Even though fatigue has been documented to be a problem post ABI it remains understudied. Toda et al. (2006) found that individuals who had sustained a TBI reported significantly higher levels of fatigue during their time in rehabilitation than they did at 6 or 12 months post injury (p=0.0092). It has been hypothesized that rehabilitation itself may play a role in exacerbating feelings of fatigue and once the patient is removed from these demands and has achieved a greater understanding of their deficits the feelings of fatigue lessen. However, the literature shows that fatigue can persist for many years post injury (Bay & de-Leon 2011; Olver et al. 1996; Ouellet & Morin 2004; Rao et al. 2006).
To gain information on the severity of the problem, data is often collected through surveys, interviews or questionnaires. Comparison groups in many of the studies are those without an ABI. Scales frequently used in these surveys include the Fatigue Severity Scale (FSS), the Fatigue Impact Scale, the Visual Analogue Scale-F, the Global Fatigue Index, the Barroso Fatigue Scale, and the Epworth Sleepiness Scale; however, none of these scales were designed specifically for use in patients with brain injury, but rather they were developed for patients with Human Immunodeficiency Virus or Multiple Sclerosis (Armutlu et al. 2007; Fish et al. 2007).
When comparing individuals with TBI to healthy controls, it is apparent that those who sustained a brain injury report greater levels of fatigue (Ashman et al. 2008; Borgaro et al. 2005; Chiou et al. 2016; LaChapelle & Finlayson 1998; Ponsford et al. 2012; Ziino & Ponsford 2006a). Between 33% and 64% of individuals reported fatigue post TBI (Englander et al. 2010; Ponsford et al. 2012). Englander et al. (2010) found that over two-thirds of participants (n=119) had abnormal sleep based on the Pittsburg Sleep Quality Index. The overwhelming conclusion is that fatigue has a greater impact on the lifestyles of those with brain injuries.
Bushnik et al. (2008) found improvements on self-reported fatigue during the first year post injury, although no further changes were seen up to two years post TBI. Unfortunately, when fatigue worsened over the course of two years, it was accompanied by poorer cognitive and motor outcomes as well as reduced levels of general functioning (Bushnik et al. 2008). The former conclusions are unfortunate as the literature suggests that pain, depression and motor deficits are significant predictors of fatigue post TBI (Englander et al. 2010), which could perpetuate a cycle of disability if fatigue is not appropriately managed. The studies have also shown pain, depression and anxiety to be associated with fatigue (Englander et al. 2010; Ponsford et al. 2012; Ziino & Ponsford 2006a). Furthermore, it is problematic given individuals are less aware of the effect of fatigue on their lifestyles (Chiou et al. 2016). Chiou et al. (2016) found that reduced awareness of fatigue in the physical and psychosocial domain is associated with anxiety, whereas reduced awareness in the physical and cognitive domain is associated with depression. Disability has also been correlated with fatigue (Juengst et al. 2013). Again, fatigue proves to be a complex and multifaceted concept.
There is level 3 evidence that those who sustain a TBI report greater levels of fatigue post injury.
Fatigue symptoms appear to be increased in individuals who sustain an ABI.
Impact of fatigue on Participation and Quality of Life post abi
There are many challenges to studying fatigue post TBI. One of the challenges is in separating fatigue from pain, depression and many other health related issues. Several assessments, including the DSM-IV (American Psychiatric Association) and the Beck Depression Inventory (Beck et al. 1996), assess fatigue as a symptom of depression. Few scales assess fatigue alone. To do so, one must reduce the overlap that exists between the various scales or tools that are used post TBI (Cantor et al. 2008). This section describes the impact that fatigue has on an individual’s life post injury.
