Neuropsychological dysfunction following repeat concussions in jockeys

BACKGROUND: Single and repeat concussions have a high prevalence in sport. However, there is limited research into longterm risks associated with single and repeat concussions. OBJECTIVES: To determine the effects of single and repeat historical concussions on the neuropsychological functioning and neurological reports of licensed jockeys. METHODS: Six hundred and ninety eight licensed jockeys in the UK were assessed for neurological and neuropsychological symptoms of concussion at least three months after potential episodes. RESULTS: Jockeys reporting multiple historical injuries versus a single injury showed reliable decrements on a measure of response inhibition and, to a less robust degree, on divided attention. Younger adults showed greater vulnerability. CONCLUSIONS: Repeated concussion is associated with reliable decrements in cognitive performance--even after a three month window for recent recovery.     

Sleep structure following status epilepticus

OBJECTIVES: To determine the effect of status epilepticus (SE) on sleep. BACKGROUND: SE has a high incidence of morbidity and mortality. The study of sleep structure following SE may have implications for recovery in these patients. METHODS: Twenty-four hour polysomnography was recorded in a 52-year-old patient following generalized convulsive SE not complicated by other medical or neurologic conditions. Another patient with no known history of seizures was recorded under similar conditions. RESULTS: The first day following SE was associated with markedly abnormal sleep structure, consisting largely of stage 1 with minimal slow wave or REM sleep. Over 4 days, slow wave and REM returned to normal values and no rebound was seen. The control patient demonstrated normal sleep parameters for their age, demonstrating that sleep disruption was not due to recording conditions alone. CONCLUSIONS: This case demonstrates that sleep structure is markedly abnormal following generalized convulsive SE. As sleep may serve a restorative function, improving sleep postictally may hasten or improve recovery. Larger studies will be required to determine whether this is a common finding in such patients, and whether outcome is associated with improved sleep quality.     

Sleep changes following intensive cognitive activity

Studies over the last 40 years have mainly investigated sleep structure changes as a result of wake duration, in the frame of the classical sleep regulation theories. However, wake intervals of the same duration can profoundly differ in their intensity, which actually reflects the degree of cognitive and physical activity. Data on how sleep can be modified by wake intensity changes (initially sparse and of little consistence) have become much more substantial, especially in the frame of the intense research debate on sleep-memory relationships. Our aim is to examine the vast repertoire of sleep modifications that depend on waking cognitive manipulations, highlighting the sleep features that appear most affected. By systematically addressing this issue, we want to set the basis for future research exploring both the specific nature of the mechanisms involved and the applicative psychosocial and clinical fall-outs, in terms of possible behavioural interventions for sleep quality improvement.     

Sleep apnea following percutaneous cervical cordotomy

Sleep apnea (Ondine's Curse) is an uncommon but potentially fatal complication of percutaneous cervical cordotomy. The authors have had the opportunity to review the case histories of 6 patients who have died of sleep apnea following this procedure. In a series of 112 patients, 144 cervical percutaneous cordotomies were performed from 1977 to 1985--80 unilateral cordotomies and 32 staged bilateral cordotomies. Six (5%) patients died as the result of sleep apnea. Five patients (16%) died following bilateral cordotomy and one (1%) patient with pulmonary disease died following unilateral cordotomy. The clinical data of these 6 patients are presented and unique spinal cord pathology is described in this report. The pathophysiology of the sleep apnea syndrome is also discussed.     

Early EEG in 300 cerebral concussions

The EEGs of 300 concussed patients were examined at the last 48 h after trauma; 166 were younger than 20 years old and 134 were between 20 and 40 years old. Amongst the youngest group 145 cases had a benign concussion with 24% alterations, and 21 cases had a mild concussion with 81% alterations. Amongst the oldest group, 93 cases had a benign concussion with 15% alterations and 41 cases had a mild concussion with 41% alterations. The mostly transient EEG abnormalities are slowing, focal abnormalities or generalized bursts. Slowing is the most frequent abnormality in the youngest and focal abnormalities are most frequently observed in the mild concussion group.     

