The Pathophysiology of Concussion

Division of Neurosurgery, Department of Neurosciences Head and Neck Surgery, S. Camillo Hospital, Rome, Italy.
PM&R (Impact Factor: 1.37). 10/2011; 3(10 Suppl 2):S359-68. DOI: 10.1016/j.pmrj.2011.07.018
Source: PubMed

ABSTRACT Concussion is defined as a biomechanically induced brain injury characterized by the absence of gross anatomic lesions. Early and late clinical symptoms, including impairments of memory and attention, headache, and alteration of mental status, are the result of neuronal dysfunction mostly caused by functional rather than structural abnormalities. The mechanical insult initiates a complex cascade of metabolic events leading to perturbation of delicate neuronal homeostatic balances. Starting from neurotoxicity, energetic metabolism disturbance caused by the initial mitochondrial dysfunction seems to be the main biochemical explanation for most postconcussive signs and symptoms. Furthermore, concussed cells enter a peculiar state of vulnerability, and if a second concussion is sustained while they are in this state, they may be irreversibly damaged by the occurrence of swelling. This condition of concussion-induced brain vulnerability is the basic pathophysiology of the second impact syndrome. N-acetylaspartate, a brain-specific compound representative of neuronal metabolic wellness, is proving a valid surrogate marker of the post-traumatic biochemical damage, and its utility in monitoring the recovery of the aforementioned "functional" disturbance as a concussion marker is emerging, because it is easily detectable through proton magnetic resonance spectroscopy.

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    ABSTRACT: Abstract Purpose: The objective of this study was to identify and describe management strategies to ensure safe return to activity (RTA) and return to school (RTS) of children with mild traumatic brain injury (MTBI) and determine whether they are evidence-based. Methods: A scoping methodology was conducted using research published between 1990 and 2013, gray literature and clinical expertise. Once the data had been charted, an expert panel of physicians and clinicians was consulted to inform and validate study findings. An analytical and thematic framework was used to examine the study findings. Results: A total of 400 potentially relevant published articles, 100 websites and 24 iPad Applications were found. Ten articles and three web-based resources met inclusion criteria and were included in the final review. Nine articles recommended a more conservative approach to RTA, as well as identified a step-wise or severity-oriented approach. General recommendations were also found regarding safe RTS. One study recommended a stepwise RTS protocol for children. Conclusions: This scoping methodology determined that the most comprehensive guidelines for management are focused on adults. Evidence concerning prolonged recovery patterns in children and the impact of concussion on the developing brain suggests that pediatric-specific guidelines are needed for RTA and RTS after MTBI/concussion. Implications for Rehabilitation Although concussion in children is an increasing concern, it has been determined that the most comprehensive guidelines for management are focused on adults. These guidelines are primarily consensus-based and are not proven fact through quality research. Evidence concerning prolonged recovery patterns in youth and the impact of concussion on the developing brain suggest that pediatric guidelines should be more conservative than for adults. Therefore, pediatric-specific guidelines need to be developed for return to activity and return to school after MTBI/concussion.
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    ABSTRACT: Concussion is a transitory brain injury resulting from a blow to the head. Concussion is considered a mild traumatic brain injury (mTBI), which is self-limited. Repetitive mTBI has been associated with chronic, progressive neurologic damage. Extreme biochemical changes occur in neuron cells as a result of mTBI. These metabolic disturbances may reflect the symptoms observed in patients who had concussions. However, it has been difficult to match clinical signs and symptoms. Currently, there is no test to diagnose concussion. Further studies are needed to elucidate the biochemical details of the metabolic cascade and the associated time frame, which will help determine when an athlete can safely return to the game.
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    ABSTRACT: Abstract Objective: Rest is a widely recommended treatment for concussion, but its utility is unclear following the acute stage of recovery. This study examined the effects of 1-week of prescribed rest in concussed adolescent athletes. Method: Participants were 13 adolescent athletes with persistent symptoms following a concussion. More than three-quarters (77%) had self-reported ADHD, learning disability or two prior concussions. All completed ImPACT® at another facility, but none completed a period of comprehensive rest prior to examination at a specialty practice. Three time points of test data were compared, to control for possible spontaneous recovery: Test 1 (external facility), Test 2 (before prescribed rest) and Test 3 (following prescribed rest). Results: Repeated measures ANOVAs revealed a significant effect of prescribed rest on all ImPACT® composite scores and the total symptom score. Post-hoc analyses revealed no significant differences between Time 1 and Time 2, whereas significant differences were present after prescribed rest. Following prescribed rest, having two or more reliably improved cognitive test scores or having improved symptoms was present in eight of the 13 patients (61.5%). Conclusions: A substantial percentage of adolescents with persistent symptoms following concussion showed improvement in symptoms and cognitive functioning following education, reassurance and 1-week of prescribed rest.
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Oct 16, 2014