The need for a long-term multidisciplinary follow-up in the management of mTBI

KEYWORDS:

• Mild traumatic brain injury
• long-term effects
• follow-up
• family physician
• cognition
• neuropsychology
• white matter
• diffusion tensor imaging
• psychiatry
• multidisciplinary

1. Introduction

Traumatic brain injury (TBI) is a physiological disruption of brain function induced by an external mechanical force. Mild traumatic brain injuries (mTBIs) are most prevalent, accounting for 70–90% of cases [1]. There is a general consensus among concussion researchers that acute functional disturbances after concussive injury are mostly attributable to two distinct, yet interrelated pathophysiological mechanisms: (1) a primary brain injury and (2) a neurometabolic cascade often referred to as a secondary brain injury. The acceleration/deceleration of the brain and the ensuing shearing and stretching of axons are well known, so too is the secondary neurometabolic cascade, which induces a transient state of excitotoxicity leading to neuronal exhaustion [2]. Mild injury severity, determined at the time of injury [3], does not mean mild consequences. Indeed, although most mTBI victims do recover in the first 3 months following the injury, it has been estimated that around 15% experience an ongoing array of physical, emotional, and cognitive symptoms [4]. Furthermore, this incidence rate could underestimate the number of people struggling with an abnormally long recovery [5]. Even in people who appear to have fully recovered, problems may emerge years, even decades, later [6–9]. When an individual reports difficulties long after the injury, it is often challenging to assess the role and consequences of the mTBI, as many distinct, yet interrelated factors come into play. This paper aims to present a framework for the follow-up assessment of these long-term effects. Although there is heterogeneity between cases, certain patterns emerge and should guide the process. An extensive review of the growing literature on the long-term effects of mTBI goes beyond the scope of this paper, but a number of frequent key consequences are highlighted, as they are inseparable from the methods used to evaluate them.

2. Long-term effects and their assessment

2.1. Cognition

An important and highly publicized preoccupation regarding the long-term effects of mTBIs is the possibility of developing a neurodegenerative disease. This follows the publication of studies, mainly focused on former athletes, presenting conjectural evidence of a higher risk of developing Alzheimer’s disease and/or chronic traumatic encephalopathy following repetitive mTBIs [10,11]. Importantly, these diseases may also be present in other subgroups of the population at high risk of repetitive head trauma such as military personnel and victims of domestic violence [8]. It is, therefore, of crucial importance for health professionals to complete an exhaustive history of prior mTBI, especially in individuals who belong to these subgroups. Alarmingly, although not as robustly documented, sustaining a single mTBI has also been associated with an increased risk of developing dementia [9]. Health professionals should not neglect close screening of cognitive decline in these individuals, especially if injury was sustained later in life [7]. Beyond the issue of neurodegenerative diseases, aging individuals may present a decline in cognitive function beyond what is expected in an otherwise healthy individual. Even in healthy retired athletes, decline in memory and executive functions has been found decades after a concussion was last sustained [6].

2.2. When should a full assessment of cognitive function be initiated?

Neuropsychological testing has been shown to be useful both to identify cognitive alterations in the acute phase and to specify cognitive changes as a late-emerging phenomenon [12,13]. It is our opinion that a complete neuropsychological evaluation should be undertaken in either of these four scenarios: (1) if cognitive difficulties persist longer than 3 months, (2) if cognitive symptoms reported tend to worsen with time, (3) if premorbid cognitive alterations were suspected in an aging individual or in a patient with a chronic disease affecting central nervous system function, or (4) to evaluate the potential interaction with premorbid developmental conditions affecting cognition, such as learning disabilities or attention-deficit hyperactivity disorder. The neuropsychologist may then objectively evaluate functions typically altered following an mTBI, namely attention and vigilance, information processing speed, learning and memory, and executive function [14], and/or evaluate the presence of a neurodegenerative disease, when indicated. Furthermore, neuropsychologists may want to include tests specifically designed to assist in evaluating the complex issues of adequate level of task engagement, valid test performance, and malingering, which can present itself in cases where litigation and compensation are at stake [15].