Sleep disturbance and deficits of sustained attention following stroke

Objective: To simultaneously investigate the prevalence of and impact that the poststroke complications of daytime sleepiness, poor sleep quality, depression, and fatigue may be having upon deficits of sustained attention, as assessed using the Psychomotor Vigilance Task (PVT). Method: Twenty-two patients with stroke (mean age: 68.23 ± 12.17 years) and 20 healthy control participants (mean age: 68.1 ± 9.5 years) completed subjective measures of daytime sleepiness, sleep quality, fatigue, and depression and an objective measure of sustained attention as assessed using the PVT. Results: Patients with stroke compared to controls showed heightened levels of fatigue (p = .001, η² = .29) and depression (p = .002, η² = .23), plus greater deficits of sustained attention as reflected by poorer performance across all PVT outcome measures including: slower mean reaction times (p = .002, η² = .22); increased number of lapses (p = .002, η² = .24); and greater variability in reaction time (RT) responses (p = .016, η² = .15). Reaction time distribution analysis suggested that daytime sleepiness and sleep quality had little influence across PVT performance; however, depressive symptomology was associated with longer RT responses, indicative of inattention, and fatigue impacted upon the entire distribution of PVT responses. Conclusions: PVT performance illustrated significant deficits across the domain of sustained attention for patients with stroke in comparison to healthy controls, in terms of inattention as well as slower sensory–motor speed. The common poststroke complications of depressive symptomology and fatigue appear to be associated with these deficits in sustained attention, warranting further investigation.     

Defining a multimodal signature of remote sports concussions

Sports‐related concussions lead to persistent anomalies of the brain structure and function that interact with the effects of normal ageing. Although post‐mortem investigations have proposed a bio‐signature of remote concussions, there is still no clear in vivo signature. In the current study, we characterized white matter integrity in retired athletes with a history of remote concussions by conducting a full‐brain, diffusion‐based connectivity analysis. Next, we combined MRI diffusion markers with MR spectroscopic, MRI volumetric, neurobehavioral and genetic markers to identify a multidimensional in vivo signature of remote concussions. Machine learning classifiers trained to detect remote concussions using this signature achieved detection accuracies up to 90% (sensitivity: 93%, specificity: 87%). These automated classifiers identified white matter integrity as the hallmark of remote concussions and could provide, following further validation, a preliminary unbiased detection tool to help medical and legal experts rule out concussion history in patients presenting or complaining about late‐life abnormal cognitive decline.     

Sleep suppression following kainic acid-induced lesions of the basal forebrain

We have described elsewhere neurons in the ventral basal forebrain of cats that have elevated discharge rates during sleep and during transitions from waking to sleep, yet have comparatively low discharge rates during waking. These sleep-active neurons may mediate the hypnogenic properties of the basal forebrain. To further evaluate their role in the control of sleep, we examined the effects of basal forebrain lesions produced by microinjections of the relatively cell-selective neurotoxin, kainic acid, on sleep. Lesions were made bilaterally in two regions that contain high densities of sleep-active neurons: the horizontal limb of the diagonal bands of Broca and the lateral preoptic area-substantia innominata. Twelve-hour polygraph recordings were made before and at various intervals after basal forebrain damage in a total of eight cats. The lesions resulted in reduced time spent in deep, nonrapid eye-movement sleep and REM sleep, and increased time spent awake. These abnormalities persisted through 6 to 7 weeks postlesion. Reductions in deep non-REM sleep were due to decreases in bout number, particularly in the number of extended deep non-REM episodes (i.e., those greater than 5 min in duration). The number of REM sleep episodes was also significantly reduced. The average duration of epochs of waking was elevated throughout the postlesion period. Thus, in the postlesion period, cats exhibited an impaired ability to initiate and maintain consolidated periods of sleep, particularly of deeper sleep stages. Lesions were also associated with reduced EEG spindling during sleep. These results are consistent with our hypothesis that sleep-active neurons are a component of a basal forebrain sleep- and EEG-regulating mechanism.     

Sleep problems in children and adolescents following traumatic life events

Rates of childhood trauma exposure are extremely high, with approximately 70% of children and adolescents experiencing at least one traumatic event. Among the most common non-specific consequences of stress and trauma are disruptions of sleep. Sleep problems, such as shorter sleep duration, difficulty falling asleep, frequent awakenings, nightmares, sleepless nights, and early-morning wakefulness appear to have a higher prevalence among children and adolescents following traumatic events. This review will illustrate the role of sleep problems in traumatized children and adolescents, and emphasize the need to consider a wide range of etiological mechanisms for these symptoms. However, the relationship of trauma exposure to sleep problems among children and adolescents needs further investigation in future research. Moreover, in view of the adverse consequences of long-term disrupted sleep on mental health outcomes following trauma, the need to effectively address sleep disturbances in traumatized children and adolescents is crucial.     

EEG and brain-stem evoked potentials in 125 recent concussions

EEG and ipsi/contralateral BEPs have been recorded in 125 cases of concussion at most 48 h after the cerebral trauma. In 100 cases of minor concussion the temporary loss of consciousness lasted not more than 2 min. In 25 cases of mild concussion, the loss of consciousness lasted until their arrival at the hospital. In minor concussions an abnormal EEG was found in 17% of the cases and in mild concussions, in 56%. The abnormalities of the BEP, more often seen in mild concussions (60%) than in minor concussions (8%), are an increase of interpeak latencies or distorted responses with average to bad reproducibility. The results are discussed.     

