Trunk control in stroke. Aspects of measurement, relation to brain lesion, and change after rehabilitation
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Stroke is a leading cause of disability worldwide and affects mostly elderly people. Neurorehabilitation is important for reducing the long-term consequences of stroke, aiming to achieve an optimal functional recovery for home and community reintegration. Physiotherapy is the most common rehabilitation intervention, and the role of the physiotherapist is mainly focussed on improvement in motor function. One of the most important functions of the central nervous system is to coordinate posture and movement to stabilise the body during movements and perturbations. Trunk control is a central aspect of postural control, and has been found to be impaired after stroke. There is limited knowledge on trunk control after stroke, and further studies are warranted. The thesis comprises three studies; one methodological, one translational and one intervention study. The overall aim was to broaden our understanding and knowledge of trunk control in patients with stroke.
The objective of Paper I was to translate the Trunk Impairment Scale (TIS), a measure of trunk control in patients with stroke, into Norwegian and to explore its construct validity, internal consistency, intertester and test-retest reliability. Data from 201 patients with stroke were used to explore construct validity by Item Response Theory and factor analysis. In this process, one of the subscales, static sitting balance, was omitted, and the remaining 14 items were included in six ordinal scales, and named the Trunk Impairment Scale – modified Norwegian version, TIS-modNV. After this modification, the TIS-modNV fitted well to a locally dependent unidimensional Item Response Theory model with one general factor which we call trunk control, and two content specific factors: lower and upper trunk stability. The scale demonstrated excellent construct validity, high internal consistency (alpha 0.85) and high intertester (ICC 0.77) and test-retest (ICC 0.85) reliability for the total score, supporting its use to evaluate trunk control in patients after stroke as well as other central nervous system disorders. We believe that we achieved a satisfactory translation and cross-cultural adaptation.
The objective of Paper 2 was to explore the relationship between middle cerebral artery lesion locations (MCA) and trunk control post stroke, and to compare trunk control between patients with lesions in different single and multiple locations, and between left and right hemispheres. A total of 109 patients with acute stroke in the MCA territory were examined using magnetic resonance imaging (MRI) and tested for trunk control using TIS-modNV. To determine the location and extent of the lesion, the MRI scans were scored using the Alberta Stroke Program Early CT Score (ASPECTS), which scores 10 areas in the supply area of the MCA. Single lesion locations were found in 38 of the patients, and data from these formed the basis for further analyses. We found that an ASPECT lesion location in the anterior part of the MCA territory, called M5, demonstrated a hemispheric differentiation for trunk control. Patients with right M5 lesion locations achieved significantly poorer scores on trunk control as compared to left, p = 0.030. However, there were few patients with M5 lesion locations (n = 19), and too few patients to investigate a relationship between other ASPECT locations and trunk control. The results indicate that there is a cortical regulation of trunk control and that the two hemispheres may have different roles in this regard.
Paper III was a group comparison study in the context of a randomised controlled trial. Three different rehabilitation models: two for early supported discharge either in a day-unit or in the patients’ own homes, and one traditional uncoordinated treatment were compared for change in physical function after acute stroke. Several outcome measures for balance and walking were used. The Postural Assessment Scale for Stroke was the primary outcome, and TIS-modNV one of the secondary outcome measures. We used data from 167 patients at baseline, 52 in the day-unit group, 60 in the home-rehabilitation group and 55 in the control group. There were no differences between the groups for baseline characteristics or physical function, and no differences between the groups for length of stay in the stroke unit; mean (SD), min-max: 8.6 (3.3) days, 3-17, p = 0.948. The patients had an overall mild to moderate disability, and high scores on PASS. There was a substantial loss to follow-up with 62.9% of the patients being retested at three months, but no significant differences between the retested groups for baseline characteristics. We found no differences in change between the groups for PASS, p > 0.05. We did find differences between the groups for some secondary measures: trunk control, median (95%CI): day-unit, 2 (0.28, 2.31); home-rehabilitation, 4 (1.80, 3.78); control, 1 (0.56, 2.53), p = 0.044, and self-report on walking, p = 0.021, and ADL, p = 0.016, with a tendency to favour the intervention groups over the control group. Mean walking speed improved above minimally important change only in the day-unit group. Bonferroni adjusted pairwise comparisons gave no differences between the groups for trunk control; for self-report on walking, the day-unit group improved more than control, p = 0.004. For self-report on ADL there was a difference between the home-rehabilitation and the control group, p = 0.006. We concluded that with regard to secondary outcomes, multidisciplinary, coordinated rehabilitation tended to be more effective than traditional treatment.
In summary, we found that the TIS-modNV has satisfactory measurement properties and can be recommended for use in clinical practice as well as in research. Using the TIS-modNV and ASPECTS, we found indication for a cortical regulation of trunk control, as well as a relationship between lesion location, hemispheric differentiation and trunk control. PASS demonstrated a substantial ceiling effect, and three months after acute stroke no difference was found in change between the groups. On a group level, rehabilitation using coordinated multidisciplinary rehabilitation favoured trunk control, and self-reported walking and ADL.