While it may be hard to believe, many doctors have a different idea of what “Chiari” actually is… Some doctors measure the cerebellar tonsils on both sides, some only on one. Some doctors only think of Chiari with a very specific set of symptoms, some consider other symptom options. Some doctors consider different radiology measurements when they are diagnosing patients. Speaking of measurements… sometimes there is even disagreement in how to actually make those measurements: where to start measuring from, for example.
All of these differences in preferences have led to a collection of research papers that are… in all honesty, very confusing. The medical evidence in the research papers that study Chiari and related disorders is… not great. The Chiari Malformation Guidelines work recently found that most of the medical evidence available to make recommendations was Class 3 or 4.1-3 This means that most of the studies done on Chiari are not statistically strong enough to draw convincing conclusions.4
In order to have Class 1 and 2 evidence, there need to be more studies that are done that have stronger statistical power and design. The problem is, those types of studies often require collaboration by multiple centers. If those centers are all calling Chiari and its related disorders by different names, or they are categorizing sets of patients differently, then those studies become completely impossible.
In order to get the evidence we need, then, research needs to be truly comparable across many academic institutions and private clinical offices around the country and world. To do that, everyone needs to speak the same “language”. Studying “Chiari” at one clinic should mean studying the same thing at all the other clinic locations, too!
Differences like this in basic definition make it almost impossible to build good, irrefutable science. But it doesn’t have to be this way.
The concept of Common Data Elements, or “CDEs” was originally developed by the National Institute of Neurological Disorders and Stroke (NINDS) at the NIH. The goal is to standardize the language of medical research so all researchers speak that same language!
The first set of Common Data Elements (CDEs) for Chiari I malformation were developed in partnership with the NINDS/NIH, clinical experts, and the Bobby Jones Chiari & Syringomyelia Foundation. They were published in Neurosurgery in 2019.5
The purpose of the Chiari I malformation CDEs is to make better Chiari research happen! CDEs provide a standard definition for the most commonly used pieces of research data in the study of Chiari and related disorders. Standard definitions make sure that all researchers are “speaking the same language” and will lead to better medical evidence. The kind of medical evidence in research that patients and families deserve.
References:
The Chiari I malformation CDEs are reviewed, refined and evaluated every year by the NINDS CDE Committee. The full list of Chiari CDEs are available on the NINDS CDE website, but we also wanted to make them available on our website, as well!
If you are a researcher and have questions about the CDEs, you may contact us.
CDEs can be classified as Core, Supplemental (Highly Recommended), Supplemental, and Exploratory.
Disease-specific Core CDEs for Chiari I malformation are the type of data points that, if not included in the research, would make studying Chiari malformation completely impossible. There are very few data points that fit this category. They only include things like tonsil position, because you can’t really study Chiari without measuring one– even if that measurement is 0 mm.
Supplemental (Highly Recommended) CDEs are what an organization like Bobby Jones CSF considers “core” but doesn’t rise to the level of being required in every single study done in Chiari. For example, syrinx location would be in this category because it’s super important to measure that if it exists, but if someone is doing a study only on Chiari patients who don’t have syringomyelia, then including this data point/CDE would be silly.
Supplemental CDEs are data points where there is already a lot of medical evidence that tell us we should probably be studying these things alongside Chiari. An example would be something like a pB-C2 measurement on imaging. It’s often reported and studied in other published work, and it may be important to include in future studies.
Exploratory CDEs are data points for which we don’t have a lot of convincing evidence for its connections with Chiari… yet! In the original submission to NINDS, there were a lot of CDEs included that had the Exploratory (sometimes called “experimental”) category. This is because there is still so much that needs to be better studied in Chiari and related disorders, that it was important to include them in the first round of CDEs! An example of an Exploratory CDE would be something like a clinical indicator for hoarse voice, since it is not very well-established as specifically Chiari-related.
The Chiari CDE work was split into several different workgroups when initial submission was being done: demographics/epidemiology, presentation/symptoms, co-morbidities/genetics, imaging, treatment, and outcomes.
