eMedicine Specialties > Clinical Procedures > Neurologic Procedures
Virtual Reality Biofeedback in Chronic Pain and Psychiatry
Updated: Jun 24, 2009
Introduction
Active modification of nociceptive perceptual states through biofeedback has been of considerable benefit in reducing patient discomfort related to several disease processes. Virtual reality (VR) allows substantial amplification of traditional biofeedback efficacy by completely immersing the patient in the process. To accomplish this, an immersive, active patient environment is generated to achieve more effective pain and anxiety reduction in the context of chronic pain, headache, and anxiety states. While the application of VR in this context is new, the neuropsychological basis for its effects has been well studied in a variety of pain and psychiatric disorders.
Pain Physiology: Why Should Virtual Reality Work?
Recent investigations with functional MRI studies have reinforced the notion that pain perception and affective response are dependent on several topographically diverse regions. In addition to primary and supplementary sensory areas, the insula also is involved, although overlap of nociceptive and nonnociceptive stimuli can produce ambiguity in the responses. Cingulate cortex has been implicated in pain processing, and also in general attention mechanisms involved with demanding tasks. In determining pain response levels, central processing appears more important than simple rate of firing of spinal neurons over regions of activation at segmental levels.
A more recent positron emission tomography (PET) approach has defined a clearer role for several regions. Gating function determining pain threshold appears to be located in anterior cingulate cortex and inferior frontal areas along with the thalamus. Pain intensity determination appears to involve periventricular gray and posterior cingulate cortex activation. The actual affective (unpleasantness) component appears to be related to activation of the posterior sections of the anterior cingulate cortex.
At all levels in the pain pathway, processing of discriminative and affective pain components appears to be separate, and modulation of processing encompasses bidirectional (ascending and descending) control systems. Descending pathways arising in cortex, thalamus, and brain stem affect processing dynamics at the spinal levels. Particularly strong bulbar descending inhibitory effects on dorsal horn nociceptive neurons have been described. Basal ganglia responses also may modulate pain perception.
Modulation of pain perception by stimulation and attention
In view of these physiological mechanisms, that redirection of attention can alter pain perception markedly is not surprising. For example, such redirection has been shown to modify nociceptive responses in neuronal populations in the dorsal medulla at the same time that pain unpleasantness characteristics are modified. Such attentional effects, arising from hypnosis anesthesia, can suppress spinal reflexes.
In contradistinction to inhibitory mechanisms, central mechanisms are also capable of producing pain hyperexcitability through neuroplastic mechanisms preconditioned by frequent noxious stimuli. Furthermore, hypnosis analgesia and acupuncture analgesia appear to affect pain perception without participation of the endorphin system. This suggests that some of these modulatory systems may be recruited during such procedures. Acupuncture has been shown to provide pain relief for diabetic neuropathy. At the same time, transcutaneous electrical nerve stimulation (TENS) has been shown in animal studies to exert a direct, segmental inhibitory influence on nociceptive dorsal horn neurons.
The multiplicity of activation at spinal, brainstem, diencephalic, and cerebral levels, coupled with the multidirectional, modulatory influences on pain processing signals, provide, at least conceptually, ample substrate for the effects of biofeedback described below.
Two major effects on pain perception are reasonable, but difficult to quantify, on the basis of these described mechanisms. A pronounced time integration effect on pain perception is based on the level of pain and its duration. Thus, a moderate, nagging, persistent pain may wear the patient down as much as a brief but more severe pain. Periods of freedom from pain allow this effect to decay, thus resetting pain perception levels. The attention-diverting amelioration of pain is bidirectional (ie, focusing attention on the pain makes it worse). This is especially evident when the patient's anxiety concerning the cause of pain is increased.
For example, a patient with persistent low-level abdominal pain will perceive it as much less severe if reassured that the cause is benign and as more severe if informed that the cause might be a malignant condition. A more dramatic example occurs in the course of sports or other physical injury environments. Often serious injuries are not perceived as painful until after the condition of high motivation (eg, scoring the touchdown, fleeing an assailant) has passed.
