Where data are to be pooled for international studies, analysis of DIF by culture is essential. Where DIF is observed, adjustments can be made to allow for cultural differences in outcome measurement.

Background and Purpose-Chronic hemiparetic patients often retain the ability to manage activities requiring both hands, either through the use of the affected arm or compensation with the unaffected limb. A measure of this overall ability was developed by adapting and validating the ABILHAND questionnaire through the Rasch measurement model. ABILHAND measures the patient's perceived difficulty in performing everyday manual activities. Methods-One hundred three chronic (Ͼ6 months) stroke outpatients (62% men; mean age, 63 years) were assessed (74 in Belgium, 29 in Italy). They lived at home and walked independently and were screened for the absence of major cognitive deficits (dementia, aphasia, hemineglect). The patients were administered the ABILHAND questionnaire, the Brunnström upper limb motricity test, the box-and-block manual dexterity test, the Semmes-Weinstein tactile sensation test, and the Geriatric Depression Scale. The brain lesion type and site were recorded. ABILHAND results were analyzed with the use of Winsteps Rasch software. Results-The Rasch refinement of ABILHAND led to a change from the original unimanual and bimanual 56-item, 4-level scale to a bimanual 23-item, 3-level scale. The resulting ability scale had sufficient sensitivity to be clinically useful. Rasch reliability was 0.90, and the item-difficulty hierarchy was stable across demographic and clinical subgroups. Grip strength, motricity, dexterity, and depression were significantly correlated with the ABILHAND measures. Key Words: arm Ⅲ disability evaluation Ⅲ rehabilitation Ⅲ stroke P oststroke hemiplegia is one of the most prevalent forms of motor disability, affecting approximately 1% of the population. 1 Although most current stroke survivors achieve an autonomous form of gait, a satisfactory recovery (if any) of the affected upper limb function is much more rare. Conclusions-TheAlthough several tests are available 2-4 for measuring upper limb function in terms of grip strength, dexterity, sensation, and performance in standardized manipulative tasks, the measurements are all made at the focal impairment level. 5 The actual disability, however, is far from linearly related to the underlying impairments. 6 It depends on complex interactions between upper limb function and compensatory behaviors of the person, such as using the unaffected limb or dividing complex movements into simpler ones. Moreover, the learning of new motor processes is influenced by the subject's motivational and emotional status, which is likely to be impaired by stroke. 7 Manual ability may be defined as the capacity to manage daily activities requiring the use of the upper limbs, whatever the strategies involved. Therefore, it should be measured per se and not simply inferred from focal impairments. Since it is a behavior, manual ability belongs to the domain of latent variables concealed within the person, such as pain, depression, and intelligence. The "amount" of manual ability can be inferred from observed activities and/or a patient's perceived difficul...

One of the most devastating consequences of early corticospinal lesions is the impaired dexterity that results in a noticeable deficit while manipulating small objects. One purpose of the present study was to investigate the extent to which a deficit in the coordination of fingertip forces when grasping and lifting an object between the thumb and index finger could account for the impaired dexterity in patients with congenital hemiplegia (CH). A second objective was to examine whether, in these patients, deficits in skilled hand movements are correlated with the importance of structural damage to the corticospinal tract. The scaling and coordination of fingertip forces during precision grip was investigated in 16 CH patients (aged 8-19 years) and 16 age- and sex-matched control subjects. Proprioception, stereognosis, pressure sensitivity and motor upper limb function (including digital and manual dexterity) were also assessed quantitatively. The structural damage of the corticospinal tract was estimated by measuring the cross-sectional area of cerebral peduncles with MRI and by calculating an index of symmetry between the two peduncles. In CH patients, a large number of parameters measured during the grip-lift task were significantly different when compared with those found in control subjects. Among those, the duration of the preloading and loading phases was significantly longer in CH patients. In addition, both the dissimilarity and time-shift between the profiles of the grip and load force rates, quantified with the cross-correlation method, were also significantly larger in CH patients; the time-shift was strongly correlated with impaired dexterity. These findings suggest that impaired dextrous finger movements in CH patients may specifically result from their inability to ensure a precise synergy between fingertip forces while manipulating an object. Finally, the finding that the time-shift also correlated with the corticospinal tract dysgenesis, as estimated with the cerebral peduncle asymmetry, argues in favour of a critical role of the corticospinal system in the temporal coordination between different muscles involved in dextrous hand movements. Both digital and manual dexterity were also altered in the non-paretic hand of CH patients. This deficit may reveal the contribution of the lesioned hemisphere to the control of ipsilateral skilled finger movements.

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