Cerebrovascular reactivity alterations due to subconcussive repetitive head trauma in asymptomatic high school football players

Chronic neurological damage as a result of chronic repetitive head trauma is a major concern for football athletes today. Repetitive concussions have been linked to many neurological disorders. Recently, it has been reported that repetitive subconcussive events can contribute to long-term neurodegeneration. For these reasons, it is important to understand the effect repetitive subconcussive head trauma has on brain health in young athletes. Past research has demonstrated that cerebrovascular reactivity (CVR), an important mediator of cerebrovascular regulation, is impaired following mild traumatic brain injury (mTBI). This impairment increases susceptibility to secondary injury following mTBI. In this study, Breath-Hold (BH) task based functional Magnetic Resonance Imaging (fMRI) was used to track CVR changes in asymptomatic high school football athletes across three competition seasons. Athletes in the first competition season had higher exposure to head impacts than the athletes during the second and the third seasons. Baseline scans were acquired before the start of the season, and follow-up scans were obtained during and after the season to track the potential changes in CVR as a result of experienced trauma. Noncollision-sport athletes were scanned over two sessions as controls during the first and third competition season. CVR decreased significantly in football athletes during the first half of their season in the first completion season but not in any other competition seasons. Controls did not show any significant changes in CVR. The results suggest that athletes getting higher exposure to head impacts in short duration of time drives cerebrovascular changes that may place athletes at higher risk of getting injured. These results also indicate that the brain may not be able to adapt quickly to abrupt increases in contact activity (as associated with the beginning of practice and competition), transiently increasing risk for symptomatic injury

Accumulation of high magnitude acceleration events predicts cerebrovascular reactivity changes in female high school soccer athletes

Mitigating the effects of repetitive exposure to head trauma has become a major concern for the general population, given the growing body of evidence that even asymptomatic exposure to head accelerations is linked with increased risk for negative life outcomes and that risk increases as exposure is prolonged over many years. Among women's sports, soccer currently exhibits the highest growth in participation and reports the largest number of mild traumatic brain injuries annually, making female soccer athletes a relevant population in assessing the effects of repetitive exposure to head trauma. Cerebrovascular biomarkers may be useful in assessing the effects of repetitive head trauma, as these are thought to contribute directly to neurocognitive symptoms associated with mild traumatic brain injury. Here we use fMRI paired with a hypercapnic breath hold task along with monitoring of head acceleration events, to assess the relationship between cerebrovascular brain changes and exposure to repetitive head trauma over a season of play in female high school soccer athletes. We identified longitudinal changes in cerebrovascular reactivity that were significantly associated with prolonged accumulation to high magnitude (> 75th percentile) head acceleration events. Findings argue for active monitoring of athletes during periods of exposure to head acceleration events, illustrate the importance of collecting baseline (i.e., pre-exposure) measurements, and suggest modeling as a means of guiding policy to mitigate the effects of repetitive head trauma

Classification of gait phases from lower limb EMG: application to exoskeleton orthosis

This paper describes the use of Bayesian Information Criteria (BIC) along with some standard feature extraction methods and Linear Discriminant Analysis (LDA) classification algorithm to separate 8 different phases of gait by using electromyographic (EMG) signal data of the lower limb. Four time domain features along with 4th order Auto-Regressive model were used to get feature vector set from the EMG data of each leg of an able bodied person. Window of 50 ms (millisecond) was used such that it is within the controller delay limit. Then, the BIC segmentation algorithm was applied on the feature vector sets of 10 different gait cycles one by one to find out the locations of the boundaries between the phases. Due to the differences in the identified boundary locations for different gait cycles, the ambiguous part around each boundary was removed. The LDA classifier was then applied to the EMG feature vector set to classify 8 phases of gait. The classification accuracy increased by a significant amount in comparison to when BIC algorithm was not used. The work is our first step towards making an EMG signal driven foot-knee exoskeleton orthosis for the stroke patient having hemiparesis.by Chetas Joshi, Uttama Lahiri and Nitish Thako

A step towards developing a virtual reality based rehabilitation system for Individuals with post-stroke forearm movement disorders

Stroke is a leading cause of adult death and disability, often followed by muscle weakness, loss of control and coordination in limbs and movement disorders. Rehabilitation is critically important to restore function in damaged body parts and help the stroke-surviving individuals regain ability to independently perform everyday activities. Continuing post-stroke rehabilitative therapy at the hospital is difficult due to economic pressure and limited resources of the health care system. Also, taking help of an always-present therapist is too expensive for many patients. A relatively new approach towards stroke rehabilitation is developing technology-assisted rehabilitative system. In this study we developed a Virtual Reality based system to enhance the endurance and coordination skill of stroke patients with forearm movement disorder. This system can be used by the patient at home as per his convenience, with minimal dependency on a physiotherapist or a caregiver. Our paper describes the system design of this proof-of-concept application. The preliminary results of testing and feasibility studies suggest that the endurance and coordination skill of the participants (two able-bodied and one stroke-surviving person) improved with repeated attempts. This indicates that our system is a definite step towards becoming a simple, technology-assisted solution for rehabilitation of upper-limb movement disorder.by Sutapa Bhattacharya, Chetas Joshi, Arvind Chauhan and Uttama Lahir