Christophe Lafosse

Trunk performance after stroke and the relationship with balance, gait and functional ability

Objective: To evaluate trunk performance in non-acute and chronic stroke patients by means of the Trunk Control Test and Trunk Impairment Scale and to compare the Trunk Control Test with the Trunk Impairment Scale and its subscales in relation to balance, gait and functional ability after stroke. Subjects: Fifty-one stroke patients, attending a rehabilitation programme, participated in the study. Main measures: Subjects were evaluated with the Trunk Control Test, Trunk Impairment Scale, Tinetti balance and gait subscales, Functional Ambulation Category, 10-m walk test, Timed Up and Go Test and motor part of the Functional Independence Measure. Results: Participants obtained a median score of 61 out of 100 on the Trunk Control Test and 11 out of 23 for the Trunk Impairment Scale. Twelve participants (24%) obtained the maximum score on the Trunk Control Test; no subject reached the maximum score on the Trunk Impairment Scale. Measures of trunk performance were significantly related with values of balance, gait and functional ability. Multivariate linear regression analysis showed an additional, significant contribution of the dynamic sitting balance subscale of the Trunk Impairment Scale in addition to the Trunk Control Test total score for measures of gait and functional ability (model R2 = 0.55-0.62). Conclusions: This study clearly indicates that trunk performance is still impaired in non-acute and chronic stroke patients. When planning future follow-up studies, use of the Trunk Impairment Scale has the advantage that it has no ceiling effect.

Additional Exercises Improve Trunk Performance After Stroke: A Pilot Randomized Controlled Trial:

Background. Sitting balance and the ability to perform selective trunk movements are important predictors of functional outcome after stroke. However, studies evaluating the effect of exercises aimed at improving trunk performance are sparse. Objective. To examine the effect of additional trunk exercises on trunk performance after stroke. Methods. An assessor-blinded randomized controlled trial was carried out at an inpatient stroke rehabilitation center. In total 33 participants were assigned to an experimental group (n = 17) or a control group (n = 16). In addition to conventional therapy, the experimental group received 10 hours of individual and supervised trunk exercises; 30 minutes, 4 times a week, for 5 weeks. Trunk performance was evaluated by the Trunk Impairment Scale (TIS) and its subscales of static and dynamic sitting balance and coordination. A general linear repeated measures model was used to analyze the results of our study. Results. No significant differences were found pretreatment between the 2 groups for the collected demographic variables, stroke-related parameters, clinical measures, number of therapy sessions received, and primary outcome measure used. Posttreatment, a significantly better improvement was noted in the experimental group compared to the control group for the dynamic sitting balance subscale only; measuring selective lateral flexion initiated from the upper and lower part of the trunk, (P = .002, post hoc power calculation = .90, effect size = 1.16). Conclusions. Our results suggest that, in addition to conventional therapy, trunk exercises aimed at improving sitting balance and selective trunk movements have a beneficial effect on the selective performance of lateral flexion of the trunk after stroke.

Randomized controlled trial of truncal exercises early after stroke to improve balance and mobility.

Background. Sitting balance and the ability to perform selective truncal movements are important predictors of functional outcome after stroke. However, few clinical trials have evaluated the effect of truncal exercises. Objective. The authors assessed the effect of additional truncal exercises on truncal function, standing balance, and mobility. Methods. An assessor-blinded randomized controlled trial was carried out at a stroke rehabilitation hospital. A total of 33 participants (mean 35 days post onset) were randomly assigned to an experimental group (n = 18) or a control group (n = 15). In addition to conventional therapy, the experimental group received 16 hours of truncal exercises. The control group received 16 hours of sham treatment. Truncal function was evaluated by the Trunk Impairment Scale (TIS) and standing balance and mobility by the Tinetti Test. The Romberg with eyes open and eyes closed, Four Test Balance Scale (FTBS), Berg Balance Scale (BBS), Rivermead Motor Assessment Battery (RMAB), Functional Ambulation Categories, and Dynamic Gait Index (DGI) were performed to elucidate the findings of the primary outcome measures. Results. A treatment effect was found for the experimental group on the TIS (P < .001), Tinetti Test (P < .001), FTBS (P = .014), BBS (P = .007), RMAB (P < .001), and DGI (P = .006). Conclusions. In addition to conventional therapy, truncal exercises have a beneficial effect on truncal function, standing balance, and mobility in people after stroke.

