Posts Tagged chronic stroke

[ARTICLE] The impact of large structural brain changes in chronic stroke patients on the electric field caused by transcranial brain stimulation – Full Text

Abstract

Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (TDCS) are two types of non-invasive transcranial brain stimulation (TBS). They are useful tools for stroke research and may be potential adjunct therapies for functional recovery. However, stroke often causes large cerebral lesions, which are commonly accompanied by a secondary enlargement of the ventricles and atrophy. These structural alterations substantially change the conductivity distribution inside the head, which may have potentially important consequences for both brain stimulation methods. We therefore aimed to characterize the impact of these changes on the spatial distribution of the electric field generated by both TBS methods. In addition to confirming the safety of TBS in the presence of large stroke-related structural changes, our aim was to clarify whether targeted stimulation is still possible. Realistic head models containing large cortical and subcortical stroke lesions in the right parietal cortex were created using MR images of two patients. For TMS, the electric field of a double coil was simulated using the finite-element method. Systematic variations of the coil position relative to the lesion were tested. For TDCS, the finite-element method was used to simulate a standard approach with two electrode pads, and the position of one electrode was systematically varied. For both TMS and TDCS, the lesion caused electric field “hot spots” in the cortex. However, these maxima were not substantially stronger than those seen in a healthy control. The electric field pattern induced by TMS was not substantially changed by the lesions. However, the average field strength generated by TDCS was substantially decreased. This effect occurred for both head models and even when both electrodes were distant to the lesion, caused by increased current shunting through the lesion and enlarged ventricles. Judging from the similar peak field strengths compared to the healthy control, both TBS methods are safe in patients with large brain lesions (in practice, however, additional factors such as potentially lowered thresholds for seizure-induction have to be considered). Focused stimulation by TMS seems to be possible, but standard tDCS protocols appear to be less efficient than they are in healthy subjects, strongly suggesting that tDCS studies in this population might benefit from individualized treatment planning based on realistic field calculations.

1. Introduction

Transcranial brain stimulation (TBS) methods are useful tools to induce and to quantify neural plasticity, and as such are increasingly being used in stroke research and as potential adjunct therapies in stroke rehabilitation. The cerebral lesions caused by stroke result in persisting physical or cognitive impairments in around 50% of all survivors (Di Carlo, 2008Leys et al., 2005 ;  Young and Forster, 2007), meaning that new therapies are urgently needed. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (TDCS) are two TBS approaches which are being increasingly utilised in stroke research. Single-pulse TMS combined with electromyography (EMG) or electroencephalography (EEG) can be used to assess cortical excitability, for example to index the functional state of the perilesional tissue. The neuromodulatory effects of repetitive TMS protocols (rTMS) may, in association with neuro-rehabilitative treatments, enhance motor recovery (Liew et al., 2014). Similar results have been demonstrated for TDCS. For example, anodal TDCS of the hand area in the primary motor cortex has been shown to improve motor performance of the affected hand (Allman et al., 2016Hummel et al., 2005 ;  Stagg et al., 2012) and anodal TDCS applied over the left frontal cortex enhanced naming accuracy in patients with aphasia (Baker et al., 2010). However, not all studies report a clear-cut positive impact of TBS on the stroke symptoms. Rather, the observed effects are often weak and not consistent across patients, demonstrating the need for a better understanding of the underlying biophysical and physiological mechanisms.

Compared with healthy subjects, several factors might contribute to a change in the neuroplastic response to TBS protocols in stroke patients, including changes in the neural responsiveness to the applied electric fields, as well as differences in the underlying physiology and metabolism (Blicher et al., 2009Blicher et al., 2015 ;  O’Shea et al., 2014). When the lesions are large, they may also substantially alter the generated electric field pattern, meaning that the assumptions on spatial targeting as derived from biophysical modelling and physiological experiments in healthy subjects might no longer be valid. Stroke lesions are often accompanied by secondary macrostructural changes such as cortical atrophy and enlargement of the ventricles (e.g., Skriver et al., 1990), which may further contribute to changes in the field pattern. In addition, the safety of TBS in patients with large lesions needs to be further clarified, as it is possible that the lesions might cause stimulation “hot spots”. In chronic patients, the stroke cavity becomes filled with corticospinal fluid (CSF), which might cause shunting of current, funnelling the generated currents towards the surrounding brain tissue and potentially causing localized areas of dangerously high field strengths.

