Concussion and Whiplash Headaches: What Does Scientific Research Tell Us?

Two Accidents, Two Mechanisms, Surprisingly Similar Headaches

Imagine two patients arriving at a clinic after separate accidents.

The first patient fell and struck the side of the head. Within hours, a headache developed along with dizziness, light sensitivity, nausea, difficulty concentrating, and unusual fatigue.

The second patient was stopped at a traffic light when another vehicle struck from behind. There was no remembered head impact. However, the patient’s head and neck moved rapidly backward and forward. By that evening, the patient had neck stiffness, headache, dizziness, difficulty concentrating, and light sensitivity.

Their symptoms sound remarkably similar.

Did both patients sustain concussions? Did the second patient develop a headache primarily from whiplash? Could that patient have sustained both a mild traumatic brain injury and cervical soft-tissue injury?

Those questions demonstrate one of the central challenges in post-injury headache medicine.

Clinicians do not classify a headache after trauma based solely on how it feels. Clinicians must consider the injury mechanism, symptom timing, neurological findings, cervical findings, headache history, functional changes, and alternative explanations.

Scientific research increasingly supports this careful approach because concussion-related and whiplash-related headaches can substantially overlap.

What Is a Headache Attributed to Traumatic Head Injury?

The International Classification of Headache Disorders, Third Edition, or ICHD-3, separates headaches caused by traumatic injury to the head from headaches attributed specifically to whiplash.

For a standard diagnosis of acute headache attributed to traumatic injury to the head, the headache is reported to begin within seven days of the head injury, recovery of consciousness, or discontinuation of medication that prevented the patient from recognizing it. The headache remains acute while it has been present for less than three months.

If it continues for more than three months, it can meet criteria for persistent headache attributed to traumatic injury to the head when the remaining criteria are satisfied (Headache Classification Committee of the International Headache Society [IHS], 2018).

The ICHD-3 further distinguishes mild traumatic brain injury from moderate or severe injury.

With mild traumatic brain injury, or concussion, a patient may experience symptoms such as:

• Confusion or disorientation
• Memory disruption
• Dizziness or vertigo
• Nausea or vomiting
• Visual disturbances
• Problems with balance
• Difficulty concentrating
• Headache

Importantly, loss of consciousness is not required for a concussion.

The Centers for Disease Control and Prevention similarly explains that mild TBI can result from either a blow to the head or a force to the body that rapidly moves the head and brain.

For additional patient education, see Dr. Jimenez’s Concussions & Post-Concussion Syndrome resource.

What Is a Headache Attributed to Whiplash?

Whiplash is different.

ICHD-3 defines whiplash as sudden acceleration-deceleration movement of the head involving flexion and extension of the neck. The classification specifically notes that whiplash may occur with either higher- or lower-impact forces.

For acute headache attributed to whiplash, the patient must have experienced whiplash associated with neck pain and/or headache, with headache developing within seven days. Symptoms lasting more than three months can meet criteria for persistent headache attributed to whiplash when other requirements are met (IHS, 2018).

Dr. Jimenez discusses this mechanism further in Cervical Acceleration-Deceleration.

This distinction is important:

Head injury classifications emphasize trauma to the head or brain, while whiplash classification emphasizes acceleration-deceleration injury involving the cervical region.

Yet real accidents do not always remain neatly inside one diagnostic category.

A motor vehicle collision can expose a person to both.

Why the Symptoms Can Look Almost Identical

Post-traumatic headache does not have one unique pain pattern.

A patient with concussion-related headache may describe:

• Throbbing pain
• Pressure
• Pain on one or both sides
• Neck discomfort
• Light sensitivity
• Noise sensitivity
• Nausea
• Dizziness
• Worsening with physical activity

A patient with whiplash-associated headache may report many of the same symptoms.

Research by Schwedt (2024) emphasizes that post-traumatic headaches frequently resemble migraine or tension-type headaches rather than demonstrating a single distinctive post-traumatic pattern. Neuroinflammation, altered pain processing, changes in pain modulation, and changes in brain function may contribute to symptoms following mTBI.

Recent clinical data reinforce that overlap.

Cortel-LeBlanc et al. (2025) examined 405 adults evaluated for post-traumatic headache following mild TBI. Common findings included throbbing pain, sensitivity to light and sound, nausea, and worsening with ordinary physical activity—features normally associated with migraine.

Therefore:

Migraine-like symptoms after an accident do not automatically mean the patient simply developed primary migraine.

Likewise, neck pain associated with headache does not automatically establish whiplash as the exclusive headache generator.

The complete clinical picture matters.

The Three-Month Distinction: Acute Versus Persistent

Both traumatic head injury headache and whiplash headache use an important clinical dividing point.

Less Than Three Months

The headache is generally classified as acute when the diagnostic criteria are otherwise satisfied.

Longer Than Three Months

The headache may be classified as persistent.

Three months should not be mistaken for a biological deadline by which everyone should recover.

