What Is a Concussion?

A concussion is a mild traumatic brain injury (mTBI), often sustained in sports, falls, motor vehicle accidents, assault, and other incidents.  Concussion cannot be seen on CT or MRI scans, but it’s a very real brain injury. The hallmarks of a concussion are:

• a temporary disruption of neurologic functioning and awareness, such as a sense of confusion or disorientation, or feeling “foggy” or “out of it” for a few seconds to minutes
• frequently, an inability to remember the injury itself, or inability to remember what happened just before the injury (retrograde amnesia)
• often, an inability to remember things after the injury (post-traumatic amnesia)

Note that someone does not have to lose consciousness in order to have suffered a concussion.

A concussion causes injury in two places, since the brain strikes the inside of the skull first at the point of impact and then again on the opposite side as it "rebounds" away from the impact site. If the head rotates at the time of impact there can also be damage to the axons that connect the brain's gray matter to the white matter below.

Other symptoms of concussion may include:

• Headache/pressure in the head 
• "Not feeling right”   
• Nervousness or anxiety
• Drowsiness
• Dizziness/vertigo   
• Slow responses   
• Irritability   
• Low energy
• Nausea   
• Poor memory   
• More emotional than usual
• Feeling slowed down
• Sensitivity to light or noise   
• Poor concentration   
• Sadness   
• Trouble falling asleep
• Numbness/tingling or neck pain   
• Repeats questions       
• Sleeping more than usual
• Balance problems           
• Looking “dazed”

Athletic directors and coaches at school programs should be trained to recognize the signs of concussion. When head injuries happen off the field—and they can happen anywhere—it can be up to the injured party, a family member or friend, or even a bystander, to suspect a concussion.

Dr. Kosofsky talks about concussions in kids on the podcast "This Is Your Brain With Dr. Phil Stieg:"

Concussion is a “functional” brain injury, not a “pathological” one. That means it’s a real injury that affects how the brain works, but those effects are usually temporary. Concussions usually resolve on their own within one to six weeks without medical treatment. They do require a patient’s cooperation, though: The brain needs rest, both physical and cognitive, in order to recover. A trained clinical neuropsychologist can assess the patient and make a recommendation on how much time will be needed to allow for a full recovery. The neuropsychologist can also identify post-concussion difficulties that do require intervention.

Diagnosing a Concussion

Diagnosing a concussion involves several steps. The first is a very careful history to document the presence and extent of any retrograde amnesia, loss of consciousness, or post-traumatic amnesia. The last sign, post-traumatic amnesia, is one of the best indicators of prognosis after a concussion. Unfortunately, many physicians not experienced with concussion will not take this type of history, even though it is the most important information in establishing the presence, severity, and prognosis of concussion. With children, well-intentioned pediatricians who are not experts in concussion may neglect important aspects of the history that help guide management.

The next step is to determine the range and severity of post-concussion symptoms, for which several standardized scales are often used by concussion experts. In athletics, many coaches and athletic directors may have made a sideline assessment of cognitive functioning using several different scales that have been developed. These will be reviewed as part of the history. If the patient has not received one of these scales, they will complete one at their first visit. 

Evaluation by a doctor in the emergency room is not always necessary, especially if the concussion is minor. If the patient is taken to an ER and if actual injury to the brain is suspected, a CT scan and possibly an MRI scan may be performed to rule out any structural damage, although these neuroimaging studies are usually not performed for uncomplicated concussions. Almost invariably the patient is not admitted after an ER visit, but is given an instruction sheet to stay awake and to look for signs of bleeding in the brain (primarily lethargy or a decline in mental status).

In the days following a concussion the patient should see a concussion expert. That expert could be a physician specializing in brain disorders (a neurosurgeon or neurologist) or a neuropsychologist specializing in assessing brain disorders through tests of mental functions such as attention, concentration, and memory. Given that the neurologic examination is almost always normal, a physician specializing in concussion usually works with a neuropsychologist as part of a team approach, ensuring a comprehensive evaluation and diagnosis. 

For additional information, see Our Services: Evaluation and Assessment