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Development of a Visual Cueing System Using Immersive Virtual Reality for Object-Centered Neglect in Stroke Patients

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Unilateral spatial neglect (USN) is defined as failure to report, respond, or adjust to novel or meaningful stimuli presented to the side opposite a brain lesion. This symptom deteriorates the rehabilitation efficiency and hinders activities of daily living. USN is classified into 2 sub-categories: body-centered neglect and object-centered neglect. No optimal intervention has been proposed for treating object-centered neglect. Thus, we developed a visual cueing system using immersive virtual reality to improve object-centered neglect. A feasibility study showed 2 typical measurements for object-centered neglect tended to improve the symptom, these results provide preliminary evidence for designing successful rehabilitation programs using a visual cueing system in patients with object-centered neglect.
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Development of a visual cueing system using
immersive virtual reality for object-centered neglect
in stroke patients
Akinori Hagiwara
Graduate School of Creative
Science and Engineering
Waseda University
Tokyo, Japan
akinori-
hagiwara@iwata.mech.waseda.ac
.jp
Kazuhiro Yasuda
Research Institute for Science
and Engineering
Waseda University
Tokyo, Japan
kazuhiro-yasuda@aoni.waseda.jp
Kenta Saichi
Graduate School of Creative
Science and Engineering
Waseda University
Tokyo, Japan
k.saichi27@gmail.com
Daisuke Muroi
Department of Rehabilitaion
Kameda Medical Center
Chiba, Japan
mutyon88@hotmail.com
Shuntarou Kawaguchi
Department of Rehabilitaion
Sonoda Rehabilitation Hospital
Tokyo, Japan
taro_0128_0112@yahoo.co.jp
Masahiro Ohira
Department of Rehabilitation
Yokohama Shinmidori General
Hospital
Midori-ku Yokohamashi, Japan
theijapan@yahoo.co.jp
Tadamitsu Matsuda
Department of Physical Therapy,
Facluty of Social Work Studies
Josai International University
Chiba, Japan
funwavesurfgogo@yahoo.co.jp
Hiroyasu Iwata
Faculuty of Science and
Engineering
Waseda University
Tokyo, Japan
jubi@waseda.ac.jp
Abstract—Unilateral spatial neglect (USN) is defined as
failure to report, respond, or adjust to novel or meaningful
stimuli presented to the side opposite a brain lesion. This
symptom deteriorates the rehabilitation efficiency and hinders
activities of daily living. USN is classified into 2 sub-categories:
body-centered neglect and object-centered neglect. No optimal
intervention has been proposed for treating object-centered
neglect. Thus, we developed a visual cueing system using
immersive virtual reality to improve object-centered neglect. A
feasibility study showed 2 typical measurements for object-
centered neglect tended to improve the symptom, these results
provide preliminary evidence for designing successful
rehabilitation programs using a visual cueing system in patients
with object-centered neglect.
Keywords—Unilateral Spatial Neglect, Object-centered Neglect,
Visualized Cueing
I. INTRODUCTION
Unilateral spatial neglect (USN) is commonly defined as a
failure to report, respond, or adjust to stimuli that are presented
contralateral to a brain lesion [1]. Approximately 50% of
stroke patients suffer from USN, which impedes the activities
of daily living [2][3][4]. For example, individuals with USN
leave food on the neglected side of their plate and fail to look
to the opposite side of the street when crossing. These
symptoms strongly interfere with these patients’ ability to live
independent lives [5]. Thus, optimal intervention for USN is
crucial for stroke rehabilitation [6].
USN is classified into 2 sub-categories: body-centered
neglect and object-centered neglect [7][8]. In body-centered
neglect, the neglected side (mainly the left side) may refer to
the left of the body midline, whereas object-centered neglect is
defined as an omission or inattention to the contralesional side
of an individual object [9]. It is well known that damage to the
frontal-parietal lobe network causes body-centered neglect, and
the temporal-parietal lobe network corresponds to object-
centered neglect [9][10].
