Category Archives: Brain Injury News and Research

Faking Mild Traumatic Brain Injury

In the October, 1996, we reported on a study1 that found that college students could not convincingly mimic the symptom profile for whiplash injuries. A new study2 examined the ability of another group of college students to malinger either multiple sclerosis (MS) or mild traumatic brain injury (MTBI).

The authors effectively summarize the problem of malingering in their introduction:

“In recent years, researchers have been examining the ability of neuropsychologists to detect malingering. The detection of malingering is of obvious importance in the context of the limited resources available for those in need of medical and rehabilitative services. Its significance also is evident in the growing number of legal claims that follow injuries in the workplace, moving vehicle accidents, and other compensable circumstances. Clinicians are increasingly being called upon to make judgments regarding the effort and performance of litigating clients.” 2

In this current study, 69 college students were divided into three groups: a group that was to malinger MS; a group that was to fake MTBI; and a control group that was asked to simply take the tests without faking any condition.

The malingering students were in turn divided into two more groups: one set of students were given an informational packet about their “condition,” and another group given no information. All of the subjects were given five minutes to plan their strategy for faking their condition.

All of the students were then run through a battery of neuropsychological tests used to measure MS and MTBI in legitimate patients.

Upon studying the resulting data, the researchers reported some interesting findings:

  • There was no significant difference between the students who were informed or uninformed about the condition they were to fake. Being informed about the condition did not assist them in malingering.
  • There was no significant difference between the MS and MTBI group of students—they all faked their conditions in the same manner, with no distinction for condition. For instance, both MS and MTBI have particular patterns of neuropsychological findings: “On measures of conceptual reasoning, the literature predicts significant MS population deficits but little or no deficits in the mild TBI population…On measures of span memory/attention, the literature predicts difficulties in the mild TBI groups yet no impairments observed in the MS groups…” None of these distinctions or patterns were found in the students asked to malinger these conditions.
  • The students consistently exaggerated the possible dysfunction and number of symptoms, as compared to what a group of physicians considered appropriate for the particular condition.
  1. Wallis BJ, Bogduk N. Faking a profile: can na�ve subjects simulate whiplash responses? Pain 1996;66:223-227.
  2. Klimczak NJ, Donovick PJ, Burright R. The malingering of multiple sclerosis and mild traumatic brain injury. Brain Injury 1997;11(5):343-352.

Post-Concussion Syndrome After Mild Traumatic Brain Injury

The purpose of this study was to investigate the relationship between Post-Concussion Syndrome (PCS) and posttraumatic stress disorder (PTSD) in a population of motor vehicle accident survivors. The authors anticipated finding more PCS in MTBI individuals with concurrent PTSD than in TBI patients without PTSD. Their hypothesis was that the additional cognitive load of anxiety and intrusive symptoms of PTSD influenced MTBI patients’ experience of PCS.

The population was divided into two groups, one group of 46 with MTBI, and one group of 59 with no TBI. Assessment for PTSD and PCS was done for both groups six months post-trauma. A clinical psychologist conducted the assessment using the PTSD module from the Composite International Diagnostic Interview (CIDI). The authors also administered a postconcussive symptom checklist requiring patients to report the presence or absence of postconcussive symptoms consisting of: dizziness, fatigue, headaches, irritability, sensitivity to light, sensitivity to sound, concentration deficits and visual disturbances.

MTBI patients with chronic PTSD reported more concentration deficits, dizziness, fatigue, headaches, sensitivity to sound and visual disturbances than MTBI patients not suffering from PTSD. Additionally, the presence of concentration deficits, dizziness, fatigue, headaches, irritability, and visual disturbances was significantly linked with the severity of PTSD. The authors surmise that their findings add to the growing body of literature linking psychological and neurological factors to PCS:

“It is possible that the heightened anxiety and cognitive load experienced by PTSD patients resulted in greater demands on their cognitive resources, and this may have contributed to PCS. This interpretation is indicated by the finding that persistent PCS were associated with the severity of intrusive, avoidance, and arousal symptoms. Intrusive and avoidance symptoms cannot be readily attributed to neurological factors. Accordingly, this finding suggests that the degree of posttraumatic stress experienced by MTBI patients contributed to persistent PCS. The presence of this pattern in the MTBI sample but not in the non-TBI sample indicates that heightened posttraumatic stress compounded the neurological effects of the MTBI. This pattern accords with Rutherford’s (1989) view that PCS is mediated by an interaction of psychological and neurological factors. This study did not obtain neuropsychological data, and the role neurological factors could be more rigorously indexed in future studies by investigating the role of cognitive deficits in the relationship between PCS and PTSD after MTBI.”

