Hemispatial neglect
Hemispatial neglect, also called hemiagnosia, hemineglect, unilateral neglect, spatial neglect, unilateral visual inattention, hemi-inattention or neglect syndrome is a neuropsychological condition in which, after damage to one hemisphere of the brain, a deficit in attention to and awareness of one side of space is observed. It is defined by the inability for a person to process and perceive stimuli on one side of the body or environment that is not due to a lack of sensation. Hemispatial neglect is very commonly contralateral to the damaged hemisphere, but instances of ipsilesional neglect (on the same side as the lesion) have been reported.


Hemispatial neglect results most commonly from brain injury
Acquired brain injury
An acquired brain injury is brain damage caused by events after birth, rather than as part of a genetic or congenital disorder such as fetal alcohol syndrome, perinatal illness or perinatal hypoxia. ABI can result in cognitive, physical, emotional, or behavioural impairments that lead to permanent...

 to the right cerebral hemisphere
Cerebral hemisphere
A cerebral hemisphere is one of the two regions of the eutherian brain that are delineated by the median plane, . The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is...

, causing visual neglect of the left-hand side of space. Right-sided spatial neglect is rare because there is redundant processing of the right space by both the left and right cerebral hemispheres, whereas in most left-dominant brains the left space is only processed by the right cerebral hemisphere. Although most strikingly affecting visual perception
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...

 ('visual neglect'), neglect in other forms of perception can also be found, either alone, or in combination with visual neglect.

For example, a stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

 affecting the right parietal lobe
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...

 of the brain can lead to neglect for the left side of the visual field
Visual field
The term visual field is sometimes used as a synonym to field of view, though they do not designate the same thing. The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments", while 'field of view' "refers to the physical...

, causing a patient with neglect to behave as if the left side of sensory space is nonexistent (although they can still turn left). In an extreme case, a patient with neglect might fail to eat the food on the left half of their plate, even though they complain of being hungry. If someone with neglect is asked to draw a clock, their drawing might show only numbers 12 to 6, or all 12 numbers on one half of the clock face, the other side being distorted or left blank. Neglect patients may also ignore the contralesional side of their body, shaving or adding make-up only to the non-neglected side. These patients may frequently collide with objects or structures such as door frames on the side being neglected.

Neglect may also present as a delusion
A delusion is a false belief held with absolute conviction despite superior evidence. Unlike hallucinations, delusions are always pathological...

al form, where the patient denies ownership of a limb or an entire side of the body. Since this delusion often occurs alone without the accompaniment of other delusions, it is often labeled as a monothematic delusion
Monothematic delusion
A monothematic delusion is a delusional state that only concerns one particular topic. This is contrasted by what is sometimes called multi-thematic or polythematic delusions where the person has a range of delusions...


Neglect not only affects present sensation but memory and recall perception as well. A patient suffering from neglect may also, when asked to recall a memory of a certain object and then draw said object, again, only draw half of the object. It is unclear, however, if this is due to a perceptive deficit of the memory (having lost pieces of spatial information of the memory) or whether the information within the memory is whole and intact, but simply being ignored, the same way portions of a physical object in the patient's presence would be ignored.


Brain areas in the parietal
Parietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...

 and frontal lobe
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...

s are associated with the deployment of attention (internally, or through eye movements, head turns or limb reaches) into contralateral space. Neglect is most closely related to damage to the temporo-parietal junction and posterior parietal cortex
Posterior parietal cortex
The posterior parietal cortex plays an important role in producing planned movements. Before an effective movement can be initiated, the nervous system must know the original positions of the body parts that are to be moved, and the positions of any external objects with which the body is going to...

