Looking at the Brain in Chronic Whiplash Injury

Injuries occurring after a motor vehicle collision can lead to chronic head and neck pain long after the damage of the injury is done repairing. These patients are generally classified as having chronic whiplash associated disorder (cWAD). A problem with cWAD is that we don’t really have a strong sense of why some people will get chronic pain after the injury while most will recover seemingly unphased.

Years of research studying biomechanical changes, ligament studies, and MRI changes in the neck have yet to show a diagnostic lesion that is predictive of a poor prognosis in whiplash patients. A number of studies have shown that psychosocial factors like work status, gender, and attorney retention appear to have a stronger correlation to chronic pain than any current medical diagnostics. This has allowed critics to say that chronic whiplash may be more psychosomatic than a true pathology. 1

How Whiplash Can Change the Brain

Conventional thought on whiplash has linked the pain of whiplash to a soft tissue injury in the cervical spine. When the neck undergoes rapid acceleration and deceleration, then the ligaments, muscles, and tendons of the cervical spine can be sprained and strained with varying levels of severity.

Instability of the cervical ligaments can lead to chronic pain in some trauma cases, but many patients who have chronic pain after an accident don’t have this level of injury. Many of these patients may even have close to normal imaging findings. Even in patients that have positive imaging findings, there’s not much difference between the imaging findings of those that will get better on their own and those that will have long lasting pain. 2

It’s easy to understand how injuries to muscular and ligamentous tissue can cause pain, but chronic whiplash injury is about more than just neck pain. Chronic whiplash often includes things like migraine headache, vertigo, and cognitive decline which are similar symptoms to mild traumatic brain injury. At least one study has shown that whiplash and concussion are indistinguishable based on symptoms alone. 3

When pain is poorly related to tissue injury, then it becomes more helpful to start thinking about pain as it relates to the brain itself. It’s easy to understand how the whipping of the head can tear and injure ligament and muscle tissue, but we have to dig a little deeper to see how whiplash can affect the brain.

Altered Cerebral Blood Flow

One of the best ways to see how a brain is changing is to monitor the way your brain uses blood. These studies are done using things like PET scans that help to identify areas of the brain that are gobbling up more glucose which tells us how active that part of the brain is at a given time.

Patients with chronic whiplash symptoms showed differences in blood flow in the brain in specific areas that play a role in how we perceive pain. These areas include the anterior cingulate cortex, insular cortex, medial prefrontal gyrus, and parahippocampus. 5

This is important because it tells us that the regions of the brain that are affected are NOT just the regions that perceive pain. Areas like the insular cortex and medial prefrontal gyrus are areas that aren’t directly responsible for feeling pain but are related to the limbic system and help us build context around pain.

If there are changes to the way these brain regions are wired, then we may also lose some of our ability to contextualize and inhibit our conscious perception of pain.

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The belief amongst these authors is that there is a mismatch between the incoming pain stimulus and the level of activation in the pain processing centers of the brain.

Axon Injury

This mechanism is pretty similar to what can happen with a concussion. When the head and neck accelerate and decelerate during a collision, the force of the head and neck moving can be stopped by a seatbelt, but it won’t not stop the brain from moving inside the skull. As the brain shifts forward and back, it can create a shearing force in the brain and damage the neurons deep within the brain. The forces from an accident like this have been shown to be similar with the forces associated with a football concussion. 4

Whiplash and the Brain

While the force may not be enough to cause a concussion, the force profiles of a concussion and whiplash are likely high enough to cause some axon injury in the brain.

Although axonal injury doesn’t really correlate well to pain, it can impact our balance, postural control, vision, and other systems that help to keep us upright in a healthy way. Breakdown of these systems can help make sense of why whiplash patients can have vertigo, concentration problems, and headaches.

Central Hyperexcitability

Imagine if you sprained your ankle playing basketball one day, but weeks later after your ankle should have healed, you start to feel pain in other areas of your body that had nothing to do with the ankle sprain. This is the phenomenon of central sensitization which is caused by hyperexcitability of the neurons in your spinal cord. Although just one part of the body was injured, the effects of a central hyperexcitability is that you may feel increased pain throughout your body as a whole.

When we describe the injury of a whiplash as a sprain/strain, then it should have more in common with a sprained ankle in terms of tissue damage and repair. We expect sprains and strains to feel close to normal again in 4-6 weeks for minor sprains. However, the pain of a minor whiplash can last months. Why?

The way the body reacts to injury of a central structure like the spine can be a lot different than the way it responds to a distal structure like the ankle or wrist. When you injure your neck and back, your nervous system perceives movement as more catastrophic because there’s a chance that injury can occur to the spinal cord. Your CNS brings your pain neurons closer to their firing threshold so that they fire easier. By doing this, it is more likely to make movement more painful and immobilize you because your pain receptors will fire more easily. Immobilizing an area of injury is one of the main purposes for pain, because tissue repair is harder for the body if you have  a cut or broken bone moving around all the time.

That’s why when you go down with a neck or back injury, you can be really cautious or apprehensive about any type of movement. Your brain is playing defense against you out of fear that your next movement may be catastrophic to your survival. This may be your body’s wave of keeping you immobilized until the inflammatory and repair response is over.

This becomes very problematic when your central nervous system retains this hyperexcitability AFTER the injured tissues have healed. It leads to a condition where you are feeling pain everywhere, but there’s no blood test or imaging to point to why you are hurting.

