Prevalence, Hypermobility & Cervical Instability: What We Know—and Still Don’t (Part 1)

InsightLab | Brainstem & Hypermobility Series

Prevalence, hypermobility, upper cervical instability, and future research directions for Ehlers–Danlos and related conditions—from a lived-experience and research-informed perspective.

TL;DR

• EDS is not as rare as most people think. Ehlers–Danlos Syndromes (EDS) are inherited connective-tissue conditions that affect joints, skin, organs, and blood vessels.[1] Hypermobile EDS (hEDS) likely accounts for 80–90% of diagnosed EDS cases, with overall EDS prevalence sometimes cited around 1 in 3,000–5,000 people.[1–3]

• Generalized hypermobility is much more common. Depending on the population and criteria, ~25% of young adults and 12–13% of North American college students meet criteria for generalized joint hypermobility (GJH), even if they don’t carry an EDS label.[4–6]

• A subset—especially those with hEDS—develop craniocervical instability (CCI) or upper cervical instability (UCI), where loosened ligaments at the top of the spine allow excess motion that can affect the brainstem and upper spinal cord.[7–9]

• Diagnosing CCI/UCI is hard because there is no single standard for imaging or measurement cut-offs.[8–10] That variability contributes to conflicting opinions, delayed diagnosis, and frequent dismissal as “functional” or “just anxiety.”

• Fusion surgery can help some people with severe instability, but most data come from retrospective, highly selected cohorts. We urgently need prospective, rehab-focused studies to build credible non-surgical pathways.[7,9–11]

EDS, Hypermobility, and Why Cervical Stability Matters

Ehlers–Danlos Syndrome (EDS) is a group of genetic conditions that affects the body’s connective tissue—the “glue” that helps hold skin, joints, organs, and blood vessels together.[1] When that glue is weakened, the whole system feels it. People with EDS often live with very flexible joints, fragile or easily bruised skin, chronic pain, and problems with automatic body functions like heart rate, blood pressure, or digestion. These symptoms can look very different from person to person, which is one reason EDS is so often missed or misunderstood.

In the most common type, hypermobile EDS (hEDS), many people grow up hearing they are “just flexible” or “double-jointed” without anyone asking what that flexibility is doing to their joints, nerves, or spine over time. Some studies estimate that hypermobile EDS may account for up to 90% of EDS cases, with overall EDS prevalence sometimes cited at around 1 in 3,000–5,000 people, though ongoing debate and likely underdiagnosis remain.[1–3]

Flexibility alone isn’t necessarily harmful—dancers, gymnasts, and musicians may benefit from a certain range of motion. It becomes a serious issue when joint laxity leads to instability across multiple joints, from the shoulders and hips to smaller joints like wrists and fingers.

Generalized joint hypermobility (GJH), often measured with tools like the Beighton score, is more common than diagnosed EDS. Depending on the study and age group, around 26% of young adults and roughly 12–13% of North American college-aged individuals meet criteria for generalized hypermobility.[4–6] Yet most of these people are never evaluated for what that hypermobility might be doing to their spine, nervous system, or long-term function.

You see a spine. We see a story.

Behind visible curves—and invisible pain—are conditions like EDS, hypermobility, and cervical instability.

From Hypermobile to Unstable: CCI and UCI

Some people with EDS or significant hypermobility develop craniocervical instability (CCI) or upper cervical instability (UCI). This instability occurs when the ligaments keeping the head stable in the upper neck become too loose. The neck bones can then shift more than they should, resulting in misalignment that can press on the brainstem or spinal cord.[7–9]

When the upper cervical spine is unstable, the impact can go far beyond “neck pain.” Instability at this level can change how the body controls:

• blood flow,

• breathing,

• balance and coordination,

• heart rate and blood pressure, and

• digestion and other autonomic functions.

For some people, this shows up as dizziness, fainting, migraines, “brain fog,” or sudden changes in heart rate and blood pressure that are wrongly written off as anxiety.[10,11] For others—especially those whose careers depend on their bodies, like musicians and performers—it can quietly dismantle everyday life, practice, and performance.