Unfortunately Individuals with TBI were shown to not only use more sleep medications but also have longer sleep latency, lower sleep quality and more daytime dysfunction compared to healthy controls (Fogelberg et al. 2012). Further, those in the TBI group showed greater levels of fatigue, depression, and pain and reported poorer health related quality of life (Cantor et al. 2008). Even when compared to a group of patients with TBI, Schnieders et al. (2012) found that those with fatigue had more anxiety and depression as well as lower quality of life. Ponsford et al. (2015) also discovered that fatigue predicts anxiety and depression, and that depression may predict excessive daytime sleepiness. Huang et al. (2013) found those with persistent sleep complaints had higher scores on the beck depression inventory and the impact event scale. It is through these studies that it becomes apparent how many facets of life are impacted by sleep disturbances and fatigue.
Sleep disturbances were shown to negatively impact ones satisfaction with life, and scores on the Functional Independence Measure and Disability Rating Scale (Fogelberg et al. 2012). Moreover, fatigue has been associated with subjective determination of cognitive problems, difficulties with decision-making, working slowly to ensure accuracy and challenges in getting things done on time (Esbjörnsson et al. 2013). Fatigue can also negatively impact upon relationships, as there is a tendency towards reacting too quickly in response to others among individuals suffering from fatigue (Esbjörnsson et al. 2013). Further, one’s ability to work is often compromised when sleep disturbances are present. Schnieders et al. (2012) found those with fatigue, compared to those without, had lower level jobs and more nonpaying jobs. Evidently, managing fatigue is imperative in helping individuals live a productive and quality life post injury.
There is Level 3 evidence to suggest that higher levels of fatigue may lead to a poorer quality of life
Higher levels of fatigue lead to a poorer quality of life.
Fatigue and sleep disturbances impact individuals physically, cognitively, and psychologically.
Individuals with fatigue and sleep disturbances may have increased levels of anxiety and depression.
Those with fatigue, compared to those without, were shown to have lower level jobs and more nonpaying jobs.
Fatigue related quality of life is associated with somatic symptoms of TBI and situational stress.
Vigilance and Fatigue
Vigilance has been defined as the ability to sustain a level of alertness over long periods of time (Parasuraman 1984). It has been noted that those who sustain a TBI do have a lower cognitive reserve and often are not able to maintain the same levels of vigilance or sustained attention as they did before the injury (Ziino & Ponsford 2006b). It has been suggested that this variability in performance may be the result of fatigue (Cohen 1993).
In the study conducted by Ziino and Ponsford (2006b), individuals with TBI demonstrated slower decision-making on the vigilance task than those without TBI (p<0.001). Despite decision-making becoming faster for controls, this was not the case for the TBI group. The movement speed was also slower for those with TBI than for controls (p<0.001). Results from the fatigue subscale indicate that both groups had increased fatigue levels following the completion of the vigilance tasks. Therefore, although participants with TBI performed at a lower level on the task, the level at which they performed was consistent during the vigilance task. Those in the TBI group also had higher diastolic blood pressure readings afterwards, which were associated with subjective fatigue levels. Ziino and Ponsford (2006b) suggest that, in order to maintain a stable level of performance, individuals with TBI are forced to expend more energy (psychologically, physiologically, etc.) and this is associated with subjectively increased levels of fatigue.
When the relationship between fatigue and vigilance was analyzed, Ponsford et al. (2015) discovered that there is a trend that decreased vigilance is associated with increased fatigue, but this relationship did not reach statistical significance. However, Ponsford et al. (2015) found that fatigue may predict and contribute to the onset of depression, anxiety, and daytime sleepiness. Depression in turn can predict decreased vigilance and is associated with anxiety and daytime sleepiness (Ponsford et al. 2015). Unfortunately, this multifaceted perpetuating cycle renders the study and treatment of fatigue complex. Ponsford et al. (2015) suggest a treatment approach that aims to alleviate fatigue could be to target these individual factors.
There is Level 3 evidence, based on one study, that individuals who sustain a TBI do experience greater levels of fatigue and a decrease in vigilance, compared to those without an injury.
Fatigue experienced post-TBI has been linked to a decrease in vigilance.
Within TBI population, the relationship between vigilance and fatigue is affected and confounded by depression, anxiety, and sleep disturbances.