Craniocervical instability and Ehlers-Danlos syndrome are often discussed together because EDS is a connective tissue disorder, and the ligaments at the craniocervical junction depend on connective tissue support. Hypermobile Ehlers-Danlos syndrome can involve joint hypermobility, tissue fragility, and ligament laxity. Those words sound clinical until they are happening inside your own neck.

The craniocervical junction depends on ligament support. When connective tissue does not provide enough stability, the skull and upper cervical spine may move beyond the range they were built to tolerate. In some people, that can contribute to neck pain, headaches, dizziness, neurological symptoms, swallowing issues, or autonomic symptoms.

During my diagnostic sequence, CCI was identified before EDS. By the time I was diagnosed with EDS, I was recovering from an occipital to C3 fusion and Chiari decompression. The order of discovery is common in this patient population as the structural failure becomes visible on imaging before the underlying connective tissue condition is named. Many patients are diagnosed with EDS only after severe instability or repeated injury forces the connective tissue pattern into view. The hEDS criteria are clinical, not genetic, which means the diagnosis depends on a clinician trained to recognize the pattern. Most clinicians have not been trained to recognize it.

Not everyone with EDS has CCI. Not everyone with CCI has EDS. But the two diagnoses, when both are present, tend to explain each other. The ligament laxity that defines hEDS is the same laxity that destabilizes the craniocervical junction in CCI. One diagnosis names the tissue. The other names what the tissue has failed to hold.

The 2017 international classification of the Ehlers-Danlos syndromes (link) is the diagnostic framework most clinicians still rely on when evaluating hypermobility disorders today.