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There are numerous associations with Arnold Chiari malformations

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and Chiari I malformations that can occur in

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the spinal canal. With Chiari I malformation,

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which is not one that is usually presenting congenitally,

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you have the possibility of a hydromyelic

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syrinx cavity within the spinal cord,

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usually presenting in the cervical spine.

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However, the Arnold Chiari malformation is the congenital lesion that

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is associated with the open dysraphic myelomeningocele.

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Occasionally, you will get a little bit of a strange twist on this story by

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having the myelomeningocele occur not low down in the

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lumbosacral region, but in an unusual location,

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as we will see in this case.

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So on the midline brain image,

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we see that the patient has low lying tonsil cerebellar

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herniation through the foramen magnum.

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The cervical medullary junction doesn't look all that bad,

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but we do see that the patient has associated hydrocephalus

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and likely some element of poor development of the

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corpus callosum. Patient has a shunt in place.

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Looking at the spinal column,

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we're a little bit surprised here because we see both a

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syrinx within the spinal cord, as well as an unusual location for

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spinal dysraphism. This is at the cervical thoracic region,

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and through this gap,

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we see that there are portions of the spinal

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cord extending out, as well as CSF.

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So the spinal cord being the myelo

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portion of the myelomeningocele,

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the CSF being the meningo portion of the

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myelomeningocele in the cervico-thoracic region.

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On the axial scans,

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we see that the patient has a central syrinx in the

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spinal cord. So intradural intramedullary cyst.

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But in the area of the spinal dysraphism,

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we see the herniation of neural tissue.

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So here we have the neural tissue leaving the thecal sac to

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enter into the extradural location where there is CSF

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and neural tissue, defining it as a myelomeningocele.

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And you can see that the neural placode in part is plastered up

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against the skin surface of this open dysraphic myelomeningocele .

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So this is a little bit atypical for patients

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who have Arnold Chiari malformation,

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where most of these occur at the lumbosacral junction.

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Here's another example on the sagittal T2-weighted scan of both

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cerebellar tonsillar tissue herniating

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down to the C4 level,

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as well as the syrinx, as well as the open myelomeningocele.