Carolina Bottari

Electrophysiology and Functional MRI in Post-Acute Mild Traumatic Brain Injury

Symptoms persisting beyond the acute phase (>2 months) after a mild traumatic brain injury (MTBI) are often reported, but their origin remains controversial. Some investigators evoke dysfunctional cerebral mechanisms, while others ascribe them to the psychological consequences of the injury. We address this controversy by exploring possible cerebral dysfunction with functional magnetic resonance imaging (fMRI) and event-related potentials (ERP) in a group of patients during the post-acute phase. Fourteen MTBI symptomatic patients (5.7±2.9 months post-injury) were tested with fMRI and ERP using a visual externally ordered working memory task, and were compared with 23 control subjects. Attenuated blood oxygen level dependent (BOLD) signal changes in the left and right mid-dorsolateral prefrontal cortex (mid-DLPFC), the putamen, the body of the caudate nucleus, and the right thalamus were found in the MTBI group compared with the control group. Moreover, symptom severity and BOLD signal changes were correlated: patients with more severe symptoms had lower BOLD signal changes in the right mid-DLPFC. For ERP, a group×task interaction was observed for N350 amplitude. A larger amplitude for the working memory task than for the control task was found in control subjects, but not in MTBI subjects, who had weak amplitudes for both tasks. This study confirms that persistent symptoms after MTBI cannot be uniquely explained by psychological factors, such as depression and/or malingering, and indicates that they can be associated with cerebral dysfunction. ERP reveals decreased amplitude of the N350 component, while fMRI demonstrates that the more severe the symptoms, the lower the BOLD signal changes in the mid-DLPFC.

Evaluating the cognitive consequences of mild traumatic brain injury and concussion by using electrophysiology

OBJECT Mild traumatic brain injury (MTBI), often referred to as concussion when it occurs in sports, produces persistent cognitive problems in at least 15% of patients. Unfortunately, conventional neuropsychological tests usually yield results within normal limits in this population. The main objective of this event-related potential (ERP) study was to understand brain functioning during the performance of a working memory (WM) task in patients who have sustained an MTBI, mostly due to motor vehicle accident or sports concussion. This study also aimed for a better understanding of the association between brain functioning as measured with ERP, behavioral performance on the WM task, postconcussion symptoms, type of injury (that is, sports concussion vs other types), and time since the injury. METHODS Forty-four patients with MTBI (7.6 ± 8.4 months postinjury) were tested on a visual WM task with simultaneous recording of ERP, and were compared with 40 control volunteers who were their equivalent for age and sex. Amplitude and latency of frontal (N200 and N350) and parietal (P200 and P300) ERP waves were measured and were compared between groups. Correlation analyses were also performed between ERP characteristics, clinical variables, and behavioral performance. RESULTS A significant group difference was found for behavioral performance on the WM task, in which the MTBI group had a lower percentage of correct answers than the control group (p < 0.05). The patients with MTBI also had smaller amplitudes of both frontal N350 and parietal P300 ERP components when compared with control volunteers (p < 0.05). No changes were found for latency of ERP components. Smaller ERP amplitudes were associated with slower reaction times and worse accuracy on the WM task among patients with MTBI (p < 0.05). Types of injury (that is, sports concussion vs other mechanisms) were not associated with different ERP characteristics. CONCLUSIONS Abnormal ERP results are observed in patients after MTBI or sports concussion, even for those in the nonacute stage after their injury. Current standard clinical evaluations most often fail to detect cerebral dysfunction after MTBI, even when patients or athletes report symptoms. Clinicians should be aware that patients with MTBI, including sports concussion, probably have underlying mild but persistent cerebral dysfunctions that require further investigation.

