Traumatic brain injury (TBI) doesn't sound like a hidden health problem. The name alone gives us vivid images of war explosions, head wounds, and extended hospital stays. But a long-brewing discussion about concussion in the National Football League (NFL) is raising awareness that TBI isn't always as obvious as we imagine.

75 former NFL players are now suing the league for concealing the long-term risks of the concussions that often happen in pro football.

These NFL players say that, over time, these mild concussions lead to long-term health problems associated with more dramatic forms of traumatic brain injury. No, they didn't have bleeding head wounds, nor did they spend days in a coma after a hard hit. But, they have symptoms like they could have have experienced these more violent scenarios.

So, what are the symptoms of mild brain injury, and what does this have to do with how we think about multiple sclerosis?

Let's answer the first question first.

According to the National Institute of Neurological Disorders and Stroke, the symptoms of mild TBI include:

• headache

• confusion

• light-headedness

• dizziness

• ringing in the ears

• fatigue or lethargy

• disruption in sleep patterns

• mood changes or depression

• concentration and attention problems

If the brain injury may be considered more severe if it includes:

• loss of coordination

• numbness and tingling in the limbs

Now, let's answer the second question.

Many with multiple sclerosis or MS-like symptoms (or a syndrome that fits in the family of degenerative neurological diseases, like Parkinson's and dementia) probably experience one or more of the common long-term symptoms of mild TBI from the list above. It's not uncommon for problems like fatigue, vertigo, and sleep problems to travel together with problems like numbness and tingling in the limbs. The question, of course, is why?

A conclusion that some may jump to is that MS patients must have a history of a TBI, like a concussion. However, while this is a history that is definitely true for some, it is not true for all. Not everyone with MS has had a memorable blow to the head that caused them to see stars...wearing a football helmet or otherwise.

If you did an autopsy of the brain of MS patients, my guess is they will not show the same damage on the cortex (brain surface) as the pro football players.

However, this new understanding of mild-brain injury as a source of confusing neurological symptoms is important to MS patients because it shows that many of these symptoms have a mechanical start.

By mechanical I mean this: first there was a trauma, then there was irritation to the nervous system, then there were symptoms.

TBI cannot be explained by genetics or a virus or a host of other things. It is explained by damage to the nerve and vascular tissue of the brain.

While many still attempt to explain MS via genetics or some other environmental factor alone, vascular surgery to reduce chronic cerebrospinal venous insufficiency (CCSVI) is showing us that MS may have a mechanical component as well.