information technologies in medicine, vol ii

The Use of Virtual Reality Technology in the Treatment of Anxiety Disorders 3.. Wiederhold gives theuse of virtual reality technologies for the treatment of many anxiety disordersincludi

JOHN WILEY & SONS, INC.

New York . Chichester . Weinheim . Brisbane . Singapore . Toronto

all instances where John Wiley & Sons, Inc., is aware of a claim, the product names appear in initial capital or all capital letters Readers, however, should contact the appropriate companies for more complete information regarding trademarks and registration.

Copyright ( 2001 by John Wiley & Sons, Inc All rights reserved.

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic or mechanical, including uploading, downloading, printing, decompiling, recording or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the Publisher Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158-0012, (212) 850-6011, fax (212) 850-6008, E-Mail: PERMREQ@WILEY.COM.

This publication is designed to provide accurate and authoritative information in regard to the subject matter covered It is sold with the understanding that the publisher is not engaged in rendering professional services If professional advice or other expert assistance is required, the services of a competent professional person should be sought.

ISBN 0-471-20645-8

This title is also available in print as ISBN 0-471-41492-1.

For more information about Wiley products, visit our website at www.Wiley.com.

Luciano Beolchi, European Commission DGXIII-C4, O½ce BU29-3/68, Rue

de la Loi 200 B-1049, Brussels, Belgium

luciano.beolchi@BXL.DB13.cec.be

Alberto Bianchi, LBHL, 50A-1148, 1 Cyclotron Road, University of nia, Berkeley, CA 94720

Califor-asarti@math.lbl.gov

Curtis Boswell, Jet Propulsion Laboratory, California Institute of Technology,

4800 Oak Grove Drive, Pasadena, CA 91109

Hari Das, Jet Propulsion Laboratory, California Institute of Technology, 4800Oak Grove Drive, Pasadena, CA 91109

Mark Draper, Human Interface Technology Laboratory, Box 352142, versity of Washington, Seattle, WA 98195-2142

Uni-Thomas A Furness, III, Human Interface Technology Laboratory, Box 352142,University of Washington, Seattle, WA 98195-2142

Roberto Gori, LBHL, 50A-1148, 1 Cyclotron Road, University of California,Berkeley, CA 94720

Zsolt Lorant, 9904 Carlyle Way W Apt.a446, Mobile, AL 36609

Claudio Marchetti, LBHL, 50A-1148, 1 Cyclotron Road, University of fornia, Berkeley, CA 94720

Cali-asarti@math.lbl.gov

v

Katsunobu Muroi, Mitsubishi Electric Corporation, Tsukaguchi-Honmachi,Amagasaki, Hyogo, JAPAN

Tim Ohm, Jet Propulsion Laboratory, California Institute of Technology, 4800Oak Grove Drive, Pasadena, CA 91109

Mieko Ohsuga, Mitsubishi Electric Corporation, Tsukaguchi-Honmachi,Amagasaki, Hyogo, JAPAN

Guiseppe Riva, Instituto Auxologico Italiano, Applied Technology for Psychology, Verbania, Italy

Neuro-Guillermo Rodriguez, Jet Propulsion Laboratory, California Institute of nology, 4800 Oak Grove Drive, Pasadena, CA 91109

Tech-Alessandro Sarti, LBHL, 50A-1148, 1 Cyclotron Road, University of nia, Berkeley, CA 94720

Califor-asarti@math.lbl.gov

Rob Steele, Jet Propulsion Laboratory, California Institute of Technology,

4800 Oak Grove Drive, Pasadena, CA 91109

Robert John Stone, Virtual Presence Ltd., Chester House, 79 Dane Road, Sale,Cheshire, M33 7BP UK

r.stone@vrsolns.co.uk

Erik Viirre, 3081Nute Way, San Diego, CA 92117

Jihong Wang, Department of Radiology, University of Texas SouthwesternMedical School, Dallas, TX 75235-9071

PREFACE ix

1 Neuro/Orthopedic Rehabilitation and Disability Solutions Using

Virtual Reality Technology

2 The Use of Virtual Reality Technology in the Treatment of

Anxiety Disorders

3 Virtual Reality for Health Care

4 Robot-Assisted Microsurgery Development at JPL

Hari Das, Tim Ohm, Curtis Boswell, Rob Steele, and Guillermo Rodriguez 85

5 Virtual Reality and the Vestibular System: A Brief Review

Erik Viirre, Zsolt Lorant, Mark Draper, and Thomas A Furness, III 101

6 Computer Imagery and Multimedia Techniques for Supporting

Telemedicine Diagnoses

7 Implementing a Picture-Achieving and Communication System

(PACS) and Teleradiology System: Practical Issues and

Considerations

8 From Engineering to Surgery: The Harsh Realities of Virtual Reality

vii

9 Maxillofacial Virtual Surgery from 3-D CT Images

Alessandro Sarti, Roberto Gori, Alberto Bianchi, Claudio Marchetti, and

For many patients, the real world is too risky or disconcerting for them to movearound in The agoraphobic patient has a fear of open or public places and somay become housebound The psychiatric technique of desensitization has been

in use for a number of years The patient is asked to imagine the things thatare most disturbing and gradually their fears are controlled Now a virtualenvironment can be created for treatment of these patients They can graduallyexperience their feared objects in a manner with complete control Similarly,people who need rehabilitation from weakness or loss of body function orcontrol can have a custom environment created for them that will represent anappropriate challenge to help them recover

Delivery of medical care has be progressively hampered by the lack of ability

to provide specialized information uniformly to all people Specialists tend to

be located in university, urban centers that are distant from many patientsand their primary care physicians With the explosion of understanding ofmany diseases, the primary care physician will need more and more access toagents able to understand and synthesize information about patients

Beyond telemedicine, telesurgery has been touted as a means of getting geon to a remote location and allowing him to operate on his patient Sincethere are many surgeons, this application of telepresence will only be useful inplaces that doctors are not willing to go, such as the battle®eld However, thereare remote locations that no surgeon is currently able to go; microscopic sitesinside the body Surgeons now manipulate blood vessels inside the eye or bones

sur-in the middle ear However, at current size, even when viewed through the bestmicroscope, the VRT can also be used in the areas of physical disabilities Vir-tual environments can be created for the treatment of the patients with themotor disturbances such as parases The speech disabilities can be assisted bysimply using the data gloves which translate the gestures into spoken words

In this volume, we will discuss the use of information technologies in in therehabilitation, treatment of physical disabilities in details and the delivery ofhealth care using the information technologies

The ®rst chapter by W J Greenleaf summarizes the current status of thevirtual reality technologies and discusses the use of these technologies in neuro/orthopedic rehabilitation as well as the new systems under development.The second chapter by B K Wiederhold and M D Wiederhold gives theuse of virtual reality technologies for the treatment of many anxiety disordersincluding fear of heights, ¯ying, spiders, driving, social phobia, and the possi-

ix

bility of using these technologies for the treatment of acute stress disorders andgeneralized anxiety disorders.

The third chapter by L Beolchi and G Riva gives an indepth summary ofvirtual reality technologoies and their applications in health care as well as thehealt care market analysis

The fourth chapter by Das et al presents the recenty developed RAM robot system and its demonstration of a simulated microsurgery procedureperformed at the JPL

tele-The ®fth chapter by Viirre et al discusses motion sickness caused by thevirtual reality technology and the application of VR for vestibular patients.The sixth chapter by Guo et al introduces a telemedicine diagnosis supportsystems based on the computer graphics and multimedia technologies

The seventh chapter by J Wang presents the implementation of a achieving and comunication system (PACS) and teleradiology system by em-phasing the practical issues in the implementation of a clinical PACS

picture-The eighth chapter by Stone discusses the adoptation of virtual reality nologies in medicine and other sectors and presents a case study of one surgicaltraining system

tech-The last chapter by Sarti et al discusses a simulation method that allows one

to deal with extremely complex anatomical geometrics and gives a detailedcomparison between virtual and real surgical opertions performed on patients

We thank the authors for their valuable contributions to this volume andGeorge Telecki, the Executive Editor and Shirley Thomas, Senior AssociateManaging Editor of John Wiley & Sons, Inc for their valuable support andencouragement througout the preparation of this volume

Metin Akay

This work was partially supported by a USA NSFgrant (IEEE EMBS shop on Virtual Reality in Medicine, BES ± 9725881) made to Professor MetinAkay