Visuoperceptual impairment in multiple sclerosis patients diagnosed with neuropsychological tasks.

A comprehensive set of 31 binocular neuropsychological tasks assessing a series of spatial and non-spatial visuoperceptual abilities was used to study visuoperceptual impairment in a representative group of 49 MS-clinic patients exhibiting neither diagnosed ophthalmological afflictions nor major psychiatric diagnoses. Among these patients, true frequency rate of visuoperceptual impairment, i.e. of subjects failing four or more tasks, was estimated at 26%. The pattern of visuoperceptual impairment was non-uniform, non-selective, restricted and idiosyncratic. Only four tasks yielded significant rates of impairment. They concerned colour discrimination, the perception of the Müller-Lyer illusion and object recognition in two separate conditions. Each of the four factors identified by factor analysis had an important representative (with factor loading 40.35) among these four tasks. Failures on these tasks correlated poorly. Together, the four tasks satisfactorily predicted visuoperceptual impairment as defined by the comprehensive set of tasks (sensitivity 86.7%; specificity 81.3%), but with regard to an uncontaminated criterion, their aggregate sensitivity and specificity was only 75 and 56% respectively. Visuoperceptual neuropsychological task performance related significantly but weakly to cognitive status, physical disability and to pyramidal, cerebellar and brain stem neurological signs, and did not correlate with other clinical neurological signs, disease duration, type of MS, a history of optic neuritis, depression or medication status.

A psychophysical study of visual extinction: ipsilesional distractor interference with contralesional orientation thresholds in visual hemineglect patients

Visual extinction was investigated in left (n=15) and right (n=25) brain-damaged patients with or without visual neglect, and in normal control subjects (n=14), using a psychophysical paradigm. Orientation discrimination thresholds were determined for both left and right hemifield gratings presented either in isolation or simultaneously with a contralateral distractor grating. To minimize the influence of possible sensory-perceptual deficits, the luminances of both target and distractor gratings were chosen to be 20 times the luminances necessary to discriminate between horizontal and vertical grating orientations. The location of the target grating was always cued, making the distractor grating task irrelevant. Even after equalizing the visibility of left and right hemifield stimuli, neglect patients still displayed an increased interference effect from an ipsilesional distractor (and no interference from a contralesional distractor). Left or right brain-damaged controls did not show this asymmetric interference of irrelevant distractors, even the patients who demonstrated extinction on standard extinction testing. This suggests that visual extinction is a critical component of the visual neglect syndrome and that it involves an attentional deficit.

Temporal and spatial resolution in foveal vision of multiple sclerosis patients

Deficits of spatial and temporal resolution were compared in a group of 49 definite multiple sclerosis(MS) patients showing no major evidence of previous optic neuritis attack but representative of the population of the Belgian National MS Centre as to age and the most important disease variables. Resolution in the two domains was measured foveally with forced-choice staircase psychophysical procedures using Landoldt C and double flash stimuli, respectively. The two measurements were equally sensitive to MS-induced deficits and did not exhibit cross-sensitivity. Since discrete deficits of either kind were equally prevalent and outnumbered combined deficits, this suggests a nonselective but nonuniform destruction of M and P visual pathway function in these patients.

