“If a 'Grade 1' concussion means you see stars after a hit, Plummer says he's had 1,000 in his career, and his ex-teammate, Junior Seau, had 1,500.”
The problem with this line of reasoning is that the premise is incorrect. Concussion grading scales were popularized by the American Academy of Neurology (AAN) in 1997. AAN described three grades of concussion, with higher grades reflecting a more significant injury. Grade 1 criteria are described as follows:
1. Transient confusion.
2. No loss of consciousness
3. Concussion symptoms or mental status abnormalities on examination resolve in less than 15 minutes.
Grade 1 concussion is the most common yet the most difficult form to recognize. The athlete is not rendered unconscious and suffers only momentary confusion (e.g., inattention, poor concentration, inability to process information or sequence tasks) or mental status alterations. Players commonly refer to this stat as having been “dinged” or having their bell rung.”
There is nothing mentioned at all about seeing stars which is why Plummer’s premise is incorrect as are all of the subsequent calculations that lead to the 1500 concussion number. Alteration of mental status can refer to disorientation (e.g., not knowing where you are or what happened), post-traumatic amnesia, or retrograde amnesia, but not seeing stars. It can also refer to loss of consciousness, but loss of consciousness is not counted in Grade 1.
Seeing stars (technically known as photopsia) can technically caused by an infarctive (lack of oxygen) stroke in the occipital lobe (the visual processing area of the brain) but that is far different from a concussion. Most often, seeing stars is caused by mechanical stimulation of the nerves of the eye, which can occur after forces are applied to the head after a hit, but again, this is not the same as a brain injury.
You can easily cause the experience of seeing stars for benign reasons as well right now. Just take your two index fingers, gently press your eyelids when your eyes are closed, and you can see stars when your eyes are closed and even more so when they are open. Did you just give yourself a brain injury? Of course not. Certain medications (e.g., quetiapine, voriconazole) are known to cause photopsia. Other causes include retinal damage, ocular melanoma (cancer), and migraine headaches. When the retina is irritated, electrical impulses are discharged, which are interpreted by the brain as flashes of light (e.g., stars). It’s that simple.
To be fair to Plummer, he stated that he received his information from a concussion seminar in the 1990s, but if his recall of what he was told is accurate, then he was provided incorrect information.
Related Article: Does Second Impact Syndrome Exist?
Reference: AAN (1997). Practice parameter: The management of concussion in sports (summary statement), 48, 581-585.