According to NFL.com, Te'o suffered his injury while trying to tackle Broncos running back Knowshon Moreno.
Luckily, the linebacker will have plenty of time to rest in preparation for 2014. Additionally, his mechanism of injury—while certainly concerning—pales in comparison to a few head or neck injuries from earlier in the season, and there is no reason to expect anything less than a full recovery.
A review of the tape, courtesy of @gifdsports, makes it clear what happened.
As seen, when Te'o attempts to tackle Moreno, he is pushed back and collides with teammate Jahleel Addae. Addae strikes the side of Te'o's head, sending the former University of Notre Dame standout to the ground.
In this particular case, the angle of the blow likely carried more influence on the outcome than the amount of force.
Concussions occur when the brain moves within the skull as the result of an outside impact. It can do so in any number of directions: forward and back, side to side, rotating on one of its axes or a combination of all three.
Though much of the underlying science on concussions remains unclear, many doctors, athletic trainers and other professionals believe rotational forces play the largest role.
Unfortunately, that's precisely what happened to Te'o.
At impact, the rookie linebacker's head sharply jolts to the right, causing his head to rotate clockwise about its front-to-back axis.
His brain, on the other hand, lags slightly behind due to the surrounding layer of cerebrospinal fluid (CSF)—a water-like buffer that absorbs minor insults. As a result, it very briefly rotates to the left relative to the skull.
Current theory states that if large enough in magnitude‚ abnormal brain motion leads to the metabolic dysfunction and other changes that underlie the global concussion process.
With time, a concussed brain will almost always recover. Symptoms will abate, and the changes at the molecular level will reverse.
Usually, the entire healing process requires a week or two.
That said, in rare cases, symptoms such as headache, sleep disturbance and an inability to concentrate will linger for weeks or months.
Even worse, anecdotal evidence suggests concussions can produce a cumulative detrimental effect.
For instance, successive concussions may lead to longer-lasting symptoms. Additionally, an athlete's "concussion threshold"—or the amount of force needed to cause another injury—might decrease with each.
Whether or not the above two theories depend on factors such as genetic predisposition and appropriate injury care remains somewhat unclear—as do the theories themselves.
Nevertheless, while doctors must view every case as unique—there is no hard and fast rule that states a player should retire after a set number of concussions—for now, Te'o's injury shouldn't factor much into next season in the acute sense.
Dr. Dave Siebert is a resident physician at the University of Washington. He plans to pursue fellowship training in Primary Care (non-operative) Sports Medicine.