The authors conclude:

“These findings point to the importance of PTSD in the development and maintenance of PCS. Considering the potential impairment caused by both PTSD and PCS, these findings indicate that rehabilitation of MTBI individuals needs to recognize that effective management of PCS may be facilitated by addressing the symptoms associated with PTSD.”

  1. Bryant RA, Harvey AG. Postconcussive symptoms and posttraumatic stress disorder after mild traumatic brain injury. Journal of Nervous and Mental Disease 1999;187(5):302-305.
  2. Peters L, Andrews G, Cottler LB, Chatterji S, Janca A, Smeets, RMW. The composite international diagnostic interview post-traumatic stress disorder module: Preliminary data. International Journal on Methods ofPsychiatric Research 1996;6:167-174.

Aggressive Behavior after Brain Injury

Traumatic brain injury (TBI) is a complex issue for a variety of reasons. First, many cases of TBI go undiagnosed for months or even years. Since patients with head injuries often times have other injuries, the brain trauma may not receive the attention it deserves.

Another problem with head injury is that it often results in psychological symptoms that can complicate the diagnosis and treatment. Traumatic brain injury can result in depression, changes in personality, anxiety, paranoia, or apathy. One of the most frustrating and challenging symptoms is aggression.

The authors of a current study on aggression after brain injury stated the problem succinctly:

“Associations between TBI and neuropsychiatric disorders have been recognized for many years. Aggressive behavior is one of the most socially and vocationally disruptive consequences of these neuropsychiatric disorders. Aggression endangers the safety of patients, families, and caregivers. It may prevent patients from receiving the care that they need and disrupt their rehabilitation process. Estimates of the frequency of aggressive behaviors during the acute period after TBI have ranged from 11% to 96%.”

In this study, the researchers assessed 89 patients with TBI and 26 patients with multiple traumas, but without TBI. All of the TBI patients in the study had post-traumatic amnesia that lasted at least 30 minutes.

Aggressive behavior was assessed with the Overt Aggression Scale (OAS). The OAS allows clinicians to quantify aggression by defining four categories of aggressive behavior: verbal aggression, physical aggression against objects, physical aggression against self, and physical aggression against others. All patients also received a thorough psychiatric assessment. The authors found the following:

Aggression After Brain Injury
The frontal lobe (shown here in blue) regulates higher “executive” functions of the brain, such as conscious thought, memory, intelligence, concentration, behavior, and personality. Injury to the frontal lobe can result in aggression in some patients.
  • Patients with TBI were much more likely to exhibit aggression. In the TBI group, 33.7% met the criteria for aggressive behavior in the first six months after injury, while only 11.5% of the non-TBI patients did.
  • Within the TBI group there were no significant differences between the aggressive and the non-aggressive groups in age, gender, race, years of education, socioeconomic status, or history of anxiety disorder.
  • There was a strong relationship between depression and aggression: of the 30 aggressive patients, 17 also met the criteria for major depression.
  • Aggressive patients also suffered from poorer social functioning.
  • Patients with aggressive behavior were more likely to have injuries to the frontal lobe. While non-aggressive patients were more likely to have diffuse brain injuries.
  • Patients with aggressive behavior had a significantly higher frequency of legal interventions for aggressive behavior prior to the brain injury, and were more likely to have a history of drug or alcohol abuse.

Clearly, patients with a history of closed head injury and aggressive behavior are at a disadvantage when it comes to receiving proper treatment and vocational rehabilitation. The authors of this current study conclude:

“In summary, aggression following TBI is associated with multiple biological and psychosocial factors, including major depression, substance abuse, and impaired social function as well as the presence of brain injury involving the frontal lobe. These findings suggest that interventions aimed at treating major depression or substance abuse and improving social function may help reduce episodes of aggression in patients who have suffered traumatic brain injury.”

Clinical Implications

Aggression after an injury may be due to brain damage. Patients that show signs of aggression should be carefully evaluated for the existence of head injury, and proper treatment should be sought out.