Here, using finite-element calculations and individual head models derived from structural MR images, we focused on the impact of a large cortical lesion in chronic stroke on the electric field pattern generated in the brain by TMS and TDCS, respectively. Firstly, we assessed the safety of the stimulation by comparing the achieved field strengths with those estimated for a healthy control. Secondly, we tested how reliably we can accurately target the perilesional tissue, often the desired target for TBS, as reorganisation here is thought to underpin functional recovery (Kwakkel et al., 2004). Finally, we were also interested to see whether any observed changes in the field pattern were specific to a patient with a cortical lesion (which is connected to the CSF layer underneath the skull), or whether similar effects might occur in case of large chronic subcortical lesion. We therefore additionally tested the field distribution in a head model of a patient with a subcortical lesion occurring at a similar position as the cortical lesion.

2. Materials and methods

2.1. Selection of patients

The aim of this study was to characterize the effect of a large chronic cortical stroke lesion on the electric field distribution generated by TBS, and to compare the effects of this lesion to that caused by a large chronic subcortical lesion. MR images of several patients were visually inspected to select two datasets, which had a cortical [P01] and subcortical lesion [P02], respectively, within the same gross anatomical regions.

Patient P01 was a 36 year old female with episodic migraine; she was admitted with left hemiparalysis, fascial palsy and a total NIHSS score of 16 due to a right ICI/MCI occlusion. She was treated with IV thrombolysis and thrombectomy and recanalization was achieved 5 h after symptom onset. One year post-stroke she still suffered from motor impairment (Wolf Motor Function Test [WMFT] score of 30) and was scanned as part of a clinical study investigating the effect of combining Constraint-Induced Movement Therapy and tDCS (Figlewski et al., 2017; Clinical trials NCT01983319, Regional Ethics approval: 1-10-72-268-13). The structural scans showed a cortical lesion in the right parietal lobe (Fig. 1A). The lesion volume, delineated manually with reference to T1- and T2-weighted imaging, was 26,415 mm3.

Fig. 1:Fig. 1.

A) Coronal view of patient P01 with a cortical lesion in the right hemisphere. The top shows the T1-weighted MR image and the bottom the reconstructed head mesh. The view was chosen to include the lesion centre. The lesion is marked by red dashed circles. B) Corresponding view of patient P02 with a large subcortical lesion at a similar location in the right hemisphere. C) Corresponding view of the data set of the healthy control. D) The coil and electrode positions were systematically moved along two directions that were approximately perpendicular to each other. Five positions were manually placed every 2 cm in posterior – anterior direction symmetrically around the centre of the cortical lesion. The same was repeated along the lateral – medial direction. Both lines share the same centre position above the lesion, resulting in 9 positions in total. E) At each position, two coil orientations were tested which resulted in a current flow underneath the coil centre from anterior to posterior (top) and from lateral to medial, respectively (bottom). F) For each position of the yellow “stimulating” electrode, two positions of the blue return electrode were tested. First, the contralateral equivalent of the electrode position above the centre of the cortical lesion was used (top). In addition, a position on the contralateral forehead was tested (bottom).

Patient P02 was a 44 year old female. She woke up with a left hemiparesis and an acute CT scan showed no bleeding. No IV thrombolysis was given due to uncertain timing of symptom onset. An embolic stroke was suspect due to a patent foramen ovale, which was subsequently closed. She was scanned with MRI 9 months post stroke showing a right subcortical infarct, at which time she had a WMFT score of 8. The lesion volume, delineated as for P01, was 56,010 mm3. She was scanned as part of a clinical study investigating the effect of combining tDCS with daily motor training (Allman et al., 2016; Regional Ethics approval: Oxfordshire REC A; 10/H0604/98)….

