The contribution of concentric electrode-evoked potentials and nociceptive withdrawal reflex to the routine neurophysiological assessment of neuropathic pain: cross-sectional study / A contribuição dos potenciais evocados por eletrodo concêntrico e reflexo de retirada nociceptiva para a avaliação neurofisiológica de rotina da dor neuropática: estudo observacional transversal

ABSTRACT BACKGROUND AND OBJECTIVES: Conventional electrodiagnostic studies (EDX) are frequently used to support the diagnosis of peripheral neuropathic pain. However, routine EDX has poor diagnostic yield for identifying small fiber neuropathy, which may be cause of neuropathic pain in some patients. This study aimed to assess the gain in diagnostic yield brought by adding pain-related evoked potentials with concentric electrode (CN-PREP) and nociceptive withdrawal reflex (NWR) assessments to EDX. METHODS: Transversal observational accuracy study which included patients referred to routine EDX in a tertiary-care hospital who reported chronic neuropathic pain in their lower limbs. Besides routine EDX, subjects underwent CN-PREP and NWR assessments. Diagnostic yield and tolerability were examined and compared between test studies. RESULTS: The study enrolled 100 patients (54% female), with 57 ± 12 years. EDX was altered in 47% of all patients. The addition of CN-PREP alone, and NWR combined with CN-PREP increased diagnostic yield to 69% and 72%, respectively. CN-PREP proved to be well tolerable, while NWR was associated with higher test-related pain intensity and discontinuation rate (9% vs. 0%). Considering EDX as the reference test, CN-PREP sensitivity was 85.1% and specificity 58.5%. CONCLUSION: Combining CN-PREP with the routine EDX for patients with neuropathic pain is feasible and results in increased diagnostic yield. Conversely, the addition of NWR to the aforementioned tests provides little improvement to this yield and is less tolerable to the patient. Further studies are needed to determine the actual sensitivity and specificity of CN-PREP when compared to the gold-standard for small fiber neuropathy diagnosis, i.e. intraepidermal nerve fiber density assessment.

RESUMO JUSTIFICATIVA E OBJETIVOS: Estudos convencionais de eletrodiagnóstico (EDX) são frequentemente usados para apoiar o diagnóstico de dor neuropática periférica. No entanto, o EDX de rotina tem baixo rendimento diagnóstico para identificar neuropatia de pequenas fibras. O objetivo deste estudo foi avaliar o ganho no rendimento diagnóstico pela adição de avaliações de potenciais evocados relacionados à dor com eletrodo concêntrico (CN-PREP) e reflexo de retirada nociceptiva (NWR) ao EDX. MÉTODOS: Estudo de precisão observacional transversal que incluiu pacientes encaminhados para EDX de rotina com dor neuropática crônica em membros inferiores. Além do EDX de rotina, os indivíduos foram submetidos às avaliações CN-PREP e NWR. O rendimento diagnóstico e a tolerabilidade foram examinados e comparados entre os estudos de teste. RESULTADOS: O estudo envolveu 100 pacientes (54% mulheres), com 57 ± 12 anos. O EDX estava alterado em 47%. A adição de CN-PREP sozinho e NWR combinado com CN-PREP aumentou o rendimento diagnóstico para 69% e 72%, respectivamente. O CN-PREP provou ser bem tolerável, enquanto o NWR foi associado a maior intensidade de dor relacionada ao teste e taxa de descontinuação (9% vs. 0%). Considerando o EDX como teste de referência, a sensibilidade do CN-PREP foi de 85,1% e a especificidade de 58,5%. CONCLUSÃO: A combinação do CN-PREP com o EDX de rotina para pacientes com dor neuropática é viável e resulta em maior rendimento diagnóstico. Já a adição de NWR aos testes mencionados fornece pouca melhora nesse rendimento e é menos tolerável para o paciente. Mais estudos são necessários para determinar a real sensibilidade e especificidade do CN-PREP quando comparado ao padrão-ouro para diagnóstico de neuropatia de pequenas fibras, ou seja, a avaliação da densidade de fibras nervosas intraepidérmicas.

Motor corticospinal excitability abnormalities differ between distinct chronic low back pain syndromes.

