Children with cerebral palsy (CP) caused by stroke and affecting one side of the body may have difficulties in activities involving both limbs — such as hitting a target with their hands — due to motor problems combined with visuospatial attention deficits, a study suggests.
Rehabilitation programs for children with this type of CP should incorporate visuospatial attention, as should clinical and research assessments, the researchers said.
The study, “Assessment of bilateral motor skills and visuospatial attention in children with perinatal stroke using a robotic object hitting task,” was published in the Journal of Neuroengineering and Rehabilitation.
Hemiparetic, or unilateral, cerebral palsy is characterized by motor problems in only one side of the body. However, prior studies indicate that children with this form of CP can also have problems in the less affected limb, and thus have impairments on both sides.
A number of neurological deficits may explain this, including deviations in visuospatial abilities, a set of skills necessary for many daily tasks involving rapid or complex activities, such as sports or driving.
Visuospatial attention is the way someone pays attention to relevant cues from the external world while ignoring irrelevant one. It involves the processes of alerting, orienting, and execution.
Children with either right or left brain lesions may have problems with visuospatial attention, but the position and type of injury involved seems to influence the frequency and severity of those deficits.
Visuospatial attention can be altered by stroke, which can affect body movements and balance. However, the interplay between motor and visuospatial deficits in children with stroke-induced hemiparetic CP is not well understood.
Researchers at the University of Calgary in Alberta, Canada, conducted a study to assess the relationship, employing a robot-aided test that enabled investigators to monitor patients’ sensorimotor control and visuospatial skills.
During the exercise — a robotic object hitting task — participants use virtual paddles on both hands to hit virtual balls that fall with increasing speed and frequency. Good performance on the task, as measured by hitting as many balls as possible, means the participant has good integration of visuospatial attention and motor skills.
The study looked at 49 children with hemiparetic CP caused by stroke (28 due to perinatal arterial ischemic stroke and 21 due to periventricular venous infarct) and 155 typically developing children. The mean age in each group was 12.
The children performed the hitting exercise on the Kinarm Exoskeleton Robot, a device that allows precise monitoring of horizontal arm movements. They sat on a wheelchair base, and a display provided augmented reality to perform the task.
Several parameters were measured, including the number of balls hit with each hand, movement speed and area, biases between hands, and spatial biases.
Researchers then matched success on the task with motor performance, including hand speed and movement, and performance on a visually guided reaching task.
They found that most CP patients hit fewer targets with the affected hand than their typically developing peers. Those who had perinatal arterial ischemic strokes (AIS) had more difficulty than children whose disease was caused by periventricular venous infarct (PVI).
Comparing the two groups, 86% of AIS and 57% of PVI patients hit fewer targets with the affected hand, compared with healthy children.
The results support previous research suggesting that the type of brain lesion impacts the severity of visuospatial deficits, “with AIS having more severe and widespread impairments compared to PVI,” the researchers said.
But patients also had trouble in the unaffected arm — 43% of AIS and 14% of PVI patients hit fewer balls with the unaffected hand — confirming that hemiparetic CP may involve bilateral deficits.
Despite the deficits in visuospatial attention, few patients had motor problems in their hands. Only 18% of children had slow hand speed or curtailed movement area.
The researchers found that difficulty in detecting or responding to visual cues coming from one side (opposite to the brain lesion) — a failure termed unilateral visual neglect, and scored by the Behavioral Inattention Test — accounted for 21%-32% of the unaffected hand’s performance.
Deficits in visuospatial attention were likely the cause of the problems seen in the less affected arm, researchers said, although an alternate explanation could be that children may also tend to pay more attention to the affected arm and disregard the other.
“Our findings are important to rehabilitation of children with HCP, as typical clinical assessments do not have significant visuospatial attention demands, despite the importance of visuospatial attention on real-world tasks,” the researchers wrote.
“As visuospatial attention impacts motor skills bilaterally, we recommend incorporating assessments of visuospatial attention, such as the Behavioral Inattention Test, into clinical and research assessments, though we acknowledge this assessment has limitations. We also suggest that rehabilitation programs for children with HCP [hemiparetic cerebral palsy] should incorporate visuospatial attention, ” they said.
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