Understanding Why Some Concussions Do Not Resolve
Most concussions get better on their own. Somewhere between sixty and eighty percent resolve without any intervention at all, on roughly the timeline people are told to expect.
This page is about the rest.
Post-concussion syndrome is the term for symptoms that persist well beyond the expected recovery window — commonly cited as affecting somewhere in the range of ten to fifteen percent of concussed patients, though estimates vary with how the condition is defined. Those patients are frequently told that their imaging is normal, that these things take time, and eventually that they should learn to live with it.
At Cerebral Chiropractic Center, we think the persistence itself is the most useful piece of information in the case. A normal recovery resolves. One that has not is telling you something is preventing it from completing — and in our experience, that something is more often mechanical than anyone has considered.
Why "Normal Imaging" Does Not Mean Nothing Is Wrong
Mild traumatic brain injury is diagnosed by its characteristic symptoms and neurological effects. Visible damage to brain tissue is rare in this category — which is precisely what makes it difficult, because significant symptoms coexist with nothing observable.
A standard brain MRI answers one question accurately: is there a bleed, a lesion, a tumor, visible structural damage. In mild injury the answer is usually no. The report is correct. It is simply answering a question that may not have been the one that needed asking.
Research imaging has detected group-level differences after mild traumatic brain injury — consistent frontal vulnerability and an anterior-to-posterior gradient in white matter change — but the authors of that work are explicit that considerably more is required before those techniques can diagnose an individual patient. That gap between research findings and clinical usefulness is much of why people end up being told nothing is wrong.
The Structure the Standard Workup Never Images
The craniocervical junction sits roughly two inches below where a standard brain MRI stops framing.
That small distance holds a great deal. The lower brainstem passes through it. The vertebral arteries thread through the bones there on their way to supply the back of the brain. The jugular vein, the main drainage route for fluid leaving the head, passes directly in front of the first vertebra. The suboccipital muscles — the most spindle-dense muscles in the human body, and the nervous system's reference for where the head sits on the trunk — attach across it. And the entire assembly is held in position by ligaments with a strikingly low tolerance for force.
If the structures producing someone's symptoms sit in that region, a perfect brain MRI will miss them every time. Not because the imaging failed, but because it was framed for a different target.
Why the Neck Is Almost Always Involved
Both mechanisms that cause concussion load the same place.
If a force strikes the head directly, we call it a concussion. If a force strikes the body and the neck whips, we call it whiplash. In both cases the head — which weighs a substantial amount and sits on a narrow, highly mobile joint — moves rapidly while the 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.
The thresholds make this unavoidable. Reconstructed concussions in football cluster near 100 G of head acceleration. Cervical ligamentous injury begins at a small fraction of that. 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 past their threshold.
Research supports the association. A review of cervical spine involvement in mild traumatic brain injury screened 4,854 abstracts and concluded that cervical involvement is supported by increasing evidence and largely accepted. Separately, in 128 patients with symptoms lasting more than three weeks after head injury, no statistical method tested could distinguish a physiologic post-concussion disorder from a cervicogenic or vestibular one using symptoms alone — the authors' recommendation was that clinicians examine the cervical spine and the vestibular and ocular systems directly.
The Five Subtypes
Post-concussion syndrome is not one thing, and useful treatment depends on identifying which pattern predominates. Most patients have a primary subtype plus features of others.
- Cervicogenic. Headache, neck pain, dizziness, and visual disturbance driven by the upper cervical spine. Symptoms often change with head position.
- Vestibular. Dizziness, imbalance, spatial disorientation, and motion sensitivity from disrupted integration of position information.
- Ocular-motor. Difficulty with convergence, tracking, and visual scanning. Screens and reading become exhausting.
- Autonomic / physiologic. Exercise intolerance, heart rate and blood pressure instability, poor temperature regulation, and a nervous system stuck in a sympathetic state.
- Mood and cognitive. Anxiety, irritability, sleep disruption, slowed processing, and memory difficulty.
Notice how much of that list can be produced by a single structure. The craniocervical junction contributes to the cervicogenic, vestibular, and autonomic subtypes directly, and to the cognitive picture indirectly through its effects on blood supply and fluid clearance.