Work-INFORMATION TECHNOLOGIES

IN MEDICINE

PART I

TREATMENT

Edited by Metin Akay, Andy Marsh Copyright © 2001 John Wiley & Sons, Inc Print ISBN 0-471-41492-1 Electronic ISBN 0-471-20645-8

Neuro/Orthopedic Rehabilitation and Disability Solutions Using Virtual

Reality Technology

WALTER J GREENLEAF, Ph.D

Greenleaf Medical Systems

Palo Alto, California

1.1 VR Environments and Interfaces

1.3Current Status of VR Technology

1.4 VR-Based Medical Applications in Development

1.4.1 Surgical Training and Planning

1.4.2 Medical Education, Modeling, and Nonsurgical Training

1.4.3Anatomically Keyed Displays with Real-Time Data Fusion

1.4.4 Telesurgery and Telemedicine

1.5 Neurologic Testing and Behavioral Intervention

1.6 Rehabilitation, Functional Movement Analysis, and Ergonomic Studies

1.6.1 The Role of VR in Disability Solutions

1.7 Conclusion

References

Virtual reality (VR) is an emerging technology that allows individuals to perience three-dimensional (3-D) visual, auditory, and tactile environments.Highly specialized sensors and interface devices allow the individual to become

immersed and to navigate and interact with objects in a computer-generatedenvironment Most people associate VR with video games; however, researchersand clinicians in the medical community are becoming increasingly aware of itspotential bene®ts for people with disabilities and for individuals recoveringfrom injuries.

1.1 VR ENVIRONMENTS AND INTERFACES

The computer-generated environment, or virtual world, consists of a 3-Dgraphics program that relies on a spatially organized, object-oriented database

in which each object in the database represents an object in the virtual world(Fig 1.1) A separate modeling program is used to create the individual objectsfor the virtual world For greater realism, these modeling programs apply state-of-the-art computer-graphics techniques, such as texture mapping and shading,

to all of the objects of the scene The object database is manipulated using areal-time dynamics controller that speci®es how objects behave within theworld according to user-speci®ed constraints and according to natural laws,such as gravity, inertia, and material properties These laws are applicationspeci®c The dynamics controller also tracks the position and orientation of theuser's head and hand

Figure 1.1 A Complete VR system HMD, head-mounted display

Common computer input devices, such as a mouse and a keyboard, do notprovide a sense of immersion in a virtual world To create a VR experience, theconventional computer interface is replaced by one that is more natural andintuitive for interaction within complex 3-D environments The need for im-proved human±computer interaction with virtual environments (VEs) has mo-tivated the development of a new generation of interface hardware To date, themost common 3-D input devices used in VR applications are head-mounteddisplays (HMDs) and instrumented clothing (gloves and suits) VEs may also

be created through circuambiant projections (1), 3-D spatialized sound (2),haptic feedback, and motion e¨ectors

1.1.1 Head-Mounted Display

The best-known tool for data output in VR is the head-mounted display Itsupports ®rst-person immersion by generating a wide ®eld of view image foreach eye, often in true 3-D Most lower-cost HMDs ($1000 range) use liquidcrystal displays (LCDs) others use small cathode ray tubes (CRTs) The moreexpensive HMDs ($60,000 and up) use optical ®bers to pipe the images fromnon-HMDs An HMD requires a position tracker in addition to the helmet.Alternatively, the binocular display can be mounted on an armature for sup-port and tracking (a Boom display) (3)

1.1.2 Instrumented Clothing

Among the most popular and widely available input devices for VR are tracking technologies Such glove-based input devices let VR users apply theirmanual dexterity to the VR activity Hand-tracking gloves currently in useinclude Sayre Glove, MIT LED Glove, Digital Data-Entry Glove, DataGlove,Dexterous HandMaster, Power Glove, CyberGlove, and Space Glove (4) Thischapter describes two prototype clinical and rehabilitation applications usinginstrumented clothing technology (Fig 1.2)

hand-Originally developed by VPL Research, the DataGlove is a thin cloth glovewith engraved optical ®bers running along the surface of each digit that loopback to a light-processing box The optical ®bers that cross each joint aretreated to increase the refractive surface area of that segment of the ®ber overthe joint Each optical ®ber originates at, and returns to, a light-processing box

In the light-processing box, light-emitting diodes send photons along the ®bers

to the photo detector When the joints of the hand bend, the optical ®bers bend

so that the photons refract out of the ®ber, thus attenuating the signal thatpasses through the ®bers The transmitted signal is proportional to the amount

of ¯exion of a single joint and is recorded as such

Because the attenuation of light along each optical ®ber is interpreted as ameasurement of joint ¯exion, the set of joint measurements can be thought of as

a hand gesture To provide feedback to the user, most VR applications render agraphic representation of the hand moving in real time; this representation

shadows the movements of the hand in the DataGlove and replicates even themost subtle actions.

To determine the orientation and the position of the hand in 3-D space, theglove relies on a spatial tracking system Tracking systems usually rely onelectromagnetic, ultrasonic, or infrared sensors to determine the position andorientation of a the glove in relation to the signal source Typically, the source

is placed at a desired point of reference and the sensor is mounted on thedorsum of the glove

The DataSuit is a custom-tailored body suit ®tted with the same cated ®beroptic sensors found in the DataGlove The sensors are able to trackthe full range of motion of the person wearing the DataGlove or DataSuit as he

sophisti-or she bends, moves, grasps, sophisti-or waves Missing from the instrumented clothing

is haptic feedback, which provides touch and force-feedback information to the

VR participant

1.1.3 3-D Spatialized Sound

The impression of immersion within a VE is greatly enhanced by inclusion of3-D spatialized sound (5) Stereo-pan e¨ects alone are inadequate because theytend to sound as if they are originating inside the head Research into 3-Daudio has shown the importance of modeling the head and pinna and using thismodel as part of the 3-D sound generation A head-related transfer function

Figure 1.2 The WristSystem, based on the VR DataGlove

(HRTF) can be used to generate the proper acoustics A number of problemsremain, such as the cone of confusion, wherein sounds behind the head areperceived to be in front of the head.

1.1.4 Other VR Interfaces

Senses of balance and motion can be generated in a VR system by a motionplatform These have been used in ¯ight simulators to provide motion cues thatthe mind integrates with other cues to perceive motion Haptics is the gen-eration of touch and force-feedback information Most systems to date havefocused on force feedback and kinesthetic senses, although some prototypesystems exist that generate tactile stimulation Many of the haptic systems thusfar are exoskeletons used for position sensing as well as for providing resistance

to movement or active force application

Some preliminary work has been conducted on generating the sense of perature in VR Small electrical heat pumps have been developed that producesensations of heat and cold as part of the simulated environment

tem-1.2 DIVERSITY OF VR APPLICATIONS

VR has been researched for decades in government laboratories and versities, but because of the enormous computing power demands and asso-ciated high costs, applications have been slow to migrate from the researchworld to other areas Recent improvements in the price:performance ratio ofgraphic computer systems have made VR technology more a¨ordable andthus used more commonly in a wider range of applications In fact, there is even

uni-a strong ``guni-aruni-age VR'' movementÐgroups of interested puni-arties shuni-aring mation on how to build extremely low cost VR systems using inexpensive o¨-the-shelf components (6) These homemade systems are often ine½cient, un-comfortable to use (sometimes painful), and slow; but they exist as a strongtestament to a fervent interest in VR technology

infor-Current VR applications are diverse and represent dramatic improvementsover conventional visualization and planning techniques:

public entertainment, with ventures ranging from shopping mall gamesimulators to low-cost VR games for the home

software allows engineers to test potential products in the design phase,even collaboratively over computer networks, without investing time ormoney for conventional hard models

into extensive networked simulations involving a variety of equipmentand situations Extensive battle simulations can now be created that net-

work tanks, ships, soldiers, and ®ghters all into the same shared trainingexperience.

their clients to walk through structural blueprints Designs may be stood more clearly by clients who often have di½culty comprehending evenconventional cardboard models The city of Atlanta credits its VR modelfor winning the site of the 1996 Olympics, and San Diego used a VR model

under-of a planned convention center addition to compete for (and obtain) the

1996 Republican Party convention

of data, VR helps users rapidly visualize large amounts of complex cial market data and thus supports faster decision making

