Unilateral Neglect

Clinical And Experimental Studies

John Marshall, Ian Robertson

• Publisher: Psychology Press
• Year: 2013
• ISBN:
  9781134831814
• Edition: 1
• Topic: Psychology
• Subtopic: History & Theory in Psychology
• Index: Psychology

Unilateral neglect is a fairly common disorder, usually associated with a stroke, which results in a neglect or lack of attention to one side of space usually, but not exclusively, the left. Theoretically, it is one of the most interesting and important areas in neuropsychology; practically, it is one of the greatest therapeutic problems facing therapists and rehabilitationists. This book covers all aspects of the disorder, from an historical survey of research to date, through the nature and anatomical bases of neglect, and on to review contemporary theories on the subject. The final section covers behavioural and physical remediation. A greater understanding of unilateral neglect will have important implications not just for this particular disorder but for the understanding of brain function as a whole.

I

What is Neglect?

1

The History and Clinical Presentation of Neglect

Peter W. Halligan

Rivermead Rehabilitation Centre, Oxford, UK

John C. Marshall

Neuropsychology Unit, Radcliffe Infirmary, Oxford, UK

Classical visual neglect is one of the simplest of clinical observations and yet one of the most striking. The fact that textbooks are already full of drawings of daisies and clock faces by neglecting patients makes it no less impressive when you first observe it for yourself (Latto, 1984).

What is Neglect?

Of the many neuropsychological consequences that follow right hemisphere brain damage, few are as striking or as puzzling as when a patient without impairment of intellectual functioning appears to ignore, forget or turn away from the left side of space—as if that half of the world had abruptly ceased to exist in any meaningful form (Mesulam, 1985). This “cognitive” inability to respond to objects and people located on the side contralateral to a cerebral lesion is usually known as unilateral neglect.

The condition can be distinguished from the behaviour associated with primary sensory and motor deficits (hemianopia and hemiplegia), although differential diagnosis may be difficult in the acute phase (Heilman, Watson, & Valenstein 1985b). Most of the classical behaviours associated with the diagnosis of neglect cannot be readily explained in terms of sensori-motor deficits: neglect is manifest in free vision and under conditions of testing that do not necessarily require the use of the motorically impaired limb. Although many patients do have visual field cuts and hemiplegia, severe neglect can be seen in cases without such deficits (Halligan, Marshall, & Wade, 1990). The lesions which produce neglect are not limited to the accepted primary sensory or motor areas. In addition, many neglect behaviours often resolve sooner than those which result from lesions of sensory or motor cortex (Friedland & Weinstein, 1977).

Even a cursory examination of the neglect patient’s behaviour suggests that the spatial disorder underlying the condition is conceptually different from what might be expected to follow impairment of basic sensory or motor abilities. Such deficits do not of themselves entail the failure to explore or respond to objects and activities on the affected side of space (Bisiach, Capitani, Luzzatti, & Perani, 1981). Patients with florid neglect often demonstrate a specific lack of awareness and behave as if they were selectively ignoring stimuli on the impaired side. The condition is more appropriately conceptualised as a failure of looking and searching rather that of seeing or moving the eyes per se (Mesulam, 1985).

Patients often believe that they have an appropriate representation of their environment and consequently additional problems of denial and minimisation of deficit emerge (Gordon & Diller, 1983). In such patients, unawareness of the deficit appears to be a central feature of the condition. This subjective lack of awareness (anosognosia) creates additional difficulties for the patient’s recovery and involvement in rehabilitation programmes. Unawareness of hemianopia and of hemiplegia are often found acutely after brain damage. Levine (1990) suggests that the underlying pathology “is not associated with any immediate sensory experience that uniquely specifies the defect”. Hence, he argues, the loss “must be discovered by a process of self-observation and inference”. It is possible that neglect may similarly need to be discovered by the patient, although the appropriate compensatory reaction is not clear as in the case of hemianopia. Other patients may show unilateral hallucinations restricted to (non-neglected) right hemispace (Chamorro et al., 1990; Mesulam, 1981), phenomena that further confuse the patient’s relationship with reality.

