Landmark NEJM Trial Provides First Randomized Evidence for Chiari Malformation Surgical Treatment

A landmark multicenter, cluster-randomized clinical trial published in the New England Journal of Medicine has delivered the first high-level evidence comparing two surgical approaches for treating Chiari type I malformation (搜索)搜索该疾病 and syringomyelia (搜索)搜索该疾病 in children and young adults. The study, representing more than 15 years of collaboration among over 40 clinical centers and nearly half of all pediatric neurosurgeons in the United States, provides long-sought answers for families facing treatment decisions for these rare neurological conditions.

The trial, led by David Limbrick, M.D., Ph.D., chair of the Department of Neurosurgery at Virginia Commonwealth University's School of Medicine and a neurosurgeon at Children's Hospital of Richmond at VCU, compared posterior fossa decompression (PFD) with duraplasty — the traditional gold-standard procedure — against PFD alone, a newer, less invasive approach.

"Fortunately, neurological diseases in children are uncommon, but when it is your child who is affected, it doesn't matter how rare a disease is. It is the most important thing in your life," Limbrick said. "This study provides long-sought answers for the thousands of kids and their families who are impacted by this condition every year."

Understanding Chiari Malformation and the Treatment Dilemma

Chiari malformation is a neurological condition in which the lowest part of the brain, the cerebellum, protrudes into the spinal canal, blocking the normal flow of cerebrospinal fluid. Affecting approximately 1 in 1,000 people, the condition can cause intense headaches, neck pain, motor skill and balance issues, numbness, dizziness, and even progressive neurological dysfunction and death if left untreated. Chiari malformation is also associated with syringomyelia (搜索)搜索该疾病 — fluid accumulation in the spinal cord that leads to numbness, spinal deformity, weakness, and neurological disability.

For more than two decades, neurosurgeons have treated Chiari malformation by combining PFD, which involves removing bone and soft tissue causing compression at the back of the skull, with duraplasty — incising and expanding the brain's protective membranous sheath. While effective, the invasive nature of duraplasty carries risks including cerebrospinal fluid leak, meningitis, brainstem injury, stroke, or death. This has led some neurosurgeons to perform PFD without duraplasty, though until now, no randomized evidence existed to guide treatment selection.

Trial Design and Key Findings

Conducted between 2016 and 2021, the Park-Reeves Syringomyelia (搜索)搜索该疾病 Research Consortium trial enrolled 162 patients aged 21 and younger diagnosed with Chiari type 1 malformation and syringomyelia. Participants underwent either PFD with duraplasty or PFD alone, depending on the center where they received care. The research team partnered with advocacy groups to ensure the clinical outcomes measured — including pain reduction and long-term spinal deformity — reflected what mattered most to patients.

The data revealed that complication rates were not significantly different between the two procedures, challenging the assumption that PFD alone reduces surgical risk. Both approaches led to similar improvements in patient symptoms and quality of life.

However, two key differences emerged. Patients who received PFD with duraplasty experienced a greater reduction in syrinx size — the fluid-filled cyst in the spinal cord — compared to those who received PFD alone (3.08 mm vs. 1.21 mm reduction). Additionally, patients in the duraplasty group were significantly less likely to require a second surgery (2.6% vs. 14.2%).

"Syrinx resolution is an important metric, because the number one reason people go back for second surgery is because the syrinx didn't respond," Limbrick explained.

A Step Forward for Individualized Treatment

Nathan Selden, M.D., Ph.D., dean of the OHSU School of Medicine and professor of neurological surgery, co-authored the study and emphasized its clinical significance. OHSU was one of the first centers in the U.S. to offer PFD alone to select children with Chiari I malformation, and Selden's previous single-institution studies at Doernbecher Children's Hospital at OHSU had shown reduced surgical complications with the less invasive procedure.

"When we identify children who will respond to the less invasive procedure, over time we are saving lives through cumulative risk reduction," Selden said. "While larger trials are needed to fully define the relative risks and benefits of these two procedures in various patient groups, this is a big step forward in the field that will benefit the children we treat using either procedure."

The study was funded through the Patient-Centered Outcomes Research Institute, with early work supported by private philanthropy. Limbrick noted the unprecedented scale of the collaboration: "Despite caring for thousands of kids, any given pediatrician may only see these conditions once or twice in their whole career. Because these conditions are rare, and they can happen anywhere, having a multi-center research study allows us to collect data on enough patients to make the information statistically valid and generalizable across the population."

"We have been trying to solve this issue for over three decades, and these study results will impact how every child in North America with Chiari and syringomyelia (搜索)搜索该疾病 is treated," Limbrick added. "Before, when families would ask what the safest and most effective treatment was for their child, there was no data to answer that question. This study provides that answer."