Marc Rousseaux

Sensitivity of clinical and behavioural tests of spatial neglect after right hemisphere stroke

Objectives: The lack of agreement regarding assessment methods is responsible for the variability in the reported rate of occurrence of spatial neglect after stroke. The aim of this study was to assess the sensitivity of different tests of neglect after right hemisphere stroke. Methods: Two hundred and six subacute right hemisphere stroke patients were given a test battery including a preliminary assessment of anosognosia and of visual extinction, a clinical assessment of gaze orientation and of personal neglect, and paper and pencil tests of spatial neglect in the peripersonal space. Patients were compared with a previously reported control group. A subgroup of patients (n=69) received a behavioural assessment of neglect in daily life situations. Results: 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. About 85% of patients presented some degree of neglect on at least one measure. An important finding was that behavioural assessment of neglect in daily life was more sensitive than any other single measure of neglect. Behavioural neglect was considered as moderate to severe in 36% of cases. A factorial analysis revealed that paper and pencil tests were related to two underlying factors. Dissociations were found between extrapersonal neglect, personal neglect, anosognosia, and extinction. Anatomical analyses showed that neglect was more common and severe when the posterior association cortex was damaged. Conclusions: The automatic rightward orientation bias is the most sensitive clinical measure of neglect. Behavioural assessment is more sensitive than any single paper and pencil test. The results also support the assumption that neglect is a heterogeneous disorder.

Validation of a Standardized Assessment of Postural Control in Stroke Patients: The Postural Assessment Scale for Stroke Patients (PASS)

BACKGROUND AND PURPOSE Few clinical tools available for assessment of postural abilities are specifically designed for stroke patients. Most have major floor or ceiling effects, and their metrological properties are not always completely known. METHODS The Postural Assessment Scale for Stroke patients (PASS), adapted from the BL Motor Assessment, was elaborated in concordance with 3 main ideas: (1) the ability to maintain a given posture and to ensure equilibrium in changing position both must be assessed; (2) the scale should be applicable for all patients, even those with very poor postural performance; and (3) it should contain items with increasing difficulty. This new scale has been validated in 70 patients tested on the 30th and 90th days after stroke onset. RESULTS Normative data obtained in 30 age-matched healthy subjects are presented. The PASS meets the following requirements: (1) good construct validity: high correlation with concomitant Functional Independence Measure (FIM) scores (r=0.73, P=10(-6)), with lower-limb motricity scores (r=0.78, P<10(-6)), and with an instrumental measure of postural stabilization (r=0.48, P<10(-2)); (2) excellent predictive validity: high correlation between PASS scores on the 30th day and FIM scores on the 90th day (r=0.75, P<10(-6)); (3) high internal consistency (Cronbach alpha-coefficient=0.95); and (4) high interrater and test-retest reliabilities (average kappa=0.88 and 0.72). CONCLUSIONS Our results confirm that the PASS is one of the most valid and reliable clinical assessments of postural control in stroke patients during the first 3 months after stroke.

EUROPEAN CONSENSUS TABLE ON THE USE OF BOTULINUM TOXIN TYPE A IN ADULT SPASTICITY

A group of clinicians from across Europe experienced in the use of botulinum toxin type A for the treatment of spasticity following acquired brain injury gathered to develop a consensus statement on best practice in managing adults with spasticity. This consensus table summarizes the current published data, which was collated following extensive literature searches, their assessment for level of evidence and discussion among the whole group. Published information is supplemented by expert opinion based on clinical experience from 16 European countries, involving 28 clinicians, who treat an average of approximately 200 patients annually, representing many thousand spasticity treatments with botulinum toxin per year.

