The Fluff Test: A simple task to assess body representation neglect

Evaluation of upper limb perception after stroke with the new Affected Limb Perception Questionnaire (ALPQ): a study protocol

BACKGROUND

Following a stroke, patients may suffer from alterations in the perception of their own body due to an acquired deficit in body representations. While such changes may impact their quality of life as well as recovery, they are not systematically assessed in clinical practice. This study aims at providing a better understanding of the rate, evolution, and impact on recovery of upper limb (UL) body perceptions (BPs) alterations following stroke. In addition, we will investigate associations among BPs alterations items, their associations with the sensorimotor functions, UL activity, damages in brain structure and connectivity.

METHODS

We developed a new tool named ALPQ (for Affected Limb Perception Questionnaire) to address the present study objectives. It assesses subjective alterations in the perception of the affected UL following stroke, by measuring several dimensions, namely: anosognosia for hemiplegia, anosodiaphoria for hemiplegia, hemiasomatognosia, somatoparaphrenia, personification of the affected limb, illusion of modification of physical characteristics (temperature, weight, length), illusory movements, super- or undernumerary limb, UL disconnection, misoplegia, and involuntary movement. This study combines a cross-sectional and longitudinal design. The completed data sample will include a minimum of 60 acute and 100 sub-acute stroke patients. When possible, patients are followed up to the chronic stage. Complementary evaluations are administered to assess patients' sensorimotor and cognitive functions as well as UL activity, and brain lesions will be analysed.

DISCUSSION

This study will provide a better understanding of BPs alterations following stroke: their rate and evolution, as well as their associations with sensorimotor deficit, cognitive profile and UL activity, brain lesions and recovery. Ultimately, the results could support the personalization of rehabilitation strategy according to patients' UL perception to maximize their recovery.

STUDY REGISTRATION

The protocol for this study has been pre-registered on the Open Science Framework on July the 7th, 2021: https://osf.io/p6v7f .

The Neuropsychological Assessment of Unilateral Spatial Neglect Through Computerized and Virtual Reality Tools: A Scoping Review

Unilateral Spatial Neglect is a disabling neuropsychological deficit. Patients with spatial neglect fail to detect and report events, and to perform actions in the side of space contralateral to a hemispheric cerebral lesion. Neglect is assessed by evaluating the patients' abilities in daily life activities and by psychometric tests. Computer-based, portable and Virtual Reality technologies may provide more and precise data, and be more sensitive and informative, compared to current paper-and-pencil procedures. Studies since 2010, in which such technologies have been used, are reviewed. Forty-two articles meeting inclusion criteria are categorized according to their technological approaches (computer-, graphics tablet or tablet-, virtual reality-based assessment, and other). The results are promising. However, a definite golden standard, technologically based procedure cannot be still established. Developing technologically based tests is a laborious process, which requires technical and user experience improvements as well as normative data, to increase the evidence of efficacy for clinical evaluation of at least some of the tests considered in this review.

The Association of Personal Neglect with Motor, Activities of Daily Living, and Participation Outcomes after Stroke: A Systematic Review

Despite its potential clinical impact, the association of personal neglect (PN) with motor, activities of daily living (ADL), and participation outcomes after stroke is not well-understood. This first-ever systematic review on the topic therefore evaluates this association, taking into account suggested subtypes of PN, including body representation neglect, somatosensory neglect, motor neglect, and premotor neglect. A systematic literature search was conducted on February 17, 2023 in PubMed, Web of Science, Scopus, PubPsych, and PsycArticles databases. The study adheres to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and its protocol was registered on PROSPERO (CRD42020187460). Eleven observational studies were included, gathering 1,400 individuals after stroke (429 showed PN). Results show that individuals with body representation neglect after stroke have significantly decreased movement control and motor strength, lower functional mobility, and ADL independency compared with those without body representation neglect after stroke. Individuals with motor neglect after stroke showed worse motor function and spasticity than to those without motor neglect after stroke. Nonspecified PN (i.e., PN evaluated with an outcome measure that does not allow subcategorization) was related to worse lateropulsion with pushing, longer length of stay and greater odds of being discharged to somewhere other than home. No study evaluated somatosensory and premotor neglect. This review highlights the limited research in this area and emphasizes the need for a more comprehensive PN assessment. However, currently available assessment tools show limited ability to accurately diagnose PN subtypes and future research should prioritize the development of comprehensive diagnostic test batteries.

Luria's fist-edge-palm test: A small change makes a big difference

Slight modifications in the instructions or administration of neuropsychological tests could result in noticeable differences in performance. A good example is offered by a test devised by Luria to assess executive functioning in motor planning, the three-step fist-edge-palm (FEP) test, which is still frequently employed in clinical settings and features in several neuropsychological test batteries such as the Frontal Assessment Battery (FAB). While Luria described the orientation of the fist as horizontal to the testing desk (hFEP), recent versions of the task indicate the fist should be vertical to the testing desk (vFEP). The current study examined whether administering the hFEP or the vFEP tests results in different performance in healthy people, and whether one version is better than the other at detecting impairments in a patient population. The hFEP proved more challenging for healthy adults than the vFEP, and people with brain damage committed more errors on the hFEP than the vFEP. Both versions correlated with executive measures but also with several other cognitive variables, indicating that the test is not a specific marker of executive functions. Although performance on the FEP is sensitive to articulatory suppression, faster pace, and the number of sequences performed, none of these conditions fully account for the differences between the hFEP and vFEP. The additional demand of the hFEP appears to be due to the less natural (i.e., automatic) orientation of the horizontal fist. In conclusion, a small change in the administration of the test, eluding Luria's instructions, grossly modified its sensitivity. Clinicians and researchers should be wary of modifying instructions or testing procedures without considering the possible consequences of such modifications.