Standard Biofeedback Applications in Pain Treatment
Multiple mechanisms for pain modulation are based on stimulus input. The rationale behind biofeedback for pain treatment is that diverting or competing stimuli may improve both immediate pain levels during the biofeedback procedure and during intervals between exposures. However, applications of biofeedback techniques have been largely empirical. With virtual reality, the capacity to increase levels of immersion is likely to increase the power of the technique.
Before considering such approaches, certain basic aspects of standard biofeedback therapy should be considered. The basic pain biofeedback paradigm is a demonstration to the patient of the effect of internal emotional states on global physiological functions (eg, skin resistance, pulse, respiratory pattern, EEG) and focal processes (ie, electromyographic [EMG] activity) in regions of pain. Studies of several conditions have demonstrated the positive effects of this approach, usually combined with other physical therapy modalities.
Peripheral pain
- Patients with fibromyalgia have benefited from biofeedback involving EMG recording of the trapezius muscle, with significant reductions in general intensity of pain and EMG activity.
- Chronic upper extremity pain due to traumatic brachial plexopathy and severe generalized trauma has been shown to respond well to physical therapy, including audiovisual biofeedback coupled with electrical stimulation.
- Cervical radiculopathy may respond symptomatically and objectively to traction controlled by a patient biofeedback closed-loop system based on cervical EMG activity, with a faster response than to conventional traction therapy.
Headache
- Migraine
- Biofeedback has been shown to be effective in selected migraine patients as an adjunctive preventive therapy. Treatment effects of biofeedback for migraine may be sustained in some patients.
- Biofeedback-assisted relaxation therapy has decreased pain and medication use significantly in patients with migraine, particularly those demonstrating higher initial middle cerebral artery blood flows, suggesting some specificity for individual patients in physiological response.
- Biofeedback, in conjunction with behavioral modification, has been useful in the majority of migraine patients in some studies, with effects lasting 1 year or longer after treatment.
- Biofeedback based on blood volume/pulse measurement has proved a useful adjunct to other therapeutic modalities, including cognitive/behavioral techniques, in the treatment of migraine.
- Biofeedback relaxation training has been shown to act synergistically with propranolol therapy in reducing migraine frequency and analgesic usage.
- Other forms of headache
- Trapezius-based EMG biofeedback has been found more effective than frontalis-based feedback in the treatment of tension headache.
- EMG biofeedback therapy combined with relaxation techniques has shown favorable results in treating tension headache, both subjectively and by EMG measurements and exteroceptive response times.
- Posttraumatic headache, like migraine and tension headache, is responsive to biofeedback relaxation therapy, with the majority of patients experiencing at least a moderate reduction in symptoms.
- Posttraumatic headache symptoms have been found to respond favorably with relaxation-oriented biofeedback, with patients reporting at least a moderate improvement in ability to relax and cope with the pain.
Generalized pain
- More general application to pain syndromes also has been beneficial.
- Biofeedback, in conjunction with electrical stimulation and more conventional relaxation techniques, has been shown to be effective in managing postsurgical pain.
- Use of multimodality biofeedback has reduced pain, affective distress, and objective measures of disease activity in patients with rheumatoid arthritis (including clinic visits and hospitalization time).
- Biofeedback techniques of assisted relaxation can reduce stress effects in hypertensive patients and also can reduce the incidence of hypotensive effects, including neurocardiogenic syncope.
Virtual Reality Applications in Biofeedback
Virtual reality (VR) techniques include a broad range of technologies. The common elements include an audiovisual system to present images and sounds controlled by the patient and his environment; a tactile input system, which can include hands; more extensive extremity contacts; and even whole-body environments. The VR system should allow for modification of stimuli based on the response of the patient.
The degree of patient sensory involvement, or immersion, varies with system configuration.
- In the simplest case, a single modality may be presented (eg, white noise or music presented through earphones to a dental patient).
- At the other extreme is a full immersive system comprising a head-mounted audiovisual display, body suit with sensors and tactile-temperature sensation generators, olfactory sensory generators, and provision for limited body acceleration. With this fully immersive system, the patient's perceived environment varies with head movement and with motion, sensed by the body suit.
- An intermediate configuration, suitable for biofeedback applications, might include a large-screen television display, high-quality audio system, and body tactile input through vibrating motors and subwoofer speaker system. The tactile input, designed primarily to stimulate dorsal columns in the back and extremities, is keyed to the audiovisual stimulation.
