Decrease in N-Acetylaspartate Following Concussion May Be Coupled to Decrease in Creatine

Abstract

Objectives:To assess the time course changes in N-acetylaspartate (NAA) and creatine (Cr) levels in the brain of athletes who suffered a sport-related concussion. Participants: Eleven nonconsecutive athletes with concussive head injury and 11 sex-and age-matched control volunteers Main outcome measures: At 3, 15, 30, and 45 days postinjury, athletes were examined by proton magnetic resonance spectroscopy for the determination of NAA, Cr, and choline (Cho) levels. Proton magnetic resonance spectroscopic data recorded for the control group were used for comparison. Results: Compared with controls (2.18 ± 0.19), athletes showed an increase in the NAA/Cr ratio at 3 (2.71 ± 0.16; P < .01) and 15 (2.54 ± 0.21; P < .01) days postconcussion, followed by a decrease and subsequent normalization at 30 (1.95 ± 0.16, P < .05) and 45 (2.17 ± 0.20; P < .05) days postconcussion. The NAA/Cho ratio decreased at 3, 15, and 30 days postinjury (P < .01 compared with controls), with no differences observed in controls at 45 days postconcussion. Compared with controls, significant increase in the Cho/Cr ratio after 3 (+33%, P < .01) and 15 (+31.5%, P < .01) days postinjury was observed whereas no differences were recorded at 30 and 45 days postinjury. Conclusions: This cohort of athletes indicates that concussion may cause concomitant decrease in cerebral NAA and Cr levels. This provokes longer time for normalization of metabolism, as well as longer time for resolution of concussion-associated clinical symptoms. Geology and Environmental Sciences, Viale A. Doria 6, 95125 Catania, Italy (lazzarig@unict.it). DOI: 10.1097/HTR.0b013e3182795045C ONCUSSION is defined as a biomechanically induced brain injury characterized by the absence of gross anatomic damages. Supported by the absence of structural lesions on traditional neuroimaging, a general and broadly accepted view is that mild traumatic brain injury (mTBI) is indeed a very frequent entity but is not a very serious injury, leading only to transient disturbances, and that no intervention other than observation is typically required. However, mTBI triggers molecular changes in neuronal cells involving a complex cascade of neurometabolic alterations 1-3 that reversibly modify the concentrations of several low-molecular-weight compounds actively involved in functions crucial for cell homeostasis and survival. 3,4 Such a cascade of molecular events is considered as the determinant of the so-called state of metabolic brain vulnerability, 5,6 which transiently exposes cerebral tissue to the cumulative effect of a second mTBI occurring during this particular period. 7,8 High-energy phosphates, 9,10 coenzyme A metabolites, 11 ATP catabolites, 11 and neurotransmitters, 12,13 are some of the substances whose concentrations are temporarily affected as a result of a traumatic insult. Of

A Longitudinal Diffusion Tensor Imaging Study Assessing White Matter Fiber Tracts after Sports-Related Concussion

“…For example, magnetic resonance spectroscopy (MRS) studies have demonstrated neurometabolic changes after SRC lasting up to 1 month postinjury. [6][7][8][9] Similarly, in a functional MRI study, hyperactivation of the dorsolateral prefrontal cortex was found to persist beyond 2 months postinjury in athletes whose symptoms subsided at 2 weeks after injury. 10 DTI studies demonstrating structural changes from repetitive concussive head impacts have been reported in ice hockey players over the course of a single season, 11 in athletes with prolonged symptoms, 12 as well as in adolescents exhibiting close-to-normal scores on the Sports Concussion Assessment Tool (SCAT2) 13 at 2 months postinjury.…”

MR Imaging Applications in Mild Traumatic Brain Injury: An Imaging Update

“…It is important, therefore, to consider that three studies suggest Cr alterations in mTBI (163)(164)(165). Elevated Cr was found in the centrum semiovale and corpus callosum (163,164), while decreased levels were reported in frontal WM (165). Interestingly, both groups showed normalization of these abnormalities over time, a behavior similar to that of NAA.…”

“…Levels of Cr, a marker of energy metabolism, are often used as the denominator in metabolic ratios, as they are assumed to vary less than the other metabolites (162). It is important, therefore, to consider that three studies suggest Cr alterations in mTBI (163)(164)(165). Elevated Cr was found in the centrum semiovale and corpus callosum (163,164), while decreased levels were reported in frontal WM (165).…”

The Presence and Role of Iron in Mild Traumatic Brain Injury: An Imaging Perspective

“…2,3 mTBI often presents without any of the more apparent structural abnormalities seen in moderate and severe brain injury; 1 however, there is a growing body of evidence that shows that single concussive episodes are associated with subtle alterations in brain structure [4][5][6][7][8][9] and function. [10][11][12][13] mTBI differs from moderate and severe TBI in that large focal lesions do not contribute to the mechanism of injury in mTBI.…”