Assessment of Unilateral Neglect
Year: 2003
Type: article
Abstract: Unilateral neglect (ULN) (or “neglect”) is a common behavioral syndrome in patients following stroke. The reported incidence of ULN varies widely from 10%1 to 82%2 following right-hemisphere stroke and from 15%3 to 65%2 following left-hemisphere stroke. Reasons for the variability in the published rates of occurrence of ULN after stroke include subject selection criteria, lesion site, and the nature and timing of the assessment.4 The clinical impression that ULN occurs more frequently following right brain damage than left brain damage has been supported in a systematic review of published data.4 Unilateral neglect is characterized by the failure to report or respond to people or objects presented to the side opposite a brain lesion. If the failure to respond can be accounted for by either sensory or motor deficits, it is not considered to be neglect.5 Patients may have one type of neglect or a combination of neglect behaviors.6 Because ULN has a wide variety of clinical presentations, no single test can be used to identify the disorder in all patients, nor will a single test provide a comprehensive diagnosis of neglect behavior.7 Some authors7,8 have recommended that assessment of neglect include a test battery. To ensure sufficient sensitivity, the battery should include measures for all types of neglect.9 The purposes of this update are: (1) to clarify the different types of neglect, as a basis for understanding the tests and measures of ULN, (2) to review the validity and reliability of determinations of ULN, and (3) to make recommendations regarding the use of these tests by physical therapists. Given the scope of this article—which is an update of the assessment of neglect—only the major tests for ULN are discussed. For an extensive discussion of the pathophysiology and types of ULN, we refer readers to recent review articles on these topics.10,11 There are 2 main classification systems for ULN. Unilateral neglect can be described in terms of the modality in which the behavior is elicited (sensory, motor, or representational) or by the distribution of the abnormal behavior (personal or spatial).12 Sensory neglect is defined as being unaware of sensory stimuli on the side of the body or space opposite the brain lesion.4 Sensory neglect can be further classified according to the modality in which it presents: visual neglect, auditory neglect, and tactile (somatosensory) neglect. A person can exhibit sensory neglect in one or more of these modalities. Sensory neglect is also referred to as “inattention,” “input neglect,” “attentional neglect,” and “perceptual neglect.”11,12 Motor neglect is defined as the failure to generate a movement response to a stimulus even though the person is aware of the stimulus. The movement failure cannot be explained by a primary motor deficit or weakness.5 Motor neglect is also referred to as “output neglect” and “intentional neglect.”11 Many types of motor neglect have been described.11,13–19 It can manifest as movement of reduced amplitude (hypometria), delayed movement initiation (hypokinesia), or unreasonable slowness in the execution of movement (bradykinesia). These disorders may occur in movements performed within the affected hemispace (eg, hemispatial hypometria) or in movements directed toward the affected hemispace (eg, directional hypometria).5 In this article, the term “hemispace” refers to one side of space, as defined by the body midline. The disorders also can manifest in movements performed with the unaffected limb and in the unaffected hemispace.20 Representational neglect is where a person ignores the contralesional half of internally generated images. Internally generated images are mental representations or visualizations of a task, action, or environment. One of the most notable demonstrations of representational neglect was by Bisiach and Luzzatti.21 Patients were asked to imagine and describe a familiar place. First, they were asked to describe the scene as though they were looking at the front of a cathedral from across a piazza. Then they were asked to imagine the scene from the opposite perspective, describing the piazza as though they were standing at the front doors of the cathedral. In both imagined views of the piazza, the patients omitted the left-side details in their description of the scene. The right-sided features of the scene described in the first instance were omitted (“neglected”) when they became left-sided features from the opposite perspective. Representational neglect is also referred to as “imagery neglect.”22 Personal neglect is defined as a lack of exploration or awareness of the side of the body opposite the brain lesion.23 Examples of personal neglect include failure to dress one half of the body or combing only one side of the head. Personal neglect is different from sensory neglect in that it refers to reduced awareness of the body or a limb itself, whereas sensory neglect refers to reduced awareness of sensory stimuli such as touch. Spatial neglect is defined as a failure to acknowledge stimuli on the contralesional side of space24 and can be further divided into peripersonal neglect and extrapersonal neglect.25Peripersonal neglect refers to neglect behaviors occurring within reaching space (near space). An example of peripersonal neglect is failure to eat the food on one half of a plate. Extrapersonal neglect refers to neglect behaviors occurring in far space. An example of extrapersonal neglect is inadvertently contacting obstacles such as a doorway when walking. A single behavior can be classified by the means in which it is elicited and the distribution of the behavior (personal or spatial). For example, failure to cross out stimuli on the left side of a page in a cancellation task may be classified as visual neglect (if the omissions are due to unawareness of the visual stimuli) and as peripersonal neglect because the behavior manifests in reaching space. This behavior is sometimes called “visuo-spatial neglect.”7 The term “spatial neglect” is therefore relatively nonspecific, as it may comprise sensory (visual, auditory, somatosensory) or motor neglect. Nonetheless, it is important for physical therapists to assess the spatial distribution of the behavior because a person may demonstrate neglect in one domain of space but not another.23–25 For example, a patient may eat food from only one side of a plate (peripersonal space) but groom both sides of the body (personal space). We suggest that physical therapists be as specific as possible when diagnosing ULN and consider both the modality and the distribution to gain a comprehensive understanding of the nature of the neglect behavior. Traditionally, the assessment of ULN in the clinical setting has involved the use of “pen-and-paper” tests such as line bisection, cancellation tasks, copying, and drawing.6,26 These tests are popular in clinical settings because they are simple and quick to administer. The Table summarizes the potential use and limitations of selected tests of ULN. Tests for Unilateral Neglect Cermak SA, Hausser J. The Behavioural Inattention Test for unilateral visual neglect: a critical review. Physical and Occupational Therapy in Geriatrics. 1989;7(3):43–53. Tests for Unilateral Neglect Cermak SA, Hausser J. The Behavioural Inattention Test for unilateral visual neglect: a critical review. Physical and Occupational Therapy in Geriatrics. 1989;7(3):43–53. Line bisection tests require people to estimate and indicate the midpoint of a horizontal line presented on a piece of paper placed in front of them. The line is usually centered with respect to the patient's midline, and a mark is made with a pencil in the preferred or unaffected hand. The test is typically scored by measuring the deviation of the bisection from the true center of the line. A deviation toward the side of the brain lesion (unaffected side) is usually regarded as being indicative of neglect, although the magnitude of deviation can vary.27,28 There are many versions of the line bisection test, and the procedures are rarely standardized, except where the line bisection test is used as an item in a standardized test battery.29 The line bisection test has construct validity for determining the presence of ULN30 and moderate test-retest reliability.31 Construct validity of the line bisection test was reported by Marsh and Kersel,30 who correlated performance on the line bisection test with the star cancellation test (Pearson r=−.40, P=.02) in a sample of 27 patients with a history of stroke in a rehabilitation unit. Moderate test-retest reliability for the line bisection test was reported (Pearson r=.64 P<.001, n=40),31 even though patients with ULN are characteristically variable in their responses to line bisection tasks.32 Cancellation tests require the person to search for and cross out target symbols presented on a page. Patients with ULN typically fail to cancel stimuli on the side of the page opposite the brain lesion. Many versions of the cancellation task exist. They include cancellation of shapes,33,34 stars,29 numbers,35 letters,36 lines,37 bells,38 and circles.39 Performance on cancellation tests varies according to the presence of distractor symbols, single or double target stimuli, and structured or unstructured stimulus arrays.34,40 Distractor symbols are non–target stimuli that must be ignored. The inclusion of distractors requires the person to decide whether a stimulus is a target before crossing it out (eg, bells cancellation test,38 star cancellation test29), rather than simply crossing out every stimulus on the page (eg, Albert test37). Cancellation tests with distractors are more sensitive in detecting ULN than tests without distractors.1,8,38,41 Cancellation tests in which a person searches for 2 target symbols instead of a single cancellation stimulus are also thought to be more sensitive in eliciting ULN.40,42 However, very limited data are reported regarding the sensitivity and specificity of the various cancellation tests, and the psychometric properties of these tests of ULN remain poorly understood. The stimulus array in cancellation tests can be presented in a uniform fashion with the symbols neatly arranged in structured rows and columns, or in a random, unstructured manner. The former method has been shown to be associated with improved performance.34,40,43 Cancellation tests, such as the star cancellation test and the bells cancellation test, have been shown to correlate with other clinical tests of ULN (Pearson r=.26–.78),30,44 indicating construct validity. Cancellation tests are believed to have greater test-retest reliability than the line bisection test31 and are often more sensitive for detecting ULN than line bisection tests.30,44 Some authors, however, have reported sensitivity of the line bisection test to be greater than45 or equal to7 that of cancellation tests. Relative test sensitivity may be influenced by the type of cancellation test used.31 Despite their validity in detecting the presence of ULN, line bisection and cancellation tests cannot be used to differentiate between sensory neglect and motor neglect because they require both visual search and manual exploration.46 For example, omission of contralesional targets in cancellation tests may be due to either a lack of awareness (visual neglect) or an inability to