Who can benefit from virtual reality to reduce experimental pain? A crossover study in healthy subjects.

BACKGROUND: The present study aimed to identify predicting factors affecting experimental pain stimuli reduction by using 'EyeToy', which is an Immersive Virtual Reality System (IVRS). METHODS: Sixty-two healthy subjects (31 M, 31 F) underwent a battery of pain tests to determine each participant's baseline sensitivity to nociceptive. The battery included thermal pain tests (hot and cold) as well as a paradigm to induce conditioned pain modulation (CPM). Later on, each subject participated in two study conditions in random order: (1) An exposure to tonic heat stimulation (46.5 °C/135 s) to the ankle while participating in VR environment which included an activity requiring limb movements; (2) Same heat stimulation with no exposure to VR. Six pain measures were taken during each study condition (baseline, test 1-5). RESULTS: An interaction of time × treatment was found (RM ANOVA, F(5, 305)  = 24.33, p < 0.001, η² = 0.28). Specifically, the reduction in pain score between baseline and test 1 was significantly greater in VR condition than in control (p < 0.001). The maximal pain reduction in both conditions was between baseline and test 1. Hierarchical regression revealed gender and the extent of CPM as predictive factors for pain reduction in the VR condition (6.1% and 7.5%, respectively). CONCLUSIONS: It can be concluded that VR can serve as an effective manipulation for pain reduction in individuals with efficient CPM and in women. These findings constitute a promising platform for future research and hold potential for the improvement and facilitation of clinical treatment.

Associations between autonomic dysfunction and pain in chemotherapy-induced polyneuropathy.

BACKGROUND: Autonomic neuropathy, a relatively common complication of several chemotherapy agents, can affect the vagus nerve and its pain inhibitory capacity, thus increasing sensitivity to pain. This study aimed to evaluate the relationships between autonomic parasympathetic function and the perception of (1) spontaneous pain; (2) experimental non-painful sensations; and (3) experimental painful sensations in chemotherapy-induced neuropathy patients. METHODS: Twenty-seven cancer patients with chemotherapy-induced polyneuropathy were enrolled (20 women, age 56.6 ± 7.9). Autonomic parameters of heart rate variability, deep-breathing and Valsalva ratios, experimental non-painful parameters of warm, cold and mechanical detection thresholds, and painful parameters of heat pain thresholds, pain rating of suprathreshold stimulus, mechanical temporal summation and conditioned pain modulation response were examined. RESULTS: Autonomic parameters and spontaneous pain levels were not associated, yet autonomic parameters were positively correlated with non-painful sensations - milder autonomic neuropathy was accompanied by milder sensory neuropathy as indicated by several parameters, e.g., lower Valsalva ratio was correlated with higher warmth detection threshold (r = -0.465; p = 0.033). Autonomic parameters were, however, negatively correlated with painful sensations - lower parasympathetic-vagal activity was associated with higher pain sensitivity as indicated by several parameters, e.g., lower Valsalva ratio was correlated with higher pain rating of suprathreshold stimulus (r = -0.559; p = 0.008). CONCLUSIONS: Diminished vagal function due to neuropathy is associated with, and may possibly underlie, pain disinhibition expressed as greater levels of experimental pain.

Complementary and alternative medicine use in patients with head and neck cancers in Europe.

The aim of the present study was to examine the patterns of complementary and alternative medicine (CAM) use in a sample of head and neck cancer patients, forming part of a larger study. A cross-sectional survey design was used collecting data through a descriptive 27-item questionnaire in nine countries in Europe. The participants were 75 patients with head and neck cancers. The prevalence rate of CAM use was 22.7%. The most common therapies used were herbal medicine (47%), medicinal teas (23.5%), use of vitamins/minerals (11.8%) and visualization (11.8%). Use of CAM dramatically increased after the diagnosis with cancer (i.e. eightfold increase in the use of herbs). A profile of CAM users was not evident in this sample. Patients used CAM for a variety of reasons together, with counteracting the ill effects from cancer and its treatment being the most common one. Information about CAM was obtained mostly from friends and family. As one in five head and neck cancer patients use CAM it is important that clinicians explore practices with their patients, improve communication about CAM with them and assist those who want to use CAM in using appropriate and safe therapies.

