Hemineglect is a neurological condition that affects a person’s attention and awareness, typically concerning one side of space or their own body. This condition means the brain struggles to process or respond to stimuli from a particular side, even if sensory organs like the eyes or ears are working properly. It is a complex disorder that highlights the intricate ways the brain manages our perception of the world around us.
The Nature of Hemineglect
Hemineglect, also known as unilateral spatial neglect, is a disorder of attention and awareness, not a primary sensory impairment. The brain fails to acknowledge or process information from one side of the environment or body, despite intact sensory pathways. Individuals may have healthy vision but not direct attention to the neglected side, failing to register sights, sounds, or touches from that area.
The condition commonly affects the side of space opposite to the brain injury, known as the contralesional side. For instance, damage to the right side of the brain often leads to neglect of the left side of space and the body. This occurs because the right hemisphere of the brain typically attends to both sides of space, while the left hemisphere primarily attends to the right side. Consequently, damage to the right hemisphere can result in a more pronounced and noticeable deficit, as the left hemisphere cannot fully compensate for the loss of attention to the left side.
Recognizing Hemineglect
Individuals with hemineglect exhibit a range of observable behaviors that reflect their reduced awareness of one side. They might only eat food from one half of a plate, leaving the other side untouched, or apply makeup or shave only one side of their face. When reading, they may overlook words or sentences on the neglected side of a page, and in drawing tasks, they often complete only one half of an object or disproportionately crowd details onto the non-neglected side.
The neglect can affect different spatial domains: personal, peripersonal, and extrapersonal space. Personal space refers to the body itself, where individuals might ignore a limb on their affected side, sometimes even denying ownership of it. Peripersonal space involves the area within arm’s reach, while extrapersonal space encompasses areas further away. For example, a person might bump into objects or doorframes on their neglected side while navigating their environment, or fail to notice people approaching from that direction.
Underlying Causes
Hemineglect typically arises from damage to specific areas of the brain that are responsible for attention and spatial processing. The most frequent cause is a stroke, particularly those affecting the right hemisphere. Damage to the right parietal lobe is commonly associated with hemineglect, but lesions in other regions, such as the frontal lobe, temporal lobe, or subcortical structures, can also lead to the condition.
Beyond stroke, traumatic brain injury (TBI) is another common cause of brain damage that can result in hemineglect. Brain tumors or certain neurodegenerative diseases, though less common, can also disrupt the neural networks involved in spatial awareness and attention, leading to similar symptoms.
Approaches to Diagnosis and Care
Diagnosis involves clinical observation of everyday behaviors and specific behavioral tasks. Standardized neuropsychological tests are also used to assess the presence and severity of neglect. These include cancellation tasks, where patients are asked to mark targets scattered across a page, and line bisection tests, where they must identify the midpoint of horizontal lines. Drawing tasks, like copying a complex figure or drawing a clock, can also reveal characteristic omissions on the neglected side. Neuroimaging techniques, such as MRI or CT scans, help identify the underlying brain damage.
Care for hemineglect primarily focuses on rehabilitation strategies aimed at improving awareness and attention to the neglected side. Visual scanning training is a common approach, encouraging patients to consciously direct their gaze and attention toward the affected space. Other techniques include limb activation, which involves moving the neglected limb to draw attention to that side, and prism adaptation, where special glasses shift the visual field to encourage compensatory eye and head movements. Environmental modifications, such as placing frequently used items or caregivers on the neglected side, also help encourage engagement with that space. A multidisciplinary team, including occupational, physical, and speech-language therapists, collaborates to improve daily functioning and safety.