Biomedical subjects
Publications and source records attributed to Philippe Azouvi.
The authors report the case of a 63-year-old patient with severe traumatic brain injury (TBI) associated with Parkinson's syndrome, whose performances were dramatically improved by bromocriptine therapy, with an improvement of the scores, not only on tests evaluating motor functions but also on tests evaluating the patient's cognitive functions. However, no improvement was observed with levodopa.
OBJECTIVE: To assess the cerebral correlates of the dysexecutive syndrome after diffuse severe traumatic brain injury (TBI). METHODS: Ten patients with sub-acute/chronic severe TBI without detectable focal cortical contusion and 11 matched healthy subjects were included in a parametric fMRI study using a planning task, the Tower of London. RESULTS: Brain activation in the left Dorsolateral Pre-frontal Cortex (DLPFC) and the Anterior Cingulate Cortex (ACC) was closely related to performance. Patients with TBI who performed the task efficiently showed, like healthy controls who obtained a similar pattern of performance, a large activation in the left DLPFC and a small activation in the ACC. In contrast, poor performance was associated with a reduced activation in these both regions. CONCLUSION: Problem-solving deficits after severe diffuse TBI could be related to an impaired activation of the DLPFC and of the ACC.
PURPOSE: The lack of agreement regarding assessment methods is responsible for the variability in the reported rate of occurrence of unilateral neglect (UN) after stroke. In addition, dissociations have been reported between performance on traditional paper-and-pencil tests and UN in everyday life situations. METHODS: In this paper, we present the validation studies of a quantitative test battery for UN, including paper-and-pencil tests, an assessment of personal neglect, extinction, and anosognosia, and a behavioural assessment, the Catherine Bergego Scale (CBS). The battery was given to healthy subjects (n=456-476) and to patients with subacute stroke, either of the right or the left hemisphere. RESULTS: In healthy subjects, a significant effect of age, education duration and acting hand was found in several tasks. In patients with right hemisphere stroke, the most sensitive paper and pencil measure was the starting point in the cancellation task. The whole battery was more sensitive than any single test alone. An important finding was that behavioural assessment was more sensitive than any other single test. Neglect was two to four times less frequent, but also less severe and less consistent after left hemisphere stroke. CONCLUSION: Assessment of UN should rely on a battery of quantitative and standardised tests. Some patients may show clinically significant UN in everyday life while obtaining a normal performance on paper-and-pencil measures. This underlines the necessity to use a behavioural assessment of UN.
When describing known places from memory, patients with left spatial neglect may mention more right- than left-sided items, thus showing representational, or imaginal, neglect. This suggests that these patients cannot either build or explore left locations in visual mental imagery. However, in place description there is no guarantee that patients are really employing visual mental imagery abilities, rather than verbal-propositional knowledge. Thus, patients providing symmetrical descriptions might be using other strategies than visual mental imagery. To address this issue, we devised a new test which strongly encourages the use of visual mental imagery. Twelve participants without brain damage and 12 right brain-damaged patients, of whom 7 had visual neglect, were invited to conjure up a visual mental image of the map of France. They subsequently had to state by pressing a left- or a right-sided key whether auditorily presented towns or regions were situated to the left or right of Paris on the imagined map. This provided measures of response time and accuracy for imagined locations. A further task, devised to assess response bias, used the words "left" or "right" as stimuli and the same keypress responses. Controls and non-neglect patients performed symmetrically. Neglect patients were slower for left than for right imagined locations. On single-case analysis, two patients with visual neglect had a greater response time asymmetry on the geographical task than predicted by the response bias task, but with symmetrical accuracy. The dissociation between response times and accuracy suggests that, in these patients, the left side of the mental map of space was not lost, but only "explored" less efficiently.