The criterion-related validity of the IADL Profile with measures of executive functions, indices of trauma severity and sociodemographic characteristics

Primary objective: To examine relationships between classical measures of executive functions (EF) and indices of traumatic brain injury (TBI) severity with the IADL Profile, a new performance-based measure of independence in instrumental activities of daily living (IADL) based on EF. This study hypothesized the presence of correlations between classical tests of EF and the IADL Profile, as the latter aims to establish whether the subjects main difficulties pertain to goal formulation, planning, carrying out the task and/or attaining the initial task goal; all important components of EF. Methods and procedures: One hundred subjects with a moderate/severe TBI aged 16–65 years (convenience sample) were recruited. Subjects were tested with the IADL Profile and three measures of EF within their home environment. Data was analysed using Pearson correlations, t-tests and multiple stepwise regressions. Results: Post-traumatic amnesia and working memory emerged as the major determinants of IADL Profile scores. Together, indices of injury severity, measures of EF, education, age and environmental factors accounted for 12–28% of the variance in IADL Profile scores. Conclusions: This study has shown that the IADL Profiles non-structured approach permits the observation of a broad range of behaviours related to EF deficits and thus provides a closer approximation of the persons independence in IADL. Further study is required to demonstrate the IADL Profiles ability to inform more targeted treatment interventions.

The factorial validity and internal consistency of the Instrumental Activities of Daily Living Profile in individuals with a traumatic brain injury

The objective of the study was to investigate the factorial validity and internal consistency of the Instrumental Activities of Daily Living (IADL) Profile. A group of 96 patients aged 16 to 65 years, with moderate to severe traumatic brain injuries, was recruited from 12 rehabilitation hospitals in Quebec. The IADL Profile was administered by an occupational therapist in each subjects home and community environment. Principal axis factoring and confirmatory factor analysis provide preliminary support for six correlated factors (F): (F1) going to grocery store/shopping for groceries, (F2) having a meal with guests/cleaning up, (F3) putting on outdoor clothing, (F4) obtaining information, (F5) making a budget, (F6) preparing a hot meal for guests. Total explained variance was 73.6%. Cronbachs alpha analysis revealed high to very high internal consistency for all scales ranging from .81 to .98; internal consistency of the total scale was very high (0.95). The findings suggest that the IADL Profile is a promising means of documenting both IADL independence and the repercussions of executive function deficits on everyday tasks in real-world environments.

Brain Functions After Sports-Related Concussion: Insights From Event-Related Potentials and Functional MRI

Abstract The high incidence of concussions in contact sports and their impact on brain functions are a major cause for concern. To improve our understanding of brain functioning after sports-related concussion, advanced functional assessment techniques, namely event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI), have been recently used in research studies. Contrary to neuropsychological tests that measure verbal and/or motor responses, ERPs and fMRI assess the neural activities associated with cognitive/behavioral demands, and thus provide access to better comprehension of brain functioning. In fact, ERPs have excellent temporal resolution, and fMRI identifies the involved structures during a task. This article describes ERP and fMRI techniques and reviews the results obtained with these tools in sports-related concussion. Although these techniques are not yet readily available, they offer a unique clinical approach, particularly for complex cases (ie, athletes with multiple concussions, chronic symptoms) and objective measures that provide valuable information to guide management and return-to-play decision making.

Independence in managing one's finances after traumatic brain injury

Primary objective: To establish whether the budgeting task of the Instrumental Activities of Daily Living (IADL) Profile discriminates individuals with a traumatic brain injury (TBI) from healthy controls and to identify the nature of the observed difficulties. Method: This study tested 27 adults with moderate or severe TBI and 27 controls matched for age, sex and education on the budgeting task of the IADL Profile. The budgeting task is a complex real-world problem involving the preparation of a yearly budget for an individual living on a fixed income with the goal of saving money to purchase a car. Main results: The results showed that TBI subjects, the majority of whom had documented frontal lesions and/or diffuse axonal injury based on CT scan reports, were more likely than control subjects to experience difficulties on all task-related operations (planning, carrying out and verifying attainment of goal), with planning being particularly affected. These deficits were shown to impact on financial abilities, an issue of particular concern for TBI individuals reporting full responsibility of their finances. Conclusions: The budgeting task of the IADL Profile discriminates TBI subjects from controls. Planning was shown to be the most significant difficulty underlying reduced independence in the task.