Continue —> The impact of large structural brain changes in chronic stroke patients on the electric field caused by transcranial brain stimulation

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[Abstract] Experience of an upper limb training program with a non-immersive virtual reality system in patients after stroke: a qualitative study

Abstract

Objectives

The YouGrabber (YG) is a new virtual reality training system that focuses on unilateral and bimanual activities. This nested study was part of a larger multicentre randomised controlled trial and explored experiences of people with chronic stroke during a 4 week intensive upper limb training with YG.

Design

A qualitative design using semi-structured, face-to-face interviews. A phenomenological descriptive approach was used, with data coded, categorized and summarized using a thematic analysis. Topics investigated included: the experience of YG training, perceived impact of YG training on arm function, and the role of the treating therapist.

Results

Five people were interviewed (1 female, age range 55-75yrs, 1-6yrs post-stroke). Seven main themes were identified: (1) general experience, (2) expectations, (3) feedback, (4) arm function, (5) physiotherapist’s role, (6) fatigue, (7) motivation. Key experiences reported included feelings of motivation and satisfaction, with positive factors identified as challenge, competition, fun and effort. The YG training appeared to trigger greater effort, however fatigue was experienced at the end of the training. Overall, patients described positive changes in upper limb motor function and activity level, e.g. automatic arm use. While the opportunity for self-practice was appreciated, input from the therapist at the start of the intervention was deemed important for safety and confidence.

Conclusions

Reported experiences were mostly positive and the participants were motivated to practice intensively. They enjoyed the challenging component of the games.

Source: Experience of an upper limb training program with a non-immersive virtual reality system in patients after stroke: a qualitative study – Physiotherapy

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[Abstract] Quantitative EEG for Predicting Upper-limb Motor Recovery in Chronic Stroke Robot-assisted Rehabilitation – IEEE Xplore Document

Abstract:

Stroke is a leading cause for adult disability, which in many cases causes motor deficits. Despite the developments in motor rehabilitation techniques, recovery of upper limb functions after stroke is limited and heterogeneous in terms of outcomes, and knowledge of important factors that may affect the outcome of the therapy is necessary to make a reasonable prediction for individual patients.
In this study, we assessed the relationship between quantitative electroencephalographic (QEEG) measures and the motor outcome in chronic stroke patients that underwent a robot-assisted rehabilitation program to evaluate the utility of QEEG indices to predict motor recovery. For this purpose, we acquired resting-state electroencephalographic signals from which the Power Ratio Index (PRI), Delta/Alpha Ratio (DAR), and Brain Symmetry Index (BSI) were calculated. The outcome of the motor rehabilitation was evaluated using upper-limb section of the Fugl-Meyer Assessment.
We found that PRI was significantly correlated with the motor recovery, suggesting that this index may provide useful information to predict the rehabilitation outcome.

Source: Quantitative EEG for Predicting Upper-limb Motor Recovery in Chronic Stroke Robot-assisted Rehabilitation – IEEE Xplore Document

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[Abstract] Executive function is associated with off-line motor learning in people with chronic stroke

Provisional Abstract:
Background and Purpose: Sleep has been shown to promote off-line motor learning in individuals following stroke. Executive function ability has been shown to be a predictor of participation in rehabilitation and motor recovery following stroke. The purpose of this study was to explore the association between executive function and off-line motor learning in individuals with chronic stroke compared to healthy control participants.

Methods: Seventeen individuals with chronic stroke (> 6 months post stroke) and nine healthy adults were included in the study. Participants underwent three consecutive nights of polysomnography (PSG), practiced a continuous tracking task (CTT) the morning of the third day, and underwent a retention test the morning after the third night. Participants underwent testing on four executive function tests after the CTT retention test.

Results: Stroke participants showed a significant positive correlation between the off-line motor learning score and performance on the Trail Making Test (TMT D-KEFS) (r= .652 p= .005), while the healthy controls did not. Regression analysis showed that the TMT D-KEFS is a significant predictor of off-line motor learning (p= .008).