This is probably the most important reason for chronic pain, not just in whiplash, but we see this in conditions like fibromyalgia or post-surgical pain syndromes. This isn’t a new idea either. Researchers have shown that central sensitization is a player in whiplash dating back to the early 2000’s. 5, 6

Changing How the Brain Perceives Pain

We know now that the brain and central nervous system can be re-wired in a way to cause chronic pain through a concept known as neural plasticity. We also know that neural plasticity can be used therapeutically to help make the brain more resilient and sometimes undo this maladaptive pain response.

Part of this means that we have to change our mindset about the nature of pain. Our patients yearn for a specific lesion with tissue damage to point to as the culprit for their pain. That way, if we get rid of the lesion, then the pain should follow suit. The obvious problem with this is that there may be no lesion at all. For some this will lead to despair and hopelessness, but for others it may lead to unnecessary procedures to cut or inject areas that are NOT the reason someone is hurting.

 

So if someone’s chronic pain is not coming from a pinched nerve, strained muscle, or injured ligament what is a doctor supposed to do for an ailing patient?

We have to engage patients in things that will change how the brain interacts with pain stimuli. Here’s a short list of useful strategies:

  1. Flip the script – Patients in pain are scared of movement because they think they are creating more injury. We can talk to our patients about this. If we have a level of confidence that pain is coming centrally, then we can teach patients not to fear their MRI or fear their movement. We can teach patients that moving their bodies may be painful right now, but they are NOT causing greater injury despite their pain. By giving patients a better sense of control over their bodies, their pain status can start dropping just by changing their mind.
  2. Lean into it – Patients consistently surprise themselves with how much pain they can tolerate as long as they know they aren’t harming themselves. Exercise and movement therapies can be powerful ways to affect central pain issues. Lots of people focus on doing exercise that help you avoid pain, but people with sensitization issues may benefit from leaning into the pain a bit. By gradually exposing the nervous system to movement with tolerable amounts of pain, you can train your body to tolerate that movement by desensitizing the fear response to that pain
  3. Adjust the Brain – most people and even many chiropractors attribute the benefits of chiropractic care to removing physical pressure on pinched nerves. This might be true in some cases, but it’s not the reason people with chronic pain syndromes get relief. A focus of chiropractic research in the past 10 years has studied how adjustments can change the way the brain processes sensory information.7, 8, 9When we combine these central changes from adjustments with movement therapies, we can make a big change in the way a person’s brain responds to movement.
  4. Biofeedback Tools– A unique way of addressing sensitization after whiplash is to use tools that provide real time feedback as a way to shift the brain’s attention on a painful area. Things like neurofeedback therapy with EEG, visual feedback with attached lasers, and wearable biofeedback devices allow the brain to shift it’s focus to another powerful stimuli. This provides a positive reinforcement to the patient to show that they can gain greater control over how pain shows up in their lives.

Closing Thoughts

The ability of our brains to change and adapt is an important piece of the rehabilitation process. While the above therapies are things I use in clinical practice on a day to day basis, these aren’t the only things that can help you recover. Our brain changes and adapts to ALL stimuli, and finding the right fit that works for you is the job of a good clinician.

  1. Dufton JA, Bruni SG, Kopec JA, Cassidy JD, Quon J. Delayed recovery in patients with whiplash-associated disorders. Injury. 2012 Jul;43(7):1141-7. doi: 10.1016/j.injury.2012.03.006. Epub 2012 Apr 2. PubMed PMID: 22475071.
  2. Curatolo M, Bogduk N, Ivancic PC, McLean SA, Siegmund GP, Winkelstein BA. The role of tissue damage in whiplash-associated disorders: discussion paper 1. Spine (Phila Pa 1976). 2011 Dec 1;36(25 Suppl):S309-15. doi: 10.1097/BRS.0b013e318238842a. Review. PubMed PMID: 22020601; PubMed Central PMCID: PMC3248632.
  3. Leddy JJ, Baker JG, Merchant A, Picano J, Gaile D, Matuszak J, Willer B. Brain or strain? Symptoms alone do not distinguish physiologic concussion from cervical/vestibular injury. Clin J Sport Med. 2015 May;25(3):237-42. doi: 10.1097/JSM.0000000000000128. PubMed PMID: 25051194.
  4. Elkin BS, Elliott JM, Siegmund GP. Whiplash Injury or Concussion? A Possible Biomechanical Explanation for Concussion Symptoms in Some Individuals Following a Rear-End Collision. J Orthop Sports Phys Ther. 2016 Oct;46(10):874-885. PubMed PMID: 27690834.
  5. Curatolo M, Petersen-Felix S, Arendt-Nielsen L, et al. Central hypersensitivity in chronic pain after whiplash injury. Clin J Pain. 2001 Dec; 17(4):306-315.
  6. Curatolo M, Arend-Nielsen L, Petersen-Felix S. Evidence, mechanisms, and clinical implications of central hypersnsitivity in chronic pain after whiplash injury. CLin J Pain. 2004 Nov-Dec;20(6):469-476.
  7. Bialosky JE, George SZ, Horn ME et al. Spinal manipulative therapy-specific changes in pain sensitivity in individuals with low back pain. J Pain. 2014 Feb; 15(2):136-148.
  8. Lelic D, Niazi IK, Holt K, et al. Manipulation of dysfunctional spinal joints affects sensorimotor integration in the prefrontal cortex: a brain source localization study. Neural Plast. 2016; 2016:3704964.
  9. Haavik-Taylor H, Murphy B. Cervical spine manipulation alters sensorimotor integration: a somatosensory evoked potential study. Clin Neurophysiol. 2007 Feb; 118(2): 391-402.