Key constructs of body awareness impairments post-stroke: a scoping review of assessment tools and interventions

PURPOSE

To summarise body awareness assessment tools and interventions relevant for stroke rehabilitation using a framework that categorises key body awareness constructs, disorders and impairments.

MATERIALS AND METHODS

Online electronic databases and trial registries were searched from inception until July 2021, in addition to hand searching reference lists of included studies and reviews. Study selection included any study design where the investigation involved assessing and/or intervening in body awareness following stroke. Data were extracted based on predefined criteria by two independent reviewers and mapped to the emergent framework.

RESULTS

The final analysis included 144 papers that reported 43 assessment tools and 8 types of interventions for body awareness. Consensus was reached on a synthesised body awareness framework. This comprised specific impairments and disorders, constructs, sub-categories and main categories leading to the overarching term of body awareness. Clinical and psychometric properties of the assessment tools were not reported or poorly evaluated, and the interventions lacked robust study designs and rigorous methods.

CONCLUSIONS

The framework produced will enable future research and clinical practice to be based on consistent concepts and definitions. Clinicians can also use this information to cautiously select assessment tools and/or interventions but are reminded of the limitations identified in this review.Implications for rehabilitationThere is limited understanding, compounded by inconsistent terminology and definitions regarding body awareness after stroke.A synthesized framework to define key constructs and definitions of body awareness is proposed.Assessment tools and interventions reported in the literature are mapped to the proposed framework.Psychometric properties of available tools are reported.Significant work remains to refine concepts of body awareness, develop and evaluate assessment tools and interventions.

The flubbed body: Pathological body size representation in personal neglect

Personal Neglect (PN) is a disorder in which patients fail to attend or explore the contralateral side of their body. An increasing number of studies have considered PN as a form of body representation disorder frequently observed following damage to parietal areas. The extent and the direction of the body misrepresentation is still unclear with recent studies suggesting a general reduction of contralesional hand size. However, little is known about the specificity of this representation and whether the misrepresentation also generalises to other body parts. We explored the features of the representation of the hands and face in a group of 9 right brain damaged patients with (PN+) and without PN (PN-), when compared to a healthy control group. For this, we used a body size estimation task with pictures, in which patients were required to choose the one that most closely matched the perceived size of their body part. We found that PN + patients showed a labile body representation for both hands and face, having a larger distorted representational range. Interestingly, in comparison with PN + patients and healthy controls, PN- patients also showed misrepresentation of the left contralesional hand which could be related to impaired motor performance of their upper limb. Our findings are discussed within a theoretical framework suggesting a reliance on multisensory integration (body representation, ownership, and motor influences) for an ordered representation of the size of the body.

Spatial neglect encompasses impaired verticality representation after right hemisphere stroke

Spatial neglect after right hemisphere stroke (RHS) was recently found to encompass lateropulsion, a deficit in body orientation with respect to gravity caused by altered brain processing of graviception. By analogy, we hypothesized that spatial neglect after RHS might encompass an altered representation of verticality. We also assumed a strong relation between body neglect and impaired postural vertical, both referring to the body. To tackle these issues, we performed contingency and correlation analyses between two domains of spatial neglect (body, extra-body) and two modalities of verticality perception (postural, visual) in 77 individuals (median age = 67) with a first-ever subacute RHS (1-3 months). All individuals with a transmodal (postural and visual) tilt in verticality perception (n = 26) had spatial neglect, but the reverse was not found. Correlation and multivariate analyses revealed that spatial neglect (and notably body neglect) was associated more with postural than visual vertical tilts. These findings indicate that after RHS, an impaired verticality representation results from a kind of graviceptive neglect, bearing first on somaesthetic graviception and second on vestibular graviception. They also suggest that the human brain uses not only a mosaic of 2D representations but also 3D maps involving a transmodal representation of verticality.

The Italian telephone-based Verbal Fluency Battery (t-VFB): standardization and preliminary clinical usability evidence

Background

This study aimed at standardizing and providing preliminary evidence on the clinical usability of the Italian telephone-based Verbal Fluency Battery (t-VFB), which includes phonemic (t-PVF), semantic (t-SVF) and alternate (t-AVF) verbal fluency tasks.

Methods

Three-hundred and thirty-five Italian healthy participants (HPs; 140 males; age range = 18-96 years; education range = 4-23 years) and 27 individuals with neurodegenerative or cerebrovascular diseases were administered the t-VFB. Switch number and cluster size were computed via latent semantic analyses. HPs underwent the telephone-based Mental State Examination (MMSE) and Backward Digit Span (BDS). Construct validity, factorial structure, internal consistency, test-retest and inter-rater reliability and equivalence with the in-person Verbal Fluency tasks were assessed. Norms were derived via Equivalent Scores. Diagnostic accuracy against clinical populations was assessed.

Results

The majority of t-VFB scores correlated among each other and with the BDS, but not with the MMSE. Switch number correlated with t-PVF, t-SVF, t-AVF scores, whilst cluster size with the t-SVF and t-AVF scores only. The t-VFB was underpinned by a mono-component structure and was internally consistent (Cronbach's α = 0.91). Test-retest (ICC = 0.69-0.95) and inter-rater reliability (ICC = 0.98-1) were optimal. Each t-VFB test was statistically equivalent to its in-person version (equivalence bounds yielding a p < 0.05). Education predicted all t-VFB scores, whereas age t-SVF and t-AVF scores and sex only some t-SVF scores. Diagnostic accuracy against clinical samples was optimal (AUC = 0.81-0.86).

Discussion

The t-VFB is a valid, reliable and normed telephone-based assessment tool for language and executive functioning, equivalent to the in-person version; results show promising evidence of its diagnostic accuracy in neurological populations.

