Phantom Limb: Possible Treatments to Kill the Pain Essay

The phenomenon of phantom limb was first described by a French doctor, Ambroise Pare, in the 16th century however it was not until 1866, after the American Civil War, when Doctor Wier Mitchell published his first account of the malady, coining the term â€Å"Phantom Limb†. Phantom limb is the experience of persisting sensory perceptions after limb amputation and remains one of the best-known, but puzzling phenomena within medical science (Oakley & Halligan, 2002). Phantom limb pain (PLP) is a frequent consequence of the amputation and causes considerable discomfort and disruption of daily activities. Originally, PLP was thought to have been secondary to nerve damage at the site of amputation but succeeding evidence showed that patients who have undergone regional anesthesia continue to experience phantom limb pain despite the cut-off of pain sensation to the amputated area (Melzack, 1997). This lead to the belief that the pain sensation experienced by patients with PLP may be due to nerve impulses or signals generated at the spinal cord level. This, however, was refuted on the basis that patients with transection of the spinal cord still complain of persisting phantom limb pain. It has been argued then that the brain areas that correspond to the human body could be the one responsible for the phantom sensations (Melzack, 1997). This was based on the fact that much of the human (and primate) body is represented by distinct brain areas located in the somatosensory and motor cortex on either side of the central sulcus. Consequently, even after limb removal, the brain areas representing those parts remain structurally and functionally intact. It has been argued that the activation of these bodily disconnected brain areas by adjacent brain areas (representing other intact body parts) may be a partial neurophysiological explanation for the production and maintenance of the continuous perceptual experience that is the ‘phantom limb’. This functional remapping results in some cases in the referral of selective sensory information from an intact body area (such as the face or shoulder) to the phantom limb (Halligan, Zeman and Benger, 1999). The remapping hypothesis is supported by functional imaging (Kew, Halligan, Marshall, Passingham, Rothwell, Ridding, Marsden and Brooks, 1997) and behavioural studies (Ramachandran, Stewart and Rogers-Ramachandran, 1992; Halligan, Marshall, Wade, Davies and Morrison, 1993). Given the magnitude and speed of onset of the reorganization (within 24 hours of amputation) it is unlikely to be a product of neural sprouting but rather the unmasking of existing but previously inhibited neural pathways (Ramachandran and Blakeslee, 1998). In addition, these abnormal plastic changes in the central nervous system associated with the phantom experience have been used to explain the consistently high incidence of pain attributed to a limb that no longer exists (Ramachandran and Blakeslee, 1998). Several other theories have been proposed to explain the pathophysiological processes behind the PLP phenomenon but despite all of these, the exact cause of PLP remains uncertain. As a consequence, the current treatments for the condition are just as varied as the litany of many possible yet complex mechanism of PLP. This literary review will assay the possible treatment options available for the management of PLP using information from published literature through searches in research databases using the keywords phantom limb, phantom limb pain, biofeedback, treatment, and phantom limb illusions. Treatments of PLP There are different modalities available in treating PLP ranging from pharmacological agents to psychophysiological therapy. The treatment outcome varies from approach to approach and more even from patient to patient. A careful evaluation is essential before considering any of of these treatments in order to obtain a more individualized approach in the management of PLP. Thermal biofeedback Biofeedback relies on instrumentation to measure moment-to-moment feedback about physiological processes. It provides patients with information about their performance in various situation (Saddock & Saddock, 2003). Using this electronic feedback, the patient is made aware of certain sensations such as skin temperature and muscle tension. A case report describing the use of thermal biofeedback combined with electromyogram (EMG) in treating a 69-year-old man suffering from burning and shooting phantom pain suggested that biofeedback is an effective treatment modality for severe phantom limb pain (Belleggia & Birbaumer, 2001). The rationale behind the treatment was based on the premise that most patients complain of intolerance to cold after amputations which tend to aggravate unpleasant or pain sensations in the stump. The treatment, however, required several sessions and in this particular case, there were 6 sessions of EMG biofeedback followed by another 6 sessions of temperature biofeedback. The patient presented in this case also did not use a prosthesis and did not receive prior treatment for chronic pain and the entire treatment process was done in a controlled environment where everything is calibrated and maintained to avoid external bias. Although the treatment outcome of the case report was favorable, there is no absolute guarantee that the same beneficial results can be expected to other patients with PLP especially to those who are already using prosthesis and to those who are already refractory to previous chronic pain therapies. Also its efficacy and adaptability in actual clinical settings remains to be studied. Electroconvulsive therapy (ECT) The use of electroconvulsive therapy have been common in patients with psychiatric disorders such as depression. This involves the