Longitudinal study of a NoGo-P3 event-related potential component following mild traumatic brain injury in adults.

BACKGROUND: Event-related potentials have repeatedly revealed electrophysiological markers of cognitive dysfunction associated with Mild Traumatic Brain Injury (MTBI) and may represent a sensitive tool to guide cognitive rehabilitative interventions. We previously found patients with symptomatic MTBI characterized by smaller P300 (or P3) wave amplitudes in a NoGo-P3 subcomponent in the acute phase of the injury. The goal of this longitudinal study was to investigate whether this early NoGo-P3 subcomponent differs over time in symptomatic MTBI patients and healthy controls. METHODS: We included adults with a diagnosis of MTBI and individually matched healthy controls tested at 1 week, 3 months, and 1 year after the MTBI. Symptoms were assessed by the Rivermead Post-Concussion Symptoms Questionnaire. NoGo-P3 was collected by using a cued Go/NoGo task and the relevant subcomponent was extracted by independent component analysis. RESULTS: Among 53 adults with a diagnosis of MTBI and 53 controls, we included 35 with symptomatic MTBI and 35 matched healthy controls (18 females each group; mean age 34.06±13.15 and 34.26±12.98 years). Amplitudes for the early NoGo-P3 subcomponent were lower for symptomatic MTBI patients than controls (P<0.05) at 1 week post-injury. Furthermore, mixed ANOVA revealed a significant time by group interaction (P<0.05), so the effect of time differed for symptomatic MTBI patients and healthy controls. The amplitudes for MTBI patients normalized from 1 week to 3 months post-injury and were comparable to those of controls from 3 months to 1 year post-injury. However, amplitudes for 3 MTBI patients with particularly severe complaints 1 year post-injury did not normalize and were lower than those for the remaining MTBI sample (P<0.05). CONCLUSIONS: Selected event-related potentials can be used as a sensitive and objective tool to illustrate the cognitive consequences of and recovery after MTBI.

Prefrontal Cortical Thickening after Mild Traumatic Brain Injury: A One-Year Magnetic Resonance Imaging Study.

The objective of this study was to evaluate group-by-time interactions between gray matter morphology of healthy controls and that of patients with mild traumatic brain injury (mTBI) as they transitioned from acute to chronic stages, and to relate these findings to long-term cognitive alterations to identify distinct recovery trajectories between good outcome (GO) and poor outcome (PO). High-resolution T1-weighted magnetic resonance images were acquired in 49 mTBI patients within 7 days and 1 year post-injury and at equivalent times in 49 healthy controls. Using linear mixed-effects models, we performed mass-univariate analyses and associated the results of the interaction with changes in cognitive performance. Morphological alterations indexed by increased or decreased cortical thickness have been expected mainly in frontal, parietal, and temporal brain regions. A significant interaction was found in cortical thickness, spatially restricted to bilateral structures of the prefrontal cortex, showing thickening in mTBI and normal developmental thinning in controls. A discrete thickness increase that can interpreted as the absence of cortical thinning typically seen in the healthy population was associated with cognitive recovery in the GO subgroup, while the exaggerated cortical thickening in the PO patients was linked to worsening cognitive performance. Thickness of the prefrontal cortex is subject to structural alterations during the first year after mTBI. Beside beneficial neuroplasticity, a prolonged state of neuroinflammation for symptomatic patients (maladaptive neuroplasticity) cannot be excluded. If the underlying cellular processes responsible for cortical thickening following mTBI have been determined, brain stimulation or even pharmacological intervention targeting the prefrontal cortex might promote endogenous neural restoration.

Altered cognitive processes in the acute phase of mTBI: an analysis of independent components of event-related potentials.

Mild traumatic brain injuries (mTBI) generate acute disruptions of brain function and a subset of patients shows persisting cognitive, affective, and somatic symptoms. Deficits in the executive function domain are among the more frequent cognitive impairments reported by mTBI patients. By means of independent component analysis, event-related potential components from a visual cued go/nogo task, namely contingent negative variation (CNV) and NoGo-P3, were decomposed into distinct independent components that have been shown to be associated with the executive processes of energization, monitoring, and task setting. A group of symptomatic mTBI patients was compared with a group of controls matched for sex, age, and education. Patients showed reduced amplitudes in the late CNV as well as in the early NoGo-P3 subcomponents. Whereas the decreased CNVlate component indicates an impaired ability to generate representations of stimulus-response associations and to energize the maintenance of response patterns, the reduced P3NOGOearly component suggests a deficient ability to invest attentional effort in the initiation of response patterns in mTBI patients. Besides indicating the effects of mTBI on cognitive brain processing, the results may open up the possibility for assessing individual mTBI profiles and facilitate personalized rehabilitative measures.

Alterations of the transverse ligament: an MRI study comparing patients with acute whiplash and matched control subjects.

OBJECTIVE: The objective of our study was to evaluate whether there is injury to the transverse ligament of the atlas in patients with acute whiplash. MATERIALS AND METHODS: Ninety patients with an acute (< 48 hours) symptomatic whiplash-associated injury and 90 healthy age- and sex-matched asymptomatic control subjects (mean age of patients and control subjects, 36 years) were included. The maximal sagittal thickness of the transverse ligament was measured on midsagittal T1 volumetric interpolated breath-hold examination (VIBE) images and transverse reformatted VIBE images. The signal intensity of the transverse ligament was measured on transverse STIR images and on transverse reformatted T1 VIBE images before and after IV administration of gadoterate. Contrast between the transverse ligament and CSF and alterations of contrast after gadoterate injection were calculated. RESULTS: Patients had a minimally thicker transverse ligament (posttraumatic swelling) than control subjects, and the difference in thickness was significant in men only (p = 0.03). In patients, a significant signal alteration of the transverse ligament (p = 0.03) was seen on STIR (posttraumatic edema) and native VIBE sequences. The contrast between the transverse ligament and the CSF on VIBE images was significantly (p = 0.005) lower in patients than in control subjects. With the application of a contrast agent, the contrast difference between the transverse ligament and CSF in patients and control subjects was less pronounced (p = 0.038). There was no abnormal uptake of contrast agent by the transverse ligament or CSF. CONCLUSION: The results of our study indicate possible involvement of the transverse ligament in whiplash injury. Although MRI may be helpful to study injury-related changes of anatomic structures in cohorts, it is not suited for individual diagnosis because the alterations are too small.