Introduction
Ranging from Iraqi war veterans to people that have been affected by car accidents, severe burns or viral infections; what all these individuals have in common are inherent difficulties in limb perception and motor control after experiencing a life altering accident that resulted in them being classified as amputees (Isaacson, 2010). As a result it becomes necessary to implement some form of sensory and motor rehabilitation in order to facilitate a more effective transition into a facsimile of a normal routine for individuals that have recently suffered the loss of a limb. What must be understood is that after the loss of a particular limb or body part nearly 80% of amputees experience the sensation that the amputated limb or body part is still attached to the body (Haggard & Wolpert, N.I.). This particular phenomenon is known as phantom limb syndrome and is actually an adverse neurological condition since newly amputated individuals suffering from this particular mental state often complain of severe pain, itching, tightness and other odd sensations (Mosley & Brugger, 2009). Unfortunately such a condition actually negatively contributes to the mental state of such patients with such cases often reporting severe depression, aggression or other forms of adverse psychological behavior.
While there are numerous theories that been put forward in an attempt to explain the origin of the phantom limb sensation ranging from inflamed severed nerve endings to cortical and neuromatrix reorganization (Brugger, 2008). The fact still remains that if left untreated it has been shown to cause severe instances of depression and self-destructive behavior and as such requires some means of intervention in order to prevent further deterioration of a patient’s mental state. Another factor to take into consideration is how amputees learn to adjust to the use of their new prosthetics and the varying degrees in which they begin to regain their mobility and functionality again. Prosthetics within the past decade have gone through considerable functional and cosmetic changes since their earlier iterations as wooden arms and legs more than a century ago. In fact some of the latest prosthetics have sensory motor detectors that enable neural commands to be transmitted from the brain directly to the computerized limb to enable some form of action. On the other hand, for a vast majority of prosthetics used by the average individual these particular limb replacements are more simplistic and are usually composed of adjustable joints and locks that can be set or interchanged for a vast majority of purposes and uses (Pasquina et al, 2006).
One of the most well known and iconic prosthetic device has been the “claw hand” an aptly named prosthesis that takes the form of an adjustable grasping claw that can be utilized for a plethora of different uses. What must be understood though is that despite the various advancements in prosthetic devices some form of motor learning is required in order to help such individuals learn how to use such devices correctly (Mayer, et al., 2008). Not only that there are also psychological concerns to deal with due to the early frustrations that amputees experience in utilizing such devices which often leads to decreased feelings of self worth and self esteem which at times evolve into suicidal tendencies (Pasquina et al, 2006). While there are numerous methods that clinicians can utilize in rehabilitation such as drugs, spinal cord stimulation, acupuncture, hypnotism and the use of an imbedded electrical stimulator this study posits that such methods can either lead to dependence, are far to invasive or are just plain useless in effectively resolving the issue of phantom limb syndrome and in fact may cause regressive tendencies when helping an amputee get used to their prosthetic device due to unrealistic expectations. Based on the study of Dahm et al. (1998) which examined the use of anti-depressants by individuals that suffer from phantom limb syndrome it was seen that the propensity for drug overdose and dependence was far higher as compared to the average national statistic (Dahm et al., 1998). The reason for this, as theorized by Dahm et al. (1998), is that due to the supposed “pain” and “feeling” originating from the phantom limb amputees have a far greater tendency to lapse into depressive states and thus consume more antidepressants as a result. Over time such a behavioral tendency leads to drug dependence and even death in certain cases due to higher than normal levels of antidepressants in an amputee’s blood stream. Taking such information into consideration it can be seen that utilizing drugs, while effective at treating depression, could lead to adverse consequences for some amputees and as such an alternative solution should be advocated as a means of gradually reducing the effects of phantom limb syndrome. Another method that has been utilized lately as means of easing the effects of phantom limb syndrome has been to utilize spinal cord stimulation in order to facilitate the process of neural reorganization.