Various rehabilitation interventions have been explored for
USN treatment. Proposals for the treatment of body-centered
neglect include visual search task, prism adaptation, limb
activation, and optokinetic stimulation [11][12]. Further, we
recently developed a first-person view in an immersive VR
environment with a head-mounted display (HMD) to develop a
tractable USN rehabilitation system that allows training in 3D
virtual environments in both near and far space [13]. However,
these interventions are not intended to treat object-centered
neglect [14]. Thus, we proposed a visual cueing system using
immersive virtual reality for object-centered neglect in stroke
patients to explore its applicability for future clinical use.
Moreover, we examined the validity and feasibility of the
proposed device through a case series of stroke patients with
object-centered neglect.
II. SYSTEM OVERVIEW
Our system consists of an HMD (Oculus Rift CV1, Oculus
VR., Inc.) and a personal computer as shown in Fig. 1. We
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2018 IEEE International Conference on Systems, Man, and Cybernetics
2577-1655/18/$31.00 ©2018 IEEE
DOI 10.1109/SMC.2018.00182
developed a VR environment using Unity software (Unity
Technologies). In this system, a tracking sensor acquires
information on the patient’s head position and the head
rotation is reflected in the VR environment. Patients with
object-centered neglect are not able to recognize the
contralesional side of an individual object [9].
Figure 1. System overview
Thus, this system displays clue stimulation in the VR
environment to guide the patient’s attention to the neglected
side of the target object. In this way, the patient is able to
recognize the neglected side of the target object. Furthermore,
this system shuts down the surrounding stimuli (i.e., other
stimulus around the target) through blackout in the VR
environment.
A. Visual cueing system
The VR system displays clue stimulation to guide the
patient’s attention to the neglected side and shuts down (i.e.,
blackout) the visual stimuli around the target object to induce
passive (inactive) attention as shown in Fig. 2. It has been
reported that damage to the ventral posterior temporal lobe,
which is the ventral pathway of visual information processing,
causes object-centered neglect [15]. In general, the ventral
stream is responsible for passive attention [15]. Accordingly,
we used red color clues and flashes to induce passive attention.
Moreover, the blackout prevented the patient from removing
attention from the clue.
In the VR intervention, the therapist operates the system with
a series of 4 actions, which are as follows: 1) display the clue
stimulation, 2) blackout the surrounding environment, 3)
move the clue stimulation, and 4) remove the blackout (Fig.
2). With these 4 actions, the system draws the patient’s
attention to the neglected side of the object (green panel).
After the 4 actions, the therapist asks the patient to read the 4-
digit number on the green panel.
Figure 2. Visual cueing in immersive VR
III. THE
CLINICAL
TRIAL
The clinical trial (case series with 4 patients) was
performed to examine the validity and feasibility of the system.
The Waseda University Ethics Committee approved all the
procedures in this study.
A. Target
Four patients with stroke (mean age: 64.0 ± 11.2 years)
were included in the study. Patients had to satisfy the following
criteria: a) a symptom of object-centered neglect, b) the ability
to communicate well and sufficiently understand instructions
provided by the researcher, and c) no other medical conditions
that could interfere with the performance on tests for visual
neglect and trial design.
B. Research design
The entire procedure was conducted at a
rehabilitation center using a pre-post design. Prior to the
intervention, patients underwent specific tests for neglect. In
the VR intervention, patients wore the HMD while in the
sitting position, and the clue stimulation was used to direct the
patient’s attention to the neglected side of the target object
(i.e., 4 actions with the VR system described in the visual
cueing system). Patients repeated the 4 actions a total of 10
times. After the intervention, patients performed the specific
test for neglect that was identical to the pre-test.