OBJECTIVES: It is not known whether cortical plastic changes reported in low-back pain (LBP) are present in all etiologies of LBP. Here we report on the assessment of patients with three LBP conditions: non-specific-LBP (ns-LBP), failed back surgery syndrome (FBSS), and sciatica (Sc). METHODS: Patients underwent a standardized assessment of clinical pain, conditioned pain modulation (CPM), and measures of motor evoked potential (MEPs)-based motor corticospinal excitability (CE) by transcranial magnetic stimulation, including short interval intracortical inhibition (SICI), and intracortical facilitation (ICF). Comparisons were also made with normative data from sex- and age-matched healthy volunteers. RESULTS: 60 patients (42 women, 55.1±9.1 years old) with LBP were included (20 in each group). Pain intensity was higher in patients with neuropathic pain [FBSS (6.8±1.3), and Sc (6.4±1.4)] than in those with ns-LBP (4.7±1.0, P<0.001). The same was shown for pain interference (5.9±2.0, 5.9±1.8, 3.2±1.9, P<0.001), disability (16.4±3.3, 16.3±4.3, 10.4±4.3, P<0.001), and catastrophism (31.1±12.3, 33.0±10.4, 17.4±10.7, P<0.001) scores for FBSS, Sc, and ns-LBP groups, respectively. Patients with neuropathic pain (FBSS, Sc) had lower CPM (-14.8±1.9, -14.1±16.7, respectively) compared to ns-LBP (-25.4±16.6; P<0.02). 80.0% of the FBSS group had defective ICF compared to the other two groups (52.5% for ns-LBP, P=0.025 and 52.5% for Sc, P=0.046). MEPs (140%-rest motor threshold) were low in 50.0% of patients in the FBSS group compared to 20.0% of ns-LBP (P=0.018) and 15.0% of Sc (P=0.001) groups. Higher MEPs were correlated with mood scores (r=0.489), and with lower neuropathic pain symptom scores(r=-0.415) in FBSS. CONCLUSIONS: Different types of LBP were associated with different clinical, CPM and CE profiles, which were not uniquely related to the presence of neuropathic pain. These results highlight the need to further characterize patients with LBP in psychophysics and cortical neurophysiology studies.

New updates on transcranial magnetic stimulation in chronic pain.

PURPOSE OF REVIEW: Chronic pain is the most prevalent symptomatic disease worldwide. Nonpharmacological interventions, such as noninvasive neuromodulation (NIN), have gained scientific evidence to support their use as an add-on strategy to pharmacological pain management. The most studied NIN technique is repetitive transcranial magnetic stimulation (rTMS). This review aims to identify the current indications for rTMS in the treatment of chronic pain and its new perspectives. RECENT FINDINGS: High-frequency rTMS delivered to the primary motor cortex (M1) is currently a treatment strategy with the most literature support for decreased pain intensity and alleviation of associated symptoms in peripheral neuropathic pain, fibromyalgia and migraine. It has been shown that stimulation sessions are well tolerated and tolerable, and the effects of daily stimulation sessions can be prolonged by spaced maintenance stimulation sessions. Despite its efficacy, some individuals will not respond to rTMS targeted to M1. Lines of research are currently being developed to improve rTMS efficacy either by exploring new therapeutic targets, using novel stimulation parameters or more comprehensively profiling patients who are likely to respond to this treatment modality. SUMMARY: Noninvasive brain stimulation for chronic TMS pain is a well tolerated and reasonable add-on treatment approach for pain syndromes such as neuropathic pain, migraine and fibromyalgia. Strategies to improve its efficacy are an active field of research.

Como mulheres avaliam expressões faciais de alegria e dor? / How do women evaluate facial expressions of happiness and pain? / ¿Cómo evalúan las mujeres las expresiones faciales de alegría y dolor?

A expressão facial de dor pode provocar diferentes reações comportamentais. Todavia, ainda não está claro se a face de dor evoca respostas motoras mais lentas ou mais rápidas, quando comparada à expressão com valência positiva, e sua interação com o sexo da pessoa que demonstra a expressão facial. O objetivo desse trabalho foi avaliar o padrão de resposta motora de mulheres em uma tarefa de reconhecimento de expressões faciais de alegria e dor em faces femininas e masculinas. Na tarefa experimental, 32 estudantes classificaram emoções faciais dinâmicas de homens e mulheres entre as opções de alegria e dor, sendo registradas as respostas de tempo de reação manual (TRM). A ANOVA indicou uma diferença entre faces masculinas e femininas apenas para a identificação da dor (p = 0,001), mas não da alegria (p = 0,064). Neste caso, a dor foi reconhecida mais rapidamente na face masculina (TRM = 625,1 ms) que na face feminina (TRM = 668,0 ms). Considera-se que este padrão de resposta motora pode estar relacionado à detecção de situações potencialmente ameaçadoras no ambiente, com possibilidade de ser estudado em pessoas com dor crônica.

The facial expression of pain can provoke different behavioral reactions. However, it is not clear whether the face of pain evokes slower or faster motor responses when compared with positive valence expression and its interaction with the gender of the person who demonstrates facial expression. The objective of this work was to evaluate the motor response pattern of women in a task of recognizing facial expressions of happiness and pain in female and male faces. In the experimental task, 32 students classified dynamic facial emotions of men and women among the options of happiness and pain, and manual reaction time (MRT) responses were recorded. The ANOVA indicated a difference between male and female faces only for the identification of pain (p = 0.001), but not happiness (p = 0.064). In this case, the pain was recognized more quickly on the male face (TRM = 625.1 ms) compared to the female face (TRM = 668.0 ms). It is considered that this pattern of motor response may be related to the detection of potentially threatening situations in the environment, with the possibility of being studied in people with chronic pain.

