A maior rede de estudos do Brasil

Grátis
7 pág.
8. Effect of concurrent cognitive tasks on gait features among children post-severe traumatic brain injury and typically-developed controls

Pré-visualização | Página 2 de 4

child’s parent were present
during testing.
All temporal and spatial gait parameters were
calculated utilizing the software of the Gaitrite
system using pre-programmed definitions, calcula-
tions and data from the three cycles. Parameters
analysed included walking velocity, step length and
step length variability, step time and step time
variability [16]. Any partial footfalls that did not
have a clearly defined beginning and ending or were
in contact with the edge of the mat were edited out.
Gait variability was expressed as the coefficient of
variation (CV) which is SD/mean �100.
Procedure
After a rest period the children were asked to walk at
their regular pace on the Gaitrite, three cycles for
each one of the trials: regular walking followed by
performing the two different cognitive tasks—the
first was to memorize and recall three random
numbers one digit each and the second was to
identify simple auditory sounds.
In a pre-test period children with post-severe TBI
were assessed for their ability to memorize and recall
three numbers consecutively. It was noticed that the
582 M. Katz-Leurer et al.
children could perform the assignment correctly and
sequentially only with one digit numbers. So for this
study, the children were asked to recall three random
numbers of one digit each. In addition, in a pre-test
period children with post-severe TBI were asked to
identify different sounds. The sounds chosen were
clear and simple as commonly experienced by
children (such as dog barking, doorbell ringing)
and included a total of 15 sounds that the children
could identify without mistakes.
After three walking cycles with no concurrent task,
the children were asked to remember the numbers
presented to them and to repeat the numbers over
and over in exactly the same order. All the children
could perform the task with no mistakes. Then the
children were asked to walk while repeating the
numbers. Correct and incorrect repetitions of num-
bers were counted and the incorrect repetitions out
of the total number were recorded. In the second
cognitive task the sounds were first projected
through a speaker at the far end of the walkway.
All of the sounds were less than 2 seconds in
duration and the children were asked to identify each
as quickly as possible by naming the sound out loud.
Then the children were asked to walk while listening
and identifying each sound as quickly as possible.
The number of sounds that each child identified
incorrectly out of the total of 15 possible sounds was
recorded.
Statistical analysis
A preliminary paired t-test was used to assess
differences in gait parameters between legs. No
significant differences were noted; therefore, the
mean value of both legs is presented. The normality
of the parameters’ distribution was verified using the
Kolmagirove Smirnove test. The values of gait
velocity, step time, step length and step time and
length variability were summarized using means and
standard deviations.
To assess differences between groups in the
fulfilling of the cognitive assignment—number of
cycles achieved in each task, a t-test was performed.
To evaluate any different effect of the task on
performance quality, a mixed ANOVA model was
performed. The between-subject factor is the group
factor (TBI vs TD), the within-subject factor is
the two cognitive tasks and the interaction term
(group� task) and the dependent variable was the
percentage error in each assignment. For assessing
any differences between the three walking conditions
without and with concurrent tasks, a mixed ANOVA
model was applied when the dependent variable was
the gait parameter. A separate model was built for
each parameter. The between-subject factor is the
group factor (TBI vs TD), within subject factor
(without and with the first and the second concur-
rent tasks) and the interaction term (group� task).
A p-value< 0.05 was considered statistically signif-
icant. All statistical analyses were performed using
SPSS v. 17 software packages.
Results
Cognitive tasks–percentage error
Both groups exhibited significantly higher mistakes
in the sound recognition assignment. The mean
percentage errors between the two cognitive tasks
was significantly different between groups; by mean,
children post-severe TBI have 31.9% more mistakes
compared to the controls (F(1: 28)¼29.6, p<0.01);
23%�5% more mistakes at the memorization
assignment (mean of 24.5% among children
post-TBI vs 1.5% among the controls) and
39%�6% more at the sound recognition assign-
ment as compared to the TD group (mean of 46.3%
among children post-TBI vs 6.7% among the con-
trols) there was a significant group*assignment
interaction effect (F(1: 28)¼ 9.45, p< 0.01), as chil-
dren post-TBI exhibited larger differences between
assignments (TBI; 20%�16%, TD 5%�7%)
(Table I).
Baseline differences between groups
Gait parameters during all three gait conditions are
presented in Table II. In the regular walking test,
only the step length was significantly different
between groups; children with post-severe TBI
walked with a smaller step length as compared with
TD controls (mean of 59.1� 10.1 cm vs
66.1�6.1 cm, respectively, t28¼ 2.34. p¼ 0.02).
Gait parameters during cognitive assignments
In the repeated model, significant differences were
noted between groups in all assessed gait parameters.
Children post-TBI exhibit significant slower gait
velocity, significant shorter step length and signifi-
cantly larger step length and step time variability.
Table I. Number of cycles and percentage of errors in task
performance by groups.
Task
Numbers Sounds
TBI TD TBI TD
No. of cycles 11.0� 4.3 16.6� 2.6 17.6� 2.6 14.7�2.0
% of error 24.5� 22.9 1.5� 3.2 46.3� 22.9 6.7�5.3
Values are mean�SD.
Effect of concurrent cognitive tasks on gait 583
There were significant differences in gait param-
eters between assignments in both groups.
Gait velocity
Gait velocity was significantly different between
trials (F2;50¼38.1, p< 0.01). After bonferroni
adjustment for multiple compression it was noted
that walking velocity was significantly faster at usual
walking and it decreased by a mean of
23.8� 3.9 cm s�1 at the number assignment (mem-
orization) and by 37.0�5.1 cm s�1 at the sound
(auditory) assignment. In addition, a significant
difference was noted between dual task conditions;
during the sound assignment children walked signif-
icantly slower as compared to the walking velocity
during the number assignment (by a mean of
13.1� 3.7 cm s�1, p< 0.01). Additionally, there
was a significant group-assignment interaction
effect; gait velocity decreased for both groups in
the dual task conditions, but significantly more
among children post-TBI. In the number assign-
ment, gait velocity decreased by 36.5� 6.9 cm s�1
among children post-TBI as compared to
8.3� 3.6 cm s�1 among TD children (p< 0.01).
In the sound assignment walking velocity decreased
by 48.7� 7.9 cm s�1 among children post-TBI as
compared to 25.3� 6.5 cm s�1 among TD children
(p¼0.03).
Step time
Step time was significantly different between trials
(F2;50¼ 23.42, p<0.01). Mean step time was sig-
nificantly increased in the dual task conditions as
compared to baseline; it increased by a mean of
0.10� 0.02 seconds in the number assignment and
by 0.10� 0.01 seconds in the sound assignment. No
significant difference was noted between dual task
conditions. A significant group-assignment interac-
tion effect was noted also for the step time param-
eters. Step time increased during dual task
conditions in both groups but significantly more
among children post TBI. In the number assign-
ment, step time increased among children post-TBI
by 0.17�0.15 seconds as compared to 0.03� 0.04
seconds among TD children (p< 0.01). In the sound
assignment, step time increased by 0.16� 0.10
seconds among children