Use of complementary and alternative medicine among cancer patients in Israel.

Complementary and alternative medicine (CAM) has gained in popularity among cancer patients in recent years. The present study assessed the patterns of CAM use among cancer patients in Israel. The design of the study was descriptive cross-sectional, and data were collected using a 27-item questionnaire. The sample consisted of 111 Israeli cancer patients who were part of a larger European study. Among the participants, past or current CAM use was reported by 32.4% (n=36). The most common therapies used included herbal medicine (22.2%), spiritual therapies (19.4%), visualization and relaxation techniques (16.7% for each), and vitamins/minerals (13.9%). Younger patients with higher education, higher annual income, and previous standard treatment were more likely to use CAM. The mean satisfaction and perceived effectiveness scores were 5.36+/-1.37 and 5.48+/-1.39, respectively, out of a maximum score of 7. The main benefits from CAM reported by patients included improvement in emotional and physical well-being (40% and 34.3%, respectively) and increased ability to fight the disease (31.4%), although 17.1% of patients reported no benefits at all from CAM. The main sources of information about CAM were friends/family and the media. Findings suggest that due to the relatively high use of CAM among cancer patients, this topic should be taken into account in a holistic approach to this patient population.

Use of complementary and alternative medicine in cancer patients: a European survey.

BACKGROUND: The aim of this study was to explore the use of complementary and alternative medicine (CAM) in cancer patients across a number of European countries. METHODS: A descriptive survey design was developed. Fourteen countries participated in the study and data was collected through a descriptive questionnaire from 956 patients. RESULTS: Data suggest that CAM is popular among cancer patients with 35.9% using some form of CAM (range among countries 14.8% to 73.1%). A heterogeneous group of 58 therapies were identified as being used. Herbal medicines and remedies were the most commonly used CAM therapies, together with homeopathy, vitamins/minerals, medicinal teas, spiritual therapies and relaxation techniques. Herbal medicine use tripled from use before diagnosis to use since diagnosis with cancer. Multivariate analysis suggested that the profile of the CAM user was that of younger people, female and with higher educational level. The source of information was mainly from friends/family and the media, while physicians and nurses played a small part in providing CAM-related information. The majority used CAM to increase the body's ability to fight cancer or improve physical and emotional well-being, and many seemed to have benefited from using CAM (even though the benefits were not necessarily related to the initial reason for using CAM). Some 4.4% of patients, however, reported side-effects, mostly transient. CONCLUSIONS: It is imperative that health professionals explore the use of CAM with their cancer patients, educate them about potentially beneficial therapies in light of the limited available evidence of effectiveness, and work towards an integrated model of health-care provision.

Prevalencia y características del dolor tras un injerto aortocoronario (DPI) / Prevalence and characteristics of post coronary artery by pass graft surgery pain (PCP)

