Type I CM in humans is a congenital disorder characterized by caudal herniation of the cerebellar tonsils through the foramen magnum into the spinal canal.1–6 In addition, type I CM in humans is an important cause of syringomyelia and frequently occurs in association with occipital dysplasia.7 There is accumulating evidence that this malformation in humans is attributable to overcrowding of the hindbrain because of an underdeveloped posterior cranial fossa, and findings in morphometric studies7–15 indicate that the posterior cranial fossa is small and shallow in comparison to the normal unaffected population.
A similar syndrome of cerebellar herniation and syringomyelia has been described in CKCSs, and the term Chiari-like malformation has been applied.16–19 There is a consensus that the underlying cause of this syndrome in dogs is the presence of a shallow and small caudal cranial fossa.16,18–20 However, to date, only a few morphometric studiesa–c have been performed. A prerequisite for identifying dogs with an increased susceptibility of developing Chiari-like malformation and syringomyelia is understanding factors leading to the development of the condition, which may thereby enable effective breeding schemes and genetic eradication programs.
The purpose of the study reported here was to perform morphometric analysis of the caudal cranial fossa in CKCSs, to assess the relationship between these dimensions and the frequency of MRI features of occipital abnormalities in CKCSs (with and without syringomyelia), and to compare these measurements in CKCSs with those of 2 groups of mesaticephalic dogs.21
Cavalier King Charles Spaniel
Magnetic resonance imaging
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Gyroscan NT 1.5 Tesla, Philips Medical System, Eindhoven, The Netherlands, or GE Signa Echospeed 1.5 Tesla, General Electric Medical Systems, Milwaukee, Wis.
Image-pro Plus software, version 6, MediaCybernetics Inc, Bethesda, Md.
MediaCybernetics Inc, Bethesda, Md.
Excel 2003, Microsoft Corp, Reading, Berkshire, England.
Minitab, version 14.0, Minitab Inc, State College, Pa.
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