This is the first in a series on the eight imaging types we use to evaluate mild traumatic brain injury. Each one answers a different question, and the reason the series exists is that the standard workup usually orders one of them, asks one question, gets a normal result, and concludes there is no injury.
We start with conventional MRI, because it is the scan almost everyone has already had.
What Is a Standard Brain MRI Actually Looking For?
Magnetic resonance imaging uses strong magnetic fields and radiofrequency pulses to produce high-detail images of soft tissue. For the brain, it answers a specific and important question: is there a bleed, a lesion, a tumor, visible structural damage.
In mild traumatic brain injury, the answer is usually no. Visible damage to brain tissue is rare in this category — the diagnosis rests on the characteristic symptoms and neurological effects rather than on anything the scan shows.
So the report reads normal, and it is not wrong. It answered the question it was asked, about the region it was asked about.
Where Does the Scan Stop?
The craniocervical junction — where your skull meets the first two vertebrae — sits roughly two inches below where a standard brain MRI stops framing.
That two inches is not empty space. The lower brainstem passes through it. The vertebral arteries thread through the bones there on their way to supply the back of your brain. The jugular vein, the main drainage route for fluid leaving your head, passes directly in front of the first vertebra. The suboccipital muscles attach across it. And the whole assembly is held in position by a set of ligaments.
Cervical spine imaging has the opposite problem. It is usually framed for the lower and mid cervical spine, where discs and degenerative change live. The junction sits above its area of interest.
The result is a region that both studies border and neither covers well.
What Does a Craniocervical Protocol Add?
The fix is not exotic. It is a thin-slice, brain-quality MRI sequence carried down through the junction instead of stopping at the brain.
What that adds is **ligament assessment**. In a review of craniocervical junction imaging in blunt trauma, the authors note that MRI allows evaluation of the associated ligaments and, in particular, the integrity of the alar ligament, the transverse ligament, and the tectorial membrane (Offiah & Day, 2017).
Those three structures matter more than their size suggests. [The upper neck has no intervertebral discs and very little bony interlocking](condition-craniocervical-instability.html), so ligaments are doing nearly all of the stabilizing work. If they have been stretched past their elastic limit, there is no second system to compensate.
A craniocervical MRI protocol also shows the soft tissue of the region generally: cord compression, Chiari malformation, disc pathology at C2–C3, and the position of the cerebellar tonsils relative to the foramen magnum.
Why Does Position Matter So Much?
Most MRI is performed lying down, and that position unloads the structures you are trying to evaluate.
When you lie flat, gravity stops pulling downward through the spine. The brain and its membranes rise slightly. Pathways that are compressed when you are upright open back up. A cerebellar tonsil that descends far enough to cause a problem in daily life can sit in an unremarkable position on the table.
Upright imaging loads the structures the way life loads them. Findings that recede when recumbent — low-lying tonsils, maximum restriction of fluid pathways — become visible.
This is why a person can be told their imaging is normal and still be describing something real. The imaging was accurate about the position they were in, and that was not the position in which the problem occurs.
What Are the Limits of This Study?
We want to be straight about what conventional MRI cannot do, because the point of ordering eight modalities is that no single one carries the diagnosis.
MRI images **structure**. It does not measure motion, so it cannot by itself establish instability — a joint that travels too far under load can look entirely normal in a still frame with no load on it. It does not measure blood flow or fluid dynamics. It does not detect the microscopic axonal injury that [diffuse-weighted sequences are built for](post-what-dti-shows-when-a-brain-mri-looks-normal.html). And the review cited above is a pictorial teaching review rather than a diagnostic-accuracy study, so "evaluation of ligamentous integrity" should be read as what the sequence is capable of showing, not as a validated sensitivity figure.
Conventional MRI is the structural baseline of the workup. Foundational, and rarely sufficient on its own.
What Should You Ask For?
If you have had a brain MRI after a head or neck injury and been told it was normal, two questions are worth asking.
The first is where the images stopped. If the field of view ended at the base of the skull, the craniocervical junction was not in the study.
The second is what position you were in. A recumbent scan and an upright scan are answering the same question under different loads, and for symptoms that occur upright, the second one is closer to the situation you actually live in.
Neither question implies the first scan was done badly. They are different studies for different purposes, and a clean brain MRI is genuinely good news about your brain. It just is not the same thing as a clean bill of health for the structure underneath it.
Does This Help Separate a Brain Problem From a Neck Problem?
That is the question worth keeping in view across this whole series, and it cuts both ways.
Most of my clinical work concerns the craniocervical junction, and a fair reading of that could be that I expect the neck to be the answer every time. I do not. An imaging protocol that could only ever confirm one conclusion would be worthless.
A conventional MRI is unusual among these eight studies in that it can look at both territories in a single sitting. Framed for the brain, it rules out the things that must be ruled out. Carried down through the junction, it shows the ligaments and soft tissue of the neck. Reading both halves is what lets you say something useful about which one is contributing.
Sometimes the answer is cervical. Sometimes there is genuinely something in the brain, and finding it changes the plan and often changes who should be treating you. Sometimes it is both, which in my experience is the most common of the three. Ordering more than one study is how you tell those apart instead of assuming.
Told Your Scan Was Normal?
If your imaging stopped at the base of your skull and your symptoms did not stop with it, the structure two inches lower is worth imaging on its own terms.
Extending the study to the [craniocervical junction](condition-concussion-and-mtbi.html) is part of how we work at Cerebral. If you'd like a real evaluation, we're here.
References
- Offiah CE, Day E. The craniocervical junction: embryology, anatomy, biomechanics and imaging in blunt trauma. *Insights into Imaging*. 2017;8(1):29–47. https://pubmed.ncbi.nlm.nih.gov/27815845/
- Godek P, Ruciński W. Differentiating the structural and functional instability of the craniocervical junction. *Healthcare (Basel)*. 2024;12(19):2003. https://pubmed.ncbi.nlm.nih.gov/39408183/
- Eierud C, Craddock RC, Fletcher S, et al. Neuroimaging after mild traumatic brain injury: review and meta-analysis. *NeuroImage: Clinical*. 2014;4:283–294. https://pubmed.ncbi.nlm.nih.gov/25061565/