®nan-VR is commonly associated with exotic fully immersive applications because ofthe overdramatized media coverage of helmets, body suits, entertainment sim-ulators, and the like As important are the window-into-world applications bywhich the user or operator is allowed to interact e¨ectively with virtual data,either locally or remotely

1.3 CURRENT STATUS OF VR TECHNOLOGY

The commercial market for VR, although taking advantage of advances in VRtechnology at large, is nonetheless contending with the lack of integrated sys-tems and the lack of reliable equipment suppliers Typically, researchers buyperipherals and software from separate companies and con®gure their ownsystems Companies that can o¨er integrated systems for commercial applica-tions are expected to ®ll this gap over the next few years Concurrently, thenature of the commercial VR medical market is expected to change as theprices of today's expensive, high-performance graphics systems decrease dra-matically High-resolution display systems will also signi®cantly drop in cost

as the VR display business can piggyback on HDTV projection and entertainment technologies

home-Technical advances have occurred in networking applications, which includeimproved visual photo realism, decreased tracker latency through predictivealgorithms, and variable resolution image generators Work to improve data-base access methods is under way Important hardware advances include eyegear with an increased ®eld of view, wireless communications, lighted andsmaller devices, and improved tracking systems

1.4 VR-BASED MEDICAL APPLICATIONS IN DEVELOPMENT

The ®rst wave of VR development e¨orts in the medical community addressedseven key categories:

Surgical training and surgical planning.

Medical education, modeling, and nonsurgical training

Anatomically keyed displays with real-time data fusion

Telesurgery and telemedicine

Patient testing and behavioral intervention

Rehabilitation, functional movement analysis, and motion/ergonomicstudies

Disability solutions

The potential of VR through education and information dissemination cates there will be few areas of medicine not taking advantage of this improvedcomputer interface However, the latent potential of VR lies in its capacity to

indi-be used to manipulate and combine heterogeneous datasets from many sources.This feature is most signi®cant and likely to transform the traditional applica-tions environment in the near future

1.4.1 Surgical Training and Planning

Various projects are under way to use VR and imaging technology to plan,simulate, and customize invasive (an minimally invasive) surgical procedures.Ranging from advanced imaging technologies for endoscopic surgery to routinehip replacements, these new developments will have a tremendous e¨ect onimproving surgical morbidity and mortality According to Merril (7), studiesshow that doctors are more likely to make errors when performing their ®rstfew to several dozen diagnostic and therapeutic surgical procedures then whenperforming later procedures Merril claims that operative risk could be sub-stantially reduced by the development of a simulator that would allow trans-ference of skills from the simulation to the actual point of patient contact Withsurgical modeling, we would generally expect a much higher degree of preci-sion, reliability, and safety, in addition to cost e½ciency

Several VR-based systems currently under development allow real-timetracking of surgical instrumentation and simultaneous display and manipulation

of 3-D anatomy corresponding to the simulated procedure (8, 9) Using thisdesign, surgeons can practice procedures and experience the possible complica-tions and variations in anatomy encountered during surgery Necessary soft-ware tools have been developed to enable the creation of virtual tissues thatre¯ect the physical characteristics of physiologic tissues This technology oper-ates in real-time using 3-D graphics, on a high-speed computer platform.1.4.2 Medical Education, Modeling, and Nonsurgical Training

Researchers at the University of California at San Diego are exploring thevalue of hybridizing elements of VR, multimedia (MM), and communicationstechnologies into a uni®ed educational paradigm (10) The goal is to develop

powerful tools that extend the ¯exibility and e¨ectiveness of medical teachingand promote lifelong learning To this end, they have undertaken a multiyearinitiative, named the VR-MM Synthesis Project Based on instructional designand user need (rather than technology per se), they plan to link the computers

of the Data Communications Gateway, the Electronic Medical Record System,and the Simulation Environment This system supports medical students, sur-gical residents, and clinical faculty and runs applications ranging from fullsurgical simulation to basic anatomic exploration and review, all via a commoninterface The plan also supports integration of learning and telecommunica-tions resources (such as interactive MM libraries, on-line textbooks, databases

of medical literature, decision support systems, email, and access to electronicmedical records)

1.4.3 Anatomically Keyed Displays with Real-Time Data Fusion

An anatomically keyed display with real-time data fusion is currently in use

at the New York University Medical Center's Department of Neurosurgery.The system allows both preoperative planning and real-time tumor visualiza-tion (11, 12) The technology o¨ers the opportunity for a surgeon to plan andrehearse a surgical approach to a deep-seated, centrally located brain tumorbefore doing of the actual procedure The imaging method (volumetric stereo-taxis) gathers, stores and reformats imaging-derived, 3-D volumetric informa-tion that de®nes an intracranial lesion (tumor) with respect to the surgical ®eld.Computer-generated information is displayed during the procedure on com-puter monitors in the operating room and on a heads-up display mounted onthe operating microscope These images provide surgeons with CT- and MRI-de®ned maps of the surgical ®eld scaled to actual size and location This infor-mation guides the surgeon in ®nding and de®ning the boundaries of braintumors The computer-generated images are indexed to the surgical ®eld bymeans of a robotics-controlled stereotactic frame that positions the patient'stumor within a de®ned targeting area

Simulated systems using VR models are also being advocated for other risk procedures, such as the alignment of radiation sources to treat canceroustumors

high-1.4.4 Telesurgery and Telemedicine

Telepresence is the sister ®eld of VR Classically de®ned as the ability to act andinteract in an o¨-site environment by making use of VR technology, tele-presence is emerging as an area of development in its own right Telemedicine(the telepresence of medical experts) is being explored as a way to reduce thecost of medical practice and to bring expertise into remote areas (13, 14).Telesurgery is a fertile area for development On the verge of realization,telesurgery (remote surgery) will help resolve issues that can complicate orcompromise surgery, including

. A patient that is too ill or injured to be moved for surgery.

requires specialized intervention

The surgeon really does operateÐon ¯esh, not a computer animation Althoughthe distance aspect of remote surgery is a provocative one, telepresence is proving

to be an aid in nonremote surgery as well It can help surgeons gain dexterityand improve their operative technique, which is expected to be particularlyimportant in endoscopic surgery For example, suturing and knot tying will be

as easy to see in endoscopic surgery as it is in open surgery, because ence o¨ers the ability to emulate the look and feel of open surgery

telepres-As initially developed at SRI International (15), telepresence not only o¨ers

a compelling sense of reality for the surgeon but also allows him or her to form the surgery according to the usual methods and procedures There isnothing new to learn Hand motions are quick and precise The visual ®eld, theinstrument motion, and the force feedback can all be scaled to make micro-surgery easier than it would be if the surgeon were at the patient's side Whilecurrent technology has been implemented in several prototypes, SRI and Tele-surgical Corporation (Redwood City, CA) are collaborating to develop a fullcomercial system based on this novel concept

per-1.5 NEUROLOGIC TESTING AND BEHAVIORAL INTERVENTIONFor Parkinson disease victims, initiating and sustaining walking becomesprogressively di½cult The condition known as akinesia can be mitigated bytreatment with drugs such as l-dopa, a precursor of the natural neural trans-mitter dopamine, but usually not without unwanted side e¨ects Now, collabo-rators at the Human Interface Technology Laboratory and the Department

of Rehabilitation Medicine at the University of Washington, along with theSan Francisco Parkinson's Institute are using virtual imagery to simulate ane¨ect called kinesia paradoxa, or the triggering of normal walking behavior inakinetic Parkinson patients (16)

Using a commercial, ®eld-multiplexed, heads-up video display, the researchteam has developed an approach that elicits near-normal walking by presentingcollimated virtual images of objects and abstract visual cues moving throughthe patient's visual ®eld at speeds that emulate normal walking The combina-tion of image collimation and animation speed reinforces the illusion of space-stabilized visual cues at the patient's feet This novel, VR-assisted technologymay also prove to be therapeutically useful for other movement disorders.Lamson and Meisner (17) investigated the diagnostic and treatment possi-bilities of VR immersion on anxiety, panic and height phobias By immersing

both patients and controls in computer-generated situations, the researcherswere able to expose the subjects to anxiety-provoking situations (such asjumping from a height) in a controlled manner Experimental results indicate asigni®cant subject habituation and desensitization through this approach, andthe approach appears clinically useful.