utilization of electric stimulation by means of two electrodes placed bilaterally on the temple to produce convulsion. The artificial seizure that followed have shown efficacy in patients with a variety of pain syndromes occurring along with depression (Rasmussen & Rummans, 2000). Using this evidence, 2 patients with severe phantom limb pain refractory to multiple therapies but without concurrent psychiatric disorder were treated using ECT. One of the patient’s previous treatments included biofeedback, transcutaneous electrical nerve stimulation, hypnosis, epidural injections, and multiple analgesic medications including non-steroidal anti-inflammatory drugs, opiates, and adjunct analgesics including carbamazepine and nortriptyline. He was referred for ECT by the anesthesia pain service due to previous good responses in depressed patients with a variety of non-phantom limb pain syndromes. The other patient in the case study also had numerous treatments including transcutaneous electrical nerve stimulation, intra-axillary alcohol injections. Epidural steroid blocks, stellate ganglion blocks, biofeedback, and medications including antidepressants, benzodiazepines, opiates and carbamazepine. After ECT, both patients enjoyed substantial relief of pain with one case in remission from PLP 3. 5years after ECT. From this clinical note, it was concluded that patients with PLP who are refractory to multiple therapies may respond to ECT. It should be emphasized that ECT have several complications including dental and muscular injuries secondary to the severe muscle twitching accompanying the induced convulsion. The concurrent use of muscle relaxants have been effective in minimizing such injuries. The most troublesome side effect of ECT, however, is memory loss. Some patients report a gap in memory for events that occurred up to 6 months before ECT, as well as impaired ability to retain new information for a month or two after the treatment (Smith, et al, 2003). You may equate this to the data loss in computers after an unexpected reboot. Hypnotic mirrors and phantom pain Hypnotic procedures have long been used in treating a variety of pain syndromes. This involves the use of suggestion and imagery to alleviate the patient’s pain experience (Chavez, 1989). A case study reports the use of a hypnotically induced ‘virtual’ mirror experience which modified long standing intractable phantom limb pain despite generating a qualitatively inferior experience of movement in the phantom limb compared to that produced with an actual mirror (Oakley & Halligan, 2002). Using hypnosis, two main approaches to modifying phantom limb pain experience were identified in the study: ipsative imagery approach and a simulated movement approach. The ipsative imagery approach takes into account the way the individual represent their pain to themselves and attempts to modify that representation in order to alleviate the pain experience. The movement imagery-based approach encourages the PLP patient through hypnosis to ‘move’ the phantom limb and to take control over it. In the study, a case of a 76-year-old woman who had an above-knee amputation of her right leg secondary to peripheral vascular disease was presented. The investigators emphasized that she was pain-free at the time of her operation and that her PLP only begun two years after surgery. There were several components of her pain in her missing limb. She complained of feeling pins and needles in her ‘foot’, her ‘toes’ felt like they were being held in a tight vice, a slicing, cutting pain in the sole of her ‘foot’ and a chiselling pain in her ‘ankles’. After several sessions using the ipsative imagery approach, the patient claimed significant pain relief of most of her pain but the vice-like pain remained. The movement imagery-based approach also showed notable pain alleviation in another case that was presented, this time of a 46-year-old man who had experienced PLP since suffering from an avulsion of his left brachial plexus some five years prior to the study. At the beginning of the study, the patient rated his pain at 7 using a scale from 0 to 10, with 0 as pain free and 10 as the worst pain imaginable. During treatment, the patient had 0 rating and immediately after treatment it was 2. 5. The result of the study showed that hypnotic movement imagery is worth investigating further, considering the comparative ease of use and the potential of additional information as to the possible neurocognitive mechanism involved in PLP. Mirror treatment Mirror treatment uses leg exercises performed in front of a mirror to demonstrate increased ‘motor control’ over the phantom limb. In contrast to hypnotic imagery techniques which uses hypnotically induced ‘virtual’ mirror experience, mirror treatment involves the use of a real mirror apparatus to replicate the movements of the real limb with the phantom limb. The first case study of the use of ‘mirror treatment’ in a person with lower limb amputation who was reporting PLP was presented by MacLaughlan, M. McDonald, D. , & Waloch, J. (2004). During the intervention, there was a significant reduction in the patient’s PLP associated with an increase in sense of ‘motor control’ over the phantom, and a change in aspects of the phantom limb that was experienced. Although this effect was successfully replicated by using hypnotic imagery alone, the significant difference between the two approaches was the qualitatively more powerful experience of movement in the phantom left hand with the real visual feedback. The case study which was conducted in a conventional clinical setting supports the potential of ‘mirror treatment’ for PLP patients with lower limb amputations. The investigators, however, emphasized that the case study cannot indicate the extent to which beneficial effects are due to somatosensory