Discussion and Conclusions: This is the first study to demonstrate that better performance on an executive function test of attention and set-shifting predicts a higher magnitude of off-line motor learning in individuals with chronic stroke. This emphasizes the need to consider attention and set-shifting abilities of individuals following stroke as these abilities predict off-line motor learning. This in turn could affect learning of ADL’s and impact functional recovery following stroke.

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Source: JUST ACCEPTED: “Executive function is associated with off-line motor learning in people with chronic stroke”

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[Abstract+References] Predicting Motor Sequence Learning in Individuals With Chronic Stroke

Background. Conventionally, change in motor performance is quantified with discrete measures of behavior taken pre- and postpractice. As a high degree of movement variability exists in motor performance after stroke, pre- and posttesting of motor skill may lack sensitivity to predict potential for motor recovery.

Objective. Evaluate the use of predictive models of motor learning based on individual performance curves and clinical characteristics of motor function in individuals with stroke.

Methods. Ten healthy and fourteen individuals with chronic stroke performed a continuous joystick-based tracking task over 6 days, and at a 24-hour delayed retention test, to assess implicit motor sequence learning.

Results. Individuals with chronic stroke demonstrated significantly slower rates of improvements in implicit sequence-specific motor performance compared with a healthy control (HC) group when root mean squared error performance data were fit to an exponential function. The HC group showed a positive relationship between a faster rate of change in implicit sequence-specific motor performance during practice and superior performance at the delayed retention test. The same relationship was shown for individuals with stroke only after accounting for overall motor function by including Wolf Motor Function Test rate in our model.

Conclusion. Nonlinear information extracted from multiple time points across practice, specifically the rate of motor skill acquisition during practice, relates strongly with changes in motor behavior at the retention test following practice and could be used to predict optimal doses of practice on an individual basis.

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Source: Predicting Motor Sequence Learning in Individuals With Chronic Stroke – Aug 10, 2016

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[Abstract] Role of corpus callosum integrity in arm function differs based on motor severity after stroke

Highlights

    Corpus callosum structural integrity could impact motor function after stroke.Corpus callosum integrity was decreased and correlated with motor function.Correlation was strongest in the subgroup with relatively greater motor capacity.In subgroup with less motor capacity, only CST integrity correlated with motor function.

Abstract

While the corpus callosum (CC) is important to normal sensorimotor function, its role in motor function after stroke is less well understood.

This study examined the relationship between structural integrity of the motor and sensory sections of the CC, as reflected by fractional anisotropy (FA), and motor function in individuals with a range of motor impairment level due to stroke.

Fifty-five individuals with chronic stroke (Fugl-Meyer motor score range 14 to 61) and 18 healthy controls underwent diffusion tensor imaging and a set of motor behavior tests. Mean FA from the motor and sensory regions of the CC and from corticospinal tract (CST) were extracted and relationships with behavioral measures evaluated. Across all participants, FA in both CC regions was significantly decreased after stroke (p < 0.001) and showed a significant, positive correlation with level of motor function. However, these relationships varied based on degree of motor impairment: in individuals with relatively less motor impairment (Fugl-Meyer motor score > 39), motor status correlated with FA in the CC but not the CST, while in individuals with relatively greater motor impairment (Fugl-Meyer motor score ≤ 39), motor status correlated with FA in the CST but not the CC.

The role interhemispheric motor connections play in motor function after stroke may differ based on level of motor impairment. These findings emphasize the heterogeneity of stroke, and suggest that biomarkers and treatment approaches targeting separate subgroups may be warranted.

Source: Role of corpus callosum integrity in arm function differs based on motor severity after stroke

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[Abstract] Chronic Stroke Survivors Improve Reaching Accuracy by Reducing Movement Variability at the Trained Movement Speed

Background. Recovery from stroke is often said to have “plateaued” after 6 to 12 months. Yet training can still improve performance even in the chronic phase. Here we investigate the biomechanics of accuracy improvements during a reaching task and test whether they are affected by the speed at which movements are practiced.