An example of presented material would be a seascape. The images of ocean waves breaking with associated audio produce a soothing effect. The wave perspective and the volume of the sound can be made responsive to patient input, either directly (by manipulation of a glove or similar input device) or indirectly by measurement of skin resistance (GSR), EMG (cervical, facial, dorsal), pulse, blood pressure, and heart rate. EEG can be added as well.
In a patient environment directed toward providing biofeedback, a totally immersive system carries increased risk of cybersickness and a feeling of isolation in some patients. In such patients, a graded approach can be used, with the initial system configured as an intermediate immersive system. Several scenes for relaxation and anxiety relief can be presented and switched by patient preference or biofeedback response. At the same time, a record is made of the patient's physiological response. Interaction with the therapist includes conventional biofeedback techniques. The power of this approach lies in the complete involvement of the patient in the biofeedback process.
Traditional methods have employed counseling and patient observation of EMG, pulse rate, and other physiological functions. For many patients, this approach is anti-intuitive for two reasons. The graphic display of physiological functions often holds little interest for the patient, who is concerned primarily with symptom relief, not physiology. The interaction of the patient with the feedback environment primarily involves verbal communication with the therapist, who advises the patient on techniques of relaxation.
While this patient-therapist interaction is important from an educational perspective, the core of the feedback process is involvement of the patient on a level of active and intuitive participation. The prolonged effects of biofeedback, when they are optimized, depend on the patient's awareness of the effects of altered perceptual and attentive states produced during the feedback process. Allowing the patient to realize that he can generate such alteration, both during the biofeedback exposure and independently, is the most important goal of therapy.
Chronic pain produces an additive, integrative effect on patients. Not only the instantaneous severity of the pain, or anxiety, is deleterious. The cumulative effect of even moderate, but prolonged, pain can produce a higher overall level of discomfort and anxiety than pain of more severe intensity but shorter duration. A period of respite from the pain, and distraction from it, can reset pain thresholds and intensity perception levels. The same considerations apply to anxiety. Limbic interactions determining the level of discomfort evoked by pain are the basis for the music/white noise effect and the effects of hypnosis.
The power of these effects, when properly harnessed, can be profound, and VR appears capable of providing a mechanism for achieving this result. Patients who have undergone cingulectomy report perception of pain, but without the negative affective component. Normal subjects can learn to dissociate the negative affective component of moderate, and even severe, pain from the sensation itself. VR techniques allow the patient to structure his environment to maximize this effect.
By extension, many of the same considerations can be applied to free-floating and specifically localized anxiety states. VR environments have been used quite successfully in these settings. While conventional biofeedback techniques have generally been of little help in psychotic disorders, environment-based anxiety states have shown promising responses, with clinical improvement seen in fear of flying, acrophobia, and arachnophobia. The salient feature is creation of a sufficiently realistic environment to evoke the phobic response while maintaining patient cognition of the safety and control available in the test environment. As discussed below, by immersing the patient, while still maintaining patient control, the disparity between the phobic response and the actual danger becomes clear through the neuroplastic modification of the patient's responses and cue perception. These mechanisms parallel those involved in pain reduction.
Neuroplasticity - Demonstration of potential
The therapeutic promise of VR approaches in several neurological conditions is based on central neuroplasticity. Potential effectiveness has been demonstrated in motor disorders and in the cognitive and perceptual realms. This potential, both theoretical and clinical, for the expansion of these techniques into motor, sensory, and biofeedback interactive systems follows from a variety of laboratory and clinical situations.
In addition to the standard biofeedback techniques, additional modalities are currently being developed, using custom-design video analysis techniques. Such a system includes the following components:
- Audiovisual stimulator
- A variety of scenic material is available, including nature scenes, virtual world scenes, and general video and graphic material (see Image 4).
- Audio stimulation includes musical selections, sounds derived from the video, and computer-generated audio appropriate to the visual material.
- Moderate immersion technique is used initially, with large-screen video.
- A head-mounted display may be appropriate for some patients, but is phased in gradually to avoid cybersickness and isolation issues at the outset.
- Tactile stimulator: Primarily, this includes dorsal column stimulation in the form of vibration modulated by the audio and visual material.