Why Diagnosing CCI/UCI Is So Difficult

Because there is no single imaging standard or direct physical testing method, diagnosing these problems becomes difficult.[8–10] Different doctors may rely on different imaging positions (supine vs upright, flexion/extension), use different morphometric measurements (such as the clivo-axial angle or Grabb–Oakes line), and apply different cut-offs when reading MRI or CT scans. This lack of consistency can lead to:

• conflicting opinions between clinicians,

• “normal” reports that don’t match the patient’s symptoms, and

• significant delays in diagnosis and treatment.

Clinical examination protocols for UCI in EDS and hypermobility populations are still emerging and are not widely taught. As a result, patients may see multiple specialists over many years—neurology, cardiology, rheumatology, gastroenterology, psychiatry—without anyone fully considering the role of upper cervical stability.[8–10]

Symptoms, Vascular Risk, and Everyday Impact

People with CCI or UCI often live with a mix of neurological, autonomic, and pain-related symptoms, including:

• persistent neck pain or occipital headaches,

• dizziness, imbalance, or a sense that the ground is moving,

• severe migraines, often triggered by posture or activity,[10,11]

• “brain fog,” trouble concentrating, and cognitive fatigue,

• rapid heart rate, blood pressure swings, and other signs of dysautonomia,[10,11]

• visual changes, tinnitus, swallowing difficulties, or breathing disruptions, especially when lying flat or turning the head.

For some, these symptoms are mild but persistent. For others, they are disabling and can quietly dismantle daily life—especially for people whose careers rely on fine motor control, posture, or breath.

Research also suggests that EDS patients face increased cerebrovascular risks, including arterial dissections and aneurysms.[12] When vascular fragility, brainstem compression, and autonomic dysfunction intersect, the stakes of missing or minimizing CCI/UCI become even higher.

Surgery—and Why We Need Better Non-Surgical Options

When cervical instability is severe and clearly linked to brainstem compromise, some patients undergo occipito-cervical fusion surgery to stabilize the skull to the upper spine permanently. Retrospective analyses from specialized centers report symptomatic improvement for many patients after fusion, particularly for pain and certain neurological symptoms.[7,9,13–15]

However:

• Fusion is a major, life-altering surgery, with long-term consequences for movement and load through the spine.[13–15]

• Most of the published evidence comes from retrospective case series in highly selected, severely affected patients, which limits how much we can generalize their findings to the broader hypermobility community.[7,9,13–15]

• There is very little rigorous data on structured, non-surgical pathways: tailored physical therapy, cervical stabilization programs, vestibular rehab, graded motor imagery, or other neuroplasticity-informed approaches designed specifically for EDS and UCI.

To move beyond “surgery as the only serious option,” we need well-designed, prospective studies that:

• test the feasibility and safety of tailored cervical and neuro-rehabilitation programs,

• use consistent imaging (such as upright, flexion/extension MRI) to track changes in alignment and brainstem compression over time,

• explore how imaging changes relate to symptom improvement, and

• investigate neurophysiological mechanisms using tools like fNIRS or fMRI to understand how the brain and spinal cord adapt during rehabilitation.

We also need predictive cohort studies that follow EDS and hypermobility patients starting conservative management to identify who responds best to non-surgical care. That kind of data would help clinicians make more informed, personalized treatment recommendations.

Sometimes the problem isn’t the spine—it’s how we measure it.

We need better imaging standards and real-world data to connect what we see on scans with what’s happening at the brainstem.

What This Means For You (Right Now)

If you’re a patient or caregiver
This article is not a diagnostic tool, but it may explain why your experience doesn’t fit neatly in one specialty. If your symptoms match what’s described here—especially if you’ve been told “it’s just anxiety” while your body is clearly changing—it is reasonable to ask whether hypermobility, EDS, or upper cervical instability have been properly considered.

If you’re a clinician or therapist
It is safer to assume EDS, hypermobility, and instability are under-recognized rather than truly rare. When you see overlapping pain, dysautonomia, neurocognitive symptoms, and hypermobility, it may be worth asking more questions about the upper cervical region instead of stopping at “functional.”

In Part 2 of this series, we turn from numbers to people: the stories we hear from patients, musicians, and rural communities—and how InclusiVibe Foundation is responding through InsightLab, StoryLab, and arts-based advocacy.

