Phantom limb pain induced in amputee by strong magnetic fields

Magnetic resonance safety

Magnetic resonance imaging (MRI) has a superior soft-tissue contrast compared to other radiological imaging modalities and its physiological and functional applications have led to a significant increase in MRI scans worldwide. A comprehensive MRI safety training to protect patients and other healthcare workers from potential bio-effects and risks of the magnetic fields in an MRI suite is therefore essential. The knowledge of the purpose of safety zones in an MRI suite as well as MRI appropriateness criteria is important for all healthcare professionals who will work in the MRI environment or refer patients for MRI scans. The purpose of this article is to give an overview of current magnetic resonance safety guidelines and discuss the safety risks of magnetic fields in an MRI suite including forces and torque of ferromagnetic objects, tissue heating, peripheral nerve stimulation, and hearing damages. MRI safety and compatibility of implanted devices, MRI scans during pregnancy, and the potential risks of MRI contrast agents will also be discussed, and a comprehensive MRI safety training to avoid fatal accidents in an MRI suite will be presented.

Anthropogenic Radio-Frequency Electromagnetic Fields Elicit Neuropathic Pain in an Amputation Model

Anecdotal and clinical reports have suggested that radio-frequency electromagnetic fields (RF EMFs) may serve as a trigger for neuropathic pain. However, these reports have been widely disregarded, as the epidemiological effects of electromagnetic fields have not been systematically proven, and are highly controversial. Here, we demonstrate that anthropogenic RF EMFs elicit post-neurotomy pain in a tibial neuroma transposition model. Behavioral assays indicate a persistent and significant pain response to RF EMFs when compared to SHAM surgery groups. Laser thermometry revealed a transient skin temperature increase during stimulation. Furthermore, immunofluorescence revealed an increased expression of temperature sensitive cation channels (TRPV4) in the neuroma bulb, suggesting that RF EMF-induced pain may be due to cytokine-mediated channel dysregulation and hypersensitization, leading to thermal allodynia. Additional behavioral assays were performed using an infrared heating lamp in place of the RF stimulus. While thermally-induced pain responses were observed, the response frequency and progression did not recapitulate the RF EMF effects. In vitro calcium imaging experiments demonstrated that our RF EMF stimulus is sufficient to directly contribute to the depolarization of dissociated sensory neurons. Furthermore, the perfusion of inflammatory cytokine TNF-α resulted in a significantly higher percentage of active sensory neurons during RF EMF stimulation. These results substantiate patient reports of RF EMF-pain, in the case of peripheral nerve injury, while confirming the public and scientific consensus that anthropogenic RF EMFs engender no adverse sensory effects in the general population.

Implementation of a comprehensive MR safety course for medical students

This review article proposes the design of an educational magnetic resonance (MR) safety course for instructing medical students about basic MR and patient-related safety. The MR safety course material can be implemented as a traditional didactic or interactive lecture in combination with hands-on safety demonstrations. The goal of the course is to ensure that medical students receive a basic understanding of MR principles and safety considerations. This course will prepare medical students for patient screening and safety consultations when ordering MR studies. A multiple-choice exam can be used to document the proficiency in MR safety of the medical students. The course can be used by various medical school programs and may help to ensure consistent quality of teaching materials and MR safety standards.

Management of phantom pain with a textile, electromagnetically-acting stump liner: a randomized, double-blind, crossover study

The treatment of phantom pain is frequently dissatisfying. We wanted to find out whether an electromagnetically shielding stump stocking interwoven with metal (medipro(R)Liner RELAX [medi Bayreuth, Bayreuth, Germany]) could have a positive effect on phantom pain. A double-blind, randomized, crossover trial in a total of 30 leg amputees compared the experimental (=verum) silicon liner (VL) fitted to the amputation stump with a dummy (=placebo) liner (PL). Each liner was worn for two weeks after a two-week baseline period. Daily documentation focused on phantom pain, quality of sleep and improvement of well-being. Twenty-seven of 30 patients completed the 6-week study, and 22 documentations proved valid. On a 0-10 numeric rating scale (NRS), the median pain intensity before treatment was 4, and the median of maximum pain was 6. VL versus PL reduced pain significantly more often (P=0.008), the odds ratio being 5.95. The degree of pain reduction was likewise highly significant (<0.001). Wilcoxon's matched-pairs signed-rank test for the medians of daily maximum pain showed a significant reduction for both PL (P < 0.001) and VL (P <0.001) as compared to baseline, with VL being highly superior again (P < 0.001) versus PL. The experimental device also led to significant amelioration of general well-being (P = 0.037) with an odds ratio of 3.85, and an improvement in the quality of sleep, which was not significantly different than PL (P = 0.223). In this study, the influence of a silicon liner with electromagnetically protecting properties on phantom pain was highly significant. The mechanisms underlying this effect are unclear. Possibilities include reduction of ectopic neuroma activity, shielding from possible electromagnetic weather impulses (sferics), or analgesic effects of changes in the electromagnetic field. PET or fMRI examination with or without a shielding silicon liner might help to elucidate this observation further.

MR procedures: biologic effects, safety, and patient care

The technology used for magnetic resonance (MR) procedures has evolved continuously during the past 20 years, yielding MR systems with stronger static magnetic fields, faster and stronger gradient magnetic fields, and more powerful radiofrequency transmission coils. Most reported cases of MR-related injuries and the few fatalities that have occurred have apparently been the result of failure to follow safety guidelines or of use of inappropriate or outdated information related to the safety aspects of biomedical implants and devices. To prevent accidents in the MR environment, therefore, it is necessary to revise information on biologic effects and safety according to changes that have occurred in MR technology and with regard to current guidelines for biomedical implants and devices. This review provides an overview of and update on MR biologic effects, discusses new or controversial MR safety topics and issues, presents evidence-based guidelines to ensure safety for patients and staff, and describes safety information for various implants and devices that have recently undergone evaluation.

Fantomski bol i postraumatska bolna stanja

After limb or body part amputation, three different types of perceptual sensitive phenomena can be recognized. They can be all named posttraumatic neuropathies: painless sensations in phantom limb ,painful phantom limb and painful posttraumatic stump. Painless sensations in phantom limb can be seen in 90% of cases in resected body parts as soon as first postoperative day, less often during the first week, and its clinical characteristics are usually stabilized during the first year. Painful posttraumatic stump appears because of pain neuroma existing, that forms at the proximal end of amputational stump as a consequence of physiological nerve regeneration attempt. Frequency of pain significantly varies considering authors from 5 - 90%, depending on definition of this phenomena and criteria used. It is considered that 5- 10% mast be under permanent medicament treatment. Phantom pain appears more often in elderly and people with specific affective personality construction. It can bee permanent, burning, nettling, tearing (25%), or intermittent, lancerating, in the shape of electrical discharging (32%), but it can also have bizarre attributes. Phantom pain appearance usually announces its duration in the longer period. After two years it is present at 59% of patients, with decreasing intensity, and only 5- 10% suffer severe pain. In our Institute in the period from 1980-2003, 48 patients have been treated, 36 patients with medicamentous treatment, local blockades and chronic stimulations, and 12 patients, who did not react at conservative treatment were operated. In operated group in 10 patients pain disappeared, one patient it was with decreasing intensity, and one patient was without change.

Phantom limb pain and related disorders

Postamputation phenomena, including painful and nonpainful phantom sensations occur following loss of limbs and other body parts. Peripheral and central nervous system mechanisms play a role in persistent phantom pain. Understanding the pathophysiology of this syndrome has improved in recent years. Comprehensive evaluation and a multimodality treatment approach comprise the current standard of care of the patient with phantom pain.