Brain function associated with reaction time after sport-related concussion

Brain Imaging and Behavior - Concussion is associated with significant functional disturbances in the first week post-injury. Computerized neurocognitive testing tools have become widely adopted in...     

Animal model for sport-related concussion; ICP and cognitive function

Bolouri H, Säljö A, Viano DC, Hamberger A. Animal model for sport‐related concussion; ICP and cognitive function.
Acta Neurol Scand: 2012: 125: 241–247.
© 2011 John Wiley & Sons A/S. Background – We have recently developed and characterized a rat model of mild traumatic brain injury which simulates the concussive injuries frequently encountered by players in American professional football. Objectives – To study the effect of multiple impacts to the head on intracranial pressure, cognitive function, and exploratory behavior. Materials and Methods – The model was employed to cause concussion. Intracranial pressure, cognitive function, and exploratory behavior were examined following the multiple impacts of a 50 or 100 g projectile at a velocity of 9.3 or 11.2 m/s to the helmet protected head. Results – Intracranial pressure measured at 6 and 10 h, and 1, 2, 3, 5, and 7 days. It was maximally elevated 10 h after impact and returned to the control levels 7 days later. Morris Water Maze assessment, 48 h after impact, revealed impaired cognitive function. Open field testing 2–4 days and 1 and 2 weeks after impacts indicated consistently reduced spontaneous exploratory activity. Conclusion – Multiple impacts to the head raise intracranial pressure and impair cognitive function and exploratory activity in this animal model.     

Standard regression-based methods for measuring recovery after sport-related concussion.

Clinical decision making about an athlete's return to competition after concussion is hampered by a lack of systematic methods to measure recovery. We applied standard regression-based methods to statistically measure individual rates of impairment at several time points after concussion in college football players. Postconcussive symptoms, cognitive functioning, and balance were assessed in 94 players with concussion (based on American Academy of Neurology Criteria) and 56 noninjured controls during preseason baseline testing, and immediately, 3 hr, and 1, 2, 3, 5, and 7 days postinjury. Ninety-five percent of injured players exhibited acute concussion symptoms and impairment on cognitive or balance testing immediately after injury, which diminished to 4% who reported elevated symptoms on postinjury day 7. In addition, a small but clinically significant percentage of players who reported being symptom free by day 2 continued to be classified as impaired on the basis of objective balance and cognitive testing. These data suggest that neuropsychological testing may be of incremental utility to subjective symptom checklists in identifying the residual effects of sport-related concussion. The implementation of neuropsychological testing to detect subtle cognitive impairment is most useful once postconcussive symptoms have resolved. This management model is also supported by practical and other methodological considerations.     

Use of computer based testing of youth hockey players with concussions

Concussion is a potentially serious injury for athletes. Recent statistics suggest that approximately 300,000 sports-related traumatic brain injuries occur annually in the United States. Soccer, rugby, football, and ice hockey are all considered high-risk team sports for concussion. Hockey-related concussions are of particular concern in Canada, where over 500,000 players compete annually in ice hockey. The United States is now registering similar numbers of players. Return to play issues are one of the most difficult issues for physicians caring for concussed athletes. The advent of computerized neuropsychological testing adds another tool to assist in this process. It also appears to enhance the education process for players, coaches, and parents on the potential seriousness of concussion for these young athletes.     

Sleep difficulties one year following mild traumatic brain injury in a population-based study

BackgroundSleep quality affects all aspects of daily functioning, and it is vital for facilitating recovery from illness and injury. Sleep commonly becomes disrupted following moderate to severe brain injury, yet little is known about the prevalence of sleep disruption over time and how it impacts on recovery following mild injury.MethodsThis was a longitudinal study of 346 adults who experienced a mild brain injury (aged ≥16 years) identified within a population-based incidence sample in New Zealand. The prevalence of sleep difficulties was assessed at baseline (within two weeks), one, six and 12 months, alongside other key outcomes.ResultsOne year post injury, 41.4% of people were identified as having clinically significant sleep difficulties, with 21.0% at a level indicative of insomnia. Poor sleep quality at baseline was significantly predictive of poorer post-concussion symptoms, mood, community integration, and cognitive ability one year post injury. The prevalence of insomnia following mild traumatic brain injury (TBI) was more than three times the rate found in the general population. Of those completing a sleep assessment at six and 12 months, 44.9% of the sample showed improvements in sleep quality, 16.2% remained stable, and 38.9% worsened.ConclusionsScreening for sleep difficulties should occur routinely following a mild brain injury to identify adults potentially at risk of poor recovery. Interventions to improve sleep are needed to facilitate recovery from injury, and to prevent persistent sleep difficulties emerging.