Tateno A, Jorge RE, Robinson RG. Clinical correlates of aggressive behavior after traumatic brain injury. Journal of Neuropsychiatry and Clinical Neurosciences 2003;15:155-160.

What Gets Patients to Work Sooner After Brain Injury?

What Gets Patients to Work Sooner After Brain Injury?Vocational rehabilitation has proven to be successful in helping patients return to work after brain injury, but is it worth the cost? It’s easy to assume additional appointments with therapists and specialists could cause patients to rack up medical bills, but few studies have actually taken the time to analyze the cost-efficacy of such treatments.

In a new study, researchers from the UK studied 94 patients admitted to Nottingham hospitals within 48 hours post brain injury, and monitored their progress for the next 15 months. Half of the patients received vocational rehabilitative (VR) treatments that included individualized interdisciplinary care provided by a team of nurses, occupational therapists, and neuro-pyschologists. The researchers analyzed patient progress and compared their results to patients under usual care (UC).

  • At three months, 37% more VR patients had returned to work compared to UC patients. Although most usual care patients were working after one year, there were still 10% more VR patients working compared to UC patients.
  • VR patients were less likely to claim welfare benefits after 12 months.
  • There were no differences in return to work in those claiming and not claiming compensation.
  • Usual care patients stayed in the hospital an average of 11 days longer than VR patients.

The vocational rehabilitation patients did see specialists more frequently but not by a significant amount. That meant there were no major differences in treatment costs between the groups.

  • VR patients spent about £75.23  more than the UC patients (about the cost of one occupational therapy session in the UK or $126.91 USD).
  • When considering lost wages due to missed work days, UC patients were at a disadvantage. As a result, when taking into account this broader perspective, VR patients had an average annual savings of £1,862 per person($3141.01 USD).

In addition to preventing lost wages, VR patients were more likely to stay working when they returned to their jobs, instead of dropping out due to lack of support. Those with moderate to severe injuries benefited the most from VR treatments, but even mild TBI patients had better outcomes with VR. That suggests that even those with mild TBI can struggle with reintegrating into the workplace after the injury.

These findings suggest possible treatment options that could aide in the rehabilitation efforts for thousands of soldiers suffering from mild traumatic brain injuries, now called the signature wound of war.

Reference

Radford K, et al. Return to work after traumatic brain injury: cohort comparison and economic evaluation. Brain Injury 2013: 27(5): 507-520.

MRI Confirms Brain Damage From “Heading” Soccer Ball

Photo courtesy of Creative Commons

Athletes using their head to move a soccer ball: It is called “heading,” and it is quite common. During competitive games, each soccer player averages six to 12 headings every game, with the ball moving up to 50 miles an hour. Players often perform the maneuver during practice time as well, with up to 30 rapid-succession headings a typical practice drill.

A recent study suggested that soccer players who head the ball may suffer impaired thinking abilities. That research included teen female soccer players subjected to cognitive tests.

New research published in the journal Radiology goes even further to show that this common maneuver injures a player’s brain, using MRI brain scans and a different demographic group as participants.

Researchers recruited 37 amateur soccer players with the average age of 31 who had played soccer an average of 22 years. They sought data about the long-term damage that may result from the small but repeated impacts to the head that are caused by heading the soccer ball. They sought to identify a threshold above which injury and cognitive problems might be detectable.

Participants were questioned about their headings over the previous year, performed neurocognitive tests, and were given MRI scans of the brain.

The study found that soccer players who repeatedly head the ball had lower performance on neurognitive testing and changes in their brain microstructure. These findings suggested that using the head to move the soccer ball may indeed lead to long-term brain injury.

The MRI scans detected three areas of white matter in the brain with lower fractional anisotropy. “We were able to detect changes to the microscopic structure of what’s essentially the brain’s wiring, the white matter axons,” head researcher Michael Lipton told MedPage Today for an article about the study.

The threshold that researchers found was a range of 885 to 1,550 headings per year; players who headed the ball in or above that range were most likely to suffer the damage visible on the brain scans.

The number of headings also affected the players in the area of memory. The threshold for this impairment was slightly higher; players heading the ball about 1,800 times per year were at risk for memory loss.

While the researchers were able to identify some safety thresholds, they also found that in a subset of the study participants, brain changes were seen even below the identified thresholds. This suggested that some players may be particularly vulnerable to brain injury from heading the ball. Why this is the case was not clear, but the study authors urged further research to identify a possible genetic cause of susceptibility.