. The lack of attention to the left side of space can manifest in the visual, auditory, proprioceptive, and olfactory domains. Although hemispatial neglect often manifests as a sensory deficit (and is frequently co-morbid
In medicine, comorbidity is either the presence of one or more disorders in addition to a primary disease or disorder, or the effect of such additional disorders or diseases.- In medicine :...

 with sensory deficit), it is essentially a failure to pay sufficient attention to sensory input. This is particularly evident in a related, but separate, condition known as extinction
Extinction (neurology)
Extinction is a neurological disorder characterized by inability to recognize two simultaneous stimuli on opposite sides of the body, or proximally and distally, though either one can be sensed alone...

. A patient with extinction following right-hemisphere damage will successfully report the presence of an object in left space when it is the only object present. However, if the same object is presented simultaneously with an object in right space, the patient will only report the object on the right.

Neglect patients can also have problems with "interior" left information, since cases have been reported in which the patient when asked to describe something he knew before his brain damage describes only its right part.

Although hemispatial neglect has been identified following left hemisphere
Lateralization of brain function
A longitudinal fissure separates the human brain into two distinct cerebral hemispheres, connected by the corpus callosum. The sides resemble each other and each hemisphere's structure is generally mirrored by the other side. Yet despite the strong anatomical similarities, the functions of each...

 damage (resulting in the neglect of the right side of space), it is most common after damage to the right hemisphere. This disparity is thought to reflect the fact that the right hemisphere of the brain is specialized for spatial perception and memory, whereas the left hemisphere is specialized for language - there is redundant processing of the right visual fields by both hemispheres. Hence the right hemisphere is able to compensate for the loss of left hemisphere function, but not vice versa.
Neglect is not to be confused with hemianopsia
Hemianopia, or hemianopsia, is a type of anopsia where the decreased vision or blindness takes place in half the visual field of one or both eyes. In most cases, the visual field loss respects the vertical midline...

. Hemianopsia arises from damage to the primary visual pathways cutting off the input to the cerebral hemispheres from the retinas. Neglect is damage to the processing areas. The Cerebral hemispheres receive the input, but there is an error in the processing that is not well understood.

Varieties of hemispatial neglect

Unilateral neglect is a heterogeneous syndrome with several subtypes, and it’s possible that many distinct disorders have been inaccurately lumped together under a single label. There is growing consensus that no single mechanism accounts for the full range of demonstrated symptoms. And it appears that impairments of several different mechanisms converge to result in neglect—each of which could exist singly without causing it. The complexity of attention alone—just one of several mechanisms that may interact—has generated multiple competing hypothetical explanations of neglect. So it’s not surprising that it’s proven difficult to assign particular presentations of neglect to specific neuroanatomical loci. But despite such limitations, we may loosely describe unilateral neglect with four overlapping variables: type, range, axis, and orientation.


Types of hemispatial neglect are broadly divided into disorders of input and disorders of output. The neglect of input, or “inattention,” includes ignoring contralesional sights, sounds, smells, or tactile stimuli. Surprisingly, this inattention can even apply to imagined stimuli. In what’s termed “representational neglect,” patients may ignore the left side of memories, dreams, and hallucinations.

Output neglect includes motor and pre-motor deficits. A patient with motor neglect does not use a contralesional limb despite the neuromuscular ability to do so. One with pre-motor neglect, or directional hypokinesia
Hypokinesia refers to decreased bodily movement. It is associated with basal ganglia diseases , mental health disorders and prolonged inactivity due to illness, amongst other diseases.Hypokinesia describes a spectrum of disorders:...

, can move unaffected limbs ably in ipsilateral space, but has difficulty directing them into contralesional space. Thus a patient with pre-motor neglect may struggle with grasping an object on the left side even when using the unaffected right arm.


Patients may neglect their own body, the reaching space around them, or the far space beyond their reach. This differentiation is significant because the majority of assessment measures test only for neglect within the reaching, or peri-personal, range. But a patient who passes a standard paper-and-pencil test of neglect may nonetheless ignore a left arm or not notice distant objects on the left side of the room.