- Biofeedback interface: Initially, monitoring of standard psychophysiological functions, including GSR and EMG as well as pulse and respiration, interacts through custom programming with the stimulus modalities.
Clinical applicability of VR biofeedback
Patients benefiting from this therapy initially would include those with subacute or chronic pain (eg, myofascitis, fibromyalgia, arthritis), posttraumatic pain, postsurgical pain, or headache (eg, migraine, tension, chronic daily, posttraumatic). As the program expands, application also may extend to certain psychiatric conditions, particularly anxiety states and phobic states. The system is likely to provide benefit to terminally ill patients. Another potential avenue for investigation is stress reduction in patients with multiple sclerosis.
As an example of the power of the immersive technique, considerable reduction in pain is possible for burn patients during debridement by employing a video game or distracting virtual environment. The key elements in this approach are the immersion and the level of patient control of the virtual environment. Early reports indicate that a semi-immersive environment also may be helpful for patients with cancer.
Computer as Therapist
In the previous section, Virtual Reality Applications in Biofeedback, the relationship between patient responses and the stimuli presented is emphasized. Traditionally, the therapist interprets physiologic responses, and the patient's demeanor, as confirmations of verbal descriptions from the patient regarding the efficacy of treatment. However, advances in technology have allowed more of that interpretive role to be transferred to the computer. Virtual reality (VR) biofeedback is a bidirectional interface comprising stimulus output modalities as described and input modalities that can receive not only basic physiologic responses but also changes in facial expression. Tracking of facial features has been available for several years on PC platforms, but what has not yet been fully developed is the extraction of behaviorally related data in scalar form for the processing video facial data.
In the author's laboratory, active development has been proceeding (patent pending) in designing video-to-scalar conversion methods to produce statistically measurable correlation with behavior. For example, processing of video facial data yields eye blink, yawn, and head position measurements that are useful in determining states of alertness versus drowsiness. More precise measurements have been achieved with refinement of these techniques. Demonstration of these techniques is available through VR Neurotech. For example, data from the eye and mouth regions can produce highly specific characterization of emotional and arousal states.
Image 1 shows this methodology applied to extract information from video monitoring of the face in the orbital region. The upper trace shows the position of the eyebrow region, and the lower trace shows the lid position (palpebral fissure). Good time resolution and quantitative position data are obtained and can be correlated with the patient's attention and emotional response.
Similarly, Image 2 demonstrates data for the mouth region and includes good characterization of the time course of jaw positioning. This level of accuracy allows distinction between actual yawning and other types of mouthing movements, such as talking or even automatisms (for further discussion, particularly regarding partial complex seizure diagnosis, see Virtual Reality to Evaluate Motor Response During Seizure Activity).
An example of such real-time acquisition is explained in Image 3. Here, both regions are acquired simultaneously. The colored rectangular areas superimposed on the raw video indicate the regions of interest (ROIs) where the image analysis takes place. The eye ROI activity is shown in the first and third traces, as labeled, and the mouth ROI activity is shown in the second and fourth traces, as labeled. This depiction explains the real-time acquisition shown in the movie clip in Image 3. Here, the actual acquisition process is seen in real time.
Processing of this ROI configuration data allows the computer to interpret in real time whether the monitored movements are likely to represent physiologically significant activity. The movie clip in Image 4 demonstrates this process. The audio represents the real-time call-out by the computer of its interpretations: "open" for active eye opening, "close" for active eye closing, and "mouth" for movements that are candidates for relevant actions (yawning in this case).
This behavioral filter represents a first approach based upon the techniques developed to date in the author's laboratory (patent pending). Further refinements are proceeding to improve the accuracy of these behavioral interpretive algorithms. Further studies are also in progress to relate these data as 12 channels obtained from 2 cameras for the prediction of drowsiness in drivers, as well as other behaviors relevant to the biofeedback sphere.
By extension of the drowsiness work, changes in facial features will likely be of predictive value for determining anxiety versus relaxation. Such input to the biofeedback system described above would constitute a major functional improvement over collecting simple physiologic data, such as EMG and GSR, and would be noninvasive.
