In 2006, the journal *Brain Injury* published a study that followed 20 hockey teams through a full season — players aged 15 to 35, from high school through junior and recreational leagues, 183 registered in total.
Over that season, 13 of them sustained either a whiplash-mechanism injury or a concussion injury.
One group had been struck in the body, producing a whipping motion of the head and neck with no impact to the head itself. Think of a hard body check. The other group took a direct blow to the head.
Different mechanisms, different points of contact, different diagnoses. You would expect two different injury patterns.
What the researchers found was that **every one of the injured players reported concussion symptoms**, regardless of which mechanism they had sustained — and that only three of the thirteen had full resolution of both their whiplash and their concussion symptoms at the seven-to-ten-day follow-up (Hynes & Dickey, 2006).
I want to be honest about the size of that. Thirteen athletes is a small number, and the authors titled it a preliminary study for good reason. It doesn't settle anything by itself. What it does is raise a question that the rest of the literature keeps answering the same way.
Were the Symptom Lists Already Identical?
That result stops being surprising once you compare the two conditions on paper, which is what my colleagues and I did during a three-year research project on mild traumatic brain injury.
We pulled the major working documents from both fields. The Quebec Task Force on Whiplash-Associated Disorders. A comprehensive whiplash review covering pathophysiology, diagnosis, treatment, and prognosis. The Department of Defense practice guidelines for management of concussion and mild traumatic brain injury. The consensus statement on concussion in sport from the International Conference on Concussion.
Then we listed the symptoms each one reported, in order of frequency.
They were the same. Headaches. Sleep disorders. Cognitive difficulty. Dizziness. Memory problems. Visual disturbance. Ringing in the ears. Mood changes. Motor and speech difficulty.
Same symptoms, same rank order, comparable prevalence. These were large, independent working groups examining what they believed were two separate conditions, and they produced matching lists. That comparison is my own work rather than a published analysis, and I'd characterize it as an observation worth taking seriously rather than as evidence in the formal sense.
Published research points the same direction. In a study of 128 patients with symptoms persisting more than three weeks after head injury, researchers tested whether self-reported symptoms could distinguish a physiologic post-concussion disorder from a cervicogenic or vestibular one. None of the statistical approaches they tried could do it. Their recommendation was that clinicians examine the cervical spine and the vestibular and ocular systems directly, because the symptoms alone will not tell you where the problem is (Leddy et al., 2015).
When two conditions with different names and different mechanisms generate overlapping symptom profiles that no symptom analysis can separate, the reasonable conclusion is that something they share is producing the symptoms.
Do Both Mechanisms Create the Same Fulcrum?
Here's the simple version, and simple is what the situation calls for.
If a force strikes the head directly, we call it a concussion or mild traumatic brain injury. It doesn't matter much whether it comes from the front or the side.
If a force strikes the body and the neck whips, we call it whiplash, or cervical acceleration-deceleration injury.
Now look at what happens mechanically in each case. In both, your head — which weighs a substantial amount and sits on top of a narrow, highly mobile joint — moves rapidly in one direction while your torso does something different.
**Both produce the same fulcrum of force, and that fulcrum sits between the head and the neck.**
The location of the impact determines what we name the injury. It does not determine where the mechanical load concentrates. That lands in the same place either way.
Why Does That Location Fail First?
The craniocervical junction is not built to absorb impact, and understanding why explains its vulnerability.
That joint exists to aim your head precisely, which is how you point your eyes and ears at whatever you need to attend to. Precision aiming requires an unusual amount of mobility, and mobility and stability trade against each other directly. There are no intervertebral discs between the skull and the first vertebra or between the first and second. The joint surfaces are curved and angled rather than interlocking. The whole assembly is held together primarily by ligaments.
The result is a structure with essentially no mechanical advantage against impact, positioned exactly where every force reaching your head has to pass through.
The numbers reflect that, and [the gap between the two thresholds is the whole story](post-how-much-force-injures-your-neck-versus-your-brain.html). Reconstructed concussions in football cluster near 100 Gs of head acceleration. The threshold for beginning to tear the ligaments of the craniocervical junction is a small fraction of that — the figure I work from clinically is roughly 4.5 Gs, which I present as my working number rather than a verified constant.
So in any event forceful enough to raise concern about the brain, the ligaments at the top of the neck have almost certainly been loaded well past their threshold, whichever direction the force came from.
What Does the Broader Literature Keep Pointing At?
That hockey study is not an isolated finding, and the pattern shows up repeatedly once you look for it.
A review of cervical spine involvement in mild traumatic brain injury searched six databases across twenty-five years, screening 4,854 abstracts down to 43 retained studies. Its summary was that cervical involvement in mild traumatic brain injury is supported by increasing evidence and largely accepted — while also noting that further study is needed to establish how it should be evaluated (Morin et al., 2016).
A narrative review focused specifically on the cervical spine's role in post-concussion syndrome reached a similar position: that cervical dysfunction from a concurrent whiplash-type injury plausibly contributes to the persistent symptoms seen in the roughly 10 to 15% of concussed patients who develop post-concussion syndrome (Marshall et al., 2015).
Neither of those is a controlled trial, and I won't present them as more than they are. Both are reviews reporting a convergence rather than proving a mechanism. But the convergence is real, and it keeps pointing at the same structure.
Why Does This Distinction Matter for Care?
The practical consequence is that the two diagnoses send people down separate paths that both stop short of the same structure.
Get struck in the head and you are categorized as a head injury, so the brain is imaged. Get struck in the body and whipped, and you're categorized as a [neck injury](condition-whiplash.html) — but the evaluation usually concerns the lower cervical spine, soft tissue, and range of motion, not the stability of the joint where your skull meets your spine.
Neither route routinely examines the craniocervical junction, which is where both mechanisms concentrated their load.
That's why the question was never really whether the neck is involved in a [concussion](condition-concussion-and-mtbi.html). The question is whether anyone checked.
Symptoms After an Injury That Was Labeled One Thing or the Other?
If you've been treated for a concussion or for whiplash and symptoms have persisted past every timeline you were given, the structure both mechanisms load is worth examining directly.
Assessing the craniocervical junction on its own terms is the work we do at Cerebral. If you'd like a real evaluation, we're here.
References
- Hynes LM, Dickey JP. Is there a relationship between whiplash-associated disorders and concussion in hockey? A preliminary study. *Brain Injury*. 2006;20(2):179–188. https://pubmed.ncbi.nlm.nih.gov/16421067/
- Leddy JJ, Baker JG, Merchant A, et al. Brain or strain? Symptoms alone do not distinguish physiologic concussion from cervical/vestibular injury. *Clinical Journal of Sport Medicine*. 2015;25(3):237–242. https://pubmed.ncbi.nlm.nih.gov/25051194/
- Morin M, Langevin P, Fait P. Cervical spine involvement in mild traumatic brain injury: a review. *Journal of Sports Medicine*. 2016;2016:1590161. https://pubmed.ncbi.nlm.nih.gov/27529079/
- Marshall CM, Vernon H, Leddy JJ, et al. The role of the cervical spine in post-concussion syndrome. *The Physician and Sportsmedicine*. 2015;43(3):274–284. https://pubmed.ncbi.nlm.nih.gov/26138797/