Análise da relação entre parâmetros da onda-M e a dor

Abstract

Pain is a subjective and individual feeling that causes many inconveniences to those who feel. Thus, we need a method to quantify pain objectively. Studies show that evoked potentials can generate responses that reflect the painful processes. In this context, this study used M-wave characteristics as potential markers of pain sensation. Sixteen volunteers, eight males and eight females, participated in five sessions with the same protocol in each. In each session the volunteers received electrical stimulation in the abductor hallucis muscle. Initially it was applied a current of 1 mA at 20 pulses, after which the volunteers reported pain levels on visual analogue scale (VAS) and any other sensations. After that the electrical current had an increment of 1 mA with repetition of the previous procedures, and were generated increments until the maximum voluntary reported pain level (VAS 10). In the female volunteers were also enrolled the day of the menstrual cycle in each session of the experiment. The electrode placement was standardized to ensure that in every session they were placed in the same place. During the data analysis were assessed several characteristics of the M-waves and observed that the global minimum of M-wave is correlated with increased electrical current, thereby to increase the pain felt by the subject. The results showed that in male subjects the threshold and pain tolerance were higher than in female volunteers, and also that the different phases of the menstrual cycle did not affect the ratings.