2.3. White matter and DTI

Recent advances in neuroscience technology have allowed the identification of abnormalities that previously went unnoticed on CT scans and conventional magnetic resonance imaging (MRI) scans. In this regard, diffusion tensor imaging (DTI) shows the most promise by demonstrating structural white matter abnormalities in acute and chronic settings following mTBI [16]. DTI, a type of diffusion-weighted MRI, measures water molecule diffusion. Within normal white matter, a high degree of directional coherence of water diffusion (fractional anisotropy) is expected, which is often reported not to be the case following mTBI [17]. Most importantly, this white matter damage correlates with cognitive impairment [18]. In a compelling study by Kraus et al. [19], TBI patients of different severities were tested an average of 8.9 years post-injury. DTI showed that white matter integrity varied according to injury severity with mTBI patients showing significantly more reduction in white matter integrity than controls, but less than patients with more severe TBI. Some variability was found among individuals who presented with injuries acutely classified as mild but who later showed a degree of pathology closer to moderate. Importantly, as suggested by the authors, this result pattern may help explain discrepancies found in functional outcomes following mTBI [19]. DTI may, therefore, be particularly useful in understanding the presence of persistent symptoms in a patient. Furthermore, DTI may play a role in detecting unrecognized pathology in the acute phase and eventually contribute to retrospective diagnosis. Although presently limited due to the lack of standardization of parameter values, the recent emergence of systematic DTI assessment in Level 1 trauma centers is likely to expand in the coming years. With the pressing need to implement this technique to support clinical diagnosis and long-term management, we are in favor of Strauss et al. recommendations aiming to create local normative samples and use quantitative analysis to compare a patient’s fractional anisotropy measures to these samples [17].

2.4. Psychiatric disorders

Psychiatric factors present before the injury as well as those following the trauma need to be considered when looking at long-term effects of mTBI. A prior history of psychiatric disorders has been identified as a significant predictor of poorer mTBI outcome [20]. Furthermore, mTBI victims are also at an increased risk of developing mental health conditions, mostly in the forms of depression and anxiety-related conditions (including but not limited to post-traumatic stress disorder and generalized anxiety), in the months, or even years following the injury [21]. Some patients may be more inclined to these disorders due to gender (higher risk in women), psychosocial factors, and psychological responses to the injury and its functional consequences [22]. Both pre-injury and post-injury psychiatric problems have been associated with the presence of persistent symptoms and functional impairment [21].

A health professional providing follow-up care after an mTBI should systematically screen for signs of mental health problems in patients. If any psychiatric disorder is suspected, it should rapidly be treated using appropriate psychotherapeutic and pharmacologic interventions [23]. It is also preferable to treat depression or anxiety before proceeding to a neuropsychological evaluation. Psychological distress can have a significant impact on cognitive functioning and may explain and/or mask some of the cognitive deficits following mTBI.

3. The family physician at the center of a multidisciplinary approach

Mild TBI patients do not necessarily seek immediate medical attention and the family physician may be the first health professional seen following the injury. It is therefore important for physicians to know how to properly diagnose an mTBI as it may have initially gone unnoticed. In this regard, a systematic and rigorous assessment of American Congress for Rehabilitation Medicine clinical criteria of mTBI [3] may be particularly helpful in retrospectively diagnosing this injury [23]. Even in acute cases admitted to the emergency department, the mTBI follow-up rapidly becomes the family physician’s responsibility. Hence, family physicians play an important frontline role and must be knowledgeable about what to expect in the acute and chronic phases.

Given the varied long-term effects of mTBI, a multidisciplinary approach should be privileged. In this multidisciplinary team, the family physician emerges as the best candidate to closely follow up on developing symptoms, to coordinate referrals according to the patient’s needs, and to closely monitor changes in the patient’s condition by integrating regular progress reports produced by the solicited specialized resources. Furthermore, a crucial issue put forth in this article is that mTBI victims may experience consequences related to their injury years after its occurrence, at a time when the only health professional still involved in follow-up is likely to be the family physician. Consequently, family physicians need to be concerned about previous history of mTBI not only due to the possible resurgence of symptoms but also due to the constantly evolving needs and potential interaction with developing health-related conditions in this clinical population. For example, a patient could first suffer from persistent cognitive symptoms, while these symptoms may predispose him/her to the later development of depressive symptoms associated with poor recovery. Years later, this same patient may develop early signs of dementia linked to a lifelong battle with cognitive symptoms and psychiatric ailments. Consistent with more severe TBIs [24], it is our opinion that clinical care for mTBI should resemble that of a chronic disease rather than that of an isolated event.

4. Conclusion

A long-term multidisciplinary team approach to managing mTBI should be implemented and led by a family physician. Family physicians should complete an exhaustive history of prior mTBI, as repetitive injuries are associated with more long-term effects, but should not neglect the possible consequences following a single injury. Health professionals involved should particularly look out for signs of cognitive and psychiatric problems that may affect daily activities. Furthermore, the development of DTI-based normative data shows great promise in objectively documenting and assisting with the long-term management of mTBI cases.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Additional information

Funding

This paper was not funded.