move toward the contralesional side (motor neglect), as motor neglect may affect the unaffected arm as well as the head or eyes or contralesional limb.5,46,47 Similarly, in line bisection tests, the rightward error observed in left ULN may be explained by an attentional bias (visual neglect) such that the person underestimates the extent of the left end of the line and overestimates the right end.48,49 Alternatively, the rightward error may be due to difficulty moving in a leftward direction.17 Because line bisection and cancellation tests are performed within reaching space, these tests can indicate the presence of neglect in peripersonal space, but they cannot identify personal neglect or neglect in extrapersonal (far) space. Some authors50,51 have suggested that “qualitative” or “dynamic” evaluation of line bisection and cancellation test performance may provide the clinician with a greater understanding of the neglect behavior than line bisection or cancellation tests alone. The term “qualitative” refers to descriptive information about the patient's behavior. In a qualitative assessment of unilateral neglect, the clinician observes the patient during the task performance and focuses on how the person performs the task rather than simply recording the outcome.50 For example, in a cancellation test, the therapist might assess where the patient commences the task (left, right, top, bottom), the scanning pattern (horizontal, vertical, unsystematic), and search time. Scanning pattern may be recorded during cancellation tests by tracing the sequence in which the patient selects the target stimuli and numbering them on a replica of the test sheet.38 At the conclusion of the test, the numbers on the examiner's sheet are joined in chronological order to reveal the visual scanning pattern. Alternately, the therapist can give the patient a different colored marker after every 10 cancellations and record the order in which the colored markers were used.51 This allows the therapist to map the order in which segments of the array were scanned. People without visual perceptual problems usually start searching on the left and progress in a systematic manner, vertically or horizontally.38 By contrast, the search strategy of individuals with attentional deficits has been described as disorganized and unmethodical.38,51 We believe that descriptive information such as starting point and scanning pattern may help the therapist to identify attentional problems that might otherwise remain undetected. For example, in a cancellation test, a patient may scan from right to left or in a disorganized manner, but still manage to cancel all of the targets. Assessment based only on the result of the test could lead the therapist to conclude that ULN is not present because the patient did not omit any stimuli. However, observation of the starting point and scanning pattern would reveal that the way in which the task was performed was atypical. From a rehabilitation perspective, these mild deficits are important to identify, as these patients have been found to have an increased accident risk.52 A “dynamic”50,51 approach to assessment of ULN refers to modifying particular aspects of the assessment task in order to determine whether the patient's performance can be improved with the addition of cues or a modification to the task. In this way, “dynamic assessment” can be likened to a hypothetico-deductive method for assessing ULN, in which the clinician develops an evolving understanding of the neglect behavior by examining how the person's performance changes in response to the task parameters. For example, in a line bisection test, the task could be modified by placing a letter (visual “anchor” or “cue”) at each end of the line to be bisected. The person would then be instructed to report any letters he or she sees prior to bisecting the line. Failure to detect the letter at the left end of the line would indicate a lack of awareness, suggesting that visual neglect is a contributing factor to impaired line bisection performance. Identification of the left-end letter with no reduction in rightward bisection error relative to the standard line bisection test suggests that motor neglect is a more likely contributing factor, because neglect was demonstrated despite awareness of left-sided stimuli. This is one example of how an evaluation of the effects of visual and verbal cues enables better understanding of the factors contributing to the neglect behavior on conventional tests of ULN. The therapist also might assess the effect on performance of hand used (affected, unaffected) or the position of the line relative to the patient's midline (center, left, right). We believe that such modifications of line bisection and cancellation tests cannot differentiate types of ULN with certainty, but can provide the clinician with useful information about the task that the of the is based on the that task modification the therapist about and possible for the impaired performance. This thought might therapists to consider the type of neglect a person rather than the presence of neglect on these tests. simple and are frequently used by to detect ULN in patients following stroke. typically used for include and from is considered to test for representational Test objects considered to be sensitive to detecting ULN are a the and a or with omissions or on the contralesional side is considered indicative of ULN. In the person may the to the unaffected side of the page. problems with and tests are: (1) in the of the and (2) for patients with all patients with ULN on this type of found that relative to star cancellation and line bisection tests both tests, the sensitivity of tests