Right spatial neglect after left hemisphere stroke: qualitative and quantitative study

Objectives: Comparatively little research has been conducted on right neglect after left brain damage. The authors sought to assess contralateral neglect in subacute left hemisphere stroke patients using a comprehensive test battery validated in a large control group after right hemisphere stroke. Methods: Seventy-eight left hemisphere stroke patients were assessed. The test battery included a preliminary assessment of anosognosia and visual extinction, a clinical assessment of gaze orientation and personal neglect, and paper-and-pencil tests of spatial neglect in the peripersonal space. Only nonverbal tests were used. Results: Drawing and cancellation tasks revealed neglect in 10 to 13% of patients. The combined battery was more sensitive than any single test alone. A total of 43.5% of patients showed some degree of neglect on at least one measure. Anatomic analyses showed that neglect was more common and severe when the posterior association cortex was damaged. Conclusions: The frequency of occurrence of right neglect was, as expected, much lower than that reported in a study using the same assessment battery in right brain damage stroke patients. Nevertheless, neglect was found in a substantial proportion of patients at a subacute stage, suggesting that it should be considered in the rehabilitation planning of left brain damage stroke patients.

Divided attention and mental effort after severe traumatic brain injury

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.

CONTROL FUNCTIONS OF THE FRONTAL LOBES. MODULARITY OF THE CENTRAL-SUPERVISORY SYSTEM?

Lesions of the prefrontal cortex result in a wide variety of neuropsychological disorders. Despite recent advances, the executive processes and their functional architecture remain poorly specified. This study assessed control processes operating in novel, conflicting and combined tasks in patients with lesion of the prefrontal or posterior cortices. Experiments used two-choice reaction time tests with similar perceptuo-motor and decision processes. It mainly showed (1) impaired short term memory in posterior patients, and (2) impairment of response inhibition and tasks combination in some frontal patients. Selective deficits with double dissociations were evidenced on novel, conflicting and combined tasks. This study provides additional evidence for the prominent role of the frontal lobes in control processes. The demonstration of selective deficits of specific control processes suggests that executive functions depend on multiple separable control processes, and that their operations can be specified in cognitive terms.

Dual Task Performance after Severe Diffuse Traumatic Brain Injury or Vascular Prefrontal Damage

The ability to perform two tasks simultaneously is a key function of the central executive of working memory (Baddeley, 1986). This study addressed dual-task performance after diffuse very severe traumatic brain injury (TBI) (mean coma duration = 21 days, mean post-traumatic amnesia = 70 days) or prefrontal damage due to a ruptured aneurysm of the anterior communicating artery (AACA). Mean time since injury was 8 and 16 months in the TBI and the AACA group respectively. A simple visual reaction time and random number generation were used as single and dual tasks. Randomization was self-paced, to control for individual differences in speed. Both patient groups had greater reaction time decrements than controls under the dual-task condition, suggesting a divided attention deficit. In addition, patients with AACA performed significantly poorer in random generation. These results suggest that patients with AACA and with severe TBI suffer from an impairment of the central executive system.

Divided and Focused Attention in Patients with Lesion of the Prefrontal Cortex

Despite the common claim of attention disorders in patients with frontal lobe lesion, attention has been poorly investigated and its contribution to behavioral changes has not been studied. The aim of this study was to assess divided (Experiment I) and focused attention (Experiment II) in patients with prefrontal damage. The study used simple detection tests measuring reaction times (RT) to successive stimuli of one modality and of randomly varying modalities (divided attention) and Go No-Go tests (focused attention). Experiment I showed that RT difference between patients and controls increased when stimuli modality was uncertain, a result we attributed to a deficit of divided attention. Experiment II showed that patients remained sensitive to irrelevant stimuli, demonstrating their inability to focus attention. The prominent behavioral change in patients consisted of increased distractibility which was correlated with divided and focused attention deficits. Finally, the presence on magnetic resonance imaging of a left lesion in the superior part of the prefrontal cortex and in the head of the caudate nucleus was the best predictor of attention disorders. In conclusion, this study shows that patients with a prefrontal lesion suffer from divided and focused attention deficits that correspond to behavioral changes.