La expresión facial del dolor puede provocar diferentes reacciones conductuales. Sin embargo, aún no está claro si el rostro de dolor evoca respuestas motoras más lentas o más rápidas, en comparación con la expresión con valencia positiva, y su interacción con el sexo de la persona que demuestra expresión facial. El objetivo de este trabajo fue evaluar el patrón de respuesta motora de las mujeres en una tarea de reconocimiento de expresiones faciales de alegría y dolor en rostros femeninos y masculinos. En la tarea experimental, 32 estudiantes clasificaron las emociones faciales dinámicas de hombres y mujeres entre las opciones de alegría y dolor, y se registraron las respuestas de tiempo de reacción manual (TRM). El ANOVA indicó una diferencia entre los rostros masculinos y femeninos solo para la identificación del dolor (p = 0.001), pero no alegría (p = 0.064). En este caso, el dolor se reconoció más rápidamente en el rostro masculino (TRM = 625.1 ms) comparado al rostro femenino (TRM = 668.0 ms). Se considera que este patrón de respuesta motora puede estar relacionado con la detección de situaciones potencialmente amenazantes en el entorno, con posibilidad de ser estudiado en personas con dolor crónico.

Latin American and Caribbean consensus on noninvasive central nervous system neuromodulation for chronic pain management (LAC2-NIN-CP).

INTRODUCTION: Chronic pain (CP) is highly prevalent and generally undertreated health condition. Noninvasive brain stimulation may contribute to decrease pain intensity and influence other aspects related to CP. OBJECTIVE: To provide consensus-based recommendations for the use of noninvasive brain stimulation in clinical practice. METHODS: Systematic review of the literature searching for randomized clinical trials followed by consensus panel. Recommendations also involved a cost-estimation study. RESULTS: The systematic review wielded 24 transcranial direct current stimulation (tDCS) and 22 repetitive transcranial magnetic stimulation (rTMS) studies. The following recommendations were provided: (1) Level A for anodal tDCS over the primary motor cortex (M1) in fibromyalgia, and level B for peripheral neuropathic pain, abdominal pain, and migraine; bifrontal (F3/F4) tDCS and M1 high-definition (HD)-tDCS for fibromyalgia; Oz/Cz tDCS for migraine and for secondary benefits such as improvement in quality of life, decrease in anxiety, and increase in pressure pain threshold; (2) level A recommendation for high-frequency (HF) rTMS over M1 for fibromyalgia and neuropathic pain, and level B for myofascial or musculoskeletal pain, complex regional pain syndrome, and migraine; (3) level A recommendation against the use of anodal M1 tDCS for low back pain; and (4) level B recommendation against the use of HF rTMS over the left dorsolateral prefrontal cortex in the control of pain. CONCLUSION: Transcranial DCS and rTMS are recommended techniques to be used in the control of CP conditions, with low to moderate analgesic effects, and no severe adverse events. These recommendations are based on a systematic review of the literature and a consensus made by experts in the field. Readers should use it as part of the resources available to decision-making.

O efeito Simon induzido pela direção do olhar em faces de dor e alegria / The Simon effect triggered by the gaze direction in painful and happy faces / El efecto Simon inducido por la dirección de la mirada en rostros de dolor y alegría

Embora irrelevante para a tarefa, a direção do olhar pode influenciar o tempo de reação em uma tarefa de Simon, gerando automaticamente um código espacial. Expressões faciais influenciam as respostas dos observadores, ativando tendências comportamentais de aproximação ou afastamento. No presente estudo, investigamos se a facilitação da resposta desencadeada pela direção do olhar seria reduzida na avaliação de expressões faciais de dor em comparação com alegria. Foi também analisado o efeito de sequência da apresentação das expressões, onde a facilitação ou inibição provocada por uma expressão emocional afeta a resposta na prova subsequente. Os resultados mostram que as faces dolorosas causam inibição da resposta na prova atual e posterior, indicando empatia emocional pela dor. O tipo da expressão facial não influenciou a facilitação da resposta promovida pela direção do olhar. Esta metodologia é apresentada como uma estratégia para investigar a empatia emocional, especialmente nos distúrbios relacionados à redução da empatia.

