Chiari I malformation with associated hydrosyringomyelia and Klippel-Feil syndrome

Case contributed by Dr Amro Omar

Patient Data

Age: 16
Gender: Male
  • cerebellar tonsillar herniation under the basion-opisthion line of about 1.6-cm with crowding of the cerebrum and cervicomedullary junction at the foramen magnum and disappearance of the cisterna magna, consistent with Chiari I malformation
  • abnormal flattening of the skull base is seen, due to hypoplasia of the clivus
  • atlantooccipital assimilation 
  • congenital C5 and C6 vertebral body fusion
  • syrinx from C4 to C7 with no evidence of a solid component (evaluation with contrast would be helpful)
  • no obvious features in the part of the brain imaged to suggest a Chiari II malformation. 

Case Discussion


Chest X-ray is recommended to assess other features of Klippel-Feil syndrome: e.g. Sprengel's deformity, omovertebral bone. An ultrasound abdomen to assess possible associated renal anomalies

This study shows a Chiari I malformation classified as stage 3 due hydrosyringomyelia.

  • Classification of Chiari I:
    • stage I: asymptomatic (14-50%)
    • stage II: brainstem compression
    • stage III: hydrosyringomyelia

Two or more non-segmented cervical vertebrae are usually sufficient for diagnosis of Klippel-Feil syndrome. This case corresponds to a type II. 

  • Classification of Klippel-Feil syndrome: 
    • type I (9%): massive fusion of cervical and upper thoracic spine resulting in neurological impairment, frequent associated abnormalities
    • type II (84%): fusion of two or three vertebrae
    • type III (7%): cervical fusion with lower thoracic or lumbar vertebral fusion
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Case information

rID: 32439
Published: 26th Nov 2014
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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