Method. We trained 36 chronic stroke survivors (57.5 years, SD ± 11.5; 10 females) over 4 consecutive days to improve endpoint accuracy in an arm-reaching task (420 repetitions/day). Half of the group trained using fast movements and the other half slow movements. The trunk was constrained allowing only shoulder and elbow movement for task performance.

Results. Before training, movements were variable, tended to undershoot the target, and terminated in contralateral workspace (flexion bias). Both groups improved movement accuracy by reducing trial-to-trial variability; however, change in endpoint bias (systematic error) was not significant. Improvements were greatest at the trained movement speed and generalized to other speeds in the fast training group. Small but significant improvements were observed in clinical measures in the fast training group.

Conclusions. The reduction in trial-to-trial variability without an alteration to endpoint bias suggests that improvements are achieved by better control over motor commands within the existing repertoire. Thus, 4 days’ training allows stroke survivors to improve movements that they can already make. Whether new movement patterns can be acquired in the chronic phase will need to be tested in longer term studies. We recommend that training needs to be performed at slow and fast movement speeds to enhance generalization.

Source: Chronic Stroke Survivors Improve Reaching Accuracy by Reducing Movement Variability at the Trained Movement Speed – Feb 01, 2017

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[Abstract] Determining the benefits of transcranial direct current stimulation on functional upper limb movement in chronic stroke. – International Journal of Rehabilitation Research

Abstract

Transcranial direct current stimulation (tDCS) has been proposed as a tool to enhance stroke rehabilitation; however, evidence to support its use is lacking. The aim of this study was to investigate the effects of anodal and cathodal tDCS on upper limb function in chronic stroke patients. Twenty five participants were allocated to receive 20 min of 1 mA of anodal, cathodal or sham cortical stimulation in a random, counterbalanced order. Patients and assessors were blinded to the intervention at each time point. The primary outcome was upper limb performance as measured by the Jebsen Taylor Test of Hand Function (total score, fine motor subtest score and gross motor subtest score) as well as grip strength. Each outcome was assessed at baseline and at the conclusion of each intervention in both upper limbs. Neither anodal nor cathodal stimulation resulted in statistically significantly improved upper limb performance on any of the measured tasks compared with sham stimulation (P>0.05). When the data were analysed according to disability, participants with moderate/severe disability showed significantly improved gross motor function following cathodal stimulation compared with sham (P=0.014). However, this was accompanied by decreased key grip strength in the unaffected hand (P=0.003). We are unable to endorse the use of anodal and cathodal tDCS in the management of upper limb dysfunction in chronic stroke patients. Although there appears to be more potential for the use of cathodal stimulation in patients with severe disability, the effects were small and must be considered with caution as they were accompanied by unanticipated effects in the unaffected upper limb.

Source: Determining the benefits of transcranial direct current stim… : International Journal of Rehabilitation Research

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[ARTICLE] Effects of two-handed task training on upper limb function of chronic hemiplegic patients after stroke – Full Text PDF

Abstract.

[Purpose] The purpose of this study was to determine whether two-handed task training is effective on motor learning of injured cerebral cortex activation and upper extremity function recovery after stroke.

[Subjects and Methods] Two hemiplegic subjects participated in this study: one patient was affected on the dominant side of the body and the other was affected on the non-dominant side of the body, and both scored in the range of 58–66 in the Fugl-Meyer assessment. The excitability of the corticospinal tract and Manual Function Test were examined.

[Results] The excitability of the corticospinal tract and the Manual Function Test showed significant differences in the activation of both sides of the cerebral cortex and in the variation in learning effect of upper extremity motor function recovery in patients with hemiplegic non-dominant hand (left).

[Conclusion] The results suggested that two-handed task training had a different influence on dominant hand (right) and non-dominant hand (left) motor recovery.

