Gait Differences in Angelman Children May Be Used to Assess Disease, Study Suggests

Specific differences in the gait of children with Angelman syndrome may be used as a tool for disease assessment and to evaluate the effects of experimental treatments, according to a recent study.

The study, “Identification of spatiotemporal gait parameters and pressure-related characteristics in children with Angelman syndrome: A pilot study,” was published in the Journal of Applied Research in Intellectual Disabilities.

Angelman syndrome is a genetic disorder that primarily affects the nervous system, causing intellectual impairments, developmental delays, and motor disabilities.

More than 95 percent of Angelman patients develop motor symptoms including movement and balance disorders, specifically ataxia, or lack of muscle coordination, and unsteady and jerky movement of limbs.

Although these motor disabilities have been described in previous research, the gait patterns of patients with Angelman have not been studied in detail. According to researchers, there is an urgent need to identify a method that accurately measures motor disability and can determine treatment benefits for pharmacological or behavioral interventions in Angelman patients.

To look at this, University of South Florida researchers designed a protocol to measure walking parameters that could be used to quantify motor disability in Angelman children.

They set up a pilot study to compare specific gait parameters between a small group of children with Angelman and healthy children; the final objective was to identify the most useful criteria to measure gait impairments in Angelman patients, which could be used to track disease progression or evaluate the effects of experimental therapies in clinical trials.

The study included six children diagnosed with Angelman, between 6 and 9 years old, and two control groups: 44 children between 6 and 9 years old and 20 children between 4 and 5 years old. This last control group served as a comparison to determine if gait in Angelman children is more similar to that of younger children. Data from control groups was retrieved from an already published study.

To measure gait, children were allowed to walked back and forth at spontaneous speeds over an instrumented walkway connected with sensors that measured several gait parameters.

Seven spatiotemporal parameters were analyzed: gait speed, cadence, step length, walk ratio (step length over cadence), stride width, and single and double support percentages — the proportion of time when the body weight is supported by one or both legs, respectively.

The technology also enabled measurements of the center of pressure during walking, and symmetry and stability of gait.

At least 40 steps were recorded for each child.

Analysis revealed significant differences in all gait parameters except walk ratio between children with Angelman and healthy children of the same age.

While walking, Angelman patients had a shorter step length, decreased cadence with consequently lower speed, less time spent on one leg, and more time spent on two legs.

Gait variability index (GVI) — a composite measure that has been proposed for the evaluation of child development — was significantly lower in children with Angelman, indicating higher variability during walking in these patients.

When patients were compared with the younger control group, all spatiotemporal parameters remained altered, except step length. Analysis of pressure-related measurements revealed a significantly less regular and less efficient walking pattern in Angelman children, even when compared with the younger control group.

Comparing Angelman children with younger healthy controls revealed that the delay in acquisition and maturation observed in these patients influences, but is not the main contributor, of gait impairment.

“[T]hese pilot data suggest using the electronic walkway in the Angelman patient population is not only feasible but also may be a valuable tool to assess change in gait after a therapeutic has been administered,” the researchers wrote.

According to the team, this method has the potential to quantify gait parameters and function, as well as determine differences between Angelman patients and healthy individuals.