It is primarily a classification boundary.

Schwedt (2024) reported that although many post-traumatic headaches improve during the acute phase, approximately one-third of people in the literature reviewed continued to experience post-traumatic headaches for at least several months.

Recovery depends on many factors, including previous migraine history, previous injuries, initial symptom burden, cervical injury, sleep disruption, physical conditioning, psychological health, medication use, and additional medical conditions.

Why Imaging Cannot Tell the Entire Story

One of the most important scientific lessons involves diagnostic imaging.

A patient may reasonably ask:

“My CT scan was normal. Does that mean I didn’t have a concussion?”

No.

The CDC specifically states that CT imaging is generally not required to identify mild TBI or concussion. CT is especially valuable when clinicians are concerned about dangerous structural problems such as intracranial bleeding.

Routine clinical CT or MRI may therefore be normal in a person who nevertheless meets clinical criteria for concussion.

The same principle applies to many soft-tissue cervical injuries.

X-rays, CT scans, and MRI examinations can provide important objective information about fractures, instability, disc abnormalities, hemorrhage, degenerative changes, and other structural pathology. But imaging does not capture every functional, microscopic, neurological, muscular, ligamentous, or pain-processing abnormality.

In the 2025 Cortel-LeBlanc study, 45.2% of patients had undergone neuroimaging. Among those patients, almost 88% of the studies reportedly showed normal results, even though the patients were being evaluated for post-traumatic headache. That specialty-clinic sample should not be generalized to every trauma patient, but it clearly demonstrates why normal neuroimaging and absence of symptoms cannot be treated as equivalent concepts.

This is why clinical examination remains essential.

What About Crash Biomechanics?

Biomechanics matters enormously—but it has limits.

Understanding the direction of impact, occupant position, restraint use, head movement, direct contact, acceleration-deceleration forces, and cervical loading helps clinicians determine whether a proposed injury mechanism is medically plausible.

But biomechanics should not be asked to answer questions it cannot answer reliably.

A force estimate alone cannot tell a clinician exactly:

“This patient’s headache came from the brain.”

or:

“This patient’s headache came exclusively from the cervical spine.”

Individuals differ in anatomy, posture, muscle activation, prior injury, age, tissue tolerance, head position, health status, and many other variables.

ICHD-3 itself recognizes that whiplash can occur after high- or low-impact forces.

Therefore, biomechanics supports mechanistic plausibility, but individual causation still requires clinical correlation.

Medical Causation Requires More Than “The Accident Happened First”

A headache beginning immediately after an accident provides important temporal evidence, but sequence alone is not sufficient to prove medical causation.

A scientifically defensible evaluation asks several questions:

• What was the patient’s headache history before the accident?
• Was there a previous migraine disorder?
• What exactly occurred during the trauma?
• Was there direct head contact?
• Was there rapid cervical acceleration-deceleration?
• When did the headache first appear?
• Were dizziness, memory problems, nausea, neck pain, or visual problems also present?
• What neurological and cervical findings were documented?
• Did headache frequency or severity measurably change from baseline?
• Are there competing explanations?
• Has the clinical course remained consistent with the proposed diagnosis?

This distinction is especially important in personal injury cases.

A plausible mechanism supports causation. It does not independently prove causation.

Likewise, an abnormal MRI can establish that an anatomical finding exists without necessarily proving when it developed or whether it produces the patient’s headache.

Good medical causation reasoning combines mechanism, chronology, examination findings, previous health history, diagnostics, functional changes, and reasonable exclusion of alternative explanations.

Looking at Both the Brain and the Neck

Post-injury headache evaluation should not force clinicians to choose between “brain” and “neck” prematurely.

The same collision can potentially involve both systems.

A comprehensive assessment may include:

• Detailed accident and symptom history
• Previous headache history
• Neurological examination
• Cognitive screening when appropriate
• Balance and vestibular assessment
• Eye-movement or oculomotor screening
• Cervical range-of-motion testing
• Muscle and soft-tissue examination
• Upper cervical joint assessment
• Reflex, sensory, and motor testing
• Headache-frequency tracking
• Functional outcome measures
• Imaging when clinically indicated

Red-flag symptoms—including progressive neurological deficits, worsening severe headache, repeated vomiting, seizures, unusual confusion, altered consciousness, or other concerning findings—require appropriate medical evaluation rather than routine conservative treatment.

Where Does Chiropractic and Rehabilitation Fit?

The answer depends on the headache generator.

Chiropractic treatment should not be presented as treatment for a brain injury itself.

Instead, when examination identifies a cervical musculoskeletal contribution—such as cervicogenic headache, impaired cervical movement, joint dysfunction, muscle guarding, or associated neck pain—appropriately selected manual therapy and rehabilitation may become part of a multidisciplinary plan.

Recent evidence supports that distinction.