Splenial Callosal Disconnection in Right Hemianopic Patients Induces Right Visual-Spatial Neglect

Posterior cerebral artery (PCA) territory infarction involving occipital cortical damage can give rise to contralateral homonymous hemianopia. Here, we report two rare cases of patients with lesions in the left hemisphere PCA territory who developed right visuo-spatial neglect. One patient suffered right hemianopia and right visuo-spatial neglect after a stroke that damaged the left primary visual cortex and the callosal splenial fibers. The other unique case is of a patient who had a brain tumor in the posterior cerebral region in the left hemisphere and initially exhibited only right hemianopia that developed into right visuo-spatial neglect after tumor resection that included the splenial fibers. These cases indicate that, as in cases with damage in the right PCA territory, lesions in the left PCA yield visuo-spatial neglect when the damage produces contralateral hemianopia and concomitant disconnection of the splenium of the corpus callosum, which interferes with the arrival of visual inputs from the intact right to the lesioned left hemisphere. These results also emphasize the necessity of sparing the splenial fibers in surgical interventions in patients who exhibit hemianopia.

Relationship Between Body-Specific Attention to a Paretic Limb and Real-World Arm Use in Stroke Patients: A Longitudinal Study

Learned nonuse is a major problem in upper limb (UL) rehabilitation after stroke. Among the various factors that contribute to learned nonuse, recent studies have focused on body representation of the paretic limb in the brain. We previously developed a method to measure body-specific attention, as a marker of body representation of the paretic limb and revealed a decline in body-specific attention to the paretic limb in chronic stroke patients by a cross-sectional study. However, longitudinal changes in body-specific attention and paretic arm use in daily life (real-world arm use) from the onset to the chronic phase, and their relationship, remain unknown. Here, in a longitudinal, prospective, observational study, we sought to elucidate the longitudinal changes in body-specific attention to the paretic limb and real-world arm use, and their relationship, by using accelerometers and psychophysical methods, respectively, in 25 patients with subacute stroke. Measurements were taken at baseline (TBL), 2 weeks (T2w), 1 month (T1M), 2 months (T2M), and 6 months (T6M) after enrollment. UL function was measured using the Fugl-Meyer Assessment (FMA) and Action Research Arm Test (ARAT). Real-world arm use was measured using accelerometers on both wrists. Body-specific attention was measured using a visual detection task. The UL function and real-world arm use improved up to T6M. Longitudinal changes in body-specific attention were most remarkable at T1M. Changes in body-specific attention up to T1M correlated positively with changes in real-world arm use up to T6M, and from T1M to T6M, and the latter more strongly correlated with changes in real-world arm use. Changes in real-world arm use up to T2M correlated positively with changes in FMA up to T2M and T6M. No correlation was found between body-specific attention and FMA scores. Thus, these results suggest that improved body-specific attention to the paretic limb during the early phase contributes to increasing long-term real-world arm use and that increased real-world use is associated with the recovery of UL function. Our results may contribute to the development of rehabilitation strategies to enhance adaptive changes in body representation in the brain and increase real-world arm use after stroke.

Effects of visual-motor illusion in stroke hemiplegic patients with left-side personal neglect: A report of two cases

Personal neglect is the neglect of self-body space, which often occurs in patients with unilateral spatial neglect (USN), but lacks a dedicated rehabilitation. The purpose of this study was to investigate the effects of visual-motor illusion (VMI) on two-stroke hemiplegic patients with left-side personal neglect. Case 1 was a 53-year-old man diagnosed with a right lenticulostriate artery infarction. Case 2 was a 76-year-old woman diagnosed with a right middle cerebral artery infarction. USN symptoms were not observed in either patient in the desk USN assessment, but personal neglect and USN symptoms in daily life were observed in both patients. Intervention effects were verified using an ABA design, comprising a 5-day three-phase (A1, B, A2). In phase B, VMI was performed on the paralyzed upper limb for 10 min in addition to conventional physical therapy. Outcomes measures were the Fluff test, Catherine Bergego Scale (CBS), Fugl-Meyer Assessment (FMA), and Functional Independence Measure (FIM). In both patients, no improvements were noted in FMA, but improvements were observed in the Fluff test, CBS, and FIM in phase B; these effects were retained in phase A2. Therefore, VMI may have contributed to improvements in Personal neglect and USN symptoms in daily life.

Attention upturned: Bias toward and away from the affected side of the body and near space in a case of complex regional pain syndrome

People with Complex Regional Pain Syndrome (CRPS) following limb injury can show neuropsychological symptoms in the absence of observable brain pathologies. These can include sensory changes, distorted body representation, and inattention to their affected limb and its surrounding space, resembling post-stroke hemispatial neglect. The precise nature and mechanisms of these neuropsychological symptoms are unclear, however insights could be gained by testing for dissociations and associations that have been observed in stroke patients. Drawing from clinical and experimental methods for investigating spatial attention bias and related symptoms in stroke patients, we conducted a detailed investigation of neuropsychological symptoms in a woman with CRPS of her left arm who initially presented to us with pronounced inattention to her affected side. The patient showed visual and tactile neglect and extinction on her affected side on confrontation tests, but no attention deficits on "bedside" tests of neglect. On sensitive computer-based measures, attention biases were found in the patient's body and near space (in Temporal Order Judgements), but not far or imagined space (on the Greyscales task and Mental Number Line Bisection). Unique to the current literature, the patient showed a reversal in her Temporal Order Judgement bias across time, from inattention (first and second session) to hyperattention (third session) to her affected side. In contrast, pain and self-reported body representation distortion were similar across the three sessions. The patient had reduced central and peripheral visual acuity, however these deficits were near symmetrical and therefore could not explain her performance on the visual attention tasks. Given that spatial attention bias has been linked to imbalance in relative activation of the two cerebral hemispheres, we administered a Global-Local processing task to test for hemispheric asymmetry. This revealed no difference in global compared to local interference refuting any hemispheric imbalance. Instead, the patient showed impaired performance (compared to controls) on incongruent trials regardless of trial type, consistent with executive impairment. We conclude that spatial attention bias in CRPS can generalize across different sensory modalities and extend beyond the affected limb to the external space around it, independent of any low-level sensory disturbances. This bias is not necessarily directed away from the affected side or stable over time. People with CRPS can also demonstrate more generalized neuropsychological changes in sensory and executive functions. Our observations refute several existing theories about the mechanisms of attention bias in CRPS, and their relationship to pain, and have potential implications for treatment.

