Medico-Legal Aspects of Concussion

Concussion and the sequelae have been controversial medico-legal issues for over 150 years. The following topics which are also important in clinical practice are discussed: definitions of concussion, neuroimaging, onset and prognosis of headaches, cognitive impairment, cognitive rehabilitation, post-traumatic stress disorder, and risk of later development of dementia.     

Headaches After Concussion in US Soldiers Returning From Iraq or Afghanistan

(Headache 2010;50:1262‐1272) Objectives.— To determine the prevalence, characteristics, impact, and treatment patterns of headaches after concussion in US Army soldiers returning from a deployment to Iraq or Afghanistan. Methods.— A cross‐sectional study was conducted with a cohort of soldiers undergoing postdeployment evaluation during a 5‐month period at the Madigan Traumatic Brain Injury Program at Ft. Lewis, WA. All soldiers screening positive for a deployment‐related concussion were given a 13‐item headache questionnaire. Results.— A total of 1033 (19.6%) of 5270 returning soldiers met criteria for a deployment‐related concussion. Among those with a concussion, 957 (97.8%) reported having headaches during the final 3 months of deployment. Posttraumatic headaches, defined as headaches beginning within 1 week after a concussion, were present in 361 (37%) soldiers. In total, 58% of posttraumatic headaches were classified as migraine. Posttraumatic headaches had a higher attack frequency than nontraumatic headaches, averaging 10 days per month. Chronic daily headache was present in 27% of soldiers with posttraumatic headache compared with 14% of soldiers with nontraumatic headache. Posttraumatic headaches interfered with duty performance in 37% of cases and caused more sick call visits compared with nontraumatic headache. In total, 78% of soldiers with posttraumatic headache used abortive medications, predominantly over‐the‐counter analgesics, and most perceived medication as effective. Conclusions.— More than 1 in 3 returning military troops who have sustained a deployment‐related concussion have headaches that meet criteria for posttraumatic headache. Migraine is the predominant headache phenotype precipitated by a concussion during military deployment. Compared with headaches not directly attributable to head trauma, posttraumatic headaches are associated with a higher frequency of headache attacks and an increased prevalence of chronic daily headache.     

Pathogenesis of Posttraumatic Headache and Migraine: A Common Headache Pathway?

In recent years, research implicating biochemical abnormalities in various pathological conditions has spiraled. Headache is an area in which numerous research studies have been conducted examining biochemical alterations. We have noticed several similarities in biochemical changes reported to occur in migraine and in experimental traumatic brain injury. The most common symptom in mild head injury or mild traumatic brain injury is headache which, in many instances, resembles migraine but has a poorly understood pathophysiology. Biochemical mechanisms believed to be similar in both conditions include: increased extracellular potassium and intracellular sodium, calcium, and chloride; excessive release of excitatory amino acids; alterations in serotonin; abnormalities in catecholamines and endogenous opioids; decline in magnesium levels and increase in intracellular calcium; impaired glucose utilization; abnormalities in nitric oxide formation and function; and alterations in neuropeptides. In this paper, these preposed biochemical alterations will be reviewed and compared. Very similar alterations suggest posttraumatic headache associated with mild head injury and migraine may share a common headache pathway.     

Post‐Traumatic Headaches in Civilians and Military Personnel: A Comparative,Clinical Review

Post‐traumatic headache (PTH) is the most frequent symptom after traumatic brain injury (TBI). We review the epidemiology and characterization of PTH in military and civilian settings. PTH appears to be more likely to develop following mild TBI (concussion) compared with moderate or severe TBI. PTH often clinically resembles primary headache disorders, usually migraine. For migraine‐like PTH, individuals who had the most severe headache pain had the highest headache frequencies. Based on studies to date in both civilian and military settings, we recommend changes to the current definition of PTH. Anxiety disorders such as post‐traumatic stress disorder (PTSD) are frequently associated with TBI, especially in military populations and in combat settings. PTSD can complicate treatment of PTH as a comorbid condition of post‐concussion syndrome. PTH should not be treated as an isolated condition. Comorbid conditions such as PTSD and sleep disturbances also need to be treated. Double‐blind placebo‐controlled trials in PTH population are necessary to see whether similar phenotypes in the primary headache disorders and PTH will respond similarly to treatment. Until blinded treatment trials are completed, we suggest that, when possible, PTH be treated as one would treat the primary headache disorder(s) that the PTH most closely resembles.     

