PowerPointPrsentation

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Case of the month August 2006
Cavalier King Charles Spaniel, m, 3.5 y
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History
Dog was referred to the Neurology division of the
Vetsuisse Faculty Berne because of
Episodes of suddenly occurring onsets of forelimb
and/or hind limb lameness. During episodes crying
out of pain. Frequency of episodes increasing.
Scratches his head.
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• Results of neurologic
• examination
• Manipulation of neck leads to withdrawal of right
  forelimb biting into paw similar reactions of
  hind limbs
• Paraesthesia
• Head scratching, episodes of agitation, then
  suddenly back to normal
• All reflexes normal

Localisation Brainstem, medulla oblongata,
cervical spine, inner ear
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MRI of head and neck
FSE T2 transverse
Normal for comparison
dorsal
dorsal
M
M
right
right
Level of middle ear
Level of middle ear (M)
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MRI of head and neck
FE 3D T1 transverse
Plain
Contrast enhanced
dorsal
dorsal
right
right
Level of middle ear
Level of middle ear
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MRI of head and neck
T2 mid sagittal
dorsal
C
rostral
C cerebellum, arrows second cervical vertebra
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Findings
?
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Findings
Both middle ears (bullae) are filled with
hyperintense material in T2 (arrows compare with
normal) and T1. Neither the material nor the
epithelial lining of the bullae takes up
contrast.
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Findings
A small part of the cerebellum is herniated
caudally to the dorsal border of the foramen
magnum (arrow) the most cranial part of the
spinal cord is incarcerated between the dens axis
(D) and the dorsal foramen magnum. The
spinal cord shows a severely widened and deformed
central canal (arrowheads).
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Summary
Fluid filled middle ears on both sides without
signs of acute middle ear inflammation.
Cerebellar herniation caudally through the
foramen magnum, incarceration of the most cranial
spinal cord and severe hydrosyringomyelia
(dilatation of the central canal) of the cervical
spinal cord.
Interpretation
These findings are consistent with Chiari
malformation type 1.
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Comment
Arnold Chiari malformations are developmental
disorders which are overrepresented in Cavalier
King Charles Spaniels. They can be clinically
silent or cause severe neurological deficits.
Their main feature is the caudal displacement of
the cerebellum, resulting in crowding of the
foramen magnum and disruption of normal
cerebrospinal fluid (CSF)-flow leading to
hydrosyringomyelia. Associated are increased
intracranial pressure and malformation of the
foramen magnum. Fluid filled middle ears are
common findings in this breed, but not related to
the Arnold Chiari malformation.
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Comment
For this condition a hereditary component is
suspected, and dogs with that malformation should
be excluded from breeding. MRI provides a safe
and non-invasive method for in vivo diagnosis of
this disorder. Further information on this
condition is available on http//www.ivis.org/ad
vances/Vite/braund16/chapter.asp?LA1
or contact martin.konar_at_kkh.unibe.ch
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