What distinguishes a brain contusion from a concussion?
As one would expect from a problem as ubiquitous as traumatic brain injury, its various manifestations should be well-known and understood. But this is not how I've seen community-based neurology work. Many people, including patients and their families, confuse concussions with cerebral (brain) contusions, thinking that the two are essentially the same thing—the only difference being that the former is a more serious version of the latter.
Let us first recognise the similarities between these two words before we delve into their distinctions.:
Both are very common and caused by head trauma. They are both very serious.
However, the parallels stop there. There are two main distinctions between concussions and cerebral contusions:
* Concussions are more widespread than contusions, which are more localized. * While concussions are small, contusions are large.
Brain anatomy, physiology, and imaging techniques will need to be covered in order to give these ideas more substance.
Bruises are known as contusions. Everyone has felt the pain of a bruise, like a slapped forearm, at some point in their lives. This resulted in internal or subcutaneous haemorrhage. As the body's healing processes broke down and absorbed the red blood cells that had leaked from the damaged blood vessels, it took on a purple hue and maybe other colours in the days after the injury.
The only difference when it happens to the brain is that the bruises won't be visible to the naked eye. Nevertheless, imaging technology allows for the visualisation of bruises (contusions). Almost exactly like the human eye, computed tomographic (CT) and magnetic resonance (MR) scans can "see" a level of detail that is comparable to what the eye can perceive, but the data is displayed in increments of one slice of bread at a time. In this case, "macroscopic" means that the contusions can be seen by the unaided eye (through a scanner, of course). A comparable process happening at a "microscopic" level would be invisible to the naked eye and any imaging scanner.
Because CT scans make new haemorrhages more obvious and critically ill patients can be better monitored during the scans, they are preferable to MR scans when evaluating patients with acute brain trauma. Images produced by computed tomography (CT) scanners show normal brain tissue as grey, whereas fresh blood looks very white.
Contusions typically manifest in a single site, though they can be numerous. A definition of "localised" would be that. Therefore, a brain contusion is both small and concentrated. An example of a typical contusion pattern is the "coup-contrecoup." A contusion is the result of the brain's proximity to the point of impact slamming against the inside surface of the hard skull when a moving head is suddenly stopped, as happens when a person's head hits the ground during a fall. We call that the "coup" injury. However, a second "contrecoup" contusion on the opposite side of the brain is caused by either the brain bouncing back inside the skull or an abruptly created vacuum.
The presence of enough contusions to cause a "salt-and-pepper" effect on computed tomography scans is possible. Larger blood-deposits can also form when adjacent contusions ooze more blood. In extreme cases, surgical removal of a blood clot may be necessary to prevent further compression and distortion of the brain.
Realise that bleeding is not the only possible cause of brain tissue injury. The same force that breaks blood vessels can also directly harm brain cells.
Now we can compare these results to what happens during a brain concussion. Macroscopic, localised blood collection is not present in a pure concussion. Even with the aid of the scanner, any bleeding that does occur is too small to be noticed by the naked eye. Brain tissue is damaged in a concussion in a homogeneous, diffuse manner, but a scan will not reveal any macroscopic, localised abnormalities.
To suggest that the alterations brought on by a concussion could be discernible even under a microscope might be stretching things too far. Concussions primarily affect the physiology (functioning) of brain cells rather than their anatomy (structure), though in extreme cases, axons (the long extensions that brain cells utilise for communication) can physically snap in half. What this means is that many brain cells become sick from the trauma but do not die. In a sick person's brain, cell performance drops. This can cause the person suffering from a concussion to become disoriented or even lose consciousness. Since emotions are also generated by connections between brain cells, a concussed patient may exhibit changes in behaviour such as irritability, tearfulness, or a lack of concentration.
While it is possible for a person with a traumatic brain injury to have a concussion without a contusion or a contusion without a concussion, it is not uncommon for the two to occur simultaneously. Although concussions and cerebral contusions are distinct injuries, a person who sustains head trauma may be unfortunate enough to experience both.