The use of spinal cord stimulation is based off the theory that it is due to the subsequent neural reorganization of the brain in response to an amputation that phantom limb syndrome occurs. Thus, by facilitating an external means of stimulation on the spinal cord it is thought that this would help in reducing the various negative sensations endued by the phantom limb. The inherent problem with utilizing this particular method is the potential for severe nerve damage in the spinal cord due to the use of an electrical device placed under the skin to stimulate the spinal cord. While it may be true that in some cases the embedded electrical device has proven itself to be quite effective in alleviating the pain by interfering with the electrical impulses sent from the amputated region to the brain resulting in nothing more than a tingling feeling, this paper still posits that such a method of rehabilitation is too invasive and could have negative long term consequences that may adversely affect the nerve pathways in the spinal cord. Other methods of attempted rehabilitation come in the form of hypnotism and acupuncture therapy which, in the opinion of this paper, have no legitimate, medically proven and academically backed means of actually helping a person with phantom limb syndrome and as such should not be considered, by and stretch of the imagination, as legitimate means of rehabilitation. Taking all the factors mentioned into consideration it seems appropriate to voice out the concern that in the field of amputee rehabilitation new practices needs to be implemented that utilize technology in a noninvasive and supportive way in order to encourage a speedy recovery, proper mental health and a more effective means of prosthesis conditioning.
One way in which this can be done is through new technologies utilizing “immersive virtual reality” which helps to augment an amputee’s perception of their phantom limb. This is done through numerous sessions and exercises wherein a slow and gradual “tricking” of the somatosensory cortex is undertaken gradually helping patients correct the distortions that cause pain in their phantom limbs and helps them to eventually reduce and altogether remove the phantom limb from their method of perception. By doing so this enables a far more effective means of prosthetic familiarization by amputees leading to a more effective means of rehabilitation. Not only that, aside from helping patients with issues related to phantom limb syndrome immersive virtual reality has also proven itself as a viable means of teaching amputees on how to properly control prosthetic limbs and as such could prove to be a viable means of not only mental rehabilitation but motor skills learning as well. It must be noted though that the process of immersive virtual reality is still in its infancy having only recently come into being as a result of advances in technology. Taking this into consideration the aim of this study is to examine the use of virtual reality immersion as a means of mitigating the effects of phantom limb syndrome as well as its possible use in motor skills training for prosthetics when compared to other proposed methods advocated by various experts in the field. As such the objective of this paper is to prove that immersive virtual reality is a far better and less invasive and addictive means of removing the mental stresses involved with phantom limb syndrome and motor skills training and as such could lead to a vastly improved rate of prosthetic familiarization. For this study, immersive virtual reality present itself as a viable method which can be utilized in order to help amputees suffering from phantom limb syndrome as well as facilitate their motor learning which would lead to a faster and effective means of rehabilitation.
Literature Review
New Innovations in Prosthesis Development
One of the latest innovations in the development of prosthetic limbs is the DEKA arm system which began trials in 2008 and is currently one best prosthetic arm replacements in the world. Instead of having a prosthetic arm system that uses interlocking joints and hooks the DEKA arm or “Luke arm” (named after the lifelike prosthesis used by Luke Skywalker) used a series of internal motors and joints to rudimentary mimic the ability of a real human arm. The effect is a blocky albeit effective means of grasping, holding, pulling and pushing. The benefit of this particular type of technology is that it doesn’t need to be set into a particular position to be effective. One way in which researchers have gotten around the compatibility of the human nervous system with artificial electronics with the current level of technology is to use the severed nerve endings that are located in the location of the amputated arm and reroute them towards the pectoral area of an amputee. The result is that when an amputee wants to think about moving their arm they in effect send signals to the chest muscles which are interpreted by attached electrodes which send a “move response” to the arm. Through practice different types of movements can be simulated and utilized with an embedded tactor vibrating at different frequencies to help patients determine the degree of grip strength currently being utilized by the arm. It must be noted though that while the DEKA arm only needs to utilize 6 control signals for effective positioning in a variety of angles the fact still remains that users still need to learn how to perform the necessary sequences in order to utilize the arm for functional tasks.
Understanding the Stages of Motor Learning
The process of motor skills learning for amputees actually comes in three distinct states: the initial phase, the intermediate phase, and the autonomous stage. This section of the paper will detail the various stages of motor learning and the processes that occur in each stage of motor skills development.
Initial Phase
During the initial phase of motor skills learning patients are introduced to various pieces of information which detail how particular tasks can be performed and what methods of prosthesis operation need to be utilized in order to perform them. This stage of motor learning is based heavily on sensory experience wherein the lessons utilize either verbal, literary or visual cues in order for the learners to understand that basic concepts of properly using a prosthesis. In this stage of development the greatest challenge for amputees is integrating the knowledge on prosthesis movement that was taught, into the ability to properly accomplish the necessary movements to accomplish a certain task. This can come in the form of learning how to properly pull and bend prosthesis, walk across a particular path using prosthetic feet or even accomplish a simple task such as pushing or pulling on a door.
