Category Archives: head injury and fatigue

BrainLine sat down with Dr. Nathan Zasler to talk about the issues of fatigue after a traumatic brain injury. Dr. Zasler is an internationally respected neuro-rehabilitation physician who specializes in brain injury.
BrainLine: Describe fatigue. What exactly is traumatic brain injury-related fatigue?
Dr. Zasler: Think about a car. It needs gas to run. If your tank is low, your car will start sputtering and then stop once you have reached the end of your reserve. It’s the same way with fatigue after TBI. Fatigue is caused by a decrease in physiological reserve, which includes a person’s physical and mental reserves. When your brain is “tapped out,” you feel tired. Basically, when a person’s brain is overtaxed, fatigue will set in.
Although one formal definition of fatigue that has been proposed states that it is the failure to initiate or sustain attention or physical activity that requires self-motivation, there continues to be debate about how best to define “fatigue.” In part, it’s difficult to define the term because fatigue is subjective — that is, it is solely based on patient report — and it is really more a symptom than a diagnosis. Just like it is difficult to tell if someone is in pain, it is also challenging to know if someone suffers from fatigue unless they tell you so. But generally, people with TBI have described fatigue as a sense of mental or physical tiredness, exhaustion, lack of energy, and/or low vitality. Unfortunately, we don’t have any definitive screening tools for fatigue, so there is no universal way to measure it.
Cognitive and physical fatigue can occur separately or together, but most people seem to have more problems with the mental side of fatigue after a brain injury. They say they are not as quick as they used to be, mental tasks that were once easy are much more difficult, and they tire far more easily even doing something that used to be simple like reading, studying, or working.
Although there are limited long-term studies, some research indicates that fatigue is usually short-lived after most mild TBIs. And in my experience as a physiatrist, fatigue in patients with mild TBI usually lasts no longer than three to six months. However, for some people with mild TBI, their fatigue is more persistent.
BrainLine: How common is fatigue after a brain injury?
Dr. Zasler: In the general population, fatigue is a common complaint with some studies citing an incidence of 10 percent. But for people with traumatic brain injury, it is one of the most common problems post-injury. Fatigue affects not only people with moderate to severe TBI, but also those with mild TBI. And we still need more research to better understand this issue.
BrainLine: What does fatigue look like after TBI?
Dr. Zasler: The spectrum of fatigue is as broad as the spectrum of traumatic brain injury, itself. Everyone’s brain injury is different and everyone’s symptoms will be different. There are also many variables when it comes to post-TBI fatigue — from levels of severity to pervasiveness. Some people may be very fatigued all the time and others may only be fatigued after mental or physical exertion.
Most people who have fatigue resulting from brain injury only experience the problem at certain times and not all the time. They have more energy in the morning and tend to be more tired later in the day. People’s levels of fatigue also depend on how much they are pushing themselves physically or cognitively, and whether they are making time to rest periodically during the day and pace themselves.
Depression, anxiety, or stress can also contribute to the degree of a person’s fatigue or, alternatively, may even be the cause of the fatigue. Not everyone with a TBI will experience fatigue due to their brain injury. So, each person’s levels of fatigue, if present, may change over time during their recovery, in terms of both cause and level of severity.
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