Common use of Movements Clause in Contracts

Movements. 2 In typical development, MMs gradually disappear during the first decade of life.3 However, in children with unilat- eral cerebral palsy (UCP), MMs are frequently more pronounced and persistent.1,4,5 Studies of these “pathological” MMs have predominantly focused on the underlying mechanisms1,4,6 and their effect on upper limb function.7-11 Two general mechanisms of MMs are typically described. First, the motor cortex of the less affected hemisphere also con- trols the affected hand (AH) by an uncrossed corticospinal tract to 0003-9993/18/$36 - see front matter ª 2018 by the American Congress of Rehabilitation Medicine ▇▇▇▇▇://▇▇▇.▇▇▇/10.1016/j.apmr.2018.01.035 the ipsilateral side of the spinal cord. This ipsilateral projection might depend on preserved ipsilateral projections to the AH or a branching of crossed corticospinal fibers.2,12 These “rewiring” profiles are suggested to cause MMs in both, but especially in the AH.6,13-15 Second, there is widespread and bilateral cortical activation that occurs when actively moving the AH, caused by sensorimotor impairments of this hand and thus increased effort required to move. This lack of “interhemispheric inhibition” is proposed to cause MMs in the less AH.6,8,13 MMs occurring in only the less AH are therefore thought to be related to sensori- motor impairments of the AH, whereas MMs in the AH have been proposed to indicate 1 motor cortex controlling both hands. Accordingly, MMs detected in the AH may act as a low-risk clinical biomarker to probe corticospinal tract wiring13 as compared to more invasive and time-consuming neuroimaging methods (eg, transcranial magnetic stimulation, functional mag- netic resonance imaging). If accurate, it would have a significant effect on clinical practice, allowing development of individualized therapy programs on the basis of the child’s rewiring profile.16 However, to date, studies11,17,18 using various assessments for MM detection report conflicting results, challenging its usefulness in probing cortical “rewiring.”‌‌ With respect to the effect of MMs on upper limb function, the results generally point to an association between pronounced MMs and impaired upper limb function,7-9 especially in bimanual tasks. However, findings are also not ubiquitous. Some studies7,9 report correlations between impaired bimanual performance and MMs in both the AH and the less AH, whereas others8,19 report an association only for MMs appearing in the less AH. Other studies10,11 report little association between MMs and bimanual performance, whereas some studies8,19 even indicate that MMs might assist movements of the AH. These contradicting results might be due to the different methods used to assess MMs. To advance our understanding of the mechanisms of MMs and their effect on upper limb function in UCP, it is essential to apply a valid, standardized, objective, and reliable clinical assessment.8,13 The universal standard for clinically evaluating MMs is a qualitative observational method based on the ▇▇▇▇▇ and ▇▇▇▇▇▇ scale (W&T).1 It is based on visual evaluation of MMs of one hand during voluntary movements of the other hand.1 Owing to its easy application and clinical utility, the W&T is widely used in studies8,9,11 of UCP, offering the potential opportunity for com- parison of data. However, its subjective scoring procedure and lack of published guidelines for administration hinder comparison of data. In fact, there is a broad variation in administration and inconsistent use of manual tasks across studies.1,8,11 The latter is especially problematic, because the severity of MMs is known to be dependent on the type and complexity of movements.1,5 AH affected hand CCCmax maximum cross-correlation coefficient MACS Manual Ability Classification System MM mirror movement MVC maximal voluntary contraction UCP unilateral cerebral palsy W&T ▇▇▇▇▇ and ▇▇▇▇▇▇ scale W&Tfist ▇▇▇▇▇ and ▇▇▇▇▇▇ fist opening and clenching W&Topposition ▇▇▇▇▇ and ▇▇▇▇▇▇ finger opposition W&Ttapping ▇▇▇▇▇ and ▇▇▇▇▇▇ finger tapping The observational nature of the W&T may affect the accuracy of detecting MMs and thereby test validity. Likewise, test sensitivity may be suboptimal, thus increasing the likelihood of not detecting MMs that are actually present. This might be due to the extent of mirroring activity (too subtle for visual detection) or the orientation of the hand under observation (eg, persistent wrist flexion of the AH). In addition, test specificity may be compromised, in this case increasing the chance of observing MMs that are not truly mirroring the intended movement of the active hand. Finally, because the close matching of both hand movements in time is not feasible using the W&T, MMs cannot be distinguished from other extraneous movements. These cumulative shortcomings might explain the conflicting results related to the use of MMs to probe cortical rewiring11,17,18 as well as to the effect of MMs on upper limb function.7-11,19 To overcome the shortcomings of the W&T, simultaneous electromyographic recordings of homologous muscles during single hand movements have been applied in earlier studies.4,6,16 However, it can be argued that these recordings reflect mirror recruitment (muscle activity) rather than actual MMs. Further- more, the clinical utility remains questionable. To objectively assess actual MMs while being clinically applicable, simultaneous grip force measurements of both hands during single hand movements might offer a solution.4,6,16 Here we introduce a new, easy-to-use, objective, standardized, and quantitative assessment for MMs, known as the Windmill-task, using grip force data of both hands during single hand squeeze movements. Quantitative data from the Windmill-task are compared with observation-based data from the W&T on a group level to examine the concurrent validity of the Windmill-data for assessing MMs and on an individual level to estimate differences between both assessment tools in terms of sensitivity and specificity for MM detection. It is hypoth- esized that the Windmill-task data correlate with the W&T data and that the Windmill-task exhibits higher sensitivity and specificity for MM detection compared to individual data from the W&T.