J Korean Neurosurg Soc.  2013 Nov;54(5):405-410. 10.3340/jkns.2013.54.5.405.

The Comparative Morphometric Study of the Posterior Cranial Fossa : What Is Effective Approaches to the Treatment of Chiari Malformation Type 1?

• Hwang HS
• Moon JG
• Kim CH
• Oh SM
• Song JH
• Jeong JH

• KMID: 2138356
• DOI: http://doi.org/10.3340/jkns.2013.54.5.405

Abstract

OBJECTIVE
The objective of this study was to investigate changes in the posterior cranial fossa in patients with symptomatic Chiari malformation type I (CMI) compared to a control group.
METHODS
We retrospectively reviewed clinical and radiological data from 12 symptomatic patients with CMI and 24 healthy control subjects. The structures of the brain and skull base were investigated using magnetic resonance imaging.
RESULTS
The length of the clivus had significantly decreased in the CMI group than in the control group (p=0.000). The angle between the clivus and the McRae line (p<0.024), as the angle between the supraocciput and the McRae line (p<0.021), and the angle between the tentorium and a line connecting the internal occipital protuberance to the opisthion (p<0.009) were significantly larger in the CMI group than in the control group. The mean vertical length of the cerebellar hemisphere (p<0.003) and the mean length of the coronal and sagittal superoinferior aspects of the cerebellum (p<0.05) were longer in the CMI group than in the control group, while the mean length of the axial anteroposterior aspect of the cerebellum (p<0.001) was significantly shorter in the CMI group relative to control subjects.
CONCLUSION
We elucidate the transformation of the posterior cranial fossa into the narrow funnel shape. The sufficient cephalocaudal extension of the craniectomy of the posterior cranial fossa has more decompression effect than other type extension of the craniectomy in CMI patients.

Keyword

Type I Arnold-Chiari malformation; Posterior cranial fossa; Decompressive craniectomy; Embryology; Congenital abnormality

MeSH Terms

Arnold-Chiari Malformation
Brain
Cerebellum
Congenital Abnormalities
Cranial Fossa, Posterior*
Decompression
Decompressive Craniectomy
Embryology
Humans
Magnetic Resonance Imaging
Retrospective Studies
Skull Base

Figure

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  Fig. 1 Midsagittal T1-weighted MRI shows the posterior cranial fossa, the brainstem and cerebellum. a : length of clivus, b : the anteroposterior length of the foramen magnum from distance between the basion and opisthion on the McRae line, c : the length of the supraocciput between the internal occipital protuberance and the opisthion.

• 

  Fig. 2 Midsagittal T1-weighted MRI illustrates demonstrating the measurements of three structural angulations. α : angle of clivus, β : angle of the cerebellar tentorium, γ : angle of occipital protuberance.

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  Fig. 3 Midsagittal T1-weighted MRI shows the neural structure of the posterior cranial fossa. d : the length of the hindbrain midbrain-pons junction and the medullocervical junction, f : the vertical length of the tentorium with cerebellum.

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  Fig. 4 Demonstration of linear measurements for the maxium diameters of posterior fossa on T2-weighted MRI. (A) Anteroposterior length and bi-cerebellar length of cerebellum on axial view, (B) supero-inferior length and bi-cerebellar diameter of cerebellum on coronal view, (C) supero-inferior length and anteroposterior length of cerebellum on sagittal view.

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  Fig. 5 Schematic illustration of the changes of the posterior cranial fossa in the Chiari malformation type I (CMI) patinets.

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