The goal of this stage of development is to place amputees on the right path of learning and enables them to have some modicum of hope at being able to attain some level of rudimentary functionality. It is noted by Meikle et al. (2002 ) that one of the main problems amputees have to initially deal with are the thought processes which connect loss of a limb to thoughts that they will be unable to live normal lives or that they will be dependent on others for the rest of their lives. Such thoughts as described by Meikle et al. (2002 ) often lead to depression and increased levels of anxiety during the early stages of recovery (Meikle et al., 2002). Taking this into consideration the initial phase of motor skills learning not only helps amputees learn how to use prosthetic limbs but also acts as a coping mechanism by which they are given the hope that they will one day be able to perform the same tasks, albeit in a rudimentary fashion, as before.
Intermediate Phase
The intermediate phase in motor skills learning development can be classified as a period of refinement of the skills and knowledge during the initial phase and their subsequent application in practice and real life situations. The aim of this particular method of learning is to enable amputees to accomplish set physical goals at a far more rapid pace as compared to their performance in the beginning. During this particular state, amputees depend on sensory guidance for motor output and use feedback from both the sensory systems and external sources to properly accomplish a task and identify errors in their use of a particular prosthesis. It must be noted though that in this particular stage physical therapists who assist in the familiarization process take a more active role in helping patients determine how to properly utilize their prosthetic limbs beyond to stages to actual fluid movements. In fact success during this particular stage of development is characterized by the ability of amputees to accomplish fluid motions with their prosthesis and thus create a more “natural” form of motion. Another factor to take into consideration during this particular stage of development is noted in the study of ( ). In this study it is shown that as amputees gain better control over their prosthesis the better their mental state becomes as compared to when they first acknowledged their amputated limbs. Such a change is thought to occur due to their perception that they would be able to live “almost normal” lives without having to depend solely on other people for menial tasks.
On the other hand it must be noted that effective transition into the intermediate phase comes with a lot of trial and error and as such is noted for increased levels of frustration and anxiety in amputees as they struggle to attain the fluid motions they are suppose to accomplish. What must be understood is that in the use of ordinary to advanced prosthetic devices amputees are in effect attempting to use old muscle groups for new purposes (Mayer, et al., 2008). Combined with the presence of phantom limb syndrome this often results in early failures. As such this presents itself as challenge that must be overcome and one of the greatest problems therapists have in helping amputees properly transition from blocky movement to coordinate and fluid motion.
Autonomous Stage
The final stage of the motor skills learning process is the autonomous stage and is marked by a fusion of continuous motor action with the desire for speed and accuracy in performing specific tasks. During this particular stage of the process amputees have now become well versed in the various nuances of utilizing their prosthesis and are now more concerned in subsequently increasing their proficiency in utilizing their prosthesis. As the name of this stage suggests amputees at this stage of the process are now able to independently use their prosthesis for everyday tasks without rely on subsequent help from therapists. In fact during this particular stage patients adapt to their prosthetics in such a way that they no longer give as much conscious thought during the process of using them for everyday tasks and in fact become more concerned with adaptive action (utilizing different types of movements and prosthetic types for new actions). One interesting facet of this stage lies in the fact that the overall speed and accuracy of prosthetic usage is increased significantly and there is a marked improvement in the behavior of the amputee.
As seen in the observations of O’Keeffe (2011) improvements in this particular stage of development actually translates into a positive mental state due to the feeling of accomplishment attained from having successfully reached a stage where an amputee feels that they have reached some level of “normalcy” (O’Keeffe, 2011). By being able to accomplish normal tasks in a proficient and fluid manner, amputees develop the idea that they are “normal” so to speak and stop thinking of themselves in a dissociative manner when comparing their physical condition with the other members of a local community. It must be noted though that the goal of prosthetic training is to achieve the final stage of motor learning and enable skilled operation of the prosthesis. Taking this into consideration, methods that can help to speed up the process and enable a far more effective means of familiarization with prosthesis would thus be considered a positive improvement in the field of motor skills training and rehabilitation. One detail that most studies often neglect to mention is the degree of anxiety, frustration and depression that individuals who are learning to adapt to their prosthesis initially go through. In fact when examining studies such as those by O’Keeffe (2011) it can be seen that there is a actually a distinct suicide level for people that have maladaptive experiences in motor skills learning and rehabilitation. Such a behavior is explained by O’Keeffe (2011) as originating from the severe depression and loss of self-worth experienced by various amputees and as such needs to be resolved by some method that enables a far better and faster means of motor skill learning and rehabilitation in order to prevent the initial stages of depression, which leads to mental degradation and eventually suicide.