A Brief History of Visual Neglect

The first clinical descriptions of neglect, in the second half of the last century, attracted intense speculation from those few neurological researchers

… who needed a respite from the intricacies of aphasic localization and classification, and wondered how the other half of the brain lived. The manifestations of hemi-inattention have also excited the imagination of those who marvelled that one could exist in a demi-world where laterality determined reality (Weinstein & Friedland, 1977).

Although left neglect is one of the most striking consequences of damage to the right hemisphere, it did not initially receive the attention given to rarer perceptual disorders such as the object agnosias. One reason for this “neglect” of visual-spatial disorders is that, unlike language or figural perception, the structure of psychological space is elusive and difficult to characterise in a precise way (Delis, Robertson, & Balliet, 1985). The very fact that the spatial components of perception are an intrinsic aspect of every visual cognition appears to hinder the scientific appreciation of space (De Renzi, 1982). Evidence of this difficulty can be seen from the diversity of terms that have been used to describe neglect: neglect of the left half of visual space (Brain, 1941); unilateral visual inattention (Allen, 1948); unilateral spatial agnosia (Duke-Elder, 1949); imperception for one half of external space (Critchley, 1953); amorphosynthesis (Denny-Brown & Banker, 1954); left-sided fixed hemianopia (Luria, 1972); hemi-inattention (Weinstein & Friedland, 1977); hemi-neglect (Kinsbourne, 1977); unilateral neglect (Hecaen & Albert, 1978); hemi-spatial agnosia (Willanger, Danielsen, & Ankerhus, 1981); contralesional neglect (Ogden, 1985); dyschiria (Bisiach & Berti, 1987) and directional hypokinesia (Coslett et al., 1990).

Studies of visual neglect can be divided into two periods: (1) early case studies and (2) later, more detailed case series and group studies. The former illustrate some of the difficulties encountered by clinicians attempting to formulate a coherent description of the condition. The majority of these studies fall within the framework of clinical neurology and emphasise neuroanatomy and pathology. The latter attempt to describe the range and types of visual neglect, using a wide variety of operational definitions, clinical tests and pathogical groups.

Hughlings Jackson’s single case report of 1876 is among the first well-documented accounts of neglect. The collective term “imperception” was used to refer to a patient with topographical disorientation, visual neglect, dressing apraxia and some signs of dementia. Jackson noted that when asked to read the Snellen visual acuity chart, the patient “... did not know how to set about [and] began at the right lower corner and tried to read backwards”. Other phenomena mentioned include what would now be termed neglect dyslexia (Ellis, Flude, & Young, 1987): the omission or substitution of letters at the beginning of words. The location of the lesion in the posterior part of the right temporal lobe appeared to confirm Jackson’s earlier intuition (1874) regarding the “leading” role of the right hemisphere in visuo-spatial processes. It should be added, however, that this case is far from representative of the condition: Jackson’s patient demonstrated many other symptoms not intrinsically related to neglect.

Visual neglect was also described at about this time by several German neurologists, but typically only as a minor symptom within a more complex neurological condition. Anton (1883) reported four patients, two of whom, after right-sided lesions, could not perceive passive movements of their left limbs, and ignored what was happening in left extrapersonal space. An early case of neglect dyslexia (with associated anosognosia) was published by Pick (1898) and, in 1909, a patient who made similar reading errors was described by Balint. In this latter case, neglect dyslexia was found in the more general context of “psychic paralysis of gaze, optic ataxia and spatial impairment of attention” (Balint’s Syndrome). In 1913, Zingerle published a case study of a 45-year-old man with hemiplegia, hemianaesthesia and hemianopia following right hemisphere stroke, whose neglect involved both personal and extrapersonal space. Zingerle’s distinctive contribution (see Bisiach & Berti, 1987, for an appraisal) was his subsequent analysis, which classified the patient’s condition as similar to the “dyschiria” which had been described earlier by Jones (1910) in the case of a patient who had a specific impairment in the appreciation of left-sided personal space despite intact sensory abilities.

Holmes and Poppelreuter

The First World War resulted in large numbers of young soldiers with relatively discrete cerebral lesions. Examination of these men and, in particular, the systematic work of Walter Poppelreuter and Gordon Holmes, led to significant insights into the factors that underlie the complex syndrome variously described as “visuo-constructive” or “visuo-orientational” disability. In discussing the condition of “visual disorientation” or “defective spatial orientation”, Holmes (1918) made a critical distinction. Whereas before “visual disorientation” was regarded as primarily a manifestation of visual agnosia, it was now possible to show that visual disorientation could occur without “object agnosia”. This distinction subsequently provided the basis for a re-examination of the concept of “visual inattention”.