Unexpectedly, these findings were not associated with prior concussion. However, the brain damage was consistent with damage seen in patients with traumatic brain injury. Another surprise that was revealed by the research was the site of the injury, which was on the opposite side of the head as the impact with the ball. The researchers wrote, “We interpret this an analogous to the phenomenon of contrecoup injury, which occurs opposite the site of impact in contusional brain injury.” They also noted that it is likely that other areas of the brain were damaged by heading the ball, but the changes were too subtle to be detected by MRI.

More research will be needed to confirm these results and more clearly establish safety thresholds, as this study was limited by its small sample size, lack of data about ball velocity and location of head impact, and the reliance on fractional anisotropy measurements for imaging. Further research may use other types of MRI studies to reveal more about mechanisms and effects.

This future work could be used to recommend safety measures analogous to “pitch counts” for baseball players, determining how many headings an individual soccer player can perform before being required to rest and recover.

References

Lipton M, Kim N, et al. Soccer heading is associated with white matter microstructural and cognitive abnormalities. Radiology (published online before print June 11, 2013). doi: 10.1148/radiol.13130545.

Walsh Nancy. ‘Heading’ soccer ball injures brain. MedPage Today (online June 11, 2013). www.medpagetoday.com/Neurology/HeadTrauma/39725.

Previous Head Injury Slows Concussion Recovery

Previous Head Injury Slows Concussion RecoveryConcussions and other mild brain injuries are becoming more and more common among children and adolescents. Some suspect that this is due to the increasing aggressiveness and competition involved in sporting activities, during which many of these injuries are occurring.

A new study has demonstrated one of the effects of these frequent head injuries. When a child has already suffered a mild traumatic brain injury, and then sustains another one, their recovery time is longer and their symptoms last longer.

Researchers from Harvard Medical School enrolled 280 young patients who were seen in a hospital emergency department for concussion. The average age of the injured youths was 14 years old, and more than half were boys. Almost two-thirds of the participants were injured during sports such as hockey, soccer, and football. The most common concussive symptom was headache, followed by fatigue and dizziness.

They found that concussion recovery time was doubled for kids who had a history of at least one previous concussion, in comparison to kids with no previous head injury. They also discovered that the time period of symptoms nearly tripled for the kids whose previous injury was less than 12 months ago.

The majority of the young patients were discharged from the emergency department with instructions for “cognitive rest”. More than 90% were advised to take time off from sports activities.

The need to avoid additional head injuries was reinforced by this study’s findings. Kids who have suffered a concussion should take extra precaution not to sustain an additional concussion, especially within a year after their injury. While many health-care providers have long given this advice, this research shows why the extra precaution is necessary.

When the researchers conducted an analysis of the variables that predicted a longer concussion recovery, they found more risk factors than a previous concussion. They also found that healing from concussive symptoms took longer for the older patients above age 13 as well as the children with more severe symptoms at time of brain injury. The researchers suggested that the older children likely took longer to get better due to the higher intensity of play and greater player contact in their sports, compared to the younger children.

The authors of the study concluded that their findings had “direct implications on the management of athletes and other at-risk individuals who sustain concussions, supporting the concept that sufficient time to recover from a concussion may improve long-term outcomes.”

The research team did note that their study was limited by their method of collecting data about symptoms, through participants’ self-reporting. As previous research has found, young athletes are often reluctant to report symptoms of brain injury because they want to resume their sport. They also wrote that other patients may have reported symptoms that were no longer present as a means to avoid schoolwork.

Another previous study also found that being overly cautious about head injuries and taking time to properly diagnose concussion can help keep young athletes safe from more serious damage from brain injury.

Reference

Eisenberg M, Andrea J, Meehan W, Mannix R. Time interval between concussions and symptom duration. Pediatrics June 10, 2013 (online). doi: 10.1542/peds.2013-0432.

 

 

 

Bright Light Therapy for Treating Mild TBI

Bright Light Therapy for Treating Mild TBINew research has suggested that bright light therapy may have positive outcomes for patients suffering from sleep problems and cognitive, emotional, and brain dysfunction following mild traumatic brain injury (TBI).

It has been estimated that at least half of all individuals with TBI experience some form of sleep disturbance following their brain injury. This is especially problematic considering the importance of sleep in increasing brain plasticity and bettering the likelihood for  recovery from TBI.