In cases of somatoparaphrenia, which may be caused by personal neglect, patients deny ownership of contralesional limbs. Sacks (1985) described a patient who fell out of bed after pushing out what he perceived to be the severed leg of a cadaver that the staff had hidden under his blanket. Patients may say things like, “I don’t know whose hand that is, but they’d better get my ring off!” or, “This is a fake arm someone put on me. I sent my daughter to find my real one.”


Most tests for neglect look for rightward or leftward errors. But patients may also neglect stimuli on one side of a horizontal or radial axis. For example, when asked to circle all the stars on a printed page, they may locate targets on both the left and right sides of the page while ignoring those across the top or bottom.

In a recent study, researchers asked patients with left neglect to project their midline with a neon bulb
Neon lamp
A neon lamp is a miniature gas discharge lamp that typically contains neon gas at a low pressure in a glass capsule. Only a thin region adjacent to the electrodes glows in these lamps, which distinguishes them from the much longer and brighter neon tubes used for signage...

 and found that they tended to point it straight ahead but position it rightward of their true midline. This shift may account for the success of therapeutic prism
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...

 glasses, which shift left visual space toward the right. By shifting visual input, they seem to correct the mind's sense of midline. The result is not only the amelioration of visual neglect, but also of tactile, motor, and even representational neglect.


An important question in studies of neglect has been: "left of what?" The answer has proven complex. It turns out that subjects may neglect objects to the left of their own midline (egocentric neglect) or may instead see all the objects in a room but neglect the left half of each individual object (allocentric neglect).

These two broad categories may be further subdivided. Patients with egocentric neglect may ignore the stimuli leftward of their trunks, their heads, or their retinae. Those with allocentric neglect may neglect the true left of a presented object or, amazingly, may first correct in their mind’s eye a slanted or inverted object and then neglect the side then interpreted as being on the left. So, for example, if patients are presented with an upside-down photograph of a face, they may mentally flip the object right side up and then neglect the left side of the adjusted image. This also occurs with slanted or mirror-image presentations. A patient looking at a mirror image
Mirror image
A mirror image is a reflected duplication of an object that appears identical but reversed. As an optical effect it results from reflection off of substances such as a mirror or water. It is also a concept in geometry and can be used as a conceptualization process for 3-D structures...

 of a map of the World
World map
A world map is a map of the surface of the Earth, which may be made using any of a number of different map projections. A map projection is any method of representing the surface of a sphere or other three-dimensional body on a plane....

 may neglect to see the Western Hemisphere
Western Hemisphere
The Western Hemisphere or western hemisphere is mainly used as a geographical term for the half of the Earth that lies west of the Prime Meridian and east of the Antimeridian , the other half being called the Eastern Hemisphere.In this sense, the western hemisphere consists of the western portions...

 despite their inverted placement onto the right side of the map.


Though frequently underappreciated, unilateral neglect can have dramatic consequences. It has more negative effect on functional ability, as measured by the Barthel ADL index, than age, sex, power, side of stroke, balance, proprioception
Proprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...

, cognition, or premorbid ADL status. Its presence within the first 10 days of a CVA is a stronger predictor of poor functional recovery after one year than several other variables, including hemiparesis
Hemiparesis is weakness on one side of the body. It is less severe than hemiplegia - the total paralysis of the arm, leg, and trunk on one side of the body. Thus, the patient can move the impaired side of his body, but with reduced muscular strength....

, hemianopsia
Hemianopia, or hemianopsia, is a type of anopsia where the decreased vision or blindness takes place in half the visual field of one or both eyes. In most cases, the visual field loss respects the vertical midline...

, age, visual memory
Visual memory
Visual memory describes the relationship between perceptual processing and the encoding, storage and retrieval of the resulting neural representations. Visual memory occurs over a broad time range spanning from eye movements to years in order to visually navigate to a previously visited location...