A major obstacle to bringing these biofeedback techniques to general use by patients in the field is the complexity, with its associated cost, of currently available techniques. However, by using digital signal processing (DSP) methods, reducing the input devices for such patient monitoring data to stand-alone boards that can be produced quite inexpensively is possible, and these can thus be deployed widely. Such a DSP system is currently under construction in this author's laboratory.
The computer responses need to be directed to produce an immersive environment. Optimally, this would comprise wide-angle, preferably 3D video, surround sound, posterior column stimulation (vibrational components), and, in selected environments, might even include transcutaneous nerve stimulation (in chronic pain situations). These responses need to be keyed and modulated by the patient's own responses. Biofeedback inputs, including facial feature changes, will control such responses.
An example of such an approach is shown in Image 4 and in the movie clip in Image 6. Several types of stimuli, visual and auditory, can be optimized for individual patients and controlled by patient responses. For example, in the movie clip in Image 6, motion of the bird, the sea, and their intermixture can be modulated and correlated with the patient's response. The behavior of the artificial designs, including the rhythmicity of their movements and their interaction with the more natural stimuli, can also be controlled by the patient's response.
In the example shown, sequences of a virtual pas-de-deux between the design avatar and the bird are present. The audio component intermixes music and sea sounds. Of course, because of technical limitations, the clip that can be shown on the Web encompasses only a fraction of the immersivity and quality of the stimuli that must be brought to bear on the problem. However, even in this clip, one can get a sense of the possibilities of the medium to tap the physiologic resources that exist in the human nervous system. Indeed, the patient can compose his or her own symphony of stimuli to interact with the intrinsic neuroplasticity involved in the generation of unpleasant sensations and their desired suppression.
Psychiatric Applications
The immersive environment has shown considerable promise as an intervention tool for several psychiatric disorders. The characteristics of immersion, attention redirection, cognitive resetting, and active environmental control by the patient all appear to contribute to its effectiveness. Following are a few examples of early indications of efficacy.
- Eating disorders
- VR is uniquely suited to evoke more rational cognitive processes to establish insight into the misperception of body image.
- VR systems actively allow a patient to characterize body image and compare it to an actual image in real time to demonstrate the misperception.
- Acrophobia, agoraphobia, arachnophobia, fear of flying: The immersive and cognitive resetting properties of VR have shown considerable promise in ameliorating anxiety and phobic states.
- In theory, these desensitization techniques also may be applicable in obsessive-compulsive disorders.
Conclusions
- Virtual reality (VR) technology will radically alter concepts of biofeedback, physical therapy, and desensitization therapy in pain management and psychiatry.
- Applications of VR to these therapeutic situations are still new and require development.
- Patients can benefit from VR techniques in a variety of clinical settings.
For excellent patient education resources, visit eMedicine's Muscle Disorders Center. Also, see eMedicine's patient education article, Chronic Pain.
For related information see Medscape's Advanced Approaches to Chronic Pain Management Resource Center.
Multimedia
 | Media file 1: Real-time acquisition of orbital position data including eyebrow region and palpebral fissure. These data allow charting of eye blinks and other relative position changes of the orbital region. |
 | Media file 2: Yawn detection by monitoring the upper and lower mouth regions. The algorithm operates essentially as in Image 1. |
 | Media file 3: Real-time facial feature acquisition for the eyes and mouth. Traces 1 and 3 show the position of the eye structures; traces 2 and 4 show the upper and lower mouth regions. The algorithm operates similar to that of Image 2. Click here to view video clip. |
 | Media file 4: Processing of ROI configuration data allows the computer to interpret in real time whether the monitored movements are likely to represent physiologically significant activity. The movie clip demonstrates this process. Click here to play video clip. |
 | Media file 5: Experiential enhancement with virtual reality (VR) biofeedback. Stimulation can be tailored to the patient's responses and monitored by patient input and physiological functions. Imagery similar to this can be combined with audio stimulation (eg, music and sea sounds) and stimulation of other modalities to engage neurophysiologic pain-suppression mechanisms. |
 | Media file 6: Several types of stimuli, visual and auditory, can be optimized for individual patients and controlled by patient responses. For example, motion of the bird, the sea, and their intermixture can be modulated and correlated with the patient's response. Click here to play video clip. |
Keywords
VR, psychiatric disorders, pain disorders, pain physiology, biofeedback in pain treatment, virtual reality applications in biofeedback, psychiatric applications of biofeedback
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References
Abuaisha BB, Costanzi JB, Boulton AJ. Acupuncture for the treatment of chronic painful peripheral diabetic neuropathy: a long-term study. Diabetes Res Clin Pract. Feb 1998;39(2):115-21. [Medline].