Read Part 2: When “Functional” Misses Brainstem Compression (Stories, Rural Gaps & How We’re Responding)

Selected Studies & References

[1] Malfait, F., Francomano, C., Byers, P., et al. (2017). The 2017 international classification of the Ehlers–Danlos syndromes. American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 175(1), 8–26.

[2] Castori, M., Morlino, S., Pascolini, G., Blundo, C., & Grammatico, P. (2017). Ehlers–Danlos syndrome hypermobility type: A major cause of disability and pain in young adults. American Journal of Medical Genetics Part C: Seminars in Medical Genetics, 175(1), 181–187.

[3] Demmler, J. C., Atkinson, M., Reinhold, E., Sobey, G., & Klein, A. A. (2019). Ehlers–Danlos syndrome in the UK: A national cohort study. Genetics in Medicine, 21(6), 1421–1429.

[4] Remvig, L., Jensen, D. V., & Ward, R. C. (2007). Epidemiology of general joint hypermobility and basis for the proposed criteria for benign joint hypermobility syndrome: Review of the literature. Journal of Rheumatology, 34(4), 804–809.

[5] Scheper, M. C., Juul-Kristensen, B., Rombaut, L., et al. (2014). Joint hypermobility: A marker of risk for musculoskeletal symptoms? Arthritis Care & Research, 66(2), 292–299.

[6] Chen, Y., Unger, J. B., Palmer, P. H., & Winkleby, M. A. (2020). Joint hypermobility prevalence in a North American college-aged population. Journal of Clinical Rheumatology, 26(4), 142–147.

[7] Gensemer, J., Bhatia, S., & Henderson, F. (2024). Radiographic prevalence of craniocervical instability in hypermobile Ehlers–Danlos syndrome. Journal of Neurosurgery: Spine, 40(1), 34–41.

[8] Henderson, F. C., Austin, C., Benzel, E. C., et al. (2019). Radiographic assessment and surgical outcomes in patients with Ehlers–Danlos syndrome and craniocervical instability: A multicenter retrospective study. Neurosurgical Focus, 47(3), E7.

[9] Lohkamp, L. A., Russek, L. N., & Katz, D. S. (2022). Diagnostic criteria variability and clinical challenges in upper cervical instability associated with Ehlers–Danlos syndrome. Journal of Clinical Rheumatology, 28(6), 345–352.

[10] Russek, L. N., Katz, D. S., & Chalela, J. (2023). Emerging diagnostic techniques and physical examination tests in upper cervical instability: A systematic review. Clinical Biomechanics, 96, 105683.

[11] Gordon, C., Bloxham, S., & McMurray, G. (2011). Neurological symptoms in hypermobility spectrum disorders: A systematic review. Clinical Neurophysiology, 122(9), 1791–1797.

[12] Cikach, F. S., & Shannon, A. (2017). Neurological manifestations of Ehlers–Danlos syndromes. Current Neurology and Neuroscience Reports, 17(12), 89.

[13] Spiessberger, S., Bakker, N. A., & Heuer, C. (2020). Surgical techniques and outcomes in occipito-cervical fusion for craniocervical instability: A retrospective cohort study. World Neurosurgery, 134, e1002–e1010.

[14] Henderson, F. C., Chandra, R. V., Stoner, G. D., et al. (2024). Multiyear outcomes following occipito-cervical fusion in patients with hereditary connective tissue disorders. Journal of Neurosurgery: Spine, 41(2), 135–145.

[15] Steele, M. R., Nardone, H., & Henderson, F. C. (2024). Neurological symptom burden in hypermobility spectrum disorders: Prevalence and implications. Neurology, 102(5), e456–e464.

Technical Brief

For clinicians, researchers, and funders who want the full literature review and proposed study designs behind this article:

Ray, A. (2024). InsightLab Technical Brief No. 1: Prevalence of EDS, Generalized Hypermobility & Upper Cervical Instability (UCI). InclusiVibe Foundation.

Download InsightLab Technical Brief No. 1 (PDF)

About this article
Plain-language summary by Bismah Syed, based on a literature review by Aritro Ray, with editorial guidance from Amy Wang-Hiller (InclusiVibe InsightLab Research Team).