Investigating the Characteristics of Covert Unilateral Spatial Neglect Using the Modified Posner Task: A Single-subject Design Study

Objectives:

Patients identified as asymptomatic for unilateral spatial neglect (USN) based on paper-and-pen tests nonetheless often collide with objects to their left while walking. This study aimed to investigate chronic USN in subjects who experienced collisions while walking.

Methods:

Two patients with chronic USN who experienced collisions while walking were evaluated using the Behavioral Inattention Test-conventional (BIT-c). Additionally, the modified Posner task (MPT) was used to evaluate the left and right reaction times. MPT targets randomly appeared either on the side indicated by the cue (valid condition) or on the opposite side (invalid condition). This study used an alternating treatments single-case design. The valid and invalid conditions of the MPT alternated rapidly and randomly to determine differences in reaction time. Statistical analysis compared left and right reaction times using a one-tailed randomization test to study valid and invalid conditions.

Results:

The total BIT-c score was in the normal range for both subjects, whereas MPT reaction times were higher on the left side than on the right side for the invalid condition. However, for the valid condition, only Case B had increased reaction times on the left side.

Conclusions:

The MPT valid condition evaluates voluntary attention, whereas the invalid condition evaluates the reorientation of attention. Consequently, for Case A, a left reorientation of attention deficit was observed, whereas, for Case B, left voluntary attention and left reorientation of attention deficits were observed. The MPT results revealed the characteristics of covert neglect signs. USN evaluation would benefit from additional research using MPT.

Quantitative Assessment of Motor Neglect

[Figure: see text].

The downsized hand in personal neglect

Introduction: Personal neglect (PN) refers to a form of hemi-inattention toward the contralesional body space and it usually occurs following a right brain lesion. Recent studies suggest that PN indicates a disorder of body representation. Specifically, patients with PN show difficulties in identifying differences between left and right hands and have an altered visuospatial body map, which is associated with disrupted mental body representations. However, the metric representation of the body, and in particular the hands, has not been systematically addressed in patients showing this form of neglect. Method: In the present study, we have investigated this representation by testing the perceived hands' width of 11 hemiplegic patients with right hemisphere cerebral lesions (5 with PN) and 12 healthy controls on a judgment of passability task. Patients and controls were asked to imagine inserting their hand (left and right) through a series of vertical apertures of different sizes and to judge whether their hand could fit through. Due to the heterogeneity of the data, both parametric and non-parametric approaches were used. Furthermore, additional single-case analyses were conducted. Results: Study findings showed that patients with PN showed a significant underestimation of the left hand compared with their right hand. In contrast, whilst the right hand was equally distorted in both patients' groups, the hemiplegic patients with no evidence of PN tended to perceive the affected hand as larger than their ipsilesional one. Conclusions: In line with the literature, our findings confirm an underlying distorted body representation following right brain damage. However, for the first time, we report both a quantitative and qualitative difference in impact of hemiplegia and PN on body representation of the contralesional body space.

Balance, Lateropulsion, and Gait Disorders in Subacute Stroke

OBJECTIVE

To test the hypothesis that impaired body orientation with respect to gravity (lateropulsion) would play a key role in poststroke balance and gait disorders.

METHODS

Cohort study of 220 individuals consecutively admitted to a neurorehabilitation ward after a first hemisphere stroke (DOBRAS cohort [Determinants of Balance Recovery After Stroke] 2012-2018, ClinicalTrials.gov: NCT03203109), with clinical data systematically collected at 1 month, then at discharge. Primary outcomes were balance and gait disorders, quantified by the Postural Assessment Scale for Stroke and the modified Fugl-Meyer Gait Assessment, to be explained by all deficits on day 30, including lateropulsion assessed with the Scale for Contraversive Pushing. Statistics comprised linear regression analysis, univariate and multivariate analyses, and receiver operating characteristic curves.

RESULTS

Lateropulsion was frequent, especially after right hemisphere stroke (RHS, D30, 48%; discharge 24%), almost always in right-handers. Among all deficits, impaired body orientation (lateropulsion) had the most detrimental effect on balance and gait. After RHS, balance disorders were proportional to lateropulsion severity, which alone explained almost all balance disorders at initial assessment (90%; 95% confidence interval [CI] [86-94], p < 0.001) and at discharge (92%; 95% CI 89-95, p < 0.001) and also the greatest part of gait disorders at initial assessment (66%; 95% CI 56-77, p < 0.001) and at discharge (68%; 95% CI 57-78, p < 0.001).

CONCLUSION

Lateropulsion is the primary factor altering poststroke balance and gait at the subacute stage and therefore should be systematically assessed. Poststroke balance and gait rehabilitation should incorporate techniques devoted to misorientation with respect to gravity.

Proprioceptive impairment in unilateral neglect after stroke: A systematic review

Introduction:

Unilateral neglect is a debilitating condition that can occur after stroke and can affect a variety of domains and modalities, including proprioception. Proprioception is a sensorimotor process essential to motor function and is thus important to consider in unilateral neglect. To date, there has not been a comprehensive review of studies examining the various aspects of proprioceptive impairment in unilateral neglect after stroke. This review aimed to determine if people with unilateral neglect have more severe proprioceptive impairments than those without unilateral neglect after stroke.