, verbal memory, or visuoconstructional ability. Neglect is likely among the reasons that patients with right hemisphere damage are twice as likely to fall as those with left brain damage. Patients with neglect rehabilitate longer and make less daily progress than other patients with similar functional status. And patients with neglect are less likely to live independently than even patients who have both severe aphasia
Aphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....

 and right hemiparesis.


Treatment consists of finding ways to bring the patient's attention toward the left, usually done incrementally, by going just a few degrees past midline, and progressing from there. Rehabilitation
Rehabilitation (neuropsychology)
Rehabilitation of sensory and cognitive function typically involves methods for retraining neural pathways or training new neural pathways to regain or improve neurocognitive functioning that has been diminished by disease or traumatic injury....

 of neglect is often carried out by Neuropsychologists
Neuropsychology studies the structure and function of the brain related to specific psychological processes and behaviors. The term neuropsychology has been applied to lesion studies in humans and animals. It has also been applied to efforts to record electrical activity from individual cells in...

, Occupational Therapists
Occupational therapy
Occupational therapy is a discipline that aims to promote health by enabling people to perform meaningful and purposeful activities. Occupational therapists work with individuals who suffer from a mentally, physically, developmentally, and/or emotionally disabling condition by utilizing treatments...

, Speech-Language Pathologists, Physical Therapists
Physical therapy
Physical therapy , often abbreviated PT, is a health care profession. Physical therapy is concerned with identifying and maximizing quality of life and movement potential within the spheres of promotion, prevention, diagnosis, treatment/intervention,and rehabilitation...

 and Orthoptists

Forms of treatment that have been tested with variable reports of success include prismatic adaptation, where a prism lens is worn to pull the vision of the patient towards the left, constrained movement therapy where the "good" limb is constrained in a sling to encourage use of the contralesional limb. Eye-patching has similarly been used, placing a patch over the "good" eye. Pharmaceutical treatments have mostly focused on dopaminergic therapies such as bromocriptine
Bromocriptine , an ergoline derivative, is a dopamine agonist that is used in the treatment of pituitary tumors, Parkinson's disease , hyperprolactinaemia, neuroleptic malignant syndrome, and type 2 diabetes.- Indications :Amenorrhea, female infertility, galactorrhea, hypogonadism, and acromegaly...

, levodopa
L-DOPA is a chemical that is made and used as part of the normal biology of some animals and plants. Some animals including humans make it via biosynthesis from the amino acid L-tyrosine. L-DOPA is the precursor to the neurotransmitters dopamine, norepinephrine , and epinephrine collectively...

, and amphetamine
Amphetamine or amfetamine is a psychostimulant drug of the phenethylamine class which produces increased wakefulness and focus in association with decreased fatigue and appetite.Brand names of medications that contain, or metabolize into, amphetamine include Adderall, Dexedrine, Dextrostat,...

s, though these tests have had mixed results, helping in some cases and accentuating hemispatial neglect in others. Vestibular caloric stimulation
Caloric reflex test
In medicine, the caloric reflex test is a test of the vestibulo-ocular reflex that involves irrigating cold or warm water or air into the external auditory canal.-Utility:...

 has been shown to bring about a brief remission in some cases.
A study done by Schindler and colleagues examined the use of neck muscle vibration on the contralesional posterior neck muscles to induce diversion of gaze from the subjective straight ahead. Subjects received 15 consecutive treatment sessions and were evaluated on different aspect of the neglect disorder including perception of midline, and scanning deficits. The study found that there is evidence that neck muscle stimulation may work, especially if combined with visual scanning techniques. The improvement was evident 2 months after the completion of treatment.

Other areas of emerging treatment options include the use of prisms, visual scanning training, mental imagery training, video feedback training, and trunk rotation. Of these emerging treatment options, the most promising intervention is prism adaptation given the growing evidence of relatively long-term functional gains from comparatively short-term usage. However, these treatment interventions are relatively new and the amount of evidence is still limited. Further research is mandatory in this field of research in order to provide more support in evidence-based practice.