Common Symptoms
- Headaches, frequently daily, often beginning at the base of the skull
- Neck pain and tension
- Dizziness, unsteadiness, or a vague sense of being off
- Pressure inside the head or behind the eyes
- Brain fog, slowed thinking, and loss of mental stamina
- Short-term memory difficulty and losing words
- Light and noise sensitivity
- Visual disturbance and difficulty with screens
- Tinnitus
- Sleep that does not restore
- Exercise intolerance and symptom flare with exertion
- Anxiety, irritability, and emotional volatility
- Fatigue that does not respond to rest
Why Waiting Is Not Neutral
The standard response to a mild injury with clean imaging is to observe, wait, and manage symptoms as they appear. That assumes the situation is static — that nothing is progressing while you wait, so waiting costs nothing.
If a structural problem is driving the picture, waiting does not pause it. Blood flow stays reduced. Drainage stays restricted. The brainstem keeps receiving inaccurate position information and keeps holding the nervous system in a stress state. The downstream consequences continue to develop while attention stays on whichever symptom is currently loudest.
The same problem addressed early is comparatively simple. Addressed years later it is complex, and more of the chain has to be unwound. That does not mean the opportunity is gone if your injury was a long time ago — it means the work takes longer.
How We Evaluate It
- A full history, including injuries that were never reported and events nobody connected to the current symptoms.
- Direct examination of the craniocervical junction for alignment and stability.
- Position-dependent testing. The Fukuda stepping test, supine leg length checked with the head neutral and rotated, and limb strength retested with the head turned. Any finding that changes with head position implicates the neck. No single one of these proves anything; several agreeing does.
- Imaging built for the question. Cone beam CT or three-dimensional upright X-ray for bony position at C0–C2, thin-slice MRI carried through the junction rather than stopping at the brain, cine phase-contrast MRI for cerebrospinal fluid flow, and where indicated SPECT for perfusion and qEEG for network function.
What Correction Aims to Do
When the evaluation identifies structural disruption at the junction, restoring alignment addresses the mechanical contributors directly: arterial supply, venous and cerebrospinal fluid drainage, and the accuracy of the position signal reaching the brainstem.
We use the Advanced Orthogonal technique — low-force, instrument-delivered, calculated from imaging, and applied without rotating the head into a strained position. Post-correction imaging and repeat neurological testing tell us whether the structure responded the way the calculation predicted, and the approach is revised based on the result rather than repeated unchanged.
We will not tell you this resolves every case. Post-concussion syndrome has multiple contributors, some patients need vestibular or ocular-motor rehabilitation alongside structural work, and some need care we do not provide. What we will tell you is whether we find a structural driver, and how confident we are that addressing it will matter for you specifically.
If Your Recovery Stalled
Being told that your scans are clean and that you should give it more time is a reasonable thing to hear once. Hearing it for two years is different.
A negative brain scan is not evidence that nothing is wrong. It is evidence that nothing was wrong in the region examined — which leaves the actual question open.
Call us at (727) 677-0001 to schedule an evaluation. We will look two inches lower than the last scan did.
References
- Marshall CM, Vernon H, Leddy JJ, Baldwin BA. The role of the cervical spine in post-concussion syndrome. The Physician and Sportsmedicine. 2015;43(3):274–284.
- 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.
- Morin M, Langevin P, Fait P. Cervical spine involvement in mild traumatic brain injury: a review. Journal of Sports Medicine. 2016;2016:1590161.
- 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.
- Eierud C, Craddock RC, Fletcher S, et al. Neuroimaging after mild traumatic brain injury: review and meta-analysis. NeuroImage: Clinical. 2014;4:283–294.
- Pertab JL, Merkley TL, Cramond AJ, et al. Concussion and the autonomic nervous system: an introduction to the field and the results of a systematic review. NeuroRehabilitation. 2018;42(4):397–427.
- Tominaga Y, Ndu AB, Coe MP, et al. Neck ligament strength is decreased following whiplash trauma. BMC Musculoskeletal Disorders. 2006;7:103.
- Peng B, Yang L, Li Y, Liu T, Liu Y. Cervical proprioception impairment in neck pain: pathophysiology, clinical evaluation, and management. Pain and Therapy. 2021;10(1):143–164.
- Johnson VE, Stewart JE, Begbie FD, et al. Inflammation and white matter degeneration persist for years after a single traumatic brain injury. Brain. 2013;136(1):28–42.