Pugnetti (18) explored the potential of enhancing the clinical evaluation andmanagement of acquired cognitive impairments in adults By using a VR-basednavigation paradigm, researchers were able to challenge both patients andnormal subjects with a complex cognitive activity and simultaneously generateperformance data Behavioral data analysis was then carried out using estab-lished scoring criteria

1.6 REHABILITATION, FUNCTIONAL MOVEMENT ANALYSIS, ANDERGONOMIC STUDIES

The ®eld of VR is still at the proof-of-concept stage, yet there is a growingnumber of potential applications related to motion monitoring, rehabilitation,and ergonomic analysis I (19) theorized that the rehabilitation process can beenhanced through the use of VR technology

Evaluation of hand impairment involves detailed physical examination andfunctional testing of the a¿icted person The physical examination is designed

to determine the presence of pain and any loss of strength, sensation, range ofmotion, and structure The results are combined to produce a numerical as-sessment of impairment that is used to evaluate the patient's progress over time,yet examinations and calculations can be time-consuming, expensive, and sub-ject to observer error

Functional evaluation is usually accomplished by subjective observation ofpatient performance on standardized tests for motor skills However, repro-ducibility of measurements becomes an issue whenever di¨erent examinersevaluate the same patient, which makes it di½cult to evaluate a patient's prog-ress over time The more objective assessments of upper extremity motion fallinto two categories: visual and e¨ective

Visual methods involve digitizing and estimating a visual record of themotion: The patient is videotaped performing a task; then the individual frames

of the video are digitized and evaluated to quantify the degree of motion ofthe joint under study The main limitation of this technique is that the cameracan view motion in only two dimensions To assess movement in the camera'svisual plane accurately, the third dimension must be held constant, i.e., theperson must move along a known line parallel to the plane of the ®lm in thecamera In most cases, the examiner cannot maintain the correct orientationeven for short periods, making this a di½cult and cumbersome technique.E¨ective methods measure the motion's e¨ect rather than the motion itself

A work simulator is one example of an e¨ective assessment tool Work lators measure the force exerted by a subject on a variety of attachments that

simu-simulate tools used in the workplace A major limitation of this approach isthat no data are collected on how the person e¨ects the force.

Ideally one would like to collect and compare range of motion data for ajoint in several planes simultaneously while speci®c tasks were being performed

by the patient, a measurement that is impossible using a standard goniometer

At one point my group considered using the DataGlove with its multiple sors as a means of collecting dynamic functional movement data However,migrating the DataGlove technology from the ®eld of VR to clinical evaluationposed several problems For example, during manufacture of the DataGlove,the treatment of individual ®beroptic cables was not identical, thus it wasimpossible to characterize and predict their behavior Moreover, empirical ob-servations show hysteresis, making repeated measurements irreproducible andmaking it di½cult to determine the accuracy of the measurements For highlyaccurate measurements, it is important to have a perfect ®t of the glove, be-cause poor placement of the sensitive areas of ®bers yields incorrect measure-ments Achieving a perfect ®t of the DataGlove posed a serious challengebecause of the variability of hand shapes and sizes across a given patientpopulation Moreover, the use of the ®beroptic DataGlove excluded the popu-lation of patients with anatomic deformities

sen-With the goal of obtaining accurate, dynamic range of motion data for thewrist joint, my group investigated other sensor materials and developed theglove-based WristSystem Fiberoptic sensors were replaced by dual-axis elec-trogoniometric sensors that could be inserted into machine-washable Lycragloves that ®t di¨erent sizes of hands

WristSystem gloves are currently being used to track ¯exion, extension,radial, and ulnar deviations of the wrist while patients are performing routinetasks A portable, lightweight DataRecorder worn in a waist pack permits thepatient to be ambulatory while data are being collected at the clinic or work site(Fig 1.3); no visual observation or supervision is required beyond the initialcalibration of the glove sensors Real-time visual and auditory feedback canalso be used to train the patient to avoid high-risk postures in the workplace or

at home

The WristSystem includes Motion Analysis System (MAS) software for theinterpretation of the dynamic-movement data collected by the DataRecorderover several minutes or hours This software o¨ers rapid, quantitative analysis

of data that includes the total and percent time the wrist spends at critical gles (minimum, maximum, and mean wrist angles in four directions), the num-ber of repetitions, and the velocity and acceleration Figure 1.4 shows a sampleplot of some of these data In this example, it can be seen that the patient's right

The WristSystem is currently being used by occupational and rehabilitationmedicine specialists (MDs, PTs, and OTs), ergonomists, industrial safety man-agers, biomechanical researchers, and risk management consultants The ulti-mate extension of this project is to build an augmented-reality environment forquantitative evaluation of functional tasks The system will link multiple input

devices or sensors worn by the patient and 3-D modeling software Therapistswill be able to design a virtual world composed of objects traditionally used infunctional assessment tests, such as balls, cubes, keys, and pencils The therapistwill be able to record the motion, location, and trajectory of the user's handthat is required to accomplish the motion and any associated hand tremors orFigure 1.3 The WristSystem being used to track functional movement at a job site.

Figure 1.4 MAS: WristSystem data plot

spasms Once the data are collected, the therapist can use statistical analysissoftware to interpret them The clinician can also elect to review the motions byanimation of the data and to change the orientation to study the motion fromanother angle.

Other control devices originally developed for VR are being improved andapplied to the ®eld of functional evaluation of movement in a variety of ways.Burdea (20) described a system that would couple a glove with force-feedbackdevices to rehabilitate a damaged hand or to diagnose a range of hand prob-lems He describes another system under development that incorporates tactilefeedback in a glove to produce feeling in the ®ngers when virtual objects are

``touched.''

My research group previously theorized that the rehabilitation process could

be enhanced through the use of VR technology (21) Perhaps the most cant advantage is that a single VR-based rehabilitation workstation can beeasily customized for individual patient needs We are currently developing somebasic components for a VR-based workstation (Fig 1.5) that will be used to

steps

Figure 1.5 Virtual reality technology for quanitative evaluation of functional tasks

. Make the rehabilitation process more realistic and less boring, enhancing

patient motivation and recovery of function

work

1.6.1 The Role of VR in Disability Solutions

One exciting aspect of VR technology is the inherent ability to enable uals with physical disabilities to accomplish tasks and have experiences thatwould otherwise be denied them There are approximately 35 million people inthe United States who have physical disabilities that a¨ect their ability to work

individ-in certaindivid-in types of jobs Computers and VR software can provide individ-increasedaccess to daily activities for people with disabilities VR technology may pro-vide an adaptable mechanism for harnessing a person's strongest physicalability to operate an input device for a computer program

A simple glove-based system allows users to record custom-tailored gesturesand to map these gestures to actions These actions can range from a simplecommand, such as a mouse click on a computer screen, to more complex func-tions, such as controlling a robotic arm An application programmer cande®ne the functional relationship between the sensor data and a task with real-time graphical representation on a computer screen Simple gestures can betranslated to a preprogrammed set of instructions for speech or movement.The prototype GloveTalker is an example of a one-to-one mapping of agesture to a computer-generated action to provide additional communica-tion skills to people with vocal impairment The patient is able to speak bysignaling the computer with his or her personalized set of gestures while wear-ing the DataGlove, which recognizes hand positions (gestures) and passes theinformation to the computer's voice-synthesis system (Fig 1.6) For example, apatient may map a speci®c gesture, such as a closed ®st, for the phrase ``Hello,

my name is Susan.'' The computer has some freedom in interpreting the gesture

so that people capable of only relatively gross muscle control may use thesystem There is also the possibility of sending the voice output through a tele-phone system, enabling vocally impaired individuals to communicate verballyover distance

1.7 CONCLUSION

VR tools and techniques are rapidly developing in the scienti®c, engineering,and medical areas Although traditionally used as input devices for virtualworlds in the entertainment and defense industry, sensor-loaded gloves maybecome the clinical tools of choice for measuring, monitoring, and amplifyingupper-extremity motion Although I have identi®ed other potential clinical ap-plications, many technological challenges must be met before such devices can

be made available for patient care

Pioneers in the ®eld of medical VR are being encouraged to design cated devices that promote both physical and psychological gains for injuredand disabled patients while keeping costs for the devices within an acceptablerange for health-care providers and third-party payors The mandate is com-plex, but like VR technology itself, the possibilities are promising and exciting.REFERENCES

sophisti-1 C Cruz-Neira, D J Sandin, and T A DeFanti Surround-screen projection-basedvirtual reality: the design and implementation of the CAVE Paper presented atComputer Graphics Anaheim, CA, 1993

