Results Summary

What was the research about?

Chiari malformation type I is a rare condition in which brain tissue extends into the spinal canal. It affects children and young adults. It may cause headaches and trouble talking and breathing. People may also have syringomyelia, or a spinal cord cyst, which can cause body pain and weakness.

Doctors use two types of surgery to treat these conditions:

  • Posterior fossa decompression, or PFD. The surgeon removes a small section of bone and tissue to reduce pressure on the brain.
  • PFD plus duraplasty, or PFDD. In addition to PFD, the surgeon opens the thick outer layer covering the brain, called the dura. The surgeon sews in a patch of tissue to make the dura bigger and relieve pressure on the brain.

In this study, the research team compared PFD with PFDD. The team looked at how well each avoided complications from surgery, relieved symptoms, and affected quality of life. The team wanted to make sure that PFD wasn’t worse at relieving symptoms than PFDD.

What were the results?

After six months, patients who had PFD or PFDD had similar rates of complications from surgery.

After a year, the two surgeries worked about the same to relieve symptoms. Quality of life didn’t differ between patients who had PFD or PFDD. Compared with patients who had PFD, those who had PFDD:

  • Had a larger decrease in their spinal cord cyst size
  • Were less likely to have another PFDD surgery because the first wasn’t helpful

Who was in the study?

The study included 162 children and young adults who had Chiari malformation type I and syringomyelia. All were receiving care at one of 38 treatment centers. Among patients, 81 percent were White, 9 percent were Black or African American, 5 percent were more than one race, 4 percent did not report a race, and less than 1 percent were Asian, American Indian, or Alaska Native; 9 percent were Hispanic or Latino. The average age was 10, and 54 percent were female.

What did the research team do?

The research team assigned treatment centers by chance to provide either PFD or PFDD. Patients received the surgery assigned to their center. Patients had visits before surgery and 1 to 6 weeks, 3 to 6 months, and 12 to 24 months after surgery. At visits, patients completed surveys about quality of life. Then, a team member performed clinical exams and collected data about problems from surgery and symptoms.

Parents of children with Chiari malformation type I and syringomyelia and advocacy groups helped design the study.

What were the limits of the study?

Doctors may not have asked patients with severe disease to take part in the study and instead offered PFDD. Results may differ for these patients.

Future research could look at health outcomes as children with Chiari malformation type I and syringomyelia age.

How can people use the results?

Doctors and parents can use the results when considering surgery for Chiari malformation type I and syringomyelia.

Final Research Report

This project's final research report is expected to be available by June 2024.

Peer-Review Summary

The Peer-Review Summary for this project will be posted here soon.

Conflict of Interest Disclosures

Project Information

David Limbrick, MD, MS, PhD
Washington University School of Medicine
Posterior Fossa Decompression with or without Duraplasty for Chiari Type I Malformation with Syringomyelia

Key Dates

September 2015
May 2023

Study Registration Information


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Last updated: November 2, 2023