A 2026 evidence-based chiropractic clinical practice guideline recommends spinal manipulation as one possible intervention for appropriately diagnosed cervicogenic headache and emphasizes multimodal approaches for tension-type headache. Evidence strength varies across interventions, including exercise and acupuncture (Trager et al., 2026).

A 2025 systematic review similarly concluded that manual therapy may provide short-term relief for adults with cervicogenic headache, while noting uncertainty surrounding longer-term effects and some combined approaches.

That is precisely why diagnosis comes first.

A patient’s care might involve cervical rehabilitation, carefully selected chiropractic treatment, medical headache management, graded physical activity, vestibular therapy, sleep interventions, neurofunctional acupuncture or electroacupuncture when clinically appropriate, and referral to neurology or other specialists when necessary.

Patients remain active decision-makers throughout that process.

For related information, see Post-Accident Headaches in El Paso: Pain Relief and Integrated Migraine Treatment, El Paso: Complete Clinical Guide.

What Makes Dr. Jimenez’s Injury Medical Chiropractic and Functional Medicine Clinic Different?

• Dr. Jimenez’s Injury Medical Chiropractic and Functional Medicine Clinic in El Paso uses a multidisciplinary model designed for complicated injury presentations where neurological, medical, and musculoskeletal findings may overlap.
• Dr. Maria Guadalupe Cardenas, MD, a board-certified internal medicine physician with more than 40 years of experience, serves as Medical Director, Clinical Director, and Collaborative Physician.
• Dr. Alex Jimenez, DC, APRN, FNP-BC, CFMP, IFMCP, combines his chiropractic background with his role as a board-certified family nurse practitioner specializing in evaluating musculoskeletal and soft-tissue injuries.

The clinic’s structure allows medical assessment, chiropractic care, rehabilitation, diagnostic testing, functional medicine evaluation, acupuncture and electroacupuncture, and other appropriate therapies to be coordinated rather than isolated.

This makes the practice one of the only clinics in El Paso, Texas, offering this level of integrated medical, chiropractic, functional, and injury-focused care.

Importantly, integration also supports patient autonomy. Patients should understand their diagnosis, the limits of available evidence, reasonable treatment alternatives, and when referral to their existing physicians or specialists is appropriate.

Additional information about the multidisciplinary clinical structure is available through About Dr. Alexander Jimenez and His Clinic.

The Scientific Takeaway

Two patients can experience different accident mechanisms and still describe nearly identical headaches.

One may have a headache attributed predominantly to mild traumatic brain injury.

Another may have a headache attributed primarily to whiplash and cervical injury.

A third may have elements of both.

Science therefore cautions against diagnosing post-injury headaches based on symptoms, imaging, or collision mechanics alone.

The more defensible approach connects the pieces:

mechanism + chronology + clinical findings + prior history + diagnostic testing + functional change + alternative-cause analysis.

That approach benefits patients by reducing the risk of treating the wrong headache mechanism.

It also produces stronger medical reasoning when causation becomes important in a personal injury case.

Most importantly, it recognizes a basic principle of modern injury science:

Similar symptoms do not necessarily mean identical injuries—and different injuries can sometimes produce remarkably similar symptoms.

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References

Centers for Disease Control and Prevention. (2025). About mild TBI and concussion. CDC: About Mild TBI and Concussion

Cortel-LeBlanc, A., Cortel-LeBlanc, M., Webster, R. J., Chen, K., Schytz, H. W., Jolliffe, K., Dodd, A. B., Terekhov, I., Dashti, F., & Zemek, R. (2025). Post-traumatic headache phenotypes and clinical characteristics. Cephalalgia, 45(12). Post-traumatic headache phenotypes and clinical characteristics

Headache Classification Committee of the International Headache Society. (2018). The International Classification of Headache Disorders, 3rd edition. Cephalalgia, 38(1), 1–211. International Classification of Headache Disorders, Third Edition

Mavroudis, I., Ciobica, A., Luca, A. C., & Balmus, I.-M. (2023). Post-traumatic headache: A review of prevalence, clinical features, risk factors, and treatment strategies. Journal of Clinical Medicine, 12(13), 4233. Post-Traumatic Headache: A Review of Prevalence, Clinical Features, Risk Factors, and Treatment Strategies

Schwedt, T. J. (2024). Posttraumatic headache. Continuum, 30(2), 411–424. Posttraumatic Headache

Trager, R. J., Daniels, C. J., Hawk, C., Taylor, D. N., Walters, S. A., Price, M. R., Anderson, K. R., Crivelli, L. S., Mooring, S. A., Staab, C. A., & Oakley, C. B. (2026). Chiropractic management of adults with cervicogenic or tension-type headaches: Development of a clinical practice guideline. Journal of Chiropractic Medicine, 32(4), 325–344. Chiropractic Management of Adults With Cervicogenic or Tension-Type Headaches

Clinical note: This article is educational and does not replace an individualized medical examination. New or worsening neurological symptoms following head or neck trauma require appropriate medical evaluation.