Cooking “Shrimp à la Créole”: A pilot study of an ecological rehabilitation in semantic dementia

New learning in semantic dementia (SD) seems to be tied to a specific temporal and spatial context. Thus, cognitive rehabilitation could capitalise upon preserved episodic memory and focus on everyday activities which, once learned, will have an impact in everyday life. This pilot study thus explores the effectiveness of an ecological approach in one patient suffering from SD. EC, a 68-year-old woman with SD, stopped cooking complex meals due to a substantial loss of knowledge related to all food types. The therapy consisted of preparing a target recipe. She was asked to generate semantic attributes of ingredients found in one target, one control and two no-therapy recipes. The number of recipes cooked by EC between therapy sessions was computed. She was also asked to prepare a generalisation recipe combining ingredients from the target and control recipes. ECs generated semantic attributes (GSA) of ingredients pertaining to the target and control recipes increased significantly (p < .001), compared to the no-therapy recipes (ps > .79). The proportion of meals cooked also increased significantly (p = .021). For the generalisation recipe, she could not succeed without assistance. Frequent food preparation may have provided EC with new memories about the context, usage and appearance of some concepts. These memories seem very context-bound, but EC nonetheless re-introduced some recipes into her day-to-day life. The impact of these results on the relationship between semantic, episodic and procedural memory is discussed, as well as the relevance of an ecological approach in SD.

Executive function, self-regulation and attribution in acquired brain injury: A scoping review

Impairments in executive function, self-regulation and attribution individually have been implicated in impairment in goal-directed behaviour, resulting in reduced participation in daily activities by individuals with brain injury. There is minimal literature that explicitly addresses the relationships among these constructs, how these may be affected by brain injury and the implications for rehabilitation. The objectives of this study were to determine what is known about the relationship between executive function, self-regulation and attribution, and to understand how these inter-relationships affect goal-directed behaviour in adults with acquired brain injury. A scoping review of the cognitive neuroscience, neuropsychology, rehabilitation, educational and social psychology literature from 1985 to 2011 was performed. The identified literature provided definitions of the constructs and insight into the relationships between them according to their neural underpinnings and theoretical models. These data also provided for the development of a new model illustrating the hypothesised relationships between constructs. This review and the model developed, suggest that attribution may play an important role in executive function and self-regulation. Rehabilitation interventions that address formulation of appropriate attributions should be considered in conjunction with those targeting self-regulation and executive function for individuals with brain injury.

The impact of poor sleep on cognition and activities of daily living after traumatic brain injury: A review

BACKGROUND/AIM Patients frequently report sleep disruptions or insomnia during their hospital stay, particularly after a traumatic brain injury (TBI). The consequences of these sleep disturbances on everyday activities are not well documented and are therefore not considered in the evaluation of independence in activities of daily living (ADLs). The goal of this narrative review is to explore the consequences of poor sleep quality on cognition and ADLs in the acute and subacute stages of a moderate and severe TBI, when patients are in acute care or inpatient rehabilitation. METHODS We will present an overview of normal sleep and its role in cognitive functioning, and then present the findings of studies that have investigated sleep characteristics in hospital settings and the consequences of sleep disturbances on ADLs. RESULTS During hospitalisation, TBI patients present severe sleep disturbances such as insomnia and sleep fragmentation, which are probably influenced by both the medical condition and the hospital or rehabilitation environment. Sleep disruption is associated with several cognitive deficits, including attention, memory and executive function impairments. Poor quality and/or insufficient quantity of sleep in acute TBI probably affect general functioning and ADLs calling for these cognitive functions. CONCLUSIONS AND SIGNIFICANCE The cognitive impairments present following TBI are probably exacerbated by poor sleep quality and sleep deprivation during hospitalisation, which in turn impact ADLs among this population. Health-care personnel should further consider sleep disturbances among people with TBI and a sleep protocol should be established.

The impact of semantic dementia on everyday actions: evidence from an ecological study.

In theory, semantic memory may trigger and support the execution of everyday activities. This study explored this question by comparing three patients with semantic dementia to 40 normal controls performing different everyday activities. Participants were tested in their home using the Instrumental Activities of Daily Living Profile, an ecological measure of everyday functioning. Participants were informed that they had unknowingly invited two guests for lunch and should prepare accordingly. With these instructions, they dress to go outdoors, go to the grocery store, shop for food, prepare a hot meal, have the meal with the guests, and clean up after the meal. Performance was analyzed on the basis of four operations related to problem solving: formulate a goal, plan, execute, and verify attainment of the goal. Results indicate that compared to normal controls, two patients had significant difficulties and needed assistance with all operations of problem-solving, particularly while preparing a meal and cleaning up after the meal. One patient showed no difficulties despite severe semantic deficits. These results suggest that semantic deficits alone cannot explain the difficulties observed, but may contribute to some aspects of everyday actions such as those involved in everyday problem-solving.