Bilateral vestibulopathy and age: experimental considerations for testing dynamic visual acuity on a treadmill.

INTRODUCTION: Bilateral vestibulopathy (BVP) can affect visual acuity in dynamic conditions, like walking. This can be assessed by testing Dynamic Visual Acuity (DVA) on a treadmill at different walking speeds. Apart from BVP, age itself might influence DVA and the ability to complete the test. The objective of this study was to investigate whether DVA tested while walking, and the drop-out rate (the inability to complete all walking speeds of the test) are significantly influenced by age in BVP-patients and healthy subjects. METHODS: Forty-four BVP-patients (20 male, mean age 59 years) and 63 healthy subjects (27 male, mean age 46 years) performed the DVA test on a treadmill at 0 (static condition), 2, 4 and 6 km/h (dynamic conditions). The dynamic visual acuity loss was calculated as the difference between visual acuity in the static condition and visual acuity in each walking condition. The dependency of the drop-out rate and dynamic visual acuity loss on BVP and age was investigated at all walking speeds, as well as the dependency of dynamic visual acuity loss on speed. RESULTS: Age and BVP significantly increased the drop-out rate (p ≤ 0.038). A significantly higher dynamic visual acuity loss was found at all speeds in BVP-patients compared to healthy subjects (p < 0.001). Age showed no effect on dynamic visual acuity loss in both groups. In BVP-patients, increasing walking speeds resulted in higher dynamic visual acuity loss (p ≤ 0.036). CONCLUSION: DVA tested while walking on a treadmill, is one of the few "close to reality" functional outcome measures of vestibular function in the vertical plane. It is able to demonstrate significant loss of DVA in bilateral vestibulopathy patients. However, since bilateral vestibulopathy and age significantly increase the drop-out rate at faster walking speeds, it is recommended to use age-matched controls. Furthermore, it could be considered to use an individual "preferred" walking speed and to limit maximum walking speed in older subjects when testing DVA on a treadmill.

Internal consistency and factor analysis of the Dutch version of the Dizziness Handicap Inventory.

CONCLUSIONS: The Dutch (Belgium) translation of the Dizziness Handicap Inventory (DHI) has proven to be as consistent as the original version. In addition to the three original subscales, factor analysis revealed a fourth component scoring self-perceived effects of insufficient functioning of the vestibulo-ocular reflex (VOR). Focus should be on the DHI total score in order to compare future results with the existing literature. OBJECTIVE: To conduct a factor analysis and to determine its internal consistency. MATERIALS AND METHODS: Charts of 214 outpatients, referred with dizziness or imbalance of vestibular and non-vestibular origin, were reviewed. RESULTS: The Cronbach's alpha coefficients for internal consistency were high for the total scale and good for the subscales. Corrected item-total correlations ranged from 0.71 for 'restricted travelling' to 0.29 for 'difficulties reading', when items were correlated with their respective subtotals, and ranged from 0.69 (restricted participation in social activities) to 0.33 (stressed relationships), when correlated with the total score. A principal component analysis with orthogonal rotation was conducted, suggesting a four-factor solution. Two factors were related to vestibular handicap, referring to the original functional and emotional subcategories. The remaining two factors related to vestibular disability, documenting motion sensitivity (original physical subscale) and insufficient VOR functioning.

Postural abnormalities and contraversive pushing following right hemisphere brain damage.

We investigated the presence of postural abnormalities in a consecutive sample of stroke patients, with either left or right brain damage, in relation to their perceived body position in space. The presence or absence of posture-related symptoms was judged by two trained therapists and subsequently analysed by hierarchical classes analysis (HICLAS). The subject classes resulting from the HICLAS model were further validated with respect to posture-related measurements, such as centre of gravity position and head position, as well as measurements related to the postural body scheme, such as the perception of postural and visual verticality. The results of the classification analysis clearly demonstrated a relation between the presence of right brain damage and abnormalities in body geometry. The HICLAS model revealed three classes of subjects: The first class contained almost all the patients without neglect and without any signs of contraversive pushing. They were mainly characterised by a normal body axis in any position. The second class were all neglect patients but predominantly without any contraversive pushing. The third class contained right brain damaged patients, all showing neglect and mostly exhibiting contraversive pushing. The patients in the third class showed a clear resistance to bringing the weight over to the ipsilesional side when the therapist attempted to make the subject achieve a vertical posture across the midline. The clear correspondence between abnormalities of the observed body geometry and the tilt of the subjective postural and visual vertical suggests that a patient's postural body geometry is characterised by leaning towards the side of space where he/she feels aligned with an altered postural body scheme. The presence of contraversive pushing after right brain damage points in to a spatial higher-order processing deficit underlying the higher frequency and severity of the axial postural abnormalities found after right brain lesions.

