8. Method • Segmentation technique on pre-op MRI scans • Parameters measured: • Posterior Fossa Volume • Intracranial Volume • Posterior Fossa to Intracranial Volume ratio • Factor analysed: syringomyelia preop • One way ANOVA, graphic data analysis (LOWESS smoothing technique)

  9. Segmentation

  10. Results Normal CMI no syrinx CMI+syrinx (n=51) (n=17) (n=25) ICV (cm3) 1383 1459 1400 p=0.363 PFV (cm3) 186 196 171p=0.036 PFV/ICV0.135 0.134 0.122p=0.004

  11. PFV in Chiari I • Two different varieties of Chiari I • Children with Chiari I without syringomyelia have normal posterior fossa volume • Children with Chiari I and syringomyelia have a smaller posterior fossa volume than normal

  12. Skull Base Geometry

  13. Aim of the Study • To establish whether the skull base in children with Chiari I is underdeveloped compared to normal controls, as it has been previously postulated • To establish the correlation between skull base geometry and the presence of syringomyelia

  14. Patients • 30 children (17 Male, 57%) • Mean Age: 128 m (range: 36-204 m) • Syrinx present pre-op: 16 patients (53%) • Comparison with 42 normal children of similar age

  15. Segmentation technique on pre-op T2w axial MRI scans: Angles Crista Galli - Dorsum Sellae - Foramen Magnum LT IAM - Foramen Magnum - RT IAM LT AC-CG-RT AC LT IAM - Dorsum Sellae - RT IAM Distances LT - RT IAM LT AC – RT AC Dorsum Sellae - Foramen Magnum Effect of syringomyelia One way ANOVA analysis Graphic data analysis Method

  16. Skull Base 3D Segmentation

  17. Results NormalChiari I/- syrinx Chiari I/+ syrinx CG-DS-FM 135° 145° 151°(p=.000) LT IAM-FM-RT IAM 110° 122° 123°(p=.001) LT AC-CG-RT AC 34° 29° 29° (p=.000) LT IAM-DS-RT IAM 96° 97° 101° (p=.394) LT IAM-RT IAM (mm) 58 75 63 (p=.000) LT AC-RT AC (mm) 32 3127(p=.001) DS-FM (mm) 46 5040 (p=.101) (p=.037, p=.009)

  18. Skull Base Geometry in Chiari I • Chiari I overall have (in comparison to normal) : • longer anterior fossa • wider and steeper posterior fossa • and different slope / angle of clivus • Patients with syringomyelia have slightly different skull base geometry than those without

  19. Conclusions • Chiari I + Syringomyelia: small posterior fossa volume • Chiari I – Syringomyelia: normal posterior fossa volume • Chiari I: all skull base structurally different from normal • Differences in skull base geometry in syringomyelia • Unlikely that the development of syringomyelia is an evolution in the natural history of Chiari malformation (difficult for posterior fossa to become smaller and geometry to change, as the syringomyelia develops, unless there is a primary skull base synostosis)

  20. Possible Pathogenesis • Possible different pathogenesis for the two subgroups of the Chiari I • Chiari I – syrinx: single hit (mesodermal deformity) • Chiari I + syrinx: double hit (mesodermal deformity + cavitation) • Ab initio formation of syringomyelia  “loss” of CSF in the spine  smaller posterior fossa (analogous to open myelomeningocele) • Anterior fossa deformity secondary to posterior fossa mesodermal defect or primary malformation affecting all the skull base?

  21. Syringomyelia 2007 • Major international conference on syringomyelia • Rugby, U.K. • October 23-26, 2007 • Abstract Closing Date: 30th June 2007 • www.syringomyelia2007.org

More Related