INTRODUCTION

The dominant hand is defined as the hand that is usually used in performing activities of daily living (ADL). The development of the motor function of the cerebral cortex is asymmetrical to the dominant hand1) . Based on such asymmetrical development of the cerebral cortex, when the left hand is performing a task, the cerebral cortex motor area of the right cerebral hemisphere activates. However, a more interesting fact is that when the right hand is used functionally, the nerve cells of the entire cerebral cortex motor area of the right and left cerebral hemispheres activate2) . This finding supports the evidence of lateralization of the cerebral hemisphere and implies that the left cerebral hemisphere acts the role of the dominant cerebral hemisphere when performing ADL2, 3) . Thus, the left hemisphere, which is the dominant cerebral hemisphere due to the lateralization of the cerebral hemisphere, is more closely related with motor planning in ADL performance, and the same relationships were shown after cerebral hemisphere injury due to stroke3, 4) . Characteristically, the patient with stroke-damaged dominant left cerebral hemisphere reports a time delay on the exercise performance of both right and left hands, whereas the patient with damaged right cerebral hemisphere reports a mild motor function disorder confined to the left hand3) . This means that, consequently, after stroke onset, the patient with hemiplegic dominant hand (right) experiences more difficulty in performing ADL5) . However, regarding upper extremity rehabilitation, there is no study that differentiated the motor function recovery of the upper extremity of patients who are affected in the dominant cerebral hemisphere (with the hemiplegic right hand) or in the non-dominant cerebral hemisphere (with the hemiplegic left hand). A specific rehabilitation approach based on laterality through classification of cerebral damage on the right or left side is needed to achieve a more successful rehabilitation of the upper extremity. Thus, the purpose of this study is to determine whether two-handed task training is effective in the motor learning of the injured cerebral cortex activation and upper extremity function recovery after stroke.

Full Text PDF

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[ARTICLE] Does the Finger-to-Nose Test measure upper limb coordination in chronic stroke? – Full Text

Abstract

Background

We aimed to kinematically validate that the time to perform the Finger-to-Nose Test (FNT) assesses coordination by determining its construct, convergent and discriminant validity.

Methods

Experimental, criterion standard study. Both clinical and experimental evaluations were done at a research facility in a rehabilitation hospital. Forty individuals (20 individuals with chronic stroke and 20 healthy, age- and gender-matched individuals) participated.. Both groups performed two blocks of 10 to-and-fro pointing movements (non-dominant/affected arm) between a sagittal target and the nose (ReachIn, ReachOut) at a self-paced speed. Time to perform the test was the main outcome. Kinematics (Optotrak, 100Hz) and clinical impairment/activity levels were evaluated. Spatiotemporal coordination was assessed with slope (IJC) and cross-correlation (LAG) between elbow and shoulder movements.

Results

Compared to controls, individuals with stroke (Fugl-Meyer Assessment, FMA-UE: 51.9 ± 13.2; Box & Blocks, BBT: 72.1 ± 26.9%) made more curved endpoint trajectories using less shoulder horizontal-abduction. For construct validity, shoulder range (β = 0.127), LAG (β = 0.855) and IJC (β = −0.191) explained 82% of FNT-time variance for ReachIn and LAG (β = 0.971) explained 94% for ReachOut in patients with stroke. In contrast, only LAG explained 62% (β = 0.790) and 79% (β = 0.889) of variance for ReachIn and ReachOut respectively in controls. For convergent validity, FNT-time correlated with FMA-UE (r = −0.67, p < 0.01), FMA-Arm (r = −0.60, p = 0.005), biceps spasticity (r = 0.39, p < 0.05) and BBT (r = −0.56, p < 0.01). A cut-off time of 10.6 s discriminated between mild and moderate-to-severe impairment (discriminant validity). Each additional second represented 42% odds increase of greater impairment.

Conclusions

For this version of the FNT, the time to perform the test showed construct, convergent and discriminant validity to measure UL coordination in stroke.