Gordon Holmes’ concept of “inattention” was similar to that of Poppelreuter (1917), which for the most part described the elicited response of “extinction” rather than the spontaneous manifestations of visual neglect. This emphasis on extinction was not altogether surprising, since florid symptoms of visual neglect are not typically found after focal penetrating lesions (Kinsbourne, 1977; Mesulam, 1985). Extinction refers to the following situation with fixed gaze: when visual fields are assessed by presentation of a single object (e.g. the clinician’s finger), detection appears normal, i.e. both left and right fields are “full to confrontation”. However, when two objects are presented at the same time, one in each field, only one of the stimuli is reported. This latter finding is known as “extinction to double simultaneous stimulation”. Holmes reports, however, that similar effects can be seen in situations other than conventional visual field testing. For example (Holmes & Horrax, 1919):

When asked to look at a needle placed on the table, he [the patient] often failed to detect a pencil placed on one side of it, or if there were two pencils, he could only see the one or the other. At one time ... while sitting in the ward, it was noticeable that the patient usually saw only what their eyes were directed on and that they took little interest in what was happening around them (Holmes. 1919) … attention lacked its normal spontaneity and facility in diverting itself to new objects.

Although both Holmes and Poppelreuter alluded to what may be regarded as neglect behaviours, many of their systematic investigations concerned the failure to attend to peripheral stimuli approaching from one side when stimuli from both sides were presented. Poppelreuter (1917) describes how such phenomena may result from an “organic weakness of attention”. The “only possibility of differentiating between hemi-inattention and a ‘perceptive’ hemianopia”, he writes, is to attempt to re-orient attention by actively directing the patient’s attention to the “neglected” side. Poppelreuter also emphasised that no explanation of heminattention can ignore the apparent “completion” of simple forms when a segment thereof falls within a “blind” or neglected area: “the totalizing apperception of form is thus capable of compensating considerably for hemianopia as well as for unilateral weakness of attention” (Poppelreuter, 1917).

Like Poppelreuter, Holmes’ description of “inattention” goes further than the elicited response of “extinction” and may more accurately be described as a “limitation of visual attention to those objects within the central vision” (Weinstein & Friedland, 1977). Some of these cases would now be described under the label “simultanagnosia”. Describing one such case, Holmes and Horrax (1919) wrote:

It is essentially a disturbance of visual attention; retinal impressions no longer attract notice with normal facility, and if two or more images claim attention, this is liable to concern itself exclusively with, and to be absorbed in, that which is at the moment in macular vision …

For Holmes, “inattention” was only one of several component features that contributed to a major disturbance of visual orientation. On several occasions, Holmes goes so far as to point out that inattention per se is not an essential part of the condition, and may often occur independently of problems with visual orientation (Holmes, 1918; 1919; Holmes & Horrax, 1919). Holmes’ analysis of inattention originated within a general evaluation of visual disabilities after predominantly bilateral damage. It is not clear that the concept of unilateral (contralesional neglect) was available to him.

The term “neglect” was first used consistently by Pineas (1931). Pineas described a 60-year-old woman whose vernachlassigung (neglect) of the left side was both severe and long-lasting, despite the absence of a field deficit or sensori-motor loss. Pineas concluded that the left half of the body schema and extrapersonal hemispace did not exist for the patient in any meaningful way. Although Holmes (1918), Poppelreuter (1917), Pineas (1931) and Scheller and Seidmann (1931) documented some of the behavioural features of visual neglect and suggested an attentional explanation, it was not considered a specific syndrome until the Second World War and the work of Russell Brain. Brain’s article in 1941 was the first report that isolated and characterised some o...

Table of contents

• Cover Page
• Half Title page
• Title Page
• Copyright Page
• Contents
• List of Contributors
• Series page
• Series Preface
• Part I What is Neglect?
• Part II Neuropsychological Processes Underlying Neglect
• Part III Rehabilitation of Unilateral Neglect
• Part IV Coda
• Author Index
• Subject Index