Arena JG, Bruno GM, Hannah SL, Meador KJ. A comparison of frontal electromyographic biofeedback training, trapezius electromyographic biofeedback training, and progressive muscle relaxation therapy in the treatment of tension headache. Headache. Jul-Aug 1995;35(7):411-9. [Medline].
Arendt-Nielsen L, Petersen-Felix S. Wind-up and neuroplasticity: is there a correlation to clinical pain?. Eur J Anaesthesiol Suppl. May 1995;10:1-7. [Medline].
Bajuk S, Jelnikar T, Ortar M. Rehabilitation of patient with brachial plexus lesion and break in axillary artery: case study. J Hand Ther. Oct-Dec 1996;9(4):399-403. [Medline].
Chudler EH, Dong WK. The role of the basal ganglia in nociception and pain. Pain. Jan 1995;60(1):3-38. [Medline].
Coghill RC, Talbot JD, Evans AC, et al. Distributed processing of pain and vibration by the human brain. J Neurosci. Jul 1994;14(7):4095-108. [Medline].
Cross SA. Pathophysiology of pain. Mayo Clin Proc. Apr 1994;69(4):375-83. [Medline].
Derbyshire SW, Vogt BA, Jones AK. Pain and Stroop interference tasks activate separate processing modules in anterior cingulate cortex. Exp Brain Res. Jan 1998;118(1):52-60. [Medline].
Disbrow E, Buonocore M, Antognini J, et al. Somatosensory cortex: a comparison of the response to noxious thermal, mechanical, and electrical stimuli using functional magnetic resonance imaging. Hum Brain Mapp. 1998;6(3):150-9. [Medline].
Garrison DW, Foreman RD. Effects of transcutaneous electrical nerve stimulation (TENS) on spontaneous and noxiously evoked dorsal horn cell activity in cats with transected spinal cords. Neurosci Lett. Sep 27 1996;216(2):125-8. [Medline].
Ham LP, Packard RC. A retrospective, follow-up study of biofeedback-assisted relaxation therapy in patients with post-traumatic headache. Biofeedback Self Regul. Jun 1996;21(2):93-104. [Medline].
Holroyd KA, France JL, Cordingley GE, et al. Enhancing the effectiveness of relaxation-thermal biofeedback training with propranolol hydrochloride. J Consult Clin Psychol. Apr 1995;63(2):327-30. [Medline].
Kiernan BD, Dane JR, Phillips LH, et al. Hypnotic analgesia reduces R-III nociceptive reflex: further evidence concerning the multifactorial nature of hypnotic analgesia. Pain. Jan 1995;60(1):39-47. [Medline].
Kropp P, Gerber WD, Keinath-Specht A, et al. Behavioral treatment in migraine. Cognitive-behavioral therapy and blood-volume-pulse biofeedback: a cross-over study with a two-year follow-up. Funct Neurol. Jan-Feb 1997;12(1):17-24. [Medline].
Lamson RJ, Meisner M. Clinical application of virtual therapy to psyciatric disorders: theory, research, practice. In: KS Morgan, HM Hoffman, D Stredney, SJ Weghorst, et al, eds. Medicine Meets Virtual Reality 4. Amsterdam: IOS Press; 1996:723-724.
Leone M, Grazzi L, D'Amico D, Moschiano F, Bussone G. A review of the treatment of primary headaches. Part I: Migraine. Ital J Neurol Sci. Dec 1995;16(9):577-86. [Medline].
Markenson JA. Mechanisms of chronic pain. Am J Med. Jul 31 1996;101(1A):6S-18S. [Medline].
McGrady A. Good news - bad press: applied psychophysiology in cardiovascular disorders. Biofeedback Self Regul. Dec 1996;21(4):335-46. [Medline].
Miron D, Duncan GH, Bushnell MC. Effects of attention on the intensity and unpleasantness of thermal pain. Pain. Dec 1989;39(3):345-52. [Medline].
