Virtual reality in rehabilitation

BMJ 1996;312:4-5 (6 January)

Editorials

Virtual reality in rehabilitation

Potential benefits for people with disability or phobias

Virtual reality is an interactive, computer generated environmentthat simulates the real world. Accessible via an interface thathas been adapted to the human senses, it provokes in the userthe sensation of immersion, like Alice in Wonderland crawlingdown the rabbit hole and finding herself in a new fantasticworld.¹ A dataglove wired with fibreoptics to record the degreeof bending of fingers and wrists, a head-mounted display, andan exoskeleton surrounding the user's limbs to give feedback,project the user into the virtual environment and report backon his or her actions within it. The user can react intuitivelyto the virtual world, any actions being detected by positionand movement sensors placed strategically on his or her body.A computer calculates the changes occurring in the virtual worldaccording to the rules chosen by its creator and feeds the resultsback to the user. Applications appeal to disabled and non-disabledpersons alike²: telepresence, for example, allows specialiststo operate on patients in remote hospitals. Three applicationsof immersive virtual reality in rehabilitation,³ two of themtherapeutic, are discussed below:

Physically disabled students are often excluded from participatingin laboratory experiments because of their reduced mobilityand manual capabilities or the risk that they might lose controlwhen in a hazardous environment. A virtual laboratory for disabledstudents has been studied.⁴ Because the interface has to meetthe special needs of the user, the researchers selected a relativelyhomogenous population. The students all had spinal cord injuriesranging from C2 to T1 and were of at least average intelligenceand emotional stability. The objects in the virtual laboratoryincluded a representation of a traditional laboratory, withsymbols representing information and illustrating principlesof physics, and a virtual vehicle that allows users to experiencethe physical phenomena under investigation, such as the accelerationcreated by a force. The students encountered few problems actingwithin the virtual world, but some were not able to put on theequipment independently or adjust it over time to avoid painfulpressure points.

Acrophobia or fear of heights is another condition in whichvirtual reality may have a role. Rothbaum et al⁵ performed acontrolled trial of graded exposure to heights using virtualreality. Sufferers were randomly assigned either to treatmentor to a waiting list. The treatment group had seven weekly 35-45minute sessions on virtual balconies, high bridges, or in theglass elevator of a skyscraper. A therapist watched and commentedon the exposure, during which the patient's subjective discomfortwas monitored. Before and after treatment, anxiety, avoidance,distress, and attitudes were measured using standard questionnaires.The results were comparable to those of standard therapy withstepwise exposure to real, frightening but sustainable stimuli.However, there was no comparison group on conventional treatment,no follow up data, and the numbers were small. Also the subjectswere volunteers, rather than people actively seeking treatment.

The third application is akinesia or freezing gait in Parkinson'sdisease. This debilitating symptom is characterised by progressiveshortening of the patient's stride and ultimately the inabilityto move forward at all. Treatment with drugs is marred by on-offeffects and side effects such as dyskinesia. However, patientswith akinesia can walk over objects or through doorways withlittle effort, an effect known as kinesia paradoxa. Using avirtual reality technique called augmented reality, Weghorstet al projected virtual objects on to the patients' physicalworld to give them the impression that they were walking overor through them, thereby restoring their mobility.⁶ They suggestedvarious aproaches to mimic steady objects on the ground whilethe patient is moving. However, existing visual displays arenot bright enough to compete with ambient light, while severeakinesia demands the creation of a highly realistic and staticrepresentation of the obstacle. Dyskinesia, too, was found torespond to augmented reality, suggesting a more complex mechanismunderlying kinesia paradoxa.

Using virtual reality techniques in rehabilitation raises ethicalconsiderations, especially when mentally challenged or veryyoung people are involved.⁷ (In the examples given above, allthe patients gave informed consent.) In addition, virtual realitycould have undesirable side effects due to equipment failure,fatigue, or motion sickness.⁸ ⁹ It could also cause unintendedchanges in the patient's attitude and behaviour, worsen existingdifficulty in distingishing between reality and delusion (forexample in patients with schizophrenia), or cause distress fromthe virtual experiences themselves.

The applications described above exemplify how virtual realitycan help even severely disabled people to participate and contributesafely even in hazardous and complex tasks. The new technologycan provide corrective experiences that can ameliorate attitudesand anxieties. It could also yield new insights into diseasemechanisms while providing ingenious and effective tools tore-enable handicapped people. Many more examples could be cited,¹² ³ ⁴ ⁶ some of which will be presented at a conference on medicineand virtual reality in San Diego later this month. To reducethe cost, the optical resolution and complexity of the environmentcan be kept low in most rehabilitation applications. The newtechnology offers great potential benefit in rehabilitationbut remains to be properly explored and evaluated.