Effects of subthalamic nucleus stimulation on parkinsonian dysarthria and speech intelligibility

Abstract.Subthalamic stimulation is known to improve tremor, akinesia and rigidity in Parkinson’s disease. However, other signs such as hypophonia and swallowing disorders can be relatively resistant to this technique. The effect on dysarthria remains unclear. The aim of this study was to investigate the effects of implantation of electrode and stimulation of the subthalamic nucleus (STN) on parkinsonian dysarthria. Seven patients were prospectively included. Electrodes (Medtronic) were implanted in both STN. The electrode contacts and stimulation parameters were adjusted to provide best relief of symptoms with fewest side effects. Assessment used global scales (Unified Parkinson Disease Rating Scale, UPDRS II and III), dyskinesia scale, exhaustive dysarthria assessment (bucco-facial movements, voice, articulation, intelligibility) and the ‘dysarthria’ item from the UPDRS III. Evaluations were performed in six conditions: before and three months after surgery (pre-op, post-op) stimulation turned off or on (off-stim, onstim), and without or with a suprathreshold levodopa dose (offdrug, on-drug). Performance level on the UPDRS III significantly improved following electrode implantation and stimulation. For dysarthria, modest beneficial effects were observed on several motor parameters, especially lip movements. Voice mildly improved, especially for the modulation in loudness and pitch. Articulation was not affected. Furthermore, intelligibility was slightly reduced in the on-stimulation condition, especially when patients received levodopa. At an individual level, negative effects on intelligibility were observed in two patients, and this was associated with a discrete increase in facial and trunk dyskinesias, but not with the electrode position or stimulation parameters. In conclusion, surgery had weak effects on dysarthria. Intelligibility can be worsened, especially in the on-drug condition. Thus, adaptation of the stimulation parameters can be difficult.

Efficacy of botulinum toxin A in upper limb function of hemiplegic patients

Abstract Botulinum toxin A has been reported to reduce spasticity and increase the comfort of hemiplegic patients. The aim of this study was to assess the efficacy of the treatment on disability, especially in manual activities, and to attempt to identify predictive factors of improvement. Twenty patients (mean age: 54.4 years; M: 14; right hemiplegia: 12) were included, with a delay of at least three months after unilateral hemispheric stroke. Botulinum toxin A (BOTOX®) was injected into the arm adductors (8 cases), forearm flexors (17 cases), pronators, wrist and finger flexors (20 cases), with a total dose of 200 to 300 U. Examination (day 1 and 15, month 2 and 5) consisted of spasticity assessment (modified Ashworth scale), muscle strength, passive range of motion (goniometry), and pain, followed by functional tests, especially the Rivermead Motor Assessment (RMA) and Nine-hole Peg Test (NHPT). Performance in daily living was assessed with the Functional Independence Measure (FIM), and an original analysis of hand grasp, grip and pinches used in domestic activities (9 items), and of comfort of patients and caregivers. Significant reduction in spasticity was observed on the elbow flexors, pronators, wrist and fingers flexors, especially at day 15 (mean 0.90 to 1 point), with wide variations in effect. Muscle strength was increased in wrist and fingers extensors, with concomitant increase in the opening of the thumb to index finger space. There was no effect on the NHPT requiring distal manipulation, but the RMA, which especially concerned picking up and releasing a tennis ball, showed significant improvement. Furthermore, use of the upper limb in daily living increased, particularly for internal grasping of objects, and for grasping by the top, transporting and releasing of objects. Patients and caregivers reported facilitation in dressing, and in proximal and distal care of the upper limb. The global flexor position of the limb improved. Adverse reactions were rare and mostly consisted of transitory pain during injection. The improvement in the RMA was better explained by the quality of the initial motor command on distal prehension (positive correlation with motor strength), and that in hand using in domestic activities by a lower level of spasticity on pronators and wrist flexors (negative correlations with spasticity). Conversely, the severity of the motor deficit (negative correlations with motor strength) and a high level of spasticity before injection (positive correlations with spasticity) mostly explained the improvement in comfort. In conclusion, botulinum toxin A is efficient in improving hand use in patients with relatively preserved distal motricity, and in increasing comfort in patients with severe global disorders.