was In these tests have validity because impaired and may or as well as ULN. and found test-retest reliability for from (Pearson P<.001, they that the of neglect in any single is In of the limitations of and tests, not the inclusion of a and in a test battery for ULN. have been to detect representational although their validity to be The Behavioural Inattention Test is a standardized test battery for assessing visual neglect, of of the most used tests letter star copying, line bisection, and as well as behavioral and setting the and copying, map and though the conventional tests that to be by the such as and copying, is by defined for the person's is based on the of omissions in each and a is for each test can be for a on the conventional test and the behavioral from have been to determine for Construct validity of the was by the performance of patients with unilateral brain damage on the behavioral to performance on conventional which were selected from published and considered measures of There was a between the conventional and behavioral test (Pearson validity to which clinical tests to the in their of the was by the on the behavioral tests with the responses to a at the of the was (Pearson the validity of data with the used to the was not found greater than between of the behavioral from the and performance on (eg, from a a in a personal a on a scanning objects in a We believe this further the validity of the reliability (Pearson P<.001, and test-retest reliability (Pearson P<.001, of the also have been the of the the important of test sensitivity to detect and of clinical of the is limited to measuring neglect in peripersonal the cannot identify personal neglect or extrapersonal (far) neglect. because the of the require both visual search and manual the cannot between sensory neglect and motor For these we believe that the used in not assess ULN. Nonetheless, the is a useful test for measuring the of neglect on peripersonal This 2 one for personal neglect and one for extrapersonal The patient is to each task with rather than to the Personal include a and The extrapersonal are and description of an environment. The patient a of to for each item based on the of or performance and a for each were found to have reliability for personal and for extrapersonal P<.001, The however, an prior to the which the of these validity was by performance of patients with neglect on the extrapersonal and personal with performance on cancellation test, letter cancellation test, There were between the extrapersonal and each conventional test and P<.001, Performance on the personal did not correlate with performance on the conventional tests not to the the failure of the personal to correlate with conventional tests of ULN suggests that conventional and personal tests different of neglect. In this the of both personal and extrapersonal in any assessment of neglect behavior. The personal however, requires further The is a for therapists to assess the presence and of ULN in a of The and the patient's rather than test The 10 are: and the left of the the left or food on the left side of the the left side of the after leftward of the left of the auditory to stimuli from the left, with objects on the left, leftward in familiar and familiar on the the on the are defined according to left ULN, the not that the can be used only for left ULN. is with for people with left-hemisphere stroke right ULN. To have been only with patients with right-hemisphere stroke left Neglect behavior is by the on a mild moderate or The for all is by 10 to a from to that are not possible to due to for example, are omitted from the The validity of the as a of ULN was by the with performance of or tests associated with ULN copying, line cancellation test, bells cancellation were although were relatively A also was found between the and the The has been shown to have reliability An of the is that it and extrapersonal the not differentiate personal and spatial neglect in the of we believe that it is possible for the clinician to identify whether the person has spatial neglect or personal neglect (or by the for on the in a recent of the psychometric properties of the suggested that such as neglect in and of the left are to personal neglect, whereas moving may be to an of of in extrapersonal space. of the other measures of ULN is to provide a of the patient's into their A of the has been as a which the patient The allows a of the observation and the patient's an of the patient's awareness of their This is the only of ULN that also In one of the is the difficulty whether sensory neglect or motor neglect to the observed in patients with that it can be to determine is due to neglect and is due to sensory or are described for where it is to an Despite these we believe that the is a useful for measuring the of neglect in a of tests for ULN, such as line bisection and cancellation tests, are not for between sensory neglect and motor neglect because they visual search and a manual We however, that these tests can provide the therapist with an of the presence of ULN, as well as a for how the patient to changes in task This information may be useful for physical In and tests are not recommended for assessing ULN because they have a to between ULN, and this update has of the tests to the of ULN. of the can between sensory neglect and motor neglect, the a way of personal and spatial neglect, information that may be useful for the therapist in and
Source: Physical Therapy
DOI: 10.1093/ptj/83.8.732
Authors: Prudence Plummer, Meg E Morris, Judith Dunai
Institutions: La Trobe University, The University of Melbourne
Language: English
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2207584963