Management of post‐traumatic headaches in children and adolescents

Traumatic brain injuries (TBI) occur in an estimated 475,000 children aged 0–14 each year. Worldwide, mild traumatic brain injuries (mTBI) represent around 75–90% of all hospital admissions for TBI. mTBI are a common occurrence in children and adolescents, particularly in those involved in athletic activities. An estimated 1.6–3.8 million sports‐related TBIs occur each year, including those for which no medical care is sought. Headache is a common occurrence following TBI, reported in as many as 86% of high school and college athletes who have suffered from head trauma. As most clinicians who manage concussion and post‐traumatic headaches (PTHs) can attest, these headaches may be difficult to treat. There are currently no established guidelines for the treatment of PTHs, especially when persistent, and practices can vary widely from one clinician to the next. Making medical management more challenging, there are currently no randomized controlled trials evaluating the efficacy of therapies for PTHs in children and adolescents.     

Clinical Review and Epidemiology of Headache Disorders in US Service Members: With Emphasis on Post-traumatic Headache

Migraine or headache is a common problem in the active duty population, in the recently deployed service members, and is a cardinal symptom of traumatic brain injury. While there is increasing appreciation of the clinical burden of post-traumatic headache (PTHA) in the military traumatic brain injury population, there remain significant research gaps related to the epidemiology of PTHA, including lack of understanding of natural history, whether there are predisposing factors that predict the development or prognosis of headache post trauma and, most basically, the features that distinguish PTHA from other forms of chronic headache. Although diagnostic criteria for PTHA are included in the International Classification of Headache Disorders, 2nd edition, revised, these criteria are somewhat arbitrary and were not empirically defined. This lack of precision about the PTHA phenotype limits the rigor of observational studies of PTH but does not appear to significantly hamper treatment, provided the treatment involves a multi-modality approach.     

Research Imaging of Brain Structure and Function After Concussion

Even when concussions are associated with prolonged physical and cognitive sequelae, concussions are typically “invisible” on diagnostic brain imaging, indicating that the neuropathology associated with concussion lies under the detection threshold of routine imaging. However, data from brain structural and functional research imaging studies using diffusion tensor imaging, resting‐state functional magnetic resonance imaging, and brain perfusion imaging indicate that these imaging sequences have a role in identifying concussion‐related neuropathology. These advanced imaging techniques provide insights into concussion neuropathology and might be useful for differentiating concussed patients from healthy controls. In this review article, we provide an overview of research findings from brain structural and functional imaging studies of concussion, and discuss the accuracy of classification models developed via machine‐learning algorithms for identifying individual patients with concussion based on imaging data.     

PTSD, Combat Injury, and Headache in Veterans Returning From Iraq/Afghanistan

Objective.— To examine the relationship between posttraumatic stress disorder, combat injury, and headache in Operation Iraqi Freedom and Operation Enduring Freedom veterans at the VA San Diego Healthcare System. Background.— Previous investigations suggest that a relationship between posttraumatic stress disorder and primary headache disorders exists and could be complicated by the contribution of physical injury, especially one that results in loss of consciousness. These associations have not been systematically examined in Operation Iraqi Freedom and Operation Enduring Freedom veterans. Methods.— In this observational cross‐sectional study, a battery of self‐report, standardized questionnaires was completed by 308 newly registered veterans between March and October 2006. The Davidson Trauma Scale was used to determine the degree of posttraumatic stress disorder symptoms and combat‐related physical injury was assessed by self‐report. The presence of headache was based on a symptom checklist measure and self‐reported doctor diagnoses. Logistic regression analysis was performed to predict presence of headache and determine odds ratios and 95% confidence intervals associated with demographic, military, in‐theatre, and mental health characteristics. Results.— About 40% of the veterans met the criteria for posttraumatic stress disorder; 40% self‐reported current headache, 10% reported a physician diagnosis of migraine, 12% a physician diagnosis of tension‐type headache, and 6% reported both types of headache. Results from the logistic regression model indicated that combat‐related physical injury (odds ratio: 2.25; 95% confidence interval: 1.17‐4.33) and posttraumatic stress disorder (odds ratio: 4.13; 95% confidence interval: 2.44‐6.99) were independent predictors of self‐reported headache. Additional analyses found that veterans with both tension and migraine headache had higher rates of posttraumatic stress disorder (chi‐square [d.f. = 3] = 15.89; P = .001) whereas veterans with migraine headache alone had higher rates of combat‐related physical injury (chi‐square [d.f. = 9] = 22.00; P = .009). Conclusion.— Posttraumatic stress disorder and combat‐related physical injury were related to higher rates of self‐reported headache in newly returning veterans. Our finding that posttraumatic stress disorder and injury during combat are differentially related to migraine and tension‐type headache, point to a complex relationship between physical and psychological trauma and headache. These findings have implications for a comprehensive approach to interventions for headache and the physical and psychological sequelae of trauma.     