The Use of Virtual Reality Environments in Prosthetic Limb Motor Learning and Rehabilitation
In the study of Resnik et al. (2011) it can be seen that VRE (Virtual Reality Environments) can be used as an effective means of training amputees in the proper use of prosthetic limbs without having the prosthesis initially attached (Resnik et al., 2011). By using a simulated version of the patient or even just the patients arm Resnik et al. (2011) was able to prove that through the use of VRE amputees were able to readily and quickly learn the basics of the initial phase of motor skill learning and progress towards the intermediate and advanced stages at a far faster rate than normal. This is due to the fact that by utilizing a virtual simulation in order to mimic everyday tasks and movements the researcher was able to provide the patient with examples to mimic and follow via the screen which amputees were readily able to follow. Some of the initial tasks that were initially explored were moving the virtual arm left, right, up and down and afterwards utilizing more complex movements such as reaching out and grasping. One particular interesting aspect of the Resnik et al. (2011) research lies with the fact that VRE can actually be classified into two distinct groups’ namely immersive or non-immersive environments. Immersive environments take the form of VRE technology using goggles or helmets which place the amputee in a simulation of reality while non-immersive VRE is a simulation of the patient on a computer or television screen (Resnik et al., 2011). As Resnik et al. (2011) indicates one of the advantages of non-immersive VRE environments is that they can actually be used by the patient at home in order to practice. This comes in the form of using either a computer program or the Nintendo Wii to use a program that is provided for by the hospital in order to create a VRE directly from a home computer monitor or television set.
The advantage of this method is that patients could practice at their leisure at home and thus increase the rate of their intermediate transition. What must be understood is that learning how to properly use a prosthesis during sessions with a therapist are limited due to time and availability. By utilizing a home based system not only does this increase the amount of time an amputee practices using a simulated version of their prosthesis but due to the increased amount of practice and the fun (some of the programs can actually be made into fun exercises and games) factor of some these exercises on the Wii the end result is far a more positive and effective transition from the initial phase, to the intermediate phase and then to the autonomous stage with few ill effects in terms of depression and little feelings of self worth due to the increased level of proficiency and practice that enables an amputee to better transition into doing everyday tasks with their prosthesis with little difficulty. Taking this into consideration it can be seen that by utilizing VRE as a means of motor learning and rehabilitation patients make a far more effective and easy transition and as such this paper advocates for its use in mainstream practices for motor skills learning for amputees.
The Use of Virtual Reality Environments in Lessening the Impact of Phantom Limb Syndrome
One of the inherent problems with properly adapting to the use of a prosthetic limb is the phenomena known as phantom limb syndrome and how it actually causes a certain degree of mal-adaption in effective prosthetic limb usage as patients struggle between learning how to control their prosthetic devices and the sensations “felt” from the phantom limb (Mcavinue & Robertson, 2011). Often time such sensations range from pain to feeling that the limb is in a strange position or stretched beyond its normal length (Mcavinue & Robertson, 2011). One way of potentially resolving this issue is to use VRE technology in order to augment an amputee’s perception of the phantom limb in order to effectively reduce its negative effects. One way in which is done is to create virtual simulation of the phantom limb that the patient describes in detail and place it on a computer screen. Then through the use of the simulator the therapist and the patient slowly over numerous sessions attempt to “fix” the phantom limb by slowly changing the patient’s perception of it. This method has proven to be incredibly effective in reducing the pain and itchiness associated with phantom limb syndrome and is actually increasingly gaining mainstream acceptance. As the amputee and the therapist work together the shape of the phantom limb slowly reaches a normal shape via the patient’s perception after which the therapist helps to reduce the phantom limb or even get rid of it all together. Due to the non-invasive nature of this particular method of therapy it is a highly recommended process by this paper since it in effect allows patients to gradually settle the mental anxiety associated with phantom limb syndrome without having to utilize various drugs and anti-depressants.