Methods:

The MEDLINE, Embase, Scopus, CINAHL and Web of Science databases were searched from inception to September 2019 using an a priori search strategy. Two independent reviewers screened abstracts and full texts, and extracted data from the included full texts. A third reviewer resolved disagreements at each step. Risk of bias was assessed using the AXIS Quality Assessment tool.

Results:

A total of 191 abstracts were identified, with 56 eligible for full-text screening. A total of 18 studies were included in the review and provided evidence that people with unilateral neglect have more severe proprioceptive impairment than people without unilateral neglect. This impairment is present in multiple subtypes of unilateral neglect and aspects of proprioception. Most studies had a moderate risk of bias.

Conclusion:

People with unilateral neglect after stroke are more likely to have impaired processing of multiple types of proprioceptive information than those without unilateral neglect. However, the available evidence is limited by the large heterogeneity of assessment tools used to identify unilateral neglect and proprioception. Unilateral neglect and proprioception were rarely assessed comprehensively.

PROSPERO Registration: CRD42018086070.

The Fluff test: Improved scoring system to account for different degrees of contralesional and ipsilesional personal neglect in brain damaged patients

The Fluff test is a simple test to assess evidence of personal neglect (PN) in brain-damaged patients. While blindfolded, patients are asked to remove targets previously attached to their body and the number of targets detached provides information about possible spatial bias. This test has been widely used for clinical and research purposes. However, the current scoring system presents some limitations, which make difficult to interpret patients' performance in terms of both contralalesional and ipsilesional PN when they omit targets on the ipsilesional side. Moreover, it does not consider possible confounding variables, such as non-spatial cognitive deficits or lack of compliance that may affect patients' performance and lead to incorrect diagnosis. The present paper proposes a new scoring method overcoming the limitations mentioned above and it analyses data from a large sample of 243 brain-damaged patients. Findings showed that contralesional PN was significantly more severe, but not more frequent, following right (31%) than left (21%) brain damage. We also found evidence of left ipsilesional PN and cases of potential mis-diagnosis that would have passed unnoticed with the original scoring system. The new scoring method allows to identify different degrees of contralesional and ipsilesional PN and potential confounding variable.

A new clinical evaluation of asomatognosia in right brain damaged patients using visual and reaching tasks

INTRODUCTION

The term asomatognosia refers to a unilateral disturbance of body ownership following a cerebrovascular incident. Patients with asomatognosia consider the contralesional limbs as missing or having disappeared from awareness. This neuropsychological disorder modifies body ownership in terms of perceptual experience, visual identification and sense of belonging of contralesional body parts. In the literature, asomatognosia is usually tested by using verbal scales.

METHOD

In this study, we first developed a new test to assess asomatognosia that includes a visual identification task and a reaching task. We examined 16 healthy participants and 20 right brain damaged patients. The participants were asked to identify, reach and touch their left hand when positioned in peripersonal space, in presence of an extraneous hand (belonging to the examiner). We analyzed how the deficit is modulated by the reciprocal positions in space of the two limbs, the relationship with personal neglect and the anatomical correlate using a Voxel-based Lesion Symptom Mapping (VLSM) analysis with CT data.

RESULTS

The results show that the asomatognosia cannot be simply considered as one of the many manifestations of personal neglect but should be taken into account as a "productive" disorder characterized by the misidentification of the own hand with an extraneous hand. The VLSM analysis of patients with asomatognosia revealed the involvement of the inferior and middle frontal lobe.

CONCLUSIONS

The novel task that has been developed in the present study could be used as an objective tool to measure this specific disorder of body ownership or to uncover subclinical conditions of asomatognosia.

The effects of repetitive neck-muscle vibration on postural disturbances after a chronic stroke

OBJECTIVE

We aimed to test a repeated program of vibration sessions of the neck muscles (rNMV) on postural disturbances and spatial perception in patients with right (RBD) versus left (LBD) vascular brain damage.

METHODS

Thirty-two chronic stroke patients (mean age 60.9±10 yrs and mean time since stroke 4.9±4 yrs), 16 RBD and 16 LBD, underwent a program of 10 sessions of NMV over two weeks. Posturography parameters (weight-bearing asymmetry (WBA), Xm, Ym, and surface), balance rating (Berg Balance Scale (BBS), Timed Up and Go (TUG)), space representation (subjective straight ahead (SSA), longitudinal body axis (LBA), subjective visual vertical (SVV)), and post-stroke deficiencies (motricity index, sensitivity, and spasticity) were tested and the data analyzed by ANOVA or a linear rank-based model, depending on whether the data were normally distributed, with lesion side and time factor (D-15, D0, D15, D21, D45).

RESULTS

The ANOVA revealed a significant interaction between lesion side and time for WBA (P<0.0001) with a significant shift towards the paretic lower limb in the RBD patients only (P=0.0001), whereas there was no effect in the LBD patients (P=0.98). Neither group showed a significant modification of spatial representation. Nonetheless, there was a significant improvement in motricity (P=0.02), TUG (P=0.0005), and BBS (P<0.0001) in both groups at the end of treatment and afterwards.

CONCLUSIONS

rNMV appeared to correct WBA in RBD patients only. This suggests that rNMV could be effective in treating sustainable imbalance due to spatial cognition disorders.

Effect of test instructions: The example of the pantomime production task

The production of pantomime is a sensible task to detect praxis deficits. It is usually assessed by presenting objects visually or by verbal command. Verbal instructions are given either by providing the name of the object (e.g., "Show me how to use a pen") or by requiring the object function (e.g., "Show me how to write"). These modes of testing are used interchangeably. The aim of this study is to investigate whether the different instructions generate different performances. Fifty-one healthy participants (17-89 years old) were assessed on three pantomime production tasks differing for the instruction given: two with verbal instructions (Pantomime by Name and Pantomime by Function) and one with the object visually presented (Pantomime by Object). Results showed that Pantomime by Function produced the poorest performance and the highest frequency of Body Parts as Tool (BPT) errors, suggesting that the way the instructions are given may determine the performance in a task. Nuances in test instructions could result in misleading outcome.

