CLINICAL COMMENTARY

Commentary on virtual reality in stroke rehabilitation: Still morevirtual than real

PATRICE L. (TAMAR) WEISS1 & HAIM RING2

1Laboratory for Innovations in Rehabilitation Technology, Department of Occupational Therapy, University of Haifa, Haifa,

Israel, and 2Neurological Rehabilitation Department C, Loewenstein Rehabilitation Center, Sackler Faculty of Medicine,

Tel Aviv University, Ramat Aviv, Israel

Accepted August 2006

In the article ‘Virtual reality in stroke rehabilita-

tion: Still more virtual than real’, Crosbie et al. [1]

aimed to assess the effectiveness of virtual reality in

stroke rehabilitation. Their two-stage methodology

first entailed the identification of studies listed in

the major electronic databases with search terms

that included specific keywords (virtual reality

(VR), rehabilitation, stroke, physiotherapy/physical

therapy and hemiplegia) and met certain inclusion

criteria (intervention using VR, stroke population,

impairment or activity level outcomes, written in

English). The second stage involved assessment of

the quality of each study using a grading system

developed by the American Academy for Cerebral

Palsy and Developmental Medicine (AACPDM).

Their search and inclusion criteria identified 11

studies which examined the use of VR for

rehabilitation of the upper or lower limbs, gait

and balance problems, or cognitive intervention.

The authors concluded that although the results of

these studies support the use of VR for rehabilita-

tion intervention, limitations in study design

preclude any definitive conclusions regarding the

clinical benefit of these technologies.

The motivation underlying systematic analyses of

the literature in order to objectively appraise a given

field of study is certainly to be lauded, and the

interest in demonstrating the effectiveness of using

VR as an assessment and intervention tool in neuro-

rehabilitation is both understandable and important.

However, it is necessary to view the conclusions

of any such analysis within the context of the

discipline’s maturity as a field of study. VR-based

rehabilitation is a young, interdisciplinary field that

has unmistakably experienced the double peril of the

Gartner Group’s (www4.gartner.com) Technology

Hype Cycle as described by Rizzo and Buckwalter

[2] and Rizzo [3]. It first ascended the ‘Peak of

Inflated Expectations’ when the media (and some

researchers) over-rated the technology’s potential

applications. It then plummeted into the ‘Trough of

Disillusionment’ when some therapists became fru-

strated by the lack of inexpensive, clinically relevant,

and readily available applications. VR-based rehabi-

litation is now progressing along the Hype Cycle

towards the ‘Slope of Enlightenment’ and, in some

clinical applications, has even reached the ‘Plateau of

Productivity’ where VR’s assets are widely demon-

strated and accepted [4]. Nevertheless, the VR

literature base for stroke rehabilitation remains small

and limited.

The question is what is the best way to assess

whether virtual reality is effective for stroke rehabi-

litation? Has the published research base of VR-

based stroke rehabilitation reached a critical mass

wherein systematic analyses of the type presented by

McDonough et al. [1] are warranted? Are the results

of their analysis better able to guide researchers and

clinicians than publications such as the recent

reviews by Holden [5], Sveistrup [6], and Weiss

et al. [7]?

In his appraisal of the advantages and disadvan-

tages of meta-analyses, Field [8] described the limi-

tations inherent in conventional literature reviews.

Correspondence: P. L. (Tamar) Weiss, Ph.D, Laboratory for Innovations in Rehabilitation Technology, Department of Occupational Therapy, University of

Haifa, Haifa, Israel. E-mail: tamar@research.haifa.ac.il

Disability and Rehabilitation, July 2007; 29(14): 1147 – 1149

ISSN 0963-8288 print/ISSN 1464-5165 online ª 2007 Informa UK Ltd.

DOI: 10.1080/09638280600965759

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When writing a traditional literature review, an

expert in a given discipline subjectively selects and

evaluates the major research findings in that area.

This ‘top-down’ approach makes for reviews of the

literature that are often highly informative. However,

they are very much dependent upon the knowledge,

experience and credibility of the expert author. The

author may be biased concerning the relative

importance of specific aspects of a topic or may be

uninformed about key sources. These limitations

inspired researchers such as Glass [9] and Rosenthal

and Rubin [10] to develop statistical techniques to

objectively arrive at conclusions taking into account

results from a series of independent studies (e.g., the

Cochrane reviews, the AACPDM’s grading system).

