Pediatric Chiari malformation Type 0: a 12-year institutional experience

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In 1998 the authors identified 5 patients with syringomyelia and no evidence of Chiari malformation Type I (CM-I). Magnetic resonance imaging of the entire neuraxis ruled out other causes of a syrinx. Ultimately, abnormal CSF flow at the foramen magnum was the suspected cause. The label “Chiari 0” was used to categorize these unique cases with no tonsillar ectopia. All of the patients underwent posterior fossa decompression and duraplasty identical to the technique used to treat patients with CM-I. Significant syrinx and symptom resolution occurred in these patients. Herein, the authors report on a follow-up study of patients with CM-0 who were derived from over 400 operative cases of pediatric CM-I decompression.


The authors present their 12-year experience with this group of patients.


Fifteen patients (3.7%) were identified. At surgery, many were found to have physical barriers to CSF flow near the foramen magnum. In most of them, the syringomyelia was greatly diminished postoperatively.


The authors stress that this subgroup represents a very small cohort among patients with Chiari malformations. They emphasize that careful patient selection is critical when diagnosing CM-0. Without an obvious CM-I, other etiologies of a spinal syrinx must be conclusively ruled out. Only then can one reasonably expect to ameliorate the clinical course of these patients via posterior fossa decompression.

Abbreviations used in this paper: CM-I = Chiari malformation Type I; PICA = posterior inferior cerebellar artery.

Article Information

Address correspondence to: R. Shane Tubbs, Ph.D., Pediatric Neurosurgery, Children's Hospital, 1600 7th Avenue South, ACC 400, Birmingham, Alabama 35233. email:

© AANS, except where prohibited by US copyright law.



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    Case 4. Preoperative sagittal MR image demonstrating a CM-0.

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    Case 4. Postoperative sagittal MR image revealing significantly decreased syringomyelia.

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    Case 5. Preoperative sagittal MR image demonstrating a CM-0.

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    Case 5. Preoperative axial MR image showing syrinx resolution, although the resolution was not as dramatic as that seen in the patients featured in Figs. 1 and 2.


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