2 M F Deering Explorations of display interfaces for virtual reality Paper presented

at IEEE Virtual Reality Annual International Symposium New York, 1993

3 M T Bolas Human factors in the design of an immersive display IEEE ComputGraph Appl 1994;14:55±59

Figure 1.6 The GloveTalker: speech communication for the vocally impaired

4 D J Sturman and D Zeltzer A survey of glove-based input IEEE Comput GraphAppl 1994;14:30±39.

5 N I Durlach, B G Shinn-Cunningham, and R M Held Supernormal auditorylocalization I General background Presence 1993;2:89±103

6 L Jacobs Garage virtual reality Indianapolis: Sams, 1994

7 J R Merril Photorealistic interactive three-dimensional graphics in surgical lation Interactive technology and the new paradigm for healthcare Burke, VA: IOSPress, 1995

simu-8 D Hon Ixion's laparoscopic surgical skills simulator Paper presented at MedicineMeets Virtual Reality II San Diego, CA, 1994

9 K T McGovern and L T McGovern Virtual clinic: a virtual reality surgical ulator Virtual Reality World 1994;2:1994

sim-10 H M Ho¨man Virtual reality and the medical curriculum: integrating extant andemerging technologies Paper presented at Medicine Meets Virtual Reality II SanDiego, CA, 1994

11 P J Kelly Quantitative virtual reality surgical simulation, minimally invasive reotactic neurosurgery and frameless stereotactic technologies Paper presented atMedicine Meets Virtual Reality II San Diego, CA, 1994

ste-12 B A Kall, P J Kelly, S O Stiving, and S J Goerss Integrated multimodalityvisualization in stereotactic neurologic surgery Paper presented at Medicine MeetsVirtual Reality II San Diego, CA, 1994

13 M Burrow A telemedicine testbed for developing and evaluating telerobotic toolsfor rural health care Paper presented at Medicine Meets Virtual Reality II SanDiego, CA, 1994

14 J Rosen The role of telemedicine and telepresence in reducing health care costs.Paper presented at Medicine Meets Virtual Reality II San Diego, CA, 1994

15 R M Satava Robotics, telepresence and virtual reality: a critical analysis of thefuture of surgery Minim Invasive Ther 1992;1:357±363

16 S Weghorst, J Prothero, and T Furness Virtual images in the treatment of kinson's disease akinesia Paper presented at Medicine Meets Virtual Reality II SanDiego, CA, 1994

par-17 R Lamson and M Meisner The e¨ects of virtual reality immersion in the treatment

of anxiety, panic, & phobia of heights Virtual reality and persons with disabilities.Paper presented at the 2nd Annual International Conference San Francisco, CA,June 8±10, 1994

18 D V Pugnetti Recovery diagnostics and monitoring in virtual environments tual reality in rehabilitation, research, experience and perspectives Paper presented

Vir-at the 1st InternVir-ational Congress on Virtual Reality in RehabilitVir-ation Gubbio,Italy, June 13±18, 1994

19 W J Greenleaf DataGlove and DataSuit: virtual reality technology applied tothe measurement of human movement Paper presented at Medicine Meets VirtualReality II San Diego, CA, 1994

20 G Burdea, J Zhuang, E Roskos, et al A portable dextrous master with forcefeedback Presence 1992;1:18±28

21 W J Greenleaf and M A Tovar Augmenting reality in rehabilitation medicine.Artif Intel Med 1994;6:289±299

CHAPTER 2

The Use of Virtual Reality Technology

in the Treatment of Anxiety Disorders

BRENDA K WIEDERHOLD, M.S., MBA

California School of Professional Psychology

San Diego, California

MARK D WIEDERHOLD, M.D., Ph.D

Scripps Clinic Medical Group

La Jolla, California

2.1 Panic Disorder with or without Agoraphobia

2.2 Agoraphobia without a History of Panic Disorder

2.6 Post-Traumatic Stress Disorder

2.7 Future Targets for VR Treatment

2.7.1 Acute Stress Disorder

2.7.2 Generalized Anxiety Disorder

2.7.3 Anxiety Disorder Owing to a General Medical Condition

2.7.4 Substance-Induced Anxiety Disorder

2.7.5 Unspeci®ed Anxiety Disorder

2.8 Conclusion

References

19

Information Technologies in Medicine, Volume II: Rehabilitation and Treatment, Edited by

Metin Akay and Andy Marsh.

ISBN 0-471-41492-1 ( 2001 John Wiley & Sons, Inc.

Edited by Metin Akay, Andy Marsh Copyright © 2001 John Wiley & Sons, Inc Print ISBN 0-471-41492-1 Electronic ISBN 0-471-20645-8

Approximately 23 million Americans will su¨er from an anxiety disorder sometime during their life Anxiety disorders are the most common mental disorders

in the United States, the ®fth most common diagnosis given to those seen byprimary care physicians, and the number one psychiatric diagnosis made byprimary-care physicians (1)

In 1990, 147.8 billion mental health dollars were spent in the United States

Of this amount $46.6 billion (32%) was spent on the treatment of anxiety orders The cost of treatment of all other mental health disorders was $101.2billion (2) In a more recent study, the following costs were estimated for anxi-ety disorders: $15 billion in direct costs, such as medical, administrative, andresearch costs, and $50 billion in indirect costs, including illness, death, and lost

dis-or reduced productivity (3)

Of patients presenting with insomnia, chest pain, or abdominal pain 33%actually had an anxiety disorder, as did 25% percent of those with headache,fatigue, or joint or limb pain (4) Women, individuals under age 45, separatedand divorced persons, and those in lower socioeconomic groups su¨er thehighest incidence of anxiety disorders Unfortunately, these are often the indi-viduals who can least a¨ord treatment (5)

Anxiety can be seen as a contributory factor in some medical disorders aswell A study of 2,000 men conducted from 1961 to 1993 found a correlationbetween high anxiety and sudden cardiac death After correcting for severalphysical conditions, high anxiety did not raise the risk of fatal or nonfatal heartdisease but did increase the chance of a sudden fatal heart attack (three to fourtimes as high as those without anxiety) (6)

As part of the National Health and Nutrition Examination Survey I(NHANES I), 2992 subjects were assessed for anxiety and depression between

1971 and 1975, and follow-ups were conducted between 1982 and 1984, and

1986 and 1987 All subjects were normotensive when the study began The searchers found that high depression and anxiety scores were independent pre-dictors of hypertension (7) The Normative Aging Study followed 1759 menwithout coronary heart disease (CHD) from 1975 to 1995 The subjects com-pleted a Worries Scale in 1975 The researchers found that worry doubledmyocardial infarction risk and CHD by 1.5 (8)

re-All anxiety disorders have two common characteristics First, patients withthese disorders usually experience apprehension, worry, and anxiety more in-tensely and for a longer period of time than the anxiety experienced by theaverage person in everyday life Second, patients often develop ritual acts, re-petitive thoughts, or avoidance mechanisms as a way to protect themselvesfrom the anxiety

Anxiety disorders are categorized according to the presence or absence ofexternal stimuli, the cause of the disorder, and the nature of the symptoms.Table 2.1 shows the 12 codable anxiety disorders contained in the Diagnosticand Statistical Manual of Mental Disorders, 4th edition (DSM-IV) (9)

Somatic symptoms associated with anxiety disorders may include fatigue,weakness, ¯ushing, chills, insomnia, dizziness, paresthesias, restlessness, pal-

pitations, chest pain, rapid heart rate, hyperventilation, choking, dry mouth,nausea, diarrhea, and urinary frequency Because of this, the average personsu¨ering from an anxiety disorder sees a primary-care physician 10 times beforebeing correctly diagnosed, increasing health-care costs (10).