Test-retest reliability of the Dutch version of the Dizziness Handicap Inventory.

In the last fifteen years the Dizziness Handicap Inventory (DHI) has gained wide acceptance as a useful measure of handicap resulting from dizziness and unsteadiness. The objective of this study was to calculate measurement error and test-retest reliability of the Dutch version of the DHI. The translation into Dutch was performed according to a double translation method. One hundred and six patients with balance problems (range 26-78 years), scheduled for vestibular rehabilitation, completed the DHI on two occasions on the same day. The test-retest reliability was excellent, with Intraclass Correlation Coefficients ranging from 0.94 to 0.99 for DHI sub-scores and DHI total score. Most weighted kappa values (kappaW) exceeded 0.80 indicating substantial item per item test-retest reliability. Over 80% agreement was noted for all items except for item 8 (74%). Item 8 asks whether the subject feels dizzy or unsteady while doing ambitious activities like sports, dancing and household activities. Consequently measurement errors were calculated, suggesting that, after an intervention, the pretreatment DHI total score should at least decrease with 12 points (lower bound 99% confidence interval for a true change) before the intervention could be said to be effective for an individual patient. Based on these data, the Dutch version of the DHI showed itself to be a highly reliable instrument to assess the self-perceived handicap imposed by vestibular system diseases.

Contraversive pushing and inattention of the contralesional hemispace.

The aim of this study was to investigate, in 114 stroke patients, the frequency of occurrence of a largely unknown neurological disorder, characterized by a postural imbalance due to a 'pushing away' reaction of the body towards the contralesional side of space, in function of hemispheric lesion localization and gender. The study also investigate the relation of this contraversive pushing with active movement, somatosensory perception deficits and, in particular, inattention of contralesional hemispace and body. The similarity of the presence of contraversive pushing and the syndrome of spatial hemineglect together with a gender-related differentiation suggest the existence of a "pusher syndrome", in which the pathophysiology points in the direction of a spatial higher-order processing deficit, related to spatial inattention, underlying the higher frequency and severity of contraversive pushing after right brain lesions.

Effect of a therapeutic intervention for the hemiplegic upper limb in the acute phase after stroke: a single-blind, randomized, controlled multicenter trial.

BACKGROUND AND PURPOSE: Arm function recovery is notoriously poor in stroke patients. The effect of treatment modalities, particularly those directed at improving upper limb function, has been studied primarily in chronic stroke patients. The purpose of this study was to investigate the effect of a specific therapeutic intervention on arm function in the acute phase after stroke. METHODS: In a single-blind, randomized, controlled multicenter trial, 100 consecutive patients were allocated to either an experimental group that received an additional treatment of sensorimotor stimulation or to a control group. The intervention was applied for 6 weeks. Patients were evaluated for level of impairment (Brunnström-Fugl-Meyer test) and disability (Action Research Arm test, Barthel Index) before, midway, and after the intervention period and at follow-up 6 and 12 months after stroke. RESULTS: Patients in the experimental group performed better on the Brunnström-Fugl-Meyer test than those in the control group throughout the study period, but differences were significant only at follow-up. Results on the Action Research Arm test and Barthel Index revealed no effect at the level of disability. The effect of the therapy was attributed to the repetitive stimulation of muscle activity. The treatment was most effective in patients with a severe motor deficit and hemianopia or hemi-inattention. No adverse effects due to the intervention were found. CONCLUSIONS: Adding a specific intervention during the acute phase after stroke improved motor recovery, which was apparent 1 year later. These results emphasize the potential beneficial effect of therapeutic interventions for the arm.