Moret V, Forster A, Laverriere MC, et al. Mechanism of analgesia induced by hypnosis and acupuncture: is there a difference?. Pain. May 1991;45(2):135-40. [Medline].
Moskowitz L. Psychological management of postsurgical pain and patient adherence. Hand Clin. Feb 1996;12(1):129-37. [Medline].
Oshiro Y, Fuijita N, Tanaka H, et al. Functional mapping of pain-related activation with echo-planar MRI: significance of the SII-insular region. Neuroreport. Jul 13 1998;9(10):2285-9. [Medline].
Oyama H, Ohsuga M, Tatsuno Y. Evaluation of the psycho-oncological effectiveness of the bedside wellness system. Cyberpsychol Behav. Feb 1999;2(1):81-84.
Reid GJ, McGrath PJ. Psychological treatments for migraine. Biomed Pharmacother. 1996;50(2):58-63. [Medline].
Riva G, Bacchetta M, Baruffi M. VREPAR 2: VR in eating disorders. Cyberpsychol Behav. Feb 1999;2(1):77-79.
Rokicki LA, Holroyd KA, France CR, et al. Change mechanisms associated with combined relaxation/EMG biofeedback training for chronic tension headache. Appl Psychophysiol Biofeedback. Mar 1997;22(1):21-41. [Medline].
Sarnoch H, Adler F, Scholz OB. Relevance of muscular sensitivity, muscular activity, and cognitive variables for pain reduction associated with EMG biofeedback in fibromyalgia. Percept Mot Skills. Jun 1997;84(3 Pt 1):1043-50. [Medline].
Steffin M. Virtual Reality: Overview of its Applications to Neurology. Available at: http://www.emedicine.com/neuro/topic463.htm. eMedicine Journal [serial online]. 2006. [Full Text].
Steffin M. Visual-Haptic Interfaces: Modification of Motor and Cognitive Performance. Available at: http://www.emedicine.com/neuro/topic464.htm. eMedicine Journal [serial online]. 2006. [Full Text].
Steffin M. Bridging the gap between "real" reality and virtual reality: intelligent human-machine therapeutic interaction in patient videospace. Cyberpsychol Behav. 2000;3(3):447-463.
Steffin M, Wahl K. Occam's approach to video critical behavior detection: a practical real time video in-vehicle alertness monitor. In: Westwood JM, Haluck RS, et al, eds. Medicine Meets Virtual Reality 12 Proceedings. Amsterdam: IOS Press;2004:370-375.
Tolle TR, Kaufmann T, Siessmeier T, et al. Region-specific encoding of sensory and affective components of pain in the human brain: a positron emission tomography correlation analysis. Ann Neurol. Jan 1999;45(1):40-7. [Medline].
Torebjork E. Human microneurography and intraneural microstimulation in the study of neuropathic pain. Muscle Nerve. Oct 1993;16(10):1063-5. [Medline].
Treede RD. Peripheral acute pain mechanisms. Ann Med. Apr 1995;27(2):213-6. [Medline].
VeHoffman H. Virtual reality: a new tool for interdisciplinary psychology research. Cyberpsychol Behav. 1998;1(2):195-200.
Villanueva L, Le Bars D. The activation of bulbo-spinal controls by peripheral nociceptive inputs: diffuse noxious inhibitory controls. Biol Res. 1995;28(1):113-25. [Medline].
Wauquier A, McGrady A, Aloe L, et al. Changes in cerebral blood flow velocity associated with biofeedback-assisted relaxation treatment of migraine headaches are specific for the middle cerebral artery. Headache. Jun 1995;35(6):358-62. [Medline].
Wong AM, Lee MY, Chang WH, Tang FT. Clinical trial of a cervical traction modality with electromyographic biofeedback. Am J Phys Med Rehabil. Jan-Feb 1997;76(1):19-25. [Medline].
Young LD, Bradley LA, Turner RA. Decreases in health care resource utilization in patients with rheumatoid arthritis following a cognitive behavioral intervention. Biofeedback Self Regul. Sep 1995;20(3):259-68. [Medline].
Further Reading
Keywords
VR, psychiatric disorders, pain disorders, pain physiology, biofeedback in pain treatment, virtual reality applications in biofeedback, psychiatric applications of biofeedback