Implications for Practice
Based on the presented data in the literature review I can say with confidence that the future of motor skills learning and rehabilitation for amputees lies in the use of VRE technology as a facilitator of both clinical and home based training regimens. It can be seen in the literature review that through the application of VRE technology amputees can in effect accelerate the process of transition from the initial to the advanced phase due to the application of VRE in home based systems such as computers or the Nintendo Wii. Taking this into consideration therapists could potentially use custom made programs that patients could take home with them and use on the Wii or their home computers in order to better facilitate the process of training. In fact, through the use of various training regimens that can be developed within the programs given, amputees will be able to access a greater range of both imaginative and fun activities that the home bases systems can provide and thus make the process of training more enjoyable rather than frustrating and cumbersome. Not only that, since the various modules utilized in the VRE don’t require the prosthesis to be attached amputees can get a “feel” of how to properly operate their prosthesis before it is actually put in place thus accelerating their ability to adapt and function normally. It must be noted though that for each type of amputation comes with it varying factors that determine what method of rehabilitation will be necessary. While it may be true that VRE technology has proven itself to be quite effective in teaching amputees of upper extremities the technology is still untested for those affected in their lower extremities. In fact, based on the study by Bragaru et al. (2011) it can be stated that the training utilized for upper extremities is in no way comparable to the training necessary for the lower extremities and as such variables, methods and processes which may work for someone that lost and arm or hand may not necessarily work for someone that lost a foot or a leg due to distinct differences in how the lost body parts work (Bragaru et al., 2011). On the other hand it cannot be stated that there is no possibility for overlap, advances in motion capture technology such as seen in the latest controllers for the Microsoft Xbox 360 do show potential in being able to assist lower extremity amputees by providing programs which help to teach them balance and precision when walking. This particular aspect of technology application though has yet to be verified and tested and as such should not be considered an option for training at this time. Another factor to take into consideration are the financial limitations of several victims of amputations. While it may be true that prosthetics have been getting progressively cheaper this still doesn’t mean that most of those who suffer from some form of amputation can afford the advanced prosthetic devices that can utilize internal motors and joints. In fact in some cases these individuals would have to contend with merely utilizing a hooking or grasping tool attached to some sort of plastic prosthetic arm. These individuals may not even possess the finances to have a computer or Wii at home based on this the use of VRE systems are not applicable in such cases. It is from this that it can be seen that the application of VRE technology does indeed have its limitations and as such should be utilized on a case by case basis and not applied to all cases universally. While the method is sound in helping patients resolve issues regarding motor skills training and phantom limb rehabilitation, financial limitations are an inescapable factor in dealing with this particular issue. On the issue of different effects in the retention and acquisition phase it is foreseeable that retention won’t be an issue due to the fact that if patients are provided with a home based system for practice they will have no issues whatsoever in retraining themselves if need be the provided programs.
Summary of Key Findings
VRE technology has the potential to revolutionize the process by which amputees’ progress from the initial stages of motor learning to the advanced and autonomous levels. This is due to the fact that not only does it enable patients to practice without the prosthetic in place but it enables them to do so at their leisure due to the use of home based VRE technology which can be used in either home computer systems or gaming consoles such as the Nintendo Wii. It must be noted though that the findings of this paper is applicable only to the motor learning rehabilitation of patients that utilize advanced prosthetics that use imbedded electrodes as a means of controlling the holding and grasping qualities of the prosthetic. This comes in the form of prosthetics similar to the “Luke arm” mentioned in the literature review. The reason for this is due to the fact that due to the nature of the input necessary for such prosthetics virtual reality based methods of training prove to be quite viable since the input that the patient would normally utilize to control the prosthetic is interpreted by the training program in the same manner. Other less advanced prosthetics don’t have the same type of input that can be utilized and as such there are distinct limits to the application of this particular type of training method for motor skills learning. On the other hand its use can be generalized across all prosthetic types when it comes to rehabilitating patients suffering from phantom limb syndrome. As seen in the literature review VRE technology can create a virtual representation of the phantom limb described by the patient and over a number of sessions the therapist and the amputee can slowly change their cognitive perception of the phantom limb to such an extent that the pain and discomfort associated with the syndrome can actually be effectively lessened or outright removed. This is a particularly interesting application of the technology due to its non-invasive nature and the fact that it doesn’t rely on drugs to remove the pain associated with phantom limb syndrome. Future avenues of research for this particular type of process could take the form of motion capture devices such as the those seen in the Xbox 360 which will enable amputees of all types including people utilizing sub-par prosthetics to train themselves in their use using interactive programs that they can use at home, such an application of the technology though has yet to be sufficiently explored.
Conclusion
Based on the presented data it can be seen that VRE technology is viable method of rehabilitation not only for motor skills training but for helping to resolve issues regarding phantom limb syndrome as well. It must be noted though that at the present the technology is still limited to individuals with advanced prosthetics however as the technology continues to grow and be adopted by more practitioners it is expected that new innovations involving motion capture technologies will enable people of different amputation and prosthetic types to be able to enhance their motor skills training through the use of VRE.
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