However, the meta-analysis approach for systema-

tic review also has limitations, particularly when

applied to young disciplines with few, and often

disparate study designs [8]. VR-based rehabilitation

is, indeed, a young discipline. The first publications,

dated from the mid-1990s, appeared in conference

proceedings and a wide variety of both popular and

peer-reviewed journals. Several pioneering venues

provided forums for the presentation of the earliest

studies including the special VR sessions at the

annual conference run by the Center on Disabilities,

at California State University, Northridge (CSUN)

(http://www.csun.edu/cod/conf/index.htm), the spe-

cial sessions on mental health at Medicine Meets

Virtual Reality (MMVR) (http://www.nextmed.com/

mmvr_virtual_reality.html), the first European Con-

ference on Disability, Virtual Reality and Asso-

ciated Technology (ECDVRAT) (http://www.icdvrat.

reading.ac.uk/1996/index.htm) and the early IEEE

VR conferences (VRAIS). Most of these conferences

have flourished in recent years, often to greatly

expanded audiences. For example, ECDVRAT

has now become the International Conference on

Disability, Virtual Reality and Associated Tech-

nology (http://www.icdvrat.reading.ac.uk/home.htm)

and the special mental health session at MMVR has

become the annual CyberTherapy conference (http://

www.interactivemediainstitute.com/conference2006/

index.htm). Moreover, relatively new conferences

have created additional opportunities to present study

results (e.g., the International Workshop on Virtual

Reality (www.iwvr.org).

In addition to specialized conferences, journal

publications such as CyberPsychology & Behavior and

Disability & Rehabilitation encourage the dissemina-

tion of VR clinical studies. Of equal importance is

the recognition of and support for large scale studies

by national agencies. For example, the Canadian

Stroke Network ‘Evidence-based Review of Stroke

Rehabilitation’ suggests that VR training, together

with conventional, real-world therapy, may improve

functional and motor outcomes for upper limb

rehabilitation in stroke. They base this remark on

preliminary evidence from small case studies and

encourage researchers to carry out clinical trials.

The focus of the early VR studies was clearly (and

necessarily) on the development of novel applications

and the demonstration of system feasibility on small

numbers of participants belonging to a variety of

populations. Given the rapid development of VR

technologies, development work will continue to be

an essential contribution to the literature. For

example, Fung et al. [11] and Subramanian [12]

have recently described novel paradigms for immer-

sive and interactive experimental protocols devel-

oped in virtual reality using Motek, Inc.’s CAREN

system for gait training post-stroke [11] and rehabi-

litation of the upper limb after stroke [12].

However, in the 2000s, the emphasis of research

has shifted to also include clinical intervention

studies with larger samples sizes. For example, You

et al. [13] studied the effects of a 4-week VR-based

intervention (60 min per day, 5 days per week) on 10

patients with chronic stroke. They used game

environments provided via GestureTek’s IREX

video capture system and showed that VR could

induce cortical reorganization as demonstrated via

fMRI. New studies are published on a regular basis

and these provide a growing body of evidence in

support of VR-based rehabilitation, e.g., our own

recent papers on applications of virtual environ-

ments for patients with unilateral neglect [14] and

spinal cord injury [15]. The papers reviewed by

Crosbie et al. [1] represent only part of the published

and not-yet-published research that has studied the

effectiveness of VR for stroke rehabilitation. Their

inclusion of key papers presented at recent confer-

ences would have provided a more balanced picture

of the state-of-the-art. However, the real problem is

that their study is premature since considerably more

research is needed to conclusively demonstrate VR’s

potential for stroke rehabilitation. Postponement of

their analysis by one to 2 years would result in a

much meaningful assessment of VR’s effectiveness

for this population.

We contend that the authors’ ‘bottom line’,

namely that ‘VR is a potentially exciting tool for

stroke rehabilitation but its evidence base is too

limited by design and power issues to permit a

definitive assessment of its value’ was a foregone

conclusion. Systematic, objective reviews of VR-

based rehabilitation for stroke must wait for another

few years until the controlled clinical trials currently

underway have reached publication and are cited in

accepted electronic databases. In the meantime, the

clinical and research community should maintain a

cautious optimism and endeavor to carry out and

publish well designed and implemented research

studies.

1148 P. L. Weiss & H. Ring

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References

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Commentary on VR in stroke rehabilitation 1149

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