C. Evaluation and variable
Variables: The following conventional variables were used
to describe the patient’s degree of neglect: a) the Apples Test
[16], which is a cancellation task, in which outline drawings of
150 apples are shown pseudorandomly scattered over an A4
paper sheet presented in landscape orientation, wherein one-
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third of the apples are full (targets) and two-thirds are open on
either the left or the right side (Fig. 3); b) the Line Bisection
Test of the Behavioral Inattention Test (BIT) [17][18], in
which patients are asked to mark the center of 3 horizontal
lines placed on the right, center, and left of an A4 sheet and
deviation from the true center is measured (Fig. 4). In general,
tests a and b were used to evaluate object-centered neglect.
Patients performed these 2 tests in far space to examine the
neglect symptoms in far spaceFrom ecological perspective,
we were interested in testing any change in test performance
related to far space (i.e., no paper and pencil test). In the Far
Space Test, the measurement test was projected on the wall,
and patients used a pointer to check the stimuli in the test [13].
Figure 3. Apples test
Figure 4. Line Bisection task
Analysis: To examine the difference between the pre- and
post-test, we calculated the ratios from the values of each
measurement at the pre- and post-test including: a). X1 is the
number of checked apples those has no clack. X2 is the number
of checked apples those has a clack on the neglect side. neglect
severity on the Apples Test as the error ratio is E, which is
calculated by
Ε=Χ2/(Χ1+Χ2) ίίί(1)
; b) neglect severity on the Line Bisection Test as the
percent deviation by the ratio of the length between the
checked position and the neglect end of the line to the length of
the line.
D. Results
The calculated ratios of each test are shown in Fig. 5 and 6. As
shown in Fig. 5, 3 of 4 patients showed reduced error ratio on
the Apples Test. The percent deviation in the Line Bisection
Test for all of the patients tended to be reduced (Fig. 6).
Figure 5. Error ratio on the Apples Test
Figure 6. Percent deviation on the Line Bisection Test
IV. DISCUSSIO N
Following the intervention, the error ratio decreased in 3 of
4 patients on the Apples Test, and there was a tendency for the
check position to be moved to the neglected side in all 4
patients. Given that these 2 typical measurements for object-
centered neglect tended to improve the symptom, these results
provide preliminary evidence for designing successful
rehabilitation programs using a visual cueing system in
patients with object-centered neglect. Although the underlying
mechanisms are still unknown, the activation of passive
attention (ventral pathway) using optimal visual stimuli in the
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immersive VR environment may be involved.
This feasibility study was conducted using only 4 stroke
patients. Furthermore, we only investigated the immediate
effect of the visual cueing system. Thus, long-term intervention
studies including larger samples are required to further
examine the therapeutic efficacy of this proposed system in
stroke patients.
V. CONCLUSION
We introduced a visual cueing system using immersive VR
to direct the patient’s attention to the neglected side of the
target object. Our feasibility study revealed that object-
centered neglect tended to improve immediately following the
intervention; thus, these results provide preliminary
knowledge for designing successful rehabilitation programs
for patients with object-centered neglect.
ACKNOWLEDGMENT
This work was supported by the Grant-in-Aid for Junior
Researchers, Research Institute for Science and Engineering,
Waseda University [Technological Research Section: 17C13]
and Global Robot Academia Institute, Waseda University
[FY2017]. The authors are grateful to the patient in our
experiment.
NOTE
Akinori Hagiwara and Kazuhiro Yasuda contributed
equally to this paper.
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... A total of 33 full-text articles were examined. As 23 studies were excluded during full-text check, 10 articles [20,[24][25][26][27][28][29][30][31][32] were considered eligible for the systematic review. Flow-chart of studies screening is available in Figure 1. ...
... Two studies used a virtual version of the line bisection test as intervention protocol [27,28]. In six studies, the intervention protocol was composed of more than one task/action [25,26,28,29,31,32]. Three studies made use of an IVR program [20,24,30]. ...
... These exercises aim to guide the patient's attention to the neglected side of the target object. The different systems turn off the surrounding stimuli (i.e., other stimuli around the target) through the blackout in the VR environment, as shown in the study by Hagiwara et al. [29]. Session frequency and duration were different in almost all of the studies; only two studies [24,32] had the same duration of the session (one hour), but their protocols were different. ...
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