Posterior Fossa Decompression With or Without Duraplasty for Chiari Type I Malformation With Syringomyelia

Participants with Chiari Malformation type I and syringomyelia will be randomized to either
have a posterior fossa decompression done with or without duraplasty. The participant will
then return to the neurosurgeon's office at the following time points which are consistent
with standard of care practice: < 6 weeks, 3-6 months, and 12 months. At these visits, the
clinician will complete a physical exam and the participant will report on the prognosis of
symptoms and complete two quality of life questionnaires. A brain and cervical spine MRI will
be performed 12 months after the decompression.

Inclusion Criteria:

1. Age ≤21 years old

2. Chiari malformation type I ≥5 mm tonsillar ectopia

3. Syrinx between 3 mm and 6 mm

4. Chiari Severity Index (CSI) classification 1

5. MRI of the brain and cervical and thoracic spine are required prior to surgery and
must be available to be shared with the Data Coordinating Center

Exclusion Criteria:

1. CSI-2 or CSI-3 classification

2. Syrinx <3 mm and/or ≥6 mm

3. Neuro-imaging demonstrating basilar invagination

4. Clival canal angle <120° (signs of severe craniovertebral junction disease)

5. Chiari Malformation I + syringomyelia secondary to other pathology (e.g. a tumor)

6. Unable to share pre-decompression MRI of the brain and cervical and thoracic spine

7. Patients who do not wish to participate