OBJECTIVE: To assess the relationships between life satisfaction and disability after a severe traumatic brain injury (TBI). DESIGN: Cross-sectional study, including 75 patients 2 years or more after a severe TBI. METHODS: Life satisfaction was assessed with the Subjective Quality of Life Profile. Impairments, activities and participation were assessed with standardized tests. RESULTS: The satisfaction profile was flat, i.e. the majority of items obtained mean satisfaction scores close to 0, suggesting that participants felt indifferent to these items or in other words that they were neither satisfied nor unsatisfied. Patients were on average slightly dissatisfied with their cognitive functions, physical abilities and self-esteem. A factor analysis revealed three underlying factors. The main finding was that the relationships between life satisfaction and disability were not linear: the lowest satisfaction scores were reported by participants with moderate disability rated by the Glasgow Outcome Scale, while individuals with severe disability did not significantly differ from the good recovery group. CONCLUSION: Life satisfaction is not linearly related to disability after severe TBI.
The aim of this study was to assess dual-task performance in TBI patients, under different experimental conditions, with or without explicit emphasis on one of two tasks. Results were compared with measurement of the subjective mental effort required to perform each task. Forty-three severe TBI patients at the subacute or chronic phase performed two tasks under single- and dual-task conditions: (a) random generation; (b) visual go-no go reaction time task. Three dual-task conditions were given, requiring either to consider both tasks as equally important or to focus preferentially on one of them. Patients were compared to matched controls. Subjective mental effort was rated on a visual analogic scale. TBI patients showed a disproportionate increase in reaction time in the go-no go task under the dual-task condition. However, they were just as able as controls to adapt performance to the specific instructions about the task to be emphasised. Patients reported significantly higher subjective mental effort, but the variation of mental effort according to task condition was similar to that of controls. These results suggest that the divided attention deficit of TBI patients is related to a reduction in available processing resources rather than an impairment of strategic processes responsible for attentional allocation and switching. The higher level of subjective mental effort may explain why TBI patients frequently complain of mental fatigue, although this subjective complaint seems to be relatively independent of cognitive impairment.
The present experiment was aimed at investigating the effects of memory and attention deficits and of information processing slowing on time estimation in patients with severe traumatic brain injury (TBI). Patients with TBI and normal control subjects reproduced and produced durations (5, 14, 38s) in both a control counting condition and in a concurrent reading condition. They also performed finger-tapping tasks at a free rate and at a 1s rate. Both groups were assessed on processing speed using a reaction-time task, and on memory and attention using a battery of neuropsychological tests. The results showed that time estimation was not less accurate in patients with TBI than in control subjects on the reproduction task or on the production task performed either in the control counting condition or in the concurrent reading condition. Conversely, duration judgments were more variable in patients with TBI than in control subjects on both tasks in both conditions. The results also showed that TBI patients exhibited slower reaction-times, and poorer working and episodic memory scores than control subjects. Most importantly, the variability index in the duration reproduction task was related to both working memory scores and processing speed measures, whereas the variability index in the duration production task was only related with the processing speed measures. The temporal performance pattern in TBI patients does not appear to reflect specific deficits in timing, but rather overall problems in attention, working memory, and processing speed mechanisms.
OBJECTIVE: To assess the psychometric properties of a scale for spatial neglect in everyday life. DESIGN: Validation study. SETTING: A neurologic rehabilitation unit in a university hospital. PARTICIPANTS: Eighty-three consecutive right-hemisphere stroke patients. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The Catherine Bergego Scale (CBS) was used to assess neglect behavior and anosognosia. Its sensitivity was compared with that of 3 conventional tests. The inner structure of the scale was studied by principal component analysis. In addition, linearity, unidimensionality, and reliability of the scale were tested through Rasch analysis. RESULTS: Behavioral assessment correlated significantly to, but was more sensitive than, conventional tests. Anosognosia correlated significantly with neglect severity, although individual dissociations occurred. Factorial analysis disclosed a single underlying factor, explaining 65.8% of total variance. Rasch analysis also revealed that the 10 items defined a common, single ability continuum with widespread measurement range and quite regular item distribution, and showed a satisfactory reliability. CONCLUSION: Behavioral assessment proved to be more sensitive than conventional paper and pencil tasks. Both conventional statistics and Rasch analysis suggest that the CBS is reliable and valid, and that the 10 items define a homogeneous construct.
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