Why do some people have persistent concussion symptoms (PCS) after a mild traumatic brain injury (mTBI)?
Following a mild traumatic brain injury (mTBI), also called concussion, the majority of folks (70-80%) will go on to experience a recovery timeline something like this:
Day 1: Concussion injury occurs
Day 5-7: Concussion symptoms & brain energy levels are typically are at their worst
Day 7-10: Symptoms typically resolve
Day ~30: Brain energy metabolism returns to baseline/normal
This places a majority of folks recovering and fully returning to school or work within 3-4 weeks. High-risk, contact athletes typically return in 4-8 weeks based upon multiple recovery and baseline testing parameters (talked about elsewhere).
What happens with the other 20-30% of folks that don’t follow this timeline?
When folks do not seek treatment for concussion (or “rest until their symptoms go away”), there’s a higher risk of dealing with persistent symptoms (i.e., Persistent Concussion Symptoms; PCS). We consider symptoms persistent if they do not recover in the expected 7-10 day timeline, more specifically:
>14 days in adults
>30 days in children
As mentioned in the header for this section, up to 30% of folks who do not engage in active recovery will go on to experience PCS. This is not due to brain damage or lingering “concussion injury.” Research suggests that PCS is due to one or more deficits or dysregulations secondary to the concussion. We put these deficits into five categories, that I call “buckets.”
When describing this to patients, I let them know that folks who go on to experience PCS are typically carrying at least one of 5 buckets. My job as their concussion specialist is to figure out which (or how many) buckets they’re carrying and how I can help them set the bucket down or empty the bucket a bit.
Bucket #1 - Autonomic/Physiologic
Those fancy words refer to brain blood flow. After a concussion, part of the reason folks have headaches, head pressure, brain fog, fatigue, etc… is because their brains can’t properly regulate blood flow to their brains. Sometimes it’s too much flow; other times, it’s not enough. Ultimately, wonky flow means inconsistent oxygen and nutrient delivery, thus, inconsistent performance.
The other piece to this bucket is the “autonomic” part. After a concussion, we often see heightened sympathetic/”fight or flight” presentations (e.g., lowered HRV, increased resting HR, insomnia, anxiety, irritability, etc…). Research shows that it’s difficult for concussion patients to “switch” from sympathetic to parasympathetic/”rest and recover.” Thus, it’s like their foot is always on the gas, and they can’t wind down.
Bucket #2 - Metabolic/Hormonal
A concussion is a mild traumatic brain injury, and injuries come with inflammation. PCS inflammation can get complicated because it may involve the brain, the gut, and maybe even some hormones. Within ~8hrs after a concussion, the “brain inflammation” makes its way to the gut to elicit some gut inflammation. If this gut inflammation makes its way back to the brain, via circulation, then folks with PCS are in a loop that TikTok couldn’t handle. Hormones are considered in PCS cases because of the pituitary hormone changes seen after concussion.
Bucket 3 - Visual/Vestibular
Headache, blurry vision, eye strain, dizziness, vertigo, etc… are among the many visual/vestibular concussions symptoms. Your visual system allows you to see your world to orient to where you are in space. Your vestibular system is what allows you to feel and “know” where you are in space. Research shows that the vast majority (damn near all) of mTBI patients have oculomotor/vestibular dysfunction, and if these systems are not evaluated and rehabilitated, these deficits may persist.
Bucket 4 - Cervical Spine
All concussion comes with whiplash. The linear acceleration forces of concussion far exceed those of cervical injury (i.e., whiplash). Thus, if a patient suffered a concussion, then their neck also suffered an injury. Symptoms of cervical spine dysfunction can look a lot like visual/vestibular symptoms (and even migraine). This is partly because your neck, eyes (visual), and ears (vestibular) are tightly, neurologically connected. Part of a thorough concussion protocol involves a mandatory and thorough evaluation of the neck and spine.
Bucket 5 - Psychological
This bucket is either completely overlooked or the only bucket a provider acknowledges (e.g., “it’s in your head”). Neither of those options is recommended. Research shows that folks struggling with anxiety, depression, PTSD, ADD/ADHD, etc.. before a concussion are more likely to deal with PCS after their concussion. Additionally, anxiety, depression, and PTSD are known symptoms in concussion. The problem is that anxiety, depression, and PTSD can look just like concussion, even without a concussion injury. Often, folks may have objectively dialed in all of their “physical buckets (#1-4),” but are still not seeing progress. Many of these patients, in my experience, are folks with childhood/relationship trauma, anxiety/depression, and/or PTSD that they’re not addressing for a myriad of reasons. The main one is likely that turning inward on a deep enough level for therapeutic change is insanely self-aware, self-compassionate, difficult, and brave. Mental health is huge.
Summary
Concussion (mTBI) is a functional and transient injury that most folks (~70%) completely recover from in 3-4 weeks. When untreated, or too much rest has taken place, ~30% of folks will experience persistent concussion symptoms (PCS). This is likely due to a deficit/dysregulation in autonomic, metabolic, visual/vestibular, cervical spine, and/or psychological function.
Dr. Mark Heisig is a licensed naturopathic doctor with continuing mTBI education from The American Academy of Neurology (AAN), Complete Concussion. Management (CCMI) and The Carrick Institute. His office is located in Scottsdale, AZ.