Diffuse and spatially variable white matter disruptions are associated with blast-related mild traumatic brain injury

Mild traumatic brain injury (mTBI) due to explosive blast is common among military service members and often associated with long term psychological and cognitive disruptions. Little is known about the neurological effects of blast-related mTBI and whether they differ from those of civilian, non-blast mTBI. Given that brain damage from blasts may be diffuse and heterogeneous, we tested the hypothesis that blast mTBI is associated with subtle white matter disruptions in the brain that are spatially inconsistent across individuals. We used diffusion tensor imaging to examine white matter integrity, as quantified by fractional anisotropy (FA), in a group of American military service members with (n = 25) or without (n = 33) blast-related mTBI who had been deployed as part of Operation Iraqi Freedom or Operation Enduring Freedom. History of civilian non-blast mTBI was equally common across groups, which enabled testing of both blast and non-blast mTBI effects on measures sensitive to (1) concentrated, spatially consistent (average FA within a region of interest [ROI]), (2) concentrated, spatially variable (number of ROIs with low average FA), and (3) diffuse (number of voxels with low FA) disruptions of white matter integrity. Blast mTBI was associated with a diffuse, global pattern of lower white matter integrity, and this pattern was not affected by previous civilian mTBI. Neither type of mTBI had an effect on the measures sensitive to more concentrated and spatially consistent white matter disruptions. Additionally, individuals with more than one blast mTBI tended to have a larger number of low FA voxels than individuals with a single blast injury. These results indicate that blast mTBI is associated with disrupted integrity of several white matter tracts, and that these disruptions are diluted by averaging across the large number of voxels within an ROI. The reported pattern of effects supports the conclusion that the neurological effects of blast mTBI are diffuse, widespread, and spatially variable.     

The Effect of Concussion History on Lower Extremity Injury Risk in College Athletes: A Systematic Review and Meta-Analysis

IntroductionCollegiate athletes who suffer a concussion may possess prolonged impairments even after clearance for return-to-participation, which may place them at an increased risk of lower extremity injury.ObjectiveTo conduct a systematic review and meta-analysis of studies examining risk of lower extremity musculoskeletal injury following a concussion in collegiate athletes.MethodsA literature search was performed using the following databases: PubMed, CINAHL, SPORTDiscus. The following search terms were used to identify relevant articles, [“concussion” OR “brain injury” OR “mild traumatic brain injury” OR “mTBI”] AND [“lower extremity injury” OR “musculoskeletal injury”]. Articles were included if they were published between January 2000 and July 2021 and examined collegiate athletes’ risk of sustaining a lower extremity musculoskeletal injury following a concussion. Methodological quality of included studies was performed with a modified Downs and Black Checklist. The primary outcome of interest was the risk of sustaining a lower extremity musculoskeletal injury following a concussion. A random effects meta-analysis was conducted in which a summative relative risk (RR) for sustaining a lower extremity injury in athletes with and without a history of concussion was calculated.ResultsSeven studies met the eligibility criteria to be included in the systematic review. There were 348 athletes in the concussion group and 482 control athletes in the included studies. Most of the studies were of good or excellent quality. Five of the seven studies were able to be included in the meta-analysis. College athletes who suffered a concussion possessed a 58% greater risk of sustaining a lower extremity musculoskeletal injury than those who did not have a history of a concussion (RR = 1.58[1.30, 1.93]).ConclusionsLower extremity injury risk is potentially increased in college athletes following a concussion compared to those without a history of a concussion. Further research is needed to investigate the mechanism behind this increased risk. Clinical assessments throughout the concussion return-to-play protocol may need to be improved in order to detect lingering impairments caused by concussions.Level of Evidence1