Background

Upper-limb (UL) coordination deficits are commonly observed in neurological patients (e.g., cerebellar ataxia, stroke, etc.). In healthy subjects, goal-directed movement requires synchronized interaction (coordination) between multiple effectors [1, 2, 3]. Characterizing UL coordination, however, is challenging for clinicians and researchers because of lack of consensus regarding its definition (e.g., see [4, 5, 6, 7]). Nevertheless, definitions usually describe coordinated movement as involving specific patterns of temporal (timing between joints) and spatial (joint movement pattern) variability [1, 2, 8]. However, trajectory formation differs for reaches made in a body-centered frame of reference (egocentric) compared to those relying on mapping of extrinsic space and visuo-motor transformations [9, 10] made away from the body (exocentric). Thus, coordination can be defined as the skill of adjusting temporal and spatial aspects of joint rotations according to the task [11].

Damage to descending pathways due to stroke can lead to movement deficits defined at two levels. At the end-effector level (e.g. hand), variables describe movement performance (time, straightness, smoothness, precision), whereas at the interjoint level, variables describe movement quality (joint ranges of motion, interjoint coordination) [12]. These variables may be affected differently for egocentric and exocentric movements.

Although it is widely recognized that training can improve performance of functional tasks even years after a stroke [13], a valid tool for the measurement of coordination has not yet been established. In healthy individuals, coordinated movements are described in terms of spatial variables, related to the positions of different joints or body segments in space and/or temporal variables, related to the timing between movements of joints/segments during the task [1]. Consideration of task specificity is important in characterizing coordination. In addition, movement may be affected by abnormal stereotypical UL movement synergies and concomitant reduction in kinematic redundancy [10, 14] as well as deficits reducing both movement performance and quality [15, 16].

In clinical practice, coordination is assumed to be measured by the time to perform alternating movements with different end effectors (e.g., supination/pronation of the forearm, sliding the heel up and down the anterior aspect of the shin). Another task commonly used to assess coordination is the Finger-to-Nose test (FNT) [17, 18]. In the standard neurological exam [19], the individual alternately touches their nose and the evaluator’s stationary or moving finger while lying supine, sitting or standing. In the Fugl-Meyer UL Assessment (FMA-UL) [18], the FNT is objectively measured as the difference in time to alternately touch the knee and nose five times between the more- and less-affected arm on a 0 to 2 point scale. Aside from FNT-time, two other features of endpoint performance, arm trajectory straightness/smoothness (tremor) and precision (dysmetria), are estimated qualitatively [18] for a total of six points.

However, the construct validity of FNT-time as an UL coordination measure in individuals with stroke has not been established using detailed kinematic assessment, where construct validity is defined as the degree to which experimentally-determined and theoretical definitions match [20]. For clinicians to use FNT as part of the UL assessment, this assumption must be verified along with its convergent and discriminant validity.

The study objectives were to determine construct, convergent and discriminant validity of FNT-time to measure UL coordination in individuals with chronic stroke using kinematic analysis. We characterized movement parameters during performance of FNT between healthy and stroke subjects. We also related FNT outcomes (time, trajectory straightness, precision) to UL impairment severity and activity limitations. We hypothesized that FNT-time would 1) be related to interjoint coordination measures (construct validity); 2) be correlated with other measures of UL impairment and/or activity limitations (convergent validity); and 3) discriminate between levels of UL impairment (discriminant validity). Preliminary data have appeared in abstract form [21].

Continue —> Does the Finger-to-Nose Test measure upper limb coordination in chronic stroke? | Journal of NeuroEngineering and Rehabilitation | Full Text

 

Fig. 1 a Experimental set up illustrating marker placement and examples of endpoint displacement for finger-to-nose test. Subject sat with one arm partially extended, index finger fully extended and target placed at 90% arm-length at eye-level. The task was to touch the target and then the nose accurately 10 times at a self-paced speed; b Examples of 10 trials of endpoint (tip of index finger) displacement over time. First row–healthy subject moving endpoint at self-paced speed; Second row–healthy subject moving endpoint at a slower speed and Third row–Stroke subject moving endpoint a self-paced speed

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