Disownership of body parts as revealed by a visual scale evaluation. An observational study

The disownership of body parts, that most frequently occurs on the left side of the body, contralateral to right-hemispheric lesions, is an infrequent disorder, as usually assessed by interviews asking for dichotomic "yes/no" responses. This observational study in right-brain-damaged stroke patients investigated the efficacy of a continuous Visual Analog Scale (VAS) to detect body disownership after right brain damage, compared to dichotomic questions. Thirty-two right-handed right-brain-damaged stroke patients were given a Standardized Interview (SI), asking "Whose hand/arm/leg is this?", followed by a VAS (asking patients to mark on a vertical line their agreement with the statement that a body part belonged to them). The neural correlates of this disorder and measures of extra-personal and personal spatial neglect were also assessed. Control data were recorded from 18 neurologically unimpaired right-handed participants. During the interview, no patient showed disownership of body parts. Conversely, on the VAS eight out of 32 (25%) patients' scores, but none of the controls' scores, indicated a judgement of disownership for left body parts, with a left-right difference larger than that of control participants. VAS-detected disownership was not systematically associated with extra-personal and personal unilateral spatial neglect. Lesion sites associated with disownership of left body parts included the caudate nucleus and the anterior part of the internal capsule. To conclude, the VAS task, compared to the interview, is a novel tool to detect disownership of left body parts in right brain-damaged patients. A revised classification of body-ownership disorders is proposed. The present variant, assessed and detected by the VAS task, is termed Covert disownership and distinguished from the Overt disownership assessed by a SI.

The Visual Scanning Test: a newly developed neuropsychological tool to assess and target rehabilitation of extrapersonal visual unilateral spatial neglect

PURPOSE

Visual unilateral spatial neglect (VUSN) is a neuropsychological condition commonly experienced after stroke whereby patients are unable to attend to stimuli on the controlesional side of their space. VUSN can occur in the personal, peripersonal, and/or extrapersonal portion of patient's space. Traditional paper-and-pencil neuropsychological tests are widely used to evaluate VUSN, but they assess peripersonal VUSN. Instead, personal and extrapersonal neglect are less easily evaluated. The aim of this study was to present normative values for the Visual Scanning Test (VST), a new neuropsychological tool to quantitatively assess the extrapersonal VUSN.

METHODS

Eighty-six healthy subjects took part in the study (61 female), with a mean age of 52.8 years (SD = 17.0) and a mean of 14.0 years of education (SD = 5.2). The VST involved a visual search for a target between similar visual distractors, projected in the far space. The test was administered twice to each participant, with an interval of 2 weeks. From the recorded data, it was possible to obtain indexes related to the reaction times and to the accuracy of the performance on the VST.

RESULTS

Multiple linear regression analysis revealed that age and education significantly influenced VST-derived indexes. From the regression analysis, a correction grid for raw scores was built. Adjusted scores were then ranked, and by means of a non-parametric procedure, tolerance limits (both outer and inner one-sided) were defined.

CONCLUSIONS

The present study provided normative data for the VST in an Italian population useful for both clinical and research purposes.

TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT03931798.

Influence of Motor Deficiency and Spatial Neglect on the Contralesional Posterior Parietal Cortex Functional and Structural Connectivity in Stroke Patients

The posterior parietal cortex (PPC) is a key structure for visual attention and upper limb function, two features that could be impaired after stroke, and could be implied in their recovery. If it is well established that stroke is responsible for intra- and interhemispheric connectivity troubles, little is known about those existing for the contralesional PPC. In this study, we aimed at mapping the functional (using resting state fMRI) and structural (using diffusion tensor imagery) networks from 3 subparts of the PPC of the contralesional hemisphere (the anterior intraparietal sulcus), the posterior intraparietal sulcus and the superior parieto-occipital cortex to bilateral frontal areas and ipsilesional homologous PPC parts in 11 chronic stroke patients compared to 13 healthy controls. We also aimed at assessing the relationship between connectivity and the severity of visuospatial and motor deficiencies. We showed that interhemispheric functional and structural connectivity between PPCs was altered in stroke patients compared to controls, without any specificity among seeds. Alterations of parieto-frontal intra- and interhemispheric connectivity were less observed. Neglect severity was associated with several alterations in intra- and interhemispheric connectivity, whereas we did not find any behavioral/connectivity correlations for motor deficiency. The results of this exploratory study shed a new light on the influence of the contralesional PPC in post-stroke patients, they have to be confirmed and refined in further larger studies.

Development of the Halifax Visual Scanning Test: A New Measure of Visual-Spatial Neglect for Personal, Peripersonal, and Extrapersonal Space

OBJECTIVES

Visual-spatial neglect is a common attentional disorder after right-hemisphere stroke and is associated with poor rehabilitation outcomes. The presence of neglect symptoms has been reported to vary across personal, peripersonal, and extrapersonal space. Currently, no measure is available to assess neglect severity equally across these spatial regions and may be missing subsets of symptoms or patients with neglect entirely. We sought to provide initial construct validity for a novel assessment tool that measures neglect symptoms equally for these spatial regions: the Halifax Visual Scanning Test (HVST).

METHODS

In Study I, the HVST was compared to conventional measures of neglect and functional outcome scores (wheelchair navigation) in 15 stroke inpatients and 14 healthy controls. In Study II, 19 additional controls were combined with the control data from Study I to establish cutoffs for impairment. Patterns of neglect in the stroke group were examined.