Participants included 18 adults with at least one documented mild TBI in addition to sleep disturbances. Researchers recruited patients who reported that their sleep problems either emerged from or were aggravated by their brain injury.

The effects of light therapy were analyzed, using Multiple Sleep Latency Tests, sleep diaries, and monitored sleep sessions. Each patient also underwent MRI and comprehensive psychiatric and neuropsychological assessments before and after the bright light therapy.

Patients were treated with six weeks of morning bright light therapy. Their daytime sleepiness decreased and their nighttime sleep quality improved. Researchers also found that patients treated with the light therapy had improvements for symptoms of depression.

“Our preliminary data suggests that morning bright light therapy might be helpful to reduce subjective daytime sleepiness and to improve nighttime sleep,” said researcher Mareen Weber, PhD. “Importantly, the research also shows changes in brain activation during a demanding cognitive task, suggesting that bright light treatment might yield changes in brain functioning.”

Light therapy is easy to facilitate and is minimally invasive. It has virtually no side effects and may help patients avoid the risks of dependency and other problems associated with sleeping pills.

Reference

American Academy of Sleep Medicine. Improving sleep and promoting recovery in patients with mild TBI suing bright light therapy. Medical News Today; June 3, 2013. www.medicalnewstoday.com.

 

 

 

New Study Reveals Brain Can Rewire Itself After TBI

New Study Reveals Brain Can Rewire Itself After TBINew research has uncovered more about how the brain compensates after a head injury or trauma. Scientists are hopeful that the new findings may result in advancements in treating a variety of health problems.

Many brain scientists have followed the thinking that when a brain injury occurs, other areas of the brain may compensate for the damaged parts. However, until this study, it was not understood how this happens.

In a UCLA news release about the discovery, the team of scientists further discussed what they found, and what it might mean for the future of neuroscience.

The group has identified the section of the brain that takes over function when the hippocampus is damaged. The hippocampus is the “learning center” of the brain, and some types of brain injury may result in a disability in this region. According to this new research, when that happens, other brain parts in the prefrontal cortex have the ability to take over the function of the hippocampus.

The researchers at UCLA labeled their findings as a “breakthrough discovery,” saying that the new knowledge could help develop new treatments for Alzheimer’s disease, stroke, and other types of brain injury.

The study involved laboratory rats with injury to the hippocampus region of their brains. Although they needed additional training compared to uninjured rats, the lab rats with brain damage were able to learn new problem-solving tasks. While this kind of success was once believed to be a result of the brain’s hippocampus repairing itself to a degree, with studies revolving around how to stimulate this repair, this new research revealed that other regions of the brain were actually responsible.

In studying the brains of the rats, the scientists were able to identify changes that took place in the prefrontal cortex. They observed that new brain circuits were created to compensate for the brain injuries. The brains actually rewired themselves.

UCLA’s Michael Fanselow, who led the research team, explained more about the process in the May 15 news release. “The brain is heavily interconnected — you can get from any neuron in the brain to any other neuron via about six synaptic connections,” he said. “So there are many alternate pathways the brain can use, but it normally doesn’t use them unless it’s forced to. Once we understand how the brain makes these decisions, then we’re in a position to encourage pathways to take over when they need to, especially in the case of brain damage.”

This could mean major advancements in treatment for brain injury involving learning or memory issues.

Reference

Fanselow M, Zelikowsky M, Vissel B, et al. Prefrontal microcircuit underlies contextual learning after hippocampal loss. Proceedings of the National Academy of Sciences of the Untied States of America. Published online before print May 15, 2013. doi: 10.1073/pnas.1301691110.

Heather A. Brain rewires itself after damage or injury, life scientists discover. UCLA Newsroom. Online May 15, 2013.

 

Multiple Brain Injuries = Greater Suicide Risk

Multiple Brain Injuries = Greater Suicide Risk People with a history of multiple concussions have greater risk of suicidal thoughts than people with only one or no concussions, according to a new study.

The study showed that soldiers who had multiple traumatic brain injuries were three times more likely to have suicidal thoughts compared to soldiers who had only a single TBI.

Suicide is now the second most common cause of death in the military. In 2008, there were 16 suicides per 100,000 service members. That represented a 50% increase in suicides since 2001, according a study from the RAND corporation.