Visuoperceptual impairment in MS patients: nature and possible neural origins

Failures on visuoperceptual neuropsychological tasks (on neuropsychological tests of visuo-spatial perception or on tests concerning semantic properties of visual objects), may indicate focal deficits of visuoperceptual function, or could be the result of (an)other (peripheral) visual deficit(s), or be the effect of a more general cognitive decline. In multiple sclerosis (MS) patients exhibiting sufficient visual acuity and not showing severe cognitive deterioration, impairment on a comprehensive set of 31 visuoperceptual neuropsychological tasks was compared with spatial resolution deficits (SRD), temporal resolution deficits (TRD) for visual stimuli, abnormal pattern shift visual evoked potential (PSVEP) responses, and failing scores on neuropsychological tasks other than visuoperceptual tasks. Impairment on the visuoperceptual neuropsychological tasks was highly independent from the other abnormal visual and cognitive neurological impairments examined, suggesting that it mostly represented focal deficits. Only TRD in both eyes related to this impairment and this relationship was rather weak. Thus in some MS patients a slowed visual information processing may be one of the combined deficits underlying visuoperceptual neuropsychological task impairment. Given that SRD and TRD were not related to another stage of MS and reflect disturbances of a P (parvocellular channel and ventral stream projections) and M (magnocellular channel and dorsal stream projections) visual-system function respectively, demyelination of a certain M pathway may become a co-determinant of visuoperceptual neuropsychological task impairment more rapidly than damage to a certain P pathway.

Graviceptive misperception of the postural vertical after right hemisphere damage.

We have systematically studied the subjective postural vertical (SPV) and the location of the centre of gravity (COG) in right brain damaged patients, classified according to the severity of their hemispatial neglect. The results indicate that the patients lean towards the side of space where they feel aligned with their ipsilesionally displaced SPV, resulting in a ipsilesional deviation of the COG. This displacement can be reduced by the effect of contralesionally applied transcutaneous electrical nerve stimulation (TENS). However, in the severe neglect patients, an increasing mismatch arised between the perceived body orientation and the direction of the gravitational force. The results indicate that this conflict is compensated by a contraversive shift of the COG towards the contraversive side in order to re-align the SPV with the gravitational vertical.

Dysfunction of right hemisphere attentional networks in Attention Deficit Hyperactivity Disorder

Although differential right-hemisphere dysfunction has been implicated in attention deficit hyperactivity disorder (ADHD) for more than 15 years, this relation remains controversial. Neuroimaging studies suggest asymmetric dysfunction, but neuropsychological evidence in support of this is rather inconsistent. This study examined attentional asymmetry in ADHD adults with a psychophysical extinction task. The interference from right- or left-hemifield distractors with contralateral orientation sensitivity was determined. In a previous study using this paradigm, right brain-damaged patients with left neglect displayed asymmetric distractor interference, meaning a significant interference from a right distractor with left-hemifield orientation sensitivity but no interference from a left distractor with right-hemifield orientation sensitivity. A similar but less pronounced asymmetry was observed in a group of ADHD adults (n = 16). These results indicate dysfunction of right-hemisphere attentional circuits in ADHD.

Upper Limb Exteroceptive Somatosensory and Proprioceptive Sensory Afferent Modulation of Hemispatial Neglect

In many paradigms of stimulation techniques aimed at reducing hemispatial neglect, somatosensory and proprioceptive stimulation are often interchanged, although the anatomical and functional pathways transmitting these signals are clearly different. Therefore, we have investigated the effects of one somatosensory stimulation technique, the cyclic pressure application (CPA), and have compared them with the effects of left transcutaneous electrical stimulation (TENS) on the expression of left hemispatial neglect in 13 stroke patients, as assessed by two visuospatial exploration tasks: the Star Cancellation task and Schenkenbergs Line Bisection task. In a first experiment, four treatment conditions were given: TENS, CPA, TENS + CPA, as well as a placebo condition. For each patient, the intensity of the TENS was determined, based on his/her conscious somatosensory threshold for the electrical impulses. In order to determine whether unconscious proprioceptive afferent information instead of exteroceptive somatosensory stimulation is a sufficient condition to improve hemispatial neglect, we carried out a second experiment, only with patients suffering from complete somatosensory loss. The effects of the different treatments were investigated, using the same sequence as for Experiment 1, but, this time, the applied intensity of TENS was manipulated over two conditions : (1) one in which the intensity of TENS stimulation was below the motor (proprioceptive) threshold and (2) one in which the intensity was determined following the degree of proprioceptive stimulation demonstrated by the point at which a visible muscle contraction during the stimulation could be elicited. The results demonstrated that proprioceptive-based TENS stimulation is a sufficient condition to reduce hemispatial neglect, even when a severe somatosensory loss was present.