RESULTS

In Study I, performance on all HVST subtests were correlated with the majority of conventional subtests and wheelchair navigation outcomes. In Study II, neglect-related deficits in visual scanning showed dissociations across spatial regions. Four inpatients exhibited symptoms of neglect on the HVST that were not detected on conventional measures, one of which showed symptoms in personal and extrapersonal space exclusively.

CONCLUSIONS

The HVST appears a useful measure of neglect symptoms in different spatial regions that may not be detected with conventional measures and that correlates with functional wheelchair performance. Preliminary control data are presented and further research to add to this normative database appears warranted.

Defending the Body Without Sensing the Body Position: Physiological Evidence in a Brain-Damaged Patient With a Proprioceptive Deficit

The ability to know where our body parts are located in space (proprioception) is fundamental for both successfully interacting with the external world and monitoring potential threats. In this case-control study, we investigated whether the absence of proprioceptive signals may affect physiological defensive responses. To this aim, a right brain-damaged patient with a left upper-limb proprioceptive deficit (P+ patient) and age-matched healthy controls, underwent the recording of the Hand-Blink Reflex (HBR). This defensive response, elicited by electrical stimulation of the median nerve and recorded from the orbicularis oculi, is modulated by the hand position: it is enhanced when the threatened hand is near to the face, inside the defensive peripersonal-space (DPPS). According to the classical neuropsychological perspective, we used P+ patient as a model to investigate the role of proprioception in HBR modulation, by manipulating the congruity/incongruity between the intended and actual positions of the stimulated hand. P+ patient, with his eyes closed, had to voluntarily place his left hand either far from or near to his face and to relieve the arm's weight over a supporting device. Then, in congruent conditions, the hand was stimulated in the actual (intended) position. In incongruent conditions, the patient's hand was moved by the examiner from the intended to the opposite (not-intended) position and then stimulated. We observed an inverse response pattern between congruent and incongruent conditions. In congruent conditions, P+ patient showed an HBR enhancement in near compared to far position, comparable to that found in healthy controls. This suggests that, even in absence of proprioceptive and visual information, the HBR modulation was still present. Conversely, in incongruent conditions, P+ patient showed a greater HBR magnitude for far position (when the hand was actually far, but the patient intended it to be near) than for near position (when the hand was actually near, but the patient intended it to be far). This result suggests that proprioceptive signals are not necessary for HBR modulation to occur. It relies more on the intended than on the actual position of the hand. The role of motor intention and planning in shaping the DPPS is discussed.

The 'Neglected' Personal Neglect

A review of patients with brain injury showing personal neglect is presented. The aim is to shed light on this aspect of neglect often unresearched or only indirectly investigated, and to discuss recent findings concerning the methods used to assess personal neglect, its neural correlates and its association with the more often explored aspect of extrapersonal neglect. The review was performed using PubMed and PsychInfo databases to search for papers published in the last 123 years (until January 2018). We reviewed 81 papers describing either single or group studies for a total of 2247 patients. The results of this review showed that various aspects of personal neglect are still controversial and outcomes potentially contradictory. Despite the data reported in the present review suggest that personal neglect is more frequently associated with lesions of the right hemisphere, the left hemisphere may also play an important role. Not surprisingly, personal neglect and extrapersonal neglect seem to co-occur. However double dissociations of these two forms of neglect have been reported, and they seem to dissociate both from a functional and an anatomical perspective. More recent interpretations of personal neglect suggest that it may result from a disrupted body representation. The development of reliable psychometric tools with shared diagnostic criteria is essential to identify different degrees of personal neglect for different body parts and to better refine personal neglect in comparison to extrapersonal neglect and disorders related to distortions of personal domain.

Unawareness for Motor Impairment and Distorted Perception of Task Difficulty

OBJECTIVES

Anosognosia for motor impairment is a complex syndrome that can manifest itself under different forms, guiding patients' behavior and task decisions. However, current diagnostic tools tend to evaluate only more explicit aspects of anosognosia (asking the patients about their motor abilities) and fail to address more subtle features of awareness. We have developed a new assessment measure, the ECT (Errand Choice Test), where patients are asked to judge task difficulty rather than estimate their own impairment.

METHODS

We assessed awareness in a group of 73 unilateral left- and right-brain damaged (30 LBD and 43 RBD, respectively) patients by means of the VATAm, which explicitly requires them to evaluate their own motor abilities, and the ECT. A control group of 65 healthy volunteers was asked to perform the ECT under two conditions: Current condition (i.e., using both hands) and Simulated conditions (i.e., simulating hemiplegia).

RESULTS

A total of 27% of the patients showed different performance on the VATAm and ECT, 21% of the patients showing lack of awareness only on VATAm and 6% only on ECT. Moreover, despite the ECT identified a higher frequency of anosognosia after RBD (33.3%) than LBD (27.6%), this hemispheric asymmetry was not significant. Remarkably, anosognosic patients performed very similarly to controls in the "current condition", suggesting that anosognosic patients' ability to perceive the complexity of each task per se is not altered.

CONCLUSION

Different methods may be able to tackle different aspects of awareness and the ECT proved to be able to detect less evident forms of awareness. (JINS, 2018, 24, 45-56).

