What is inattention in stroke?

Definition of Inattention in Stroke

Inattention in stroke, also called hemispatial neglect, hemi-inattention, or unilateral spatial neglect, is a neuropsychological condition characterized by decreased attention to and awareness of one side of space (typically the contralesional side) following brain damage, which cannot be attributed to primary sensory or motor deficits. 1

Core Clinical Features

Inattention manifests as a failure to attend to stimuli on the side of space opposite to the brain lesion, despite intact basic sensory and motor function. 1 The condition represents an attentional disorder rather than a sensory loss. 2

Observable Behaviors

Patients with inattention demonstrate characteristic behaviors that reveal their lack of awareness:

• Donning clothing on only one arm 3
• Shaving only half of the face 3, 4
• Failing to notice food on half of the lunch tray 3, 4
• Fixed gaze deviation toward the side of the brain lesion 3
• Ignoring the contralateral side of body and environment 3

A critical feature is that patients do not realize they are failing to attend to one side of their world, creating significant safety concerns. 3

Subtypes of Inattention

Lateralized vs. Non-Lateralized Inattention

The literature distinguishes between two important patterns:

• Lateralized (contralesional) inattention: Spatial neglect specifically affecting the side opposite the lesion 5
• Non-lateralized (general) inattention: Diffuse attentional deficits affecting both sides of space 6, 5

Allocentric vs. Egocentric Subtypes

• Allocentric (object-centered) neglect: Inattention localized to the contralesional side of an object regardless of its position relative to the observer, associated with lesions to superior/inferior parietal cortices and superior/middle temporal gyri 7
• Egocentric (viewer-centered) neglect: Inattention localized to the contralesional side of the individual's midline, associated with lesions to precentral gyrus, middle frontal gyrus, insula, and putamen 7

Components of Attention Affected

Stroke can impair multiple attention domains beyond spatial neglect:

• Intensive attention components: Including tonic and phasic alertness, more impaired with right hemisphere lesions 8
• Selective attention: The ability to focus on relevant stimuli while ignoring distractors, can be impaired with either hemisphere damage 8
• Divided attention: The capacity to attend to multiple tasks simultaneously 1
• Sustained attention: Maintaining attention over time 1

Research demonstrates that 44.4% of stroke patients have impairments in both intensive and selective attention, while 31.8% have deficits only in selective tasks, with more than 80% showing deficits on at least one attention measure. 8

Hemispheric Lateralization

Right hemisphere damage produces more severe and frequent inattention than left hemisphere damage, particularly for intensive attention components. 1, 8 However, spatial attention deficits can occur after left hemisphere stroke and should not be overlooked. 9

The right hemisphere maintains awareness of the left side of body and environment, and houses the dorsal attention network critical for cognitive control. 4 When damaged, patients may even deny ownership of their left body parts (anosognosia), creating profound safety risks. 4

Clinical Assessment

The NIH Stroke Scale evaluates inattention in item 11 with specific scoring:

• 0 = No abnormality 3
• 1 = Visual, tactile, auditory, spatial, or personal inattention or extinction to bilateral simultaneous stimulation in one sensory modality 3
• 2 = Profound hemi-inattention or extinction to more than one modality 3

Standard clinical tests include cancellation tests (star, letter, line cancellation) and line bisection tests. 1, 7 Testing by trained professionals is necessary to distinguish neglect from visual field cuts, impaired attention, and planning or visuospatial deficits. 3

Clinical Significance

Unilateral spatial neglect has a substantial negative impact on functional ability and is a significant contributor to poor prognosis after stroke. 3 The condition significantly impairs the ability to participate effectively in rehabilitation. 1

Acute lateralized inattention is an important and independent predictor of functional dependency following right hemisphere damage. 5 Reading, writing, drawing, and mobility may all be negatively impacted. 3

Recovery Patterns

Many patients with mild neglect experience spontaneous improvement within weeks of onset, while those with profound neglect may improve over many months. 3 However, neglect symptoms continue to interfere with daily functioning long after stroke. 1, 2