La cirugía de derivación coronaria o injerto aortocoronario (IAC) es uno de los procedimientos quirúrgicos más habituales que se realizan en todo el mundo. No obstante, su complicación frecuente, el síndrome de dolor posterior a un injerto aortocoronario (DPI), sigue sin conocerse bien. Este estudio retrospectivo de una cohorte tuvo como finalidad investigar la prevalencia y las características de dicho síndrome. Quinientos cuatro de los 540 pacientes que se sometieron a cirugía de derivación coronaria en nuestro centro entre enero de 1995 y diciembre de 1996 y que pudieron ser identificados, recibieron por correo cuestionarios referentes a la presencia de dolor de la pared torácica y sus características. Ochenta de los 217 pacientes que se definieron como pacientes con DPI en base a esos cuestionarios, fueron evaluados con detenimiento. Las principales herramientas de evaluación fueron un cuestionario preliminar sobre el dolor, la localización del dolor en un esquema del cuerpo humano, una escala verbal de cinco puntos y la Escala Visual Analógica ( EVA) para medir la intensidad del dolor. Las características del dolor, la discapacidad y la depresión se midieron utilizando el Cuestionario sobre el Dolor de McGill (CDM), el Índice de Discapacidad por Dolor (IDD) y el Inventario sobre la Depresión de Beck (IDB), respectivamente. También se realizaron exploraciones médicas y neurológicas, así como pruebas térmicas cuantitativas (PTC) de la pared torácica. Según los cuestionarios preliminares del dolor, 219 de los 387 pacientes que respondieron (56 por ciento) refirieron dolor de la pared torácica, que se clasificó como DPI. Ciento cuarenta y dos (65 por ciento) de los pacientes con DPI refirieron dolor de intensidad al menos moderada, y 151 (72 por ciento) declararon que el dolor interfería con sus actividades de la vida diaria. Ochenta pacientes con DPI estuvieron disponibles para una evaluación más detallada. El dolor de la pared torácica se localiza en el lado izquierdo en 53 pacientes, en la cicatriz de la línea media en 47 pacientes y en el lado derecho en 9. La intensidad del dolor (EVA) fue de 35 ñ 22 (media ñ DE), la puntuación obtenida en el CDM fue de 4,9 ñ 3,7, el valor obtenido del IDD fue de 2,0 ñ 0,7, y la puntuación del IDB fue de 9,3 ñ 7,3. La exploración neurológica y las PTC indicaron tres subcategorías de DPI: (1) dolor de la pared torácica en el lado izquierdo, asociado con frecuencia a hipoestesia, alodinia mecánica y elevación de los umbrales térmicos ; (2) dolor en la cicatriz de la línea media acompañado principalmente de alodinia mecánica; (3) dolor en el lado derecho, relativamente poco frecuente. Mientras que las dos primeras subcategorías parecen tener una etiología neurogénica, la de la tercera está mal definida. El presente estudio indica que el DPI es un grupo de síndromes de dolor con una elevada prevalencia y con una influencia negativa en el estado de ánimo y la realización de las actividades diarias. Por lo tanto, el riesgo de aparición de DPI y sus posibles consecuencias deberían comentarse con todos los pacientes antes de someterse a una cirugía de derivación coronaria. Estos resultados tendrán que ser confirmados por estudios multicéntricos a mayor escala (AU)

Prevalence and characteristics of post coronary artery bypass graft surgery pain (PCP).

Coronary artery bypass grafting (CABG) is one of the most common surgical procedures performed worldwide. However, its frequent complication, the post-CABG pain (PCP) syndrome, remains poorly documented. This retrospective cohort study was aimed to investigate the prevalence and characteristics of this syndrome. Five hundred and four of 540 subjects, who underwent CABG surgery at our institution between January 1995 and December 1996 and who could be identified, were mailed questionnaires regarding the presence and characteristics of chest wall pain. Eighty of 217 patients, who were defined as having PCP based on these questionnaires, were evaluated in detail. Main outcome measures included a preliminary pain questionnaire, pain localization on a body scheme, a five-point verbal scale and the Visual Analogue Scale (VAS) for measuring pain intensity. Pain qualities, disability and depression were measured by the McGill Pain Questionnaire (MPQ), the Pain Disability Index (PDI), and the Beck Depression Inventory (BDI), respectively. Medical and neurological examinations were also conducted, as well as quantitative thermal testing (QTT) of the chest wall. The preliminary pain questionnaires indicated that 219 of the 387 respondents (56%) reported chest wall pain, which was categorized as PCP. One hundred and forty-two (65%) of the patients with PCP reported pain of at least moderate severity, and 151 (72%) reported that the pain interfered with their daily activities. Eighty PCP patients were available for a detailed evaluation. Left-sided chest wall pain was noted by 53 subjects, midline scar pain by 47, and right-sided pain by nine subjects. Pain intensity (VAS) was 35 +/- 22 (mean +/- SD), MPQ score was 4.9 +/- 3.7, PDI score was 2.0 +/- 0.7, and BDI score was 9.3 +/- 7.3. The neurological examination and the QTT indicated three subcategories of PCP: (1) left-sided chest wall pain often associated with hypoesthesia, mechanical allodynia, and elevated thermal thresholds; (2) midline scar pain accompanied primarily by mechanical allodynia; (3) right-sided, relatively infrequent pain. While the first two subcategories seem to have a neurogenic etiology, this later subcategory of pain is of a mal-defined etiology. This study indicates that PCP is a group of pain syndromes with a high prevalence, and with a negative effect on mood and performance of daily activities. The risk of developing PCP and its potential consequences should therefore be discussed with every patient prior to CABG surgery. These results will need to be confirmed in larger, multi-center studies.

