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Posted On March 17, 2015 Current Events and News

The 3 Types of Brain Injuries Don’t Mean What You Think They Mean

Any brain injury has the potential to be serious, but how much do you know about the categories doctors use to describe them? What makes a moderate injury different from a severe one? Does a mild injury translate to an easy recovery and no lasting symptoms? You might be surprised to learn that “mild,” “moderate,” and “severe” might not have as much to do with the patient’s long-term prognosis as you’d expect.

Which part of the brain sustains damage is an important factor in a patient’s prognosis, but it has nothing to do with categorizing the injury. Photo Credit: Flickr (Creative Commons license).

Doctors classify traumatic brain injuries (TBIs) into three types: mild, moderate, and severe. This system may sound pretty simple. A mild brain injury should be less serious than a moderate one, which is still less serious than a severe one – or so you would think. In reality, though, these terms aren’t as clear as you would expect. Classification depends on the initial symptoms a brain injury victim exhibits and where those symptoms place the patient on a measurement called the Glasgow Coma Scale. They don’t necessarily correspond to the patient’s prognosis and how difficult, or complete, his or her recovery may be.

The Glasgow Coma Scale

The tool doctors typically use to assess the level of neurological injury sustained in a TBI is called the Glasgow Coma Scale (GCS). Doctors assign a number of points based on the patient’s motor responses (movements), verbal responses (communication or lack thereof), and whether and when they open their eyes. The lower the score, the more severe the brain injury.

Mild Brain Injuries

A mild brain injury is one which falls between 13 and 15 on the GCS. Typically, victims who have sustained a mild brain injury lose consciousness for no longer than a few minutes, while some lose consciousness for just seconds. It’s also possible for these patients to never lose consciousness at all, but instead act confused or disoriented. They may still suffer symptoms such as a headache, nausea, vomiting, fatigue, difficulty concentrating and remembering things, and dizziness. However, they usually won’t exhibit symptoms that indicate more serious neurological damage, like slurred speech, convulsions, or numbness and weakness in extremities.

A person with a mild brain injury that rates as a 15 on the GCS could be fully awake and alert – however, even an alert patient with a seemingly mild injury should undergo a thorough examination by a medical provider. Some patients experience a lucid interval, in which they may seem to be fine but later deteriorate, in the moments after a brain injury. These patients may have a high GCS score but could still need a life-saving surgery. Without a meticulous examination by an experienced physician, you simply can’t tell if what seems to be a mild injury really is mild, after all.

Moderate Brain Injuries

A score between nine and 12 on the GCS translates to a moderate brain injury. Patients with moderate brain injuries lose consciousness for a longer span of time, typically somewhere between 20 or 30 minutes and six hours (but potentially up to 24 hours). They may suffer many of the same symptoms as you would see in a mild brain injury, but those symptoms could linger around longer – often for weeks. In patients who suffer moderate brain injuries, the results of brain imaging tests will often show an abnormality, while patients with only mild brain injuries may still have normal test results.


Patients with moderate TBIs may still need to undergo rehabilitation therapy – and some must relearn how to walk and talk. Photo Credit: Flickr (Creative Commons license).

Both moderate and severe brain injuries may result in symptoms not usually seen in mild injuries, including dilated pupils, slurred speech, seizures, loss of coordination, and physical weakness or numbness. Despite the severity of their symptoms, patients suffering from moderate TBIs often recover generally well, and “other parts of the brain sometimes learn to take over some of the duties of the destroyed area,” according to to Merck. However, the classification of brain injury doesn’t necessarily indicate the patient’s long-term prognosis, and any journey toward recovery could take a great deal of time, hard work, and support.

Severe Brain Injuries

The lowest score a patient can get on the Glasgow Coma Scale is three. Any score between three and eight indicates a severe brain injury. Patients with severe brain injuries lose consciousness for several hours – some experts consider at least six hours of unconsciousness to be the cutoff for severe TBIs, while others consider 24 hours to be the minimum. There is no maximum duration. Comas or unconscious states can last for days, weeks, months, and even years.


Years after sustaining a serious TBI, individuals’ brain imaging scans may still show the damage. Photo Credit: James Heilman, MDWikimedia Commons (Creative Commons license).

As with moderate brain injury cases, severe brain injuries bring symptoms of a mild injury as well as more serious ones, like slurred speech, seizures, and losses of coordination. Recovery from a severe brain injury can very difficult. Some patients are able to make excellent recoveries, though they may still suffer some permanent cognitive, physical, or sensory impairment. Other patients make less progress. The long-term effect of a brain injury on an individual’s life depends on a number of factors, from which functions the injury does and does not affect to what resources a patient has access to during their work toward recovery.

‘Mild’ Can Be Misleading

Don’t dismiss a mild brain injury as being insignificant just because of the name. As the Brain Injury Association of America aptly puts it, “keep in mind that there is nothing ‘mild’ about a brain injury—the term ‘mild’ brain injury is used to describe a level of neurological injury. Any injury to the brain is a real and serious medical condition.” Even a mild brain injury can cause long-term problems, which means that it’s essential to get a patient help for even a mild injury as soon as possible.

While many patients who suffer mild brain injuries do recover without permanent problems, not all of them do, and some of them find that their journey to rehabilitation takes far longer than others’. “There may be no correlation between the initial Glasgow Coma Scale score and the initial level of brain injury and a person’s short or long term recovery, or functional abilities,” the Brain Injury Association of America reported.

A Prognosis Is Not a Limitation

In many ways, brain injuries remain mysterious. The effects of a TBI vary based on which region(s) of the brain sustained the injury, how serious the impact was, and other factors beyond your control. When doctors tell patients (and family members) their prognosis, they do so to set realistic expectations, not to limit patients’ recovery. There have been inspiring stories of TBI patients learning to walk again, when doctors had believed they never would. I’ve known brain injury survivors who went on to go to medical school and become physicians themselves. One of the most famous presidents in American history suffered a brain injury in childhood, but still went on to lead the nation.

It’s unquestionably important for patients and family members to have realistic expectations for recovery so that they don’t get discouraged, but it’s also important for them to have hope and to celebrate every achievement, no matter how small. Recovery from a brain injury often happens in baby steps, but even these small steps are progress.