cortex re-mapping, psychosocial factors such as individual differences in ‘body plasticity’, somatic preoccupation or creative imagination, or to other factors. Since it is the first case study of the use of ‘mirror treatment’ in a person with lower limb amputation, similar case studies are needed to ascertain the treatment’s applicability to other patients with lower limb amputations. Botulinum toxin Pharmacological agents have also been employed in the management of PLP. , Botulinum toxin type A, however, has not been previously used for this indication. In fact, it was only recently that this toxin has been used for medical purposes, especially in the field of cosmetics. Botox, as it is popularly known, has been beneficial in relieving muscular tension in the face due to its muscle-relaxing effect. Once considered a biological weapon which causes gas gangrene, this toxin inhibits the synaptic transmission of acetylcholine at the motor end plate and muscle spindles of the skeletal musculature and influences nociceptive transmitters. A pilot study on the influence of the agent on phantom pain after amputations was recently reported (Kern, Martin, Scheicher, et al, 2003). Four cases of patients with knee amputations who were suffering from severe stump pain following surgery were presented. After botulinum toxin injection, significant reduction of pain in the amputation stump was experienced among the patients. Citing a strong correlation between stump pain and PLP and the occurrence of of stump pain without obvious pathology, the study clearly emphasized the need for further investigation into the use of botulinum toxin in the treatment of post amputation pain. Other treatments of PLP Multiple other modalities, adjunct medications and anesthetic/surgical procedures have been used in the treatment of PLP with varying long term success. Although at least 60 methods of treating PLP have been identified, successful treatment of persistent type is not commonly reported. Tricyclic antidepressants, anticonvulsants, calcitonin and mexilitine have been used with varying success (Delisa, Gans, Bochenek, et al, 1998). Other surgical procedures and drug regimens have also been proposed. Despite all these, an established role of each of these treatments in the management of PLP remains a subject for future investigation. Summary Despite the advances in medical research and treatment, PLP is a phenomenon that continues to perplex the medical field. Several theories that were proposed to explain the etiology of the condition remain the subject of continued discussion. The pathophysiology involved in PLP could be multifactorial rather than the effect of a single factor. In the United States, there are approximately 1. 6 million people are living with limb loss according to the National Limb Loss Foundation Information Center. Between 1988 & 1999, an average of 133,735 hospital discharges per year was due to amputation. It is estimated that 50%-80% of patients with amputations complain of PLP (Delisa, Gans, Bochenek, et al, 1998). The actual incidence of this problem is, however, unclear because the condition tends to be underreported because of the complexity and strange nature of the complaint. Finding the most appropriate treatment for PLP has proven to be a difficult challenge for medical practitioners. The current treatment options for the condition are just as varied as the litany of many possible yet complex mechanism of PLP. Thermal biofeedback combined with electromyogram (EMG) have been demonstrated to completely eliminate PLP after treatment. In a case study, the use of ECT have shown pain relief in patients with PLP refractory to multiple therapies. The use of hypnosis and visual imagery in several case reports has indicated significant success in modifying the pain experience of PLP patients. Interestingly, the success of this technique in treating PLP has given a deeper insight on the psychological aspect of the condition. Botulinum toxin, a drug considered as a very dangerous toxin that causes gas gangrene, has also shown promising results in alleviating stump pain. Multiple other modalities, adjunct medications and anesthetic/surgical procedures have been used in the treatment of PLP with varying long term success. Establishing an accepted role of each of these treatments in the management of PLP, however, would require further investigation. The highly varied approaches involved in the treatment of PLP present a unique burden especially for the General Practitioners (GPs) who provide the primary health for amputees in the community. A recent study suggests that GPs underestimate the prevalence, intensity and duration of phantom and residual limb pain. Moreover, inconsistencies in the reasons given for referral to specialist services for the management of phantom pain were reported. These findings have serious implications for the management of phantom limb pain, disability and psychological distress in amputees in that GPs not only provide first line treatment, but are also the gatekeepers for referral to other services (Kern, Martin, Scheicher, et al 2003). The prevalence of case studies presented in this review clearly shows the lack of major clinical trials targeted into identifying the best approach in the management of PLP. Most of these treatments are already being used for other diseases and there is ample literature to justify their use for PLP yet there is not a single searchable literature involving a bigger study population investigating any of the above methods. It is obvious that the efficacy and cost-effectiveness of these individual treatment methods cannot be ascertained by only a handful of case reports. More comprehensive studies should be done in order to formulate an acceptable protocol for the adequate treatment of PLP.