Traumatic brain injuries are likely behind the rising suicide rates as more soldiers suffer from the signature wound of war, the researchers explained in the study published in the journal JAMA Psychiatry. Although TBIs have been linked to suicide, it was unclear whether having cumulative concussions lead to greater risks, according to lead author Craig Bryan, PsyD, of the University of Utah National Center for Veterans’ Studies.

Bryan and his colleagues studied 157 service members and 4 contractors who were treated at a military hospital in Iraq for suspected brain injuries. Eighteen soldiers said they’d never been diagnosed with a TBI in the past, 58 had been diagnosed with one TBI previously, and 85 had experienced multiple brain injuries in their lifetime. Most TBIs were mild.

Patients without a history of previous concussions did report having suicidal thoughts. In soldiers who had a single previous concussion, 6.9% reported having suicidal thoughts at some point in their life, and 3.4% had such thoughts in the past year. The numbers were much greater for soldiers with cumulative concussions: 21.7% reported lifetime suicidal thoughts and 12% reported having suicidal thoughts in the previous year. The more concussions a solider had, the greater their risk was for suicidal thoughts, even after adjusting for depression, PTSD, and injury severity.

Although the study was limited to soldiers, Bryan said their results may have implications for other groups at risk of multiple concussions, like athletes. Brain injuries in football and other contact sports have received increasing attention in the past few years, as more athletes suffer from depression and cognitive deficits associated with multiple TBIs.

However, the study doesn’t imply that concussions cause suicidal thoughts, Bryan explained to the Chicago Tribune. The majority of soldiers with TBI didn’t report suicidal thoughts in his study. Furthermore having suicidal thoughts doesn’t necessarily mean someone will commit suicide, especially if adequate treatments are available.

Growing suicide rates in soldiers led 53 congressmembers to send a letter to Defense Secretary Chuck Hagel and Veterans Affairs Secretary Eric Shinseki, asking them to investigate the link between IED-blast brain injuries and suicides.

“As we prepare to bring 34,000 troops home from Afghanistan this year and the entirety of the 66,000 members strong force by the end of 2014, we must gain a better understanding of the psychological impact of injuries from IEDs,” they wrote.

Reference

Bryan C, et al. Repetitive traumatic brain injury, psychological symptoms, and suicide risk in a clinical sample of deployed military personnel. JAMA Psychiatry 2013; 1-6. doi:10.1001/jamapsychiatry.2013.1093.

Some Children At Greater Disability Risk From Brain Injury

Some Children At Greater Disability Risk From Brain InjuryIt is tragic when children and teens suffer a traumatic brain injury (TBI). All too often, such injuries result in disability and reduced quality of life, with the devastating effects sometimes lasting the victim’s lifetime.

A new study published in the journal Pediatrics examined the disparities in disability in certain young populations after TBI. Researchers compared the extent of disability in life functions between Hispanic and non-Hispanic white children.

Children and adolescents younger than 18 years old with either a mild, moderate, or severe TBI diagnosis were included. There were 74 Hispanic participants and 457 non-Hispanic participants. The study included measures of health-related quality of life, adaptive skills, and participation in activities. The patients were examined at 3, 12, 24, and 36 months after their brain injury, and their functional levels were compared to their abilities before the injury was sustained.

Sadly, all the children in the study suffered a lower health-related quality of life as a result of their injuries, but some had a better prognosis than others. The disparity lied in comparing the two groups. The non-Hispanic patients showed a greater improvement during the first three years after their injuries, but the Hispanic patients were at a higher risk of lasting impairments.

The study authors also noted that there were significant differences with disability in the domains of communication and self-care, with the Hispanic participants more likely to have problems in these areas. There was also a disparity among the children regarding participation in activities, although the difference was only observed at the examination three months after injury.

The researchers concluded that Hispanic children report larger and longer-term disabilities as a result of traumatic brain injuries, compared to non-Hispanic white children. But what is the reason for the disparity? Further research is needed before interventions can be employed to improve the outcomes for all young brain injury victims.

Former research about TBI has shown that children are particularly susceptible to long-term disability and noted that many kids face a lifelong recovery process.

Reference

Jimenez N, Ebel BE, et al. Disparities in disability after traumatic brain injury among Hispanic children and adolescents. Pediatrics 2013 May 6. [Epub ahead of print]. http://www.ncbi.nlm.nih.gov/pubmed/23650302.