Although irrelevant to the task, gaze direction can influence reaction time responses in a Simon task insofar as it automatically generates a spatial code. Facial expressions also influence observers' responses and they can activate approach or avoidance behavioral tendencies. In the present study, we investigated whether the facilitation of the response triggered by gaze direction would be reduced for the evaluation of facial expressions of pain as compared to happiness. We also analyzed the effect of sequence presentation of the facial expressions, in which the facilitation or inhibition caused by an emotional expression affects the response in a subsequent trial. Results show that painful faces cause a response inhibition in the present and subsequent trials, indicating an emotional empathy for pain. The type of the facial expression (happiness or pain) did not influenced the facilitation of the response promoted by gaze direction. This methodology is presented as a new strategy to investigate emotional empathy, especially in disorders related to the reduction of the empathy.

Aunque irrelevante para la tarea, la dirección de la mirada puede influir en las respuestas del tiempo de reacción en una tarea de Simon en la medida en que genera automáticamente un código espacial. Las expresiones faciales también influyen en las respuestas de los observadores y pueden activar tendencias de comportamiento de acercamiento o evitación. En el presente estudio, se investigó si la facilitación de la respuesta provocada por la dirección de la mirada se reduciría para la evaluación de expresiones faciales del dolor en comparación con felicidad. También analizamos el efecto de la secuencia de la presentación de las expresiones faciales, en que la facilitación o inhibición causada por una expresión emocional afecta la respuesta en el ensayo posterior. Los resultados muestran que las caras dolorosas causan una inhibición de la respuesta en los ensayos presentes y posteriores, lo que indica una empatía emocional por el dolor. El tipo de expresión facial (felicidad o dolor) no influyó en la facilitación de la respuesta promovida por la dirección de la mirada. Esta metodología se presenta como una nueva estrategia para investigar la empatía emocional, especialmente en los trastornos relacionados con la reducción de la empatía.

Efeitos da prática de exercício físico sobre o desempenho da marcha e da mobilidade funcional em idosos / Effects of physical training on gait performance and functional mobility in elderly

INTRODUÇÃO: A população idosa apresenta-se em um acelerado processo de crescimento associado ao aumento da expectativa de vida. As alterações no envelhecimento podem comprometer o padrão de marcha e equilíbrio dos idosos, predispondo-os a quedas. Como estratégia de prevenção, indica-se a atividade física regular direcionada para ganho de força, equilíbrio, propriocepção e melhoria da marcha. OBJETIVO: Verificar os efeitos de um programa de exercícios físicos na marcha e na mobilidade funcional de idosos. MATERIAIS E MÉTODOS: Participaram do estudo oito idosos com mais de 60 anos (três homens e cinco mulheres). Os participantes realizaram duas avaliações antes e após a intervenção de seis meses: (1) marcha, pelo método de marcação de passarelas e (2) equilíbrio, por meio do Time Up and Go Test (TUGT). Para análise dos dados utilizou-se o software R (2.9.0). Para comparação dos dados, foi utilizado o teste t de Student pareado e o teste de correlação de Pearson, com p < 0,05. RESULTADOS: Verificou-se aumento no comprimento dos passos E (de 0,71 ± 0,19 para 0,80 ± 0,19 cm) e D (de 0,73 ± 0,17 para 0,81 ± 0,17 cm), e das passadas E (de 1,44 ± 0,36 para 1,59 ± 0,32 cm). Para o TUGT, além de forte correlação entre idade e velocidade da marcha e base de suporte, observou-se diminuição no tempo de realização do teste (de 13,92 ± 3,84 para 9,46 ± 1,68 segundos). CONCLUSÃO: O programa de exercícios físicos direcionados para a prevenção de quedas melhorou o desempenho funcional de idosos e alterou positivamente as variáveis da marcha.

INTRODUCTION: The elderly population is presented in an accelerated growth associated with increased life expectancy. The changes in aging can affect the pattern of gait and balance in the elderly may predispose them to falls. As prevention strategy, regular physical activity is indicated to gain strength, balance, proprioception and gait improvement. OBJECTIVE: To investigate the effects of an exercise program on gait and mobility of elderly. MATERIALS ANS METHODS: Eight subjects (three men and five women) over 60 years old participated in the study. They underwent two assessments: 1) march, by the method of marking walkways, and balance through the Time Up and Go Test (TUGT) before and after the six months intervention. For data analysis, we used R software (2.9.0). To compare the data we used the Student's "t" test paired and Pearson correlation, p < 0.05. RESULTS: An increase in stride length and (0.71 ± 0.19 to 0.80 ± 0.19 cm) and D (0.73 ± 0.17 to 0.81 ± 0.17 cm), and stride E (1.44 ± 0.36 to 1.59 ± 0.32 cm). For TUGT observed reduction in the time of the test (of 13.92 ± 3.84 to 9.46 ± 1.68 seconds), and a strong correlation between age and gait speed and support base. CONCLUSION: The exercise program targeted to prevention of falls improved the performance of elderly and positively affected the gait variables.