Utilizing physiological studies following severe brain injury in humans called Positron Emission Tomography (PET), Bergsneider and Hovda showed rapid uptake and utilization of glucose up to 8 days following TBI. (Bergsneider 1997). Kawamata was able to use a certain technique known as microdialysis and attenuate the increased glucose utilization seen after concussive brain injury (Kawamata 1992).
In animal studies, a rapid increase in glucose uptake has been evidenced after TBI. A second injury before the recovery of the first causes worse physiological changes in brain functioning and prolonged symptoms. After the second injury, this condition is a result of the greater mismatch in energy supply and demand than that from the first injury. The presence of signs and symptoms of concussion generally means that the energy mismatch is ongoing, and a second injury should be avoided at all cost.
The study reported by Prins in 2013 in the Journal of Neuro-trauma, evaluating vulnerability in the brain based on the timing of injury, showed that a second concussion during the period of metabolic impairment (glucose utilization) results in worse metabolic (brain physiological functioning) disruption and cognition impairment in the memory areas of the brain. This is the main reason the return-to-play policy is so critical (Prins 2013).
Second Impact Syndrome (SIS) is a result when another concussion occurs while a person is still symptomatic and in the process of healing from a previous injury that occurred days or weeks or months earlier. The condition occurs during a period of vulnerability before the symptoms from a prior injury are resolved.
SIS can result in the following:
• Massive swelling of the brain shortly after impact, known as diffuse cerebral edema, can cause the brain to be pushed through very narrow structures, a condition called brain herniation. Shifting of the brain and herniation cause increased pressure in the brain, and this can result in a collapse of the blood vessels that supply blood, nutrients, and oxygen to the brain. Any limitation in blood supply to the brain can result in further damage to brain cells, causing cell dropout or the death of nerve cells and their supporting cells. Due to the fact that the brains of younger individuals are without atrophy (with less space) when compared to older individuals, the “full” younger brain is more vulnerable to this condition. SIS generally occurs in young athletes under the age of 20 (Cantu 1998, Field 2003, Scramstad 2017).
• During the vulnerable period, there is an abject failure of the brain’s ability to regulate blood flow (also known as failure of autoregulation), and thus, wide fluxes in blood pressures can be seen.
• This condition can be fatal or result in death in 50% of cases, and severe disability in 100% of cases, as we saw in the instance of Mario (Case #1) (Stovitz 2017).
• There is also a higher risk of long-term cognitive dysfunction.
What really happens during a concussion?
A TIME CAPSULE is perhaps the best way to define what transpires following a concussion. All of a sudden, a person goes from functioning as what one can call normal to losing control. How long does this last?
Table # 3 -- Paula Durben (Case # 2) – A cheerleader
| Immediate Period | |
| Impact | She landed on her head after performing a summersault. |
| Immediate knowledge | She recalled her head hitting against the concrete in the most brutal way and thinking to herself, “I am dead.” |
| LOC | No |
| Anterograde amnesia | She had no recollection of the events that transpired for the next 5 minutes except for what she was later informed of by her friends. |
| The most common early symptoms | The next thing she knew was that she woke up with everything in her visual field dark and was hyperventilating with the most excruciating headache. This was followed by blurred vision, the inability to stand up, and a sensation of dizziness and spinning (vertigo), followed by nausea. |
| Sensory integration issues | While she could hear people speaking around her, she was not able to completely understand what they were saying. |
| Cognitive and neurobehavioral issues | Around that time, she noted difficulties focusing and concentrating and recalled feeling fearful and out of control. |
| PTA – Time between impact and her ability to form new memories and to realize her person | Paula was unable to recall all the events as they had transpired but had a patchy recollection until she was in the ambulance on her way to the hospital. After being hit, she was in a state of altered consciousness where she was not totally aware of what was going on around her. In less than an hour, she realized that she was not the same person. |
| Retrograde amnesia | She had no recollection of what she was doing for at least one hour before the impact. |
Two of the most important features of her condition were cognitive-behavioral and balance issues during the early stages, which are common adverse effects reported after concussions (Dougan 2014). This was accompanied by some of the most common symptoms, including headaches and dizziness with noted dysfunction of the vestibular system, which was responsible for the early imbalance that Paula experienced.
Fortunately, most injured athlete’s cognitive deficits and the associated balance symptoms together with the accompanying experience recover within 2 weeks after injury (Williams 2015, McCrea 2015, Nelson 2016). Those who generally continue to experience the negative effects of cerebral concussion beyond 30 days have a story to tell.
Table # 4 -- Paula’s symptoms lasted for about 30 days from the injury, and her symptoms dissipated thereafter.
| Up to day 2 | Symptoms of dizziness, vertigo, headache, excessive sleep, fatigue, and hypervigilance; aggravation noted with light, noise, and motion. |
| Week 1–2 | Symptoms improved over time but now with difficulties falling asleep and with racing thoughts. She was not able to return to work or school. She had trouble focusing, paying attention, and multi-tasking. She was not able to use computers, iPads, or tolerate smart boards in class. |
| Week 3–4 | She returned to school and work but was still symptomatic to a much lesser degree. She needed special accommodations to complete her classwork and perform on her job. |
| Week 4 | By day 30, she was symptom-free and able to perform all of her activities without limitations. |
Paula: 7 years later …
She was working and performing well at her job, as well as attending college. The last time I saw her was a few months after her injury. I had lost track of Paula, assuming all was going well when I happened to see her as a patient again 7 years later. During her visit, she said to me, “Till this day since the concussion, I have not felt like myself.”
While she has not been able to pinpoint a specific symptom, she was aware that something was not quite right. So, what about the fact that seven years earlier, she had been released to play competitive sports and was given a clean bill of health?
I decided to do a full battery of neuropsychological testing on her.
Table # 5 – Paula – seven years later
| Neuropsychological testing | • Excellent memory• Easily distracted with a poor attention span• Deficits in executive functions |
| Moral of the story | Even though a person may think they have fully recovered from a TBI/concussion, watch out! There may be silent situations that go unrecognized and then manifest later in life. |
| Impact of attention deficit and trouble in executive function | • The issues of attention deficit and deficits in some of her executive functions that went unrecognized for years caused Paula major setbacks in her life and relationships.• She developed chronic depression and anxiety.• She lost her university scholarship, as she could not maintain her grades, and had to transfer to a community college, as she had trouble at the Ivy League school that she was attending at the time of her injury.• She got involved in multiple pathological relationships.• The testing revealed that she had poor self-esteem, which was supported by her own
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