Intravenous lidocaine, amantadine, and placebo in the treatment of sciatica: a double-blind, randomized, controlled study.

BACKGROUND AND OBJECTIVES: Sciatica is a neuropathic pain syndrome caused by compression and/or inflammation of spinal nerve roots by herniated disc material, and its treatment is therefore usually aimed at reducing compression and inflammation. Studies have shown that both systemic local anesthetics and N-methyl-D-aspartate (NMDA) receptor antagonists may produce analgesia in a variety of neuropathic pain syndromes. The present study evaluated the analgesic efficacy of i.v. infusions of the local anesthetic lidocaine, the NMDA receptor antagonist amantadine, and a placebo in sciatica. METHODS: Thirty patients with sciatica, as confirmed by physical examination and imaging studies, were enrolled in a randomized, double-blind, three-arm crossover trial. Infusions of amantadine (2.5 mg/kg), lidocaine (5 mg/kg), and a placebo were administered over a 2-hour period, 2-7 days apart from each other. Spontaneous pain (visual analog scale) and evoked pain (straight leg raise) were measured every 30 minutes for 3 hours. RESULTS: Lidocaine reduced spontaneous pain as compared with amantadine and with the placebo for all measurements and at a significant level at the 30 (P < .05), 120, and 180 (P < .01) minute time points. Maximal pain reduction from the baseline was 62 +/- 7% for lidocaine, 43 +/- 7% for amantadine, and 47 +/- 7% for the placebo. Straight leg raise test also significantly improved with lidocaine (from 30 to 37 degrees; P < .05), as compared to amantadine (34-36 degrees) and to the placebo (32-34 degrees). All three treatments were relatively well tolerated. CONCLUSIONS: Intravenous lidocaine, rather than amantadine, reduces both spontaneous and evoked sciatic pain.

The NMDA receptor antagonist amantadine reduces surgical neuropathic pain in cancer patients: a double blind, randomized, placebo controlled trial.

Neuropathic pain is often severe, persistent, and responds poorly to analgesic medications. Recent evidence suggests that N-methyl-D-aspartate (NMDA) receptor antagonists may be effective in the treatment of neuropathic pain. The present trial was designed to test the efficacy of acute administration of the NMDA receptor antagonist amantadine in relieving surgical neuropathic pain in patients with cancer. The study sample consisted of 15 cancer patients with the diagnosis of surgical neuropathic pain. Two 500 ml infusions of either 200 mg amantadine or placebo were administered over a 3 h period, in a randomized order, 1 week apart from each other. Spontaneous and evoked pain were measured for 48 h before treatment, during treatment, and for 48 h following treatment. An average pain reduction of 85% was recorded at the end of amantadine infusion vs. 45% following placebo administration. The difference in pain relief between the two treatments was statistically significant (P = 0.009). Mean pain intensity remained significantly lower during the 48 h following amantadine treatment as compared with the 48 h prior to treatment (31% reduction; P = 0.006), whereas no such effect was found with the placebo (6% reduction; P = 0.40). Amantadine, but not the placebo, also reduced 'wind up' like pain (caused by repeated pinpricking) in four patients. We conclude that amantadine infusion is a safe and effective acute treatment for surgical neuropathic pain in cancer patients. Further trials with long-term oral or parenteral amantadine treatment should be conducted.

Can patients with chronic neuropathic pain be cured by acute administration of the NMDA receptor antagonist amantadine?

The treatment of neuropathic pain remains a challenge as it rarely leads to long-term relief of symptoms. We report three patients with chronic neuropathic pain, in whom acute administration of the N-methyl-D-aspartate (NMDA) receptor antagonist amantadine resulted in complete resolution of symptoms, presumably due to termination the central 'wind-up' phenomenon.