Since the mid-1980s, surveys have shown a general improvement in care diagnosis of anxiety, but these disorders are still missed one third of thetime Anxiety disorders are thought now to arise from to a combination ofgenetic vulnerability and environmental factors (4; www.nimh.nih.gov) Earlydiagnosis is important to prevent secondary problems (such as agoraphobia,depression, or alcoholism) (10)

primary-In a study of nine New England clinics in 1993, the following methods oftreatment for anxiety disorders were administered either alone or in combina-tion with another method of treatment: 45% of patients were receiving a be-havioral method of treatment (relaxation, exposure, or role play), 42% werereceiving a cognitive method of treatment (thought stopping, mental distrac-tion, or recording of thoughts); 93% were receiving medication; 76% were re-ceiving psychodynamic treatment; 45% were receiving family therapy; and 3%were receiving biofeedback therapy Obsessive±compulsive disorder (OCD) andagoraphobia were the two most common anxiety disorders treated with a be-havioral method Although many studies have shown the e½cacy of behavioralmethods for the treatment of anxiety disorders, these therapies as a group arestill being underused Anxiety disorders included in the survey were generalizedanxiety disorder, social phobia, agoraphobia without a history of panic disor-der, and panic disorder with or without agoraphobia Psychodynamic psycho-therapy, which has not been proven e½cacious for panic disorder, was the mostwidely used nonpharmacologic treatment used in this sample (11)

Each major anxiety disorder category is described below and current ment modalities are evaluated When viewing mental health disorders and sta-tistics, it is important to remember that incidence refers to the number of new

treat-TABLE 2.1 Codable Anxiety Disordersa

Panic disorder without agoraphobia

Panic disorder with agoraphobia

Agoraphobia without a history of panic disorder

Speci®c phobias

Social phobia

Obsessive±compulsive disorder

Post-traumatic stress disorder

Acute stress disorder

Generalized anxiety disorder

Anxiety disorder owing to a general medical condition

Substance-induced anxiety disorder

Anxiety disorder not otherwise speci®ed

aAdapted from Ref 9.

cases in a speci®c time period, whereas prevalence refers to the total number ofcases at a given time For instance, lifetime prevalence would mean that a per-son had the disorder at some point in his or her life but may not have had it atthe time of the survey (12).

2.1 PANIC DISORDER WITH OR WITHOUT AGORAPHOBIA

Each year, panic disorder (PD) strikes more individuals than does AIDS,epilepsy, or stroke (www.nimh.nih.gov) As noted in the DSM-IV:

The essential feature of Panic Disorder (PD) is the presence of recurrent, pected Panic Attacks followed by at least 1 month of persistent concern abouthaving another Panic Attack, worry about the possible implications or conse-quences of Panic Attacks, or a signi®cant behavioral change related to the attacks.Lifetime prevalence of panic disorder (with or without agoraphobia) is 1.5 to3.5%, with 1-year prevalence estimated at 1 to 2% In community samples, onethird to one have of those with PD also have agoraphobia Typical age of onset

unex-is either in late adolescence or in the mid-30s It unex-is twice as common in women

as in men (9) It has been shown that 2.8 to 5.7% of the population sample used

in the ECA study (sponsored by the National Institute of Mental Health) metDSM-IV criteria for agoraphobia, and another 1% met DSM-IV criteria forpanic disorder (13)

Treatment of PD usually involves medication or cognitive-behavioral apy, sometimes in combination Cognitive-behavioral therapies may includerelaxation, breathing retraining (biofeedback), exposure therapy, and cognitiverestructuring Medications used include benzodiazepines and antidepressants(14)

ther-Exposure therapies include systematic desensitization, in vivo exposure, andimaginal exposure Systematic desensitization is a type of exposure therapy thatpairs relaxation with imagined scenes depicting situations the client has in-dicated cause him or her anxiety In vivo exposure involves exposing the patient

to the actual real-life phobic situation This may be done after teaching thepatient anxiety management techniques, (e.g., thought stopping, relaxation,and diaphragmatic breathing), or it may be done without ®rst teaching any ofthese techniques Imaginal exposure involves having the patient imagine thephobic situation The patient ®rst builds a fear hierarchy of more and moreanxiety-provoking situations and moves step by step through the hierarchy.When a scene no longer causes anxiety, the next imaginal scene in the hierarchy

is attempted, until all scenes can be imagined with no resulting anxiety sure techniques are usually found to be e¨ective, with some improvement beingachieved in 70% of cases (15)

Expo-Although cognitive therapy is often incorporated into exposure treatments,some studies have indicated that cognitive therapy adds no signi®cant advan-tage (16, 17), and in fact was shown to be detrimental in one study (18)

Relaxation procedures, sometimes using biofeedback to aid patient ness, have been helpful when taught before exposure therapy Relaxation isthen used during exposure therapy as a coping technique (19) Relaxation mayinclude helping the patient to relax muscles using electromyography (EMG)recording The therapist guides the patient through exercises that allow him orher to experience muscle tension and muscle relaxation Breathing retrainingusing biofeedback may also help the patient become aware of slow, diaphrag-matic breathing versus fast, chest breathing During panic attacks, there is atendency to hyperventilate, actually achieving mild respiratory alkalosis, soproviding the patient with breath awareness is a useful adjunct to treatment(20).

aware-2.2 AGORAPHOBIA WITHOUT A HISTORY OF PANIC DISORDERIndividuals su¨ering from agoraphobia have anxiety that focuses on ``the oc-currence of incapacitating or extremely embarrassing panic-like symptoms orlimited-symptom attacks rather than full panic attacks The patient fears being

in places where escape would be di½cult or embarrassing'' (9) Little is knownabout the course of this disorder, but evidence suggests that considerable im-pairment persists for long periods of time without treatment Lifetime preva-lence for agoraphobia has been reported at 6.7% and a 30-day prevalence of2.3% was found (21)

Exposure therapy, sometimes in combination with medication, breathingretraining (biofeedback), and relaxation techniques are currently acceptableforms of treatment (14) Exposure treatments have not been shown e¨ective forall individuals, however Some individuals may also not be able to tolerate theside e¨ects associated with pharmacological therapy (14) Because of short-comings with current available treatments, North's group (22) has begun toexperiment with virtual reality (VR) exposure therapy to treat agoraphobia.Because one of the criteria for agoraphobia is anxiety about being in places orsituations in which escape might be di½cult or embarrassing, and because fearsusually involve a cluster of situations rather than just one, several virtual sce-narios were used Scenes included a series of bridges suspended over a canyon,hot-air balloons positioned at di¨erent heights, an empty room, a dark barn, adark barn with a black cat, a covered bridge, an elevator, and a series of bal-conies Participants in the ®rst study were 30 undergraduate students presentingwith agoraphobia They were treated individually with eight 15-min sessions(one per week for eight consecutive weeks), using VR exposure A total of 24subjects (80%) experienced a 50% decrease in discomfort levels

The proposed advantages of virtual reality compared to in vivo exposureinclude the following

1 No loss of patient con®dentiality The entire treatment is done in thetherapist's o½ce The patient and therapist do not have to venture out

into public and risk exposing the patient to possible embarrassment if he

or she would prefer the treatment remain con®dential

2 No safety issues The patient is in the safety of the therapist's o½ce, andthe VR system can be turned o¨ at any time the patient requests When inreal life, there is less control of the exposure scenario

3 More ¯exibility of the session If a patient is scared of only one aspect ofexposure, e.g., the actual experience of standing in a grocery checkoutline, then this can be practiced over and over in the virtual world In thereal world, a patient may feel conspicuous checking out over and overagain at the grocery store

4 Just unreal enough so that many patients who have resisted therapy owing

to in vivo approaches are willing to try it They know they can stop thevirtual experience instead of being trapped in a real-life scenario (23, 24)

5 Less time involved The clinician does not have to drive to the store, goshopping with the patient, etc This should prove to be more cost e¨ec-tive, because of the time savings (23, 24)

Despite signi®cant evidence of role impairment in phobias, only 18.6% of thosewith phobias ever seek professional treatment (25) Without treatment, only20% of cases will remit (www.nimh.nih.gov) Perhaps VR therapy may be atherapy more patients are willing to try

The advantages of virtual reality over imaginal exposure include are as lows

fol-1 The highly immersive nature of VR Some patients cannot visualize and,therefore, imaginal exposure doesn't work as well for them VR shouldwork better for this group of individuals because it provides several sen-sory modalities

2 The therapist sees what the patient sees Emotional processing theorypurports that to successfully treat a phobia, the patient's fear structuremust be activated and modi®ed (26) With VR, the therapist has a chance

to see exactly what stimuli is activating the patient's fear structure andwill then be better able to work on reducing the fear

