Chiari 1 malformation with syrinx

Case contributed by Prof Peter Mitchell


Ataxia, gait unsteadiness, dysarthria, episodes of severe bradycardia to 45.

Patient Data

Age: 35
Gender: Female

Cerebellar tonsillar descent is noted with the tonsils extending to at least 10 mm below the level of the foramen magnum. 

At the level of C2, there is a discrete syrinx. A second syrinx is identified extending from C6 to the midpoint of T3. The remaining spinal cord is normal and the conus ends at L1. No fatty filum identified. Right sided posterolateral disk herniation at C5/6 causes flattening of the
cord but without focal edema, just above the more inferior syrinx. 

Vertebral height, disc height, bone marrow signal and prevertebral soft tissues are normal.  Loss of the normal cervical lordosis.

Conclusion:  A type 1 Chiari malformation is identified with secondary syrinx formation in the cervical and upper thoracic spinal cord.  Mild prominence of temporal horns. C5/6 disc as described, would not be related to provided clinical details. No supratentorial abnormality is identified.



There has been a dramatic improvement following posterior fossa decompression, with resection of the margin of occiput, posterior arch of C1, with marked decompression of the foramen Magnum. The syrinx has dramatically decreased in volume. There is no evidence of complication of the surgery. There is no hydrocephalus. Cerebral parenchymal signal intensity and architecture are within normal limits. A moderate-sized C5/6 disc protrusion persists, now more prominent than on
prior imaging.


A dramatic response to posterior fossa decompression, with a marked decrease in degree of tonsillar herniation, and in the volume of the cervical cord syrinx. Persistent cervical disc protrusion.

Case Discussion

This case illustrates how a syrinx can be distal to the posterior fossa compression, and the rapid response possible following posterior fossa decompression.

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Case information

rID: 22950
Published: 7th May 2013
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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