Unilateral spatial neglect after posterior parietal damage

Unilateral spatial neglect is a disabling neurologic deficit, most frequent and severe after right-hemispheric lesions. In most patients neglect involves the left side of space, contralateral to a right-hemispheric lesion. About 50% of stroke patients exhibit neglect in the acute phase. Patients fail to orient, respond to, and report sensory events occurring in the contralateral sides of space and of the body, to explore these portions of space through movements by action effectors (eye, limbs), and to move the contralateral limbs. Neglect is a multicomponent higher-level disorder of spatial awareness, cognition, and attention. Spatial neglect may occur independently of elementary sensory and motor neurologic deficits, but it can mimic and make them more severe. Diagnostic tests include: motor exploratory target cancellation; setting the midpoint of a horizontal line (bisection), that requires the estimation of lateral extent; drawing by copy and from memory; reading, assessing neglect dyslexia; and exploring the side of the body contralateral to the lesion. Activities of daily living scales are also used. Patients are typically not aware of neglect, although they may exhibit varying degrees of awareness toward different components of the deficit. The neural correlates include lesions to the inferior parietal lobule of the posterior parietal cortex, which was long considered the unique neuropathologic correlate of neglect, to the premotor and to the dorsolateral prefrontal cortices, to the posterior superior temporal gyrus, at the temporoparietal junction, to subcortical gray nuclei (thalamus, basal ganglia), and to parietofrontal white-matter fiber tracts, such as the superior longitudinal fascicle. Damage to the inferior parietal lobule of the posterior parietal cortex is specifically associated with the mainly egocentric, perceptual, and exploratory extrapersonal, and with the personal, bodily components of neglect. Productive manifestations, such as perseveration, are not a correlate of posterior parietal cortex damage.

Implicit and Explicit Routes to Recognize the Own Body: Evidence from Brain Damaged Patients

Much research suggested that recognizing our own body-parts and attributing a body-part to our physical self-likely involve distinct processes. Accordingly, facilitation for self-body-parts was found when an implicit, but not an explicit, self-recognition was required. Here, we assess whether implicit and explicit bodily self-recognition is mediated by different cerebral networks and can be selectively impaired after brain lesion. To this aim, right- (RBD) and left- (LBD) brain damaged patients and age-matched controls were presented with rotated pictures of either self- or other-people hands. In the Implicit task participants were submitted to hand laterality judgments. In the Explicit task they had to judge whether the hand belonged, or not, to them. In the Implicit task, controls and LBD patients, but not RBD patients, showed an advantage for self-body stimuli. In the Explicit task a disadvantage emerged for self-compared to others' body stimuli in controls as well as in patients. Moreover, when we directly compared the performance of patients and controls, we found RBD, but not LBD, patients to be impaired in both the implicit and explicit recognition of self-body-part stimuli. Conversely, no differences were found for others' body-part stimuli. Crucially, 40% RBD patients showed a selective deficit for implicit processing of self-body-part stimuli, whereas 27% of them showed a selective deficit in the explicit recognition of their own body. Additionally, we provide anatomical evidence revealing the neural basis of this dissociation. Based on both behavioral and anatomical data, we suggest that different areas of the right hemisphere underpin implicit and explicit self-body knowledge.

Semiology of neglect: An update

Hemispatial neglect is a common disabling condition following brain damage to the right hemisphere. Generally, it involves behavioral bias directed ipsilaterally to the damaged hemisphere and loss of spatial awareness for the contralesional side. In this syndrome, several clinical subtypes were identified. The objective of this article is to provide a nosological analysis of the recent data from the literature on the different subtypes of neglect (visual, auditory, somatosensory, motor, egocentric, allocentric and representational neglect), associated ipsilesional and contralesional productive manifestations and their anatomical lesion correlates. These different anatomical-clinical subtypes can be associated or dissociated. They reflect the heterogeneity of this unilateral neglect syndrome that cannot be approached or interpreted in a single manner. We propose that these subtypes result from different underlying deficits: exogenous attentional deficit (visual, auditory neglect); representational deficit (personal neglect, representational neglect, hyperschematia); shift of the egocentric reference frame (egocentric neglect); attentional deficit between objects and within objects (allocentric neglect), endogenous attentional deficit (representational neglect) and transsaccadic working memory or spatial remapping deficit (ipsilesional productive manifestations). Taking into account the different facets of the unilateral neglect syndrome should promote the development of more targeted cognitive rehabilitation protocols.

Assessment and rehabilitation of neglect using virtual reality: a systematic review

After experiencing a stroke in the right hemisphere, almost 50% of patients showed Unilateral Spatial Neglect (USN). In recent decades, Virtual Reality (VR) has been used as an effective tool both for the assessment and rehabilitation of USN. Indeed, this advanced technology allows post-stroke patients to interact with ecological and engaging environments similar to real ones, but in a safe and controlled way. To provide an overview of the most recent VR applications for the assessment and rehabilitation of USN, a systematic review has been carried out. Since 2010, 13 studies have proposed and tested innovative VR tools for USN. After a wide description of the selected studies, we discuss the main features of these VR tools in order to provide crucial indications for future studies, neurorehabilitation interventions, and clinical practice.

Are movements necessary for the sense of body ownership? Evidence from the rubber hand illusion in pure hemiplegic patients

A question still debated within cognitive neuroscience is whether signals present during actions significantly contribute to the emergence of human’s body ownership. In the present study, we aimed at answer this question by means of a neuropsychological approach. We administered the classical rubber hand illusion paradigm to a group of healthy participants and to a group of neurological patients affected by a complete left upper limb hemiplegia, but without any propriceptive/tactile deficits. The illusion strength was measured both subjectively (i.e., by a self-report questionnaire) and behaviorally (i.e., the location of one’s own hand is shifted towards the rubber hand). We aimed at examining whether, and to which extent, an enduring absence of movements related signals affects body ownership. Our results showed that patients displayed, respect to healthy participants, stronger illusory effects when the left (affected) hand was stimulated and no effects when the right (unaffected) hand was stimulated. In other words, hemiplegics had a weaker/more flexible sense of body ownership for the affected hand, but an enhanced/more rigid one for the healthy hand. Possible interpretations of such asymmetrical distribution of body ownership, as well as limits of our results, are discussed. Broadly speaking, our findings suggest that the alteration of the normal flow of signals present during movements impacts on human’s body ownership. This in turn, means that movements have a role per se in developing and maintaining a coherent body ownership.