3 The therapy is more realistic than imaginal for most people, which shouldallow for less treatment sessions and, therefore, less cost for treatment(23, 24)

2 Exposure to the phobic stimulus provokes an anxiety response.

3 The person recognizes that the fear is excessive

4 The phobic situation is avoided or else endured with intense anxiety

5 The anxiety response interferes signi®cantly with the person's normalfunctioning

Phobias are found to be the most common psychiatric disorder in the nity, more common than major depression, alcohol abuse, or alcohol depen-dence The 1-year prevalence rate is estimated at 9%, with lifetime prevalenceestimated at between 10 and 11.3% (25)

commu-There is a strong familial pattern with phobias; ®rst-degree relatives have agreater likelihood to also have a phobia of the same speci®c subtype Thestrongest risk factor associated with phobias is the presence of another psychi-atric disorder, and the most frequent co-occurrence is with panic disorder (25).Prevalence rates are found to be signi®cantly higher in women, who make up

75 to 90% of those who seek treatment for phobias Of those with a speci®cphobia, 83.4% also report having another mental health disorder sometime intheir life Phobias are strongly comorbid with each other, with other anxietydisorders, and with a¨ective disorders (such as mania and depression) Age ofonset may be either childhood or in the mid-20s Speci®c phobias are negativelyrelated to education but not income and are signi®cantly elevated among His-panics, among those who are not employed, and among those who live withtheir parents (21) Only 12.4% of those with a speci®c phobia ever seek treat-ment (25)

Those su¨ering from a speci®c phobia have anxiety that is provoked byconfronting a speci®c stimulus or anticipating confronting the stimulus Morethan 200 phobias have been identi®ed; the DSM-IV subtypes for speci®c pho-bias are as follows:

Animal type Generally has a childhood onset; females account for 75 to90% of those with this subtype

Natural environment type Includes fear of heights, water, and storms andgenerally has a childhood onset; females account for 75 to 90% of thosewith this subtype

Blood-injection-injury type Includes invasive medical procedures other thanjust injections and produces a vasovagal response; females account for 55

to 70% of those with this subtype

Situational type Includes fear of ¯ying, bridges, elevators, driving, and closed places; age of onset is either during childhood or in the mid-20s;most frequent subtype seen in adults; females account for 75 to 90% ofthose with this subtype

en-Other type Includes fear of falling down when away from walls, fear ofvomiting, contracting an illness, fear of loud sounds, and fear of costumedcharacters (in children) (9)

In community samples, lifetime prevalence rates range from 10 to 11.3%, with a1-year prevalence of 9% Without treatment, only 20% of cases that persist intoadulthood will remit (www.nimh.nih.gov).

Exposure therapy, sometimes in combination with relaxation training, isgenerally used to treat phobias Medication may also be used as an adjunct(14) VR-graded exposure therapy (VRGET) has been researched most for use

in the area of speci®c phobias Initial studies show promise for incorporatingVRGET into standard treatment protocols

2.3.1 Fear of Heights

The ®rst study by Hodges et al (27±29) used VR exposure to treat fear ofheights A VR-treatment group and a no-treatment control group were used Atotal of 17 subjects were exposed to virtual height situations: a glass elevator, aseries of bridges with varying heights and degrees of stability, and a series ofbalconies with varying heights Subjective ratings of fear, anxiety, and avoid-ance decreased signi®cantly for all participants in the VR exposure group afterseven 35- to 45-min exposure sessions, but remained unchanged for the controlgroup Some of those in the treatment group also exposed themselves to real-world height situations although not required to do so, which seems to showthat training does carry over to the real world

The same group (30) performed a case study The participant showed a duction in fear, anxiety, and avoidance and was able to put himself into heightsituations in real life once treatment was completed

re-In another study, Lamson (31) exposed 30 participants to simulated heightsituations Of these 90% were able to put themselves into height situations inthe real world after 1 week of simulation And 30 months later, 90% were stillable to ride in a glass elevator while looking out This shows that treatmente¨ects are lasting

To follow-up on these studies, which did not include a group receiving anyother treatment, Huang et al (32) conducted a study to compare in vivo expo-sure and VR exposure to treat fear of heights They modeled a virtual world toexactly duplicate a staircase at the University of Michigan One treatmentgroup was treated using VR exposure and the other group was given in vivoexposure

2.3.2 Fear of Flying

Characterized by an unreasonable or excessive fear cued by ¯ying or the pation of ¯ying, fear of ¯ying a¨ects an estimated 10 to 20% of people in theUnited States (33) Two cases studies using VR exposure to treat fear of ¯yinghave appeared in the literature The ®rst, involved a subject who had not ¯ownfor 2 years before treatment (28, 34, 35) She had become progressively moreanxious about ¯ying and had ®nally discontinued ¯ying for business or pleasure.After seven sessions of anxiety-management techniques, such as relaxation skills

antici-and thought stopping, antici-and six sessions of VR exposure in a virtual ®xed wingaircraft, she was able to ¯y again with her family on vacation, self-reporting lessfear on exposure.

North et al (36) did a case study with one of the subjects who had beentreated for fear of heights in the ®rst VR study After ®ve VR exposure sessions

in a virtual helicopter, he was able to ¯y with less self-reported anxiety.Research is now under way at the Center for Advanced Multimedia Psy-chotherapy in San Diego to look at VRGET vs imaginal exposure to treat fear

of ¯ying (23, 24) Real-time physiologic monitoring and feedback are also beingincorporated for one group During the exposure sessions, physiology is moni-tored for all patients Based on studies initiated by Jung in 1907, which revealedthat skin resistance was a means to objectify emotional tones previouslythought to be invisible, skin resistance levels are being fed back to patients as anindicator of arousal and anxiety Jung found that skin resistance tends to re¯ectmental events more quickly and with more resolution than other physiologicalmeasures (20) Because other VR studies have not reported these physiologicparameters, the San Diego Study is monitoring heart rate, respiration rate, pe-ripheral skin temperature, and brain wave activity Analysis will reveal whetherother physiologic data may be important to note as patients become desensi-tized to the phobic stimuli Emotional processing theory indicates that tochange a fear structure, it must be activated and information incompatible withthe fear must be provided For instance, if a patient has a fear of ¯ying thatcenters around crashing and during therapy numerous imagined or in vivo

¯ights are taken with no crashes, the patient's fear structure would be providedwith incompatible information that should modify it (26) According to Foaand Kozak (26), there are three indications that emotional processing is occur-ring: physiologic arousal and self-reported fear during exposure, diminution offear responses within sessions, and a decline of arousal across sessions (37) Thisstudy will examine how physiology, self-report measures, and behavioral indicescorrelate

All patients receiving VR treatment will receive two sessions of relaxationtraining before exposure treatment The groups receiving VRGET will then beallowed to progress through a series of VR scenarios, including sitting on theplane with the engines on and engines o¨, taxiing down the runway, taking o¨,experiencing a smooth ¯ight, experiencing a turbulent ¯ight with thunder-storms, and landing Exposure will be once per week for 6 weeks Patients re-ceiving imaginal exposure will be guided by the therapist through visualization

of an individualized fear hierarchy, which the patient and therapist have createdduring an initial two sessions of relaxation training

2.3.3 Fear of Spiders

Carlin et al (38) completed a case study to treat fear of spiders using both VRand augmented reality The subject had been phobic for 20 years Treatmentinvolved exposure to a tarantula and a black widow in the virtual world, then

eventually touching a furry toy spider while viewing a corresponding spider inthe virtual world After twelve 1-h sessions, the patient was able to go camping inthe woods and successfully encounter a spider in her home The 1-year follow-upindicated that treatment gains were still intact.

