Posterior fossa decompression (PFD) surgery has been shown to reduce progression of syringomyelia (SM) and scoliosis in patients with Chiari I malformation (CM-I), according to an ongoing series of studies led by Jay Wellons, M.D., division chief of pediatric neurosurgery at Monroe Carell Jr. Children’s Hospital at Vanderbilt and medical director of the Surgical Outcomes Center for Kids.
CM-I occurs at the base of the skull when part of the cerebellum extends into the upper spinal canal. While it is not uncommon to see some degree of crowding in this area on MRIs done for other reasons, symptomatic patients present with severe, debilitating headaches in the back of the head that worsen with Valsalva-type maneuvers, a fluid collection – or syrinx – in the spinal cord, or other less-common issues involving swallowing or central sleep apnea. Symptoms are typically first noticed in adolescence or early adulthood.
Vanderbilt University Medical Center is a primary research site in the Park-Reeves Syringomyelia Research Consortium, the largest multicenter cohort of CM-I-associated syringomyelia (CM-I/SM) research.
“Syringomyelia, or an abnormal buildup of spinal fluid within the spinal cord, can cause severe scoliosis, pain and even paralysis if left untreated,” said Wellons, Vanderbilt’s principal investigator for the work. “Our goal with this research is to fundamentally improve the medical and surgical care of these children.”
Tracking Surgical Impact
Silky Chotai, M.D., a neurosurgery resident at Vanderbilt, is primary investigator on a study seeking to understand the timeline of reduction in syringomyelia in patients with CM-I as they undergo posterior fossa decompression.
Most post-PFD reduction in the syrinx occurs in the first year, with the biggest change in the initial three months after surgery, the authors noted. This allows the surgeon to know how long to expect imaging and symptom improvement over time. Furthermore, it will facilitate evidence-based discussions with the patient and family, empowering their ability to make decisions.
“The key with Chiari patients is to be able to clearly communicate the reason to intervene and outline expectations for recovery after surgery.”
Chotai is also primary investigator on studies that highlight the variability of change in scoliosis after CM-I surgery. One study was specific to the Vanderbilt cohort and involved pediatric spine surgeon Chris Bonfield, M.D. A second study was performed in conjunction with Washington University and several other consortium centers.
“Understanding this variability (of change),” wrote the authors, “is a first step toward building a prediction model for outcomes for these patients.”
Instrumentation and fusion surgery are often required in patients with severe scoliosis. An earlier consortium study examined the differences in complication rates within six months of surgery by comparing autograft and nonautologous grafts for a cohort of pediatric patients who underwent PFD with duraplasty for CM-I/SM.
“Our experience is that a person’s own tissue works best for dural augmentation,” Wellons said, “but we wanted to test this among the patients in the consortium database. These data show that autologous grafts produced better outcomes.”
Communication Is Everything
The most crucial decisions for physicians caring for CM-I/SM patients involve who would benefit from surgery, determining the best procedure for them, and deciding the ideal time to intervene.
“The key with Chiari patients is to be able to clearly communicate the reason to intervene and outline expectations for recovery after surgery,” Wellons noted. “It is critical to give the families an idea of what to expect postoperatively, including the time it can take to see an imaging and symptom difference.”
One of Wellons’ patients, Adelynn, had initial headaches that were frontal and more migrainous in nature.
“We know that surgery will not benefit these types of headaches, but often medication will,” he explained. “However, over time she developed headaches typical for Chiari – occurring in the back of the head and neck and worsening when bearing down to cough, laugh or sneeze. Because her mom picked up on the new pattern and brought her back in to us, she is much improved today.
“I always tell parents, with rare exception, this is not a life-limiting situation. But it is a quality of life-limiting situation. You can live your life with the headaches related to Chiari but often you cannot do the things that you want to. Decompressive surgery makes a tremendous difference in these patients, allowing them to engage in life without the debilitating symptoms.”
An Ongoing Research Effort
Vanderbilt is internationally known for its groundbreaking research in Chiari II malformation and fetal myelomeningocele repair.
“The work we’ve done here as a major Chiari referral center in addition to the research done with the Park-Reeves Syringomyelia Research Consortium really details a stepwise attempt to walk down the many questions facing patients with Chiari I malformations and their surgeons,” Wellons said.
“We set out to not just help our individual patients, certainly an important task alone, but to also really impact the entire field with scientifically sound, relevant answers that will help solve some of the unknowns that have been around in this area for such a long time.”