The focus of this review is outcome from mild traumatic brain injury. Recent literature relating to pathophysiology, neuropsychological outcome, and the persistent postconcussion syndrome will be integrated into the existing literature.
The MTBI literature is enormous, complex, methodologically flawed, and controversial. There have been dozens of studies relating to pathophysiology, neuropsychological outcome, and the postconcussion syndrome during the past year. Two major reviews have been published. Some of the most interesting prospective research has been done with athletes.
The cognitive and neurobehavioral sequelae are self-limiting and reasonably predictable. Mild traumatic brain injuries are characterized by immediate physiological changes conceptualized as a multilayered neurometabolic cascade in which affected cells typically recover, although under certain circumstances a small number might degenerate and die. The primary pathophysiologies include ionic shifts, abnormal energy metabolism, diminished cerebral blood flow, and impaired neurotransmission. During the first week after injury the brain undergoes a dynamic restorative process. Athletes typically return to pre-injury functioning (assessed using symptom ratings or brief neuropsychological measures) within 2-14 days. Trauma patients usually take longer to return to their pre-injury functioning. In these patients recovery can be incomplete and can be complicated by preexisting psychiatric or substance abuse problems, poor general health, concurrent orthopedic injuries, or comorbid problems (e.g. chronic pain, depression, substance abuse, life stress, unemployment, and protracted litigation).
"Clinical understanding and care for individuals with these diagnoses is further challenged when mild TBI, PTSD, and/or depression are comorbid, as there is substantial overlap and sharing of their associated symptoms. The symptoms shared among mild TBI, PTSD and depression include, for example , headache, insomnia, fatigue, irritability, cognitive dysfunction , and chronic pain (Hoge et al. 2008; Iverson 2005), all which can be considered independently existing clinical processes or as components of a complex syndrome (Scholten et al. 2012). These symptoms and conditions also frequently co-occur, which further complicates clinical understanding and may ultimately impede treatment and recovery (Carlson et al. 2010, 2011; Hill et al. 2009; Schneiderman et al. 2008; Vanderploeg et al. 2012; Vanderploeg 2007; Walker et al. 2012). "
[Show abstract][Hide abstract] ABSTRACT: U. S. veterans of Iraq and Afghanistan are known to have a high prevalence of traumatic brain injury (TBI), posttraumatic stress disorder (PTSD), and depression, which are often comorbid and share many symptoms. Attempts to describe this cohort by single diagnoses have limited our understanding of the complex nature of this population. The objective of this study was to identify subgroups of Iraq and Afghanistan veterans (IAVs) with distinct compositions of symptoms associated with TBI, PTSD, and depression. Our cross-sectional, observational study included 303,716 IAVs who received care in the Veterans Health Administration in 2010-2011. Symptoms and conditions were defined using International Classification of Diseases, Ninth Revision codes and symptom-clusters were identified using latent class analysis. We identified seven classes with distinct symptom compositions. One class had low probability of any condition and low health care utilization (HCU) (48 %). Other classes were characterized by high probabilities of mental health comorbidities (14 %); chronic pain and sleep disturbance (20 %); headaches and memory problems (6 %); and auditory problems (2.5 %). Another class had mental health comorbidities and chronic pain (7 %), and the last had high probabilities of most symptoms examined (3 %). These last two classes had the highest likelihood of TBI, PTSD, and depression and were identified as high healthcare utilizers. There are subgroups of IAVs with distinct clusters of symptom that are meaningfully associated with TBI, PTSD, depression, and HCU. Additional studies examining these veteran subgroups could improve our understanding of this complex comorbid patient population.
Brain Imaging and Behavior 05/2015; DOI:10.1007/s11682-015-9402-8 · 4.60 Impact Factor
"Instead they may be seen in private clinics, by primary care physicians, or may not seek or receive any medical attention (NCIPC 2003; Langlois et al. 2006). In the majority of individuals, the somatic, affective, and cognitive symptoms seen after mTBI (Ryan and Warden 2003) resolve within 3 months of injury (Korinthenberg et al. 2004; Lundin et al. 2006; Lannsjo et al. 2009; Sigurdardottir et al. 2009; Yang et al. 2009), but 5–10% of individuals go on to have persistent postconcussion syndrome [PCS (WHO 1992; Iverson 2005; Bigler 2008)] which can last a year or more postinjury (Killam et al. 2005; Sterr et al. 2006; Stulemeijer et al. 2007; Hessen et al. 2008; Dikmen et al. 2010). This is a potentially long-lasting problem as a large proportion of those reporting to hospital with mTBI are in younger age groups [e.g., around 30% are between 15 and 34 years old (Bazarian et al. 2005)]. "
[Show abstract][Hide abstract] ABSTRACT: Persistent postconcussion syndrome (PCS) occurs in around 5-10% of individuals after mild traumatic brain injury (mTBI), but research into the underlying biology of these ongoing symptoms is limited and inconsistent. One reason for this could be the heterogeneity inherent to mTBI, with individualized injury mechanisms and psychological factors. A multimodal imaging study may be able to characterize the injury better.
To look at the relationship between functional (fMRI), structural (diffusion tensor imaging), and metabolic (magnetic resonance spectroscopy) data in the same participants in the long term (>1 year) after injury. It was hypothesized that only those mTBI participants with persistent PCS would show functional changes, and that these changes would be related to reduced structural integrity and altered metabolite concentrations.
Functional changes associated with persistent PCS after mTBI (>1 year postinjury) were investigated in participants with and without PCS (both n = 8) and non-head injured participants (n = 9) during performance of working memory and attention/processing speed tasks. Correlation analyses were performed to look at the relationship between the functional data and structural and metabolic alterations in the same participants.
There were no behavioral differences between the groups, but participants with greater PCS symptoms exhibited greater activation in attention-related areas (anterior cingulate), along with reduced activation in temporal, default mode network, and working memory areas (left prefrontal) as cognitive load was increased from the easiest to the most difficult task. Functional changes in these areas correlated with reduced structural integrity in corpus callosum and anterior white matter, and reduced creatine concentration in right dorsolateral prefrontal cortex.
These data suggest that the top-down attentional regulation and deactivation of task-irrelevant areas may be compensating for the reduction in working memory capacity and variation in white matter transmission caused by the structural and metabolic changes after injury. This may in turn be contributing to secondary PCS symptoms such as fatigue and headache. Further research is required using multimodal data to investigate the mechanisms of injury after mTBI, but also to aid individualized diagnosis and prognosis.
Brain and Behavior 02/2015; 5(1):45-61. DOI:10.1002/brb3.292 · 2.24 Impact Factor
"Further, the Consensus Statement on Concussion in Sport only recommends multidisciplinary, conservative RTP for concussion cases with prolonged symptoms (>10 days; McCrory et al. 2013). Physical symptoms of concussion resolve within days or weeks of injury (Iverson 2005), but the length of recovery from other concussion-induced deficits (cognitive, balance, etc) is not well known, nor is concussion recovery known to correlate with physical symptom recovery. Broglio et al. (2007) investigated the relationship between resolution of symptoms and cognitive impairment in previously concussed varsity athletes. "
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