2.3.4 Claustrophobia

Bullinger et al (39) have begun to explore VR for the treatment of phobia, using a head-mounted display (HMD) and a three-dimensional (3-D)joystick Claustrophobia, which has a lifetime prevalence of 2%, involves fear

claustro-of enclosed places During virtual exposure, the patient is allowed to increase ordecrease the size of a virtual room, bringing the walls closer and closer as de-sensitization continues The patient can at any time go through a virtual door atone end of the virtual room and end the simulation at any time that anxietybecomes too intense Patients in the initial study received 3 sessions per weekfor 4 weeks (12 sessions) Initial results show a decrease in overall anxietyscores

2.3.5 Fear of Driving

Berger et al (40) are currently conducting a study on the treatment of fear ofdriving The study compares imaginal exposure therapy and VR exposuretreatment Data collection is in the initial stages Because a fear of driving mayoccur as part of a simple phobia or as part of agoraphobia and because drivingde®cits are often seen after head trauma, stroke, or other physical insult, thisarea has a wide range of potential applications for VR technology

2.4 SOCIAL PHOBIA

Social phobia has a lifetime prevalence of 13.3% with a 30-day prevalence ported at 4.5% Of those with social phobia, 59% also have a speci®c phobia(21) Social phobia may include such things as fear of eating in public, signingchecks in front of others, or and public speaking (9)

re-Those with social phobia show increased risk of alcohol abuse, alcoholdependence, and suicide attempts (41) It is often di½cult to arrange in-vivoexposure for social phobia if it involves, for example, confronting authority

®gures Treatment must, therefore, resort to imaginal exposure, which has vious limitations (15) It would be much more powerful to digitize the authority

ob-®gure's face into the virtual world and allow the patient to do repeated roleplaying With intelligent software, perhaps driven by neural networks, the vir-tual personae of the authority ®gure could teach social skills and assertion,provide systematic desensitization, and react di¨erently according to how thepatient handled himself or herself

The most common social phobia is a fear of public speaking It is the third

most common psychiatric disorder, and was listed by the Book of Lists (42) asthe number one fear among Americans (43) At a 1983 American College ofCardiology meeting, 13% of speakers admitted to having used b-blockersbefore speaking at the meeting (44) Treatment usually involves cognitive-behavioral therapy, medications, or a combination of the two Therapy mayinvolve exposure, reframing thoughts about a social scene, social skills training,

or relaxation techniques Medications may include MAO inhibitors or blockers (which are used on the day of performance) (14) In a Wall StreetJournal article (45), stage fright was said to a¿ict approximately 20 millionpeople at some point during their lifetime High blood pressure medications (b-blockers) such as propranolol have been used for years to stop the physiologice¨ects of stage fright, such as hand tremors and rapid heart beat, but anti-anxiety drugs and antidepressants are now being explored for treatment Thedrawback to antidepressants is that they must be taken daily to work; but somenewer short-acting antianxiety drugs can be used as needed There is no indi-cation that the use of drugs has a lasting a¨ect on curing stage fright; however,thus for many patients a better answer might be behavioral therapy

b-North et al (22) have begun using VR to treat fear of public speaking.Subjects in the initial study were exposed to a virtual audience and experiencedmany of the same symptoms someone with a fear might experience when infront of a real audienceÐdry mouth, sweaty palms, and increased heart rate.Self-reported anxiety (SUDs) and scores on the Attitude Toward PublicSpeaking Questionnaire decreased after treatment

A concomitant disorder with social phobia is body dysmorphic disorder Ifthis is present, role playing during therapy appears to increase the chance ofsuccessful treatment (41) A good use of VR technology might be to have thepatient role-play in a VR environment in which di¨erent scenarios can be actedout and then discussed This may provide a beginning point for meaningful di-alogue between therapist and patient

OCD strikes equal numbers of men and women, a¿icting 1 in 50 people, or

5 million Americans (3) As many as 80% of patients with OCD may also haveconcurrent depression OCD generally begins when a patient is his or her teens

or early adult years and appears to run in families (46)

The most e¨ective behavioral treatment used for OCD is exposure and sponse prevention In this treatment, the patient is exposed to situations that

re-normally cause compulsive behavior The patient is then prevented from forming the associated ritual Results from 18 studies conclude 51% of patientsare symptom-free after treatment and another 39% are moderately improved(47) Two medications used to treat OCD are clomipramine and ¯uoxetine.Studies on the medications e¨ectiveness have shown mixed results, but the cer-tainty is that relapse should be expected when medications are discontinued(48).

per-A group in Georgia is now exploring the e½cacy of treating OCD withVRGET (22) Moving in this direction, another study that began in 1994 dealswith a telephone interface for simulated behavior therapy of OCD The system,called BT Steps, appears to be helpful in reducing symptoms (49) The programhas nine steps, four that prepare patients, two that set them on a therapeuticcourse, and three that continue them through their therapy The steps involveeducation, behavioral assessment, a treatment plan, treatment, and relapseprevention It is an interactive voice-response system using a prerecorded voicethat responds to the callers' answers to several questions Step 7 in the program,which is the ®rst exposure and ritual prevention session, may be done again andagain to maintain gains There are 700 frames within the computer-assistedphone system The phone system remembers the patient's previous responsesand helps the patient build an exposure and ritual prevention hierarchy Duringthe ®rst controlled study, 17 subjects completed at least two sessions using thesystem Of those completing the sessions, a decrease in discomfort of >50%was obtained; 85% of patients subjectively rated themselves as very much ormuch improved (49)

2.6 POST-TRAUMATIC STRESS DISORDER

Post-traumatic stress disorder (PTSD) is a heterogeneous disorder that mayoccur after exposure to actual or threatened events of death or serious injury toself or others Symptoms include dissociation, ¯ashbacks, and increased anxiety

or arousal (9) Antidepressants, anxiety-reducing medications, support fromfamily and friends, and cognitive-behavioral therapy (with some exposure in-volved) can help with recovery (14)

Approximately 15.2% of the men and 8.5% of the women stationed in nam were found to be su¨ering from PTSD 15 or more years after their service.Because of its varied symptomatology and resistance to treatment, many treat-ment modalities have been investigated (50) Currently, only 66% of peoplewith PTSD fully recover (51) Because most studies have used some form ofexposure therapy as part of the treatment regimen, a group led by Hodges isexploring VRGET at the Atlanta Veteran's Administration Hospital to treatPTSD Currently, ®ve case studies are being performed using VRGET Treat-ment involves exposing the veterans to virtual Huey helicopters that will ¯ythem over the jungles of Vietnam Treatment will involve nine 60-min individ-ual sessions over a period of 5 weeks (52)

Viet-VA researchers identi®ed biochemical markers that are associated withPTSD In addition, they found psychophysiologic instruments to be reliableand valid at discriminating between PTSD and non-PTSD persons VRGETand physiologic feedback may lead to treatments that will bene®t not only vet-erans but also those su¨ering from PTSD owing to violent crimes, natural dis-asters, and terrorism (50).

2.7 FUTURE TARGETS FOR VR TREATMENT

2.7.1 Acute Stress Disorder

Acute stress disorder (ASD) is diagnosed when someone is exposed to a matic event but su¨ers from 2 days to <4 weeks with symptoms including dis-sociation, ¯ashbacks, and increased anxiety If symptoms persist for more than

trau-1 month, the PTSD diagnosis is given (9) Although no VR application is rently available to treat ASD, its use might allow for powerful, immediatetreatment of the patient following a stressful event This might allow the patient

cur-to recover from the stressor without developing PTSD

2.7.2 Generalized Anxiety Disorder

Generalized anxiety disorder (GAD) is characterized by worry and excessiveanxiety that occur more often than not for a period of 6 months or more.Worry and anxiety are not directed toward one speci®c event or stimulus butare rather more di¨use and occur about several activities Because of the anxi-ety, restlessness, easy fatiguability, irritability, sleep disturbances, concentrationdi½culties, or muscle tension may occur GAD often co-occurs with otheranxiety disorders, mood disorders such as depression, substance-related dis-orders, and psychophysiologic disorders often associated with stress such asirritable bowel syndrome and tension headache There is a 5.1% lifetime prev-alence, with most cases beginning between age 15 and 45 (9)

Successful treatments used for GAD include nonbenzodiazepine anxiolytics(e.g., buspirone), benzodiazepines (e.g., xanax and klonopin), relaxation tech-niques, cognitive-behavioral therapy, and biofeedback (www.nimh.nih.gov).Among anxiety disorders, benzodiazepine drug treatments for GAD have beenthe most competently and extensively tested Results of numerous well-controlled, double-blind studies indicate short-term value for using these drugsbut no long-term e¨ectiveness Given the side e¨ects associated with the drugs,such as impaired cognitions and psychological dependence, another form oftreatment would be considered preferable (14)

To target somatic components of GAD, biofeedback and relaxation niques have been investigated Some studies (53) have shown superiority ofEMG biofeedback over relaxation training, but others (54) have shown re-laxation training superior to biofeedback Both, however, have been shown assuperior to no treatment (14)