In a review article by Pierce & Buxbaum (2002), they concluded that the evidence for Hemispheric Activation Approaches, which focuses on moving the limb on the side of the neglect, has conflicting evidence in the literature. The authors note that a possible limitation in this approach is the requirement for the patients to actively move the neglected limb, which may be not be possible for many patients. Constraint-Induced Therapy (CIT), appears to be an effective, long-term treatment for improving neglect in various studies. However, the use of CIT is limited to patients who have active control of wrist and hand extension. Prism Glasses, Hemispatial Glasses, and Eye-Patching have all appear to be effective in improving performance on neglect tests. Caloric Stimulation treatment appears to be effective in improving neglect; however, the effects are generally short-term. The review also suggests that Optokinetic Stimulation is effective in improving position sense, motor skills, body orientation, and perceptual neglect on a short-term basis. As with Caloric Stimulation treatment, long-term studies will be necessary to show its effectiveness. A few Trunk Rotation Therapy studies suggest its effectiveness in improving performance on neglect tests as well as the Functional Independence Measure (FIM). Some less studied treatment possibilities include treatments that target Dorsal Stream of visual processing, Mental Imagery Training, and Neck Vibration Therapy. Trunk rotation therapies aimed at improving postural disorders and balance deficits in patients with unilateral neglect, have demonstrated optimistic results in regaining voluntary trunk control when using specific postural rehabilitative devices. One such device is the Bon Saint Côme apparatus, which uses spatial exploratory tasks in combination with auditory and visual feedback mechanisms to develop trunk control. The Bon Saint Côme device has been shown to be effective with hemiplegic subjects due to the combination of trunk stability exercises, along with the cognitive requirements needed to perform the postural tasks.

See also

  • Blindsight
    Blindsight is a phenomenon in which people who are perceptually blind in a certain area of their visual field demonstrate some response to visual stimuli...

  • Brain damage
    Brain damage
    "Brain damage" or "brain injury" is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors...

  • Anosognosia
    Anosognosia /æˌnɒsɒgˈnəʊsɪə/ is a condition in which a person who suffers disability seems unaware of the existence of his or her disability. Unlike denial, which is a defense mechanism, anosognosia is rooted in physiology...

  • Delusion
    A delusion is a false belief held with absolute conviction despite superior evidence. Unlike hallucinations, delusions are always pathological...

  • Monothematic delusion
    Monothematic delusion
    A monothematic delusion is a delusional state that only concerns one particular topic. This is contrasted by what is sometimes called multi-thematic or polythematic delusions where the person has a range of delusions...

  • Agnosia
    Agnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss...

     (Particularly Mirror Agnosia)
  • Allochiria
    Allochiria is associated to spatial transpositions, usually symmetrical, of stimuli from one side of the body to the opposite one. It is a neurological disorder in which the patient responds to stimuli presented to one side of their body as if the stimuli had been presented at the opposite side...

External links

  • Hemineglect at Scholarpedia
    Scholarpedia is an English-language online wiki-based encyclopedia that uses the same MediaWiki software as Wikipedia, but has features more commonly associated with open-access online academic journals....

  • What is Unilateral Neglect at University of Waterloo
    University of Waterloo
    The University of Waterloo is a comprehensive public university in the city of Waterloo, Ontario, Canada. The school was founded in 1957 by Drs. Gerry Hagey and Ira G. Needles, and has since grown to an institution of more than 30,000 students, faculty, and staff...

  • Unilateral Neglect: Clinical and Experimental Studies detailed book review
    Book review
    A book review is a form of literary criticism in which a book is analyzed based on content, style, and merit. A book review could be a primary source opinion piece, summary review or scholarly review. It is often carried out in periodicals, as school work, or on the internet. Reviews are also often...

     at Monash University
    Monash University
    Monash University is a public university based in Melbourne, Victoria. It was founded in 1958 and is the second oldest university in the state. Monash is a member of Australia's Group of Eight and the ASAIHL....

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