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.
Professional Abstract
Objective
To compare risks and benefits of posterior fossa decompression surgery with and without duraplasty among patients with Chiari malformation type I and syringomyelia
Study Design
| Design Element | Description |
|---|---|
| Design | Randomized controlled trial |
| Population | 162 children and young adults under age 22 with Chiari malformation type I with ≥5 mm tonsillar ectopia and syrinx diameter between 3 mm and 9 mm |
| Interventions/ Comparators |
|
| Outcomes | Primary: intra-operative and postoperative surgical complications, need for surgical procedures to manage complications Secondary: treatment efficacy based on symptoms, neurological findings, syrinx size, and need for revision decompression surgery; quality of life |
| Timeframe | 6-month follow-up for primary outcomes |
Chiari malformation type I is a condition affecting children and young adults in which the cerebellum descends into the spinal canal, putting pressure on important structures of the brain. It is associated with syringomyelia, a cyst that damages the spinal cord and causes symptoms such as pain, weakness, or stiffness. Surgical decompression, which relieves pressure, is the usual treatment, but doctors use two different methods.
This cluster randomized controlled trial compared the effect of posterior fossa decompression with and without duraplasty among patients with Chiari malformation type I and syringomyelia on surgical complications, treatment effectiveness, and quality of life.
Researchers randomly assigned treatment centers to provide decompression surgery with or without duraplasty. Patients received the surgery assigned to their center. Duraplasty involves opening and expanding the dura with an autologous graft or dural substitute.
The study included 162 children and young adults with Chiari malformation type I and syringomyelia receiving treatment at one of 38 centers. Among patients, 81% were White, 9% were Black or African American, 5% were more than one race, 4% did not report race, and less than 1% were Asian, American Indian, or Alaska Native; 9% were Hispanic or Latino. The average age was 10, and 54% were female.
At visits before surgery and 1 to 6 weeks, 3 to 6 months, and 12 to 24 months later, researchers collected information about complications and symptoms and performed clinical exams. Patients completed surveys about quality of life. Researchers examined noninferiority of decompression without duraplasty based on a predetermined margin of no less than 20% lower clinical improvement than with duraplasty. Researchers then examined superiority of decompression with and without duraplasty.
Parents of children with Chiari malformation type I and patient advocacy organizations helped design the study.
Results
At six months, the odds of intra-operative and postoperative complications did not differ significantly between patients receiving decompression with and without duraplasty.
At one year, decompression alone was noninferior to decompression with duraplasty for clinical improvement. However, decompression with duraplasty was superior to decompression alone for syrinx regression (p=0.0001).
Patients without duraplasty were more likely to need surgical revision compared to patients with duraplasty (p=0.045). Quality of life did not differ significantly between patients with and without duraplasty.
Limitations
Doctors may not have enrolled patients with more severe disease in the study. Results may differ for these patients.
Conclusions and Relevance
In this study, complication rates and quality of life did not differ among patients with Chiari malformation type I and syringomyelia who had decompression surgery with and without duraplasty. Decompression without duraplasty was noninferior for clinical improvement; however, decompression with duraplasty was superior for syrinx regression.
Future Research Needs
Future research could examine the effects of decompression with and without duraplasty on longer term neurodevelopmental outcomes among children with Chiari malformation type I and syringomyelia as they age.
Final Research Report
This project's final research report is expected to be available by June 2024.
Peer-Review Summary
Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also assesses how the project addressed PCORI’s Methodology Standards. During peer review, experts read a draft report of the research and provide comments about the report. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. These reviewers cannot have conflicts of interest with the study.
The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve descriptions of the conduct of the study or to clarify the connection between results and conclusions. Sometimes, awardees revise their draft reports twice or more to address all of the reviewers’ comments.
Peer reviewers commented and the researchers made changes or provided responses. Those comments and responses included the following:
- The reviewers had questions about how the researchers ran power calculations for the non-inferiority hypotheses in this study. The reviewers indicated that based on their understanding of the non-inferiority margin used, the calculations should have resulted in the need for a larger sample size than stated in the report. The researchers detailed their process for calculating power and sample size for each of their aims, including their calculations for non-inferiority margins based on previous research and clinical experience.
- The reviewers asked the researchers to explain how they derived the binary clinical improvement outcome based on a large number of clinical signs. The researchers added to the description of this outcome measure, providing detailed information about how each clinical symptom was rated (i.e., resolved, improved, stable or worse) and how the overall score was based on an average of those ratings per patient and per site.
- The reviewers requested more detail on the group of patients who required a second surgical procedure, as this would be very important to clinicians and caregivers making decisions about treatment. The researchers added considerable detail in the report’s results section.
- The reviewers noted that the quality of life (QOL) measure did not show much improvement between baseline and the 12-month follow up and asked if the problem was that QOL was already quite high among these patients, leaving little room to improve. The researchers explained that part of the reason was an overall sample size that was smaller than anticipated, and the effect sizes for the QOL components were also small. Based on the results, the researchers did not believe that there was a ceiling effect indicating that there was no room to improve QOL for study participants.
- The reviewers noted that the choice of optimal treatment for Chiari Type I Malformation (CM) might be linked to the severity of the illness in the patient, and requested that the researchers share any data they had about the correlation between CM severity and treatment success. The researchers explained that the premise of the study was that there was clinical equipoise between the two surgical treatments for CM, although the researchers admitted that the treatments might not be in equipoise at higher levels of clinical morbidity. They went on to note that their analyses for heterogeneity of treatment effects did not demonstrate significant differences in treatment outcomes related to disease severity. The researchers did acknowledge the potential for this line of research in the future.