Spinal Circuits Transmitting Mechanical Pain and Itch / 神经科学通报·英文版

In 1905, Henry Head first suggested that transmission of pain-related protopathic information can be negatively modulated by inputs from afferents sensing innocuous touch and temperature. In 1965, Melzak and Wall proposed a more concrete gate control theory of pain that highlights the interaction between unmyelinated C fibers and myelinated A fibers in pain transmission. Here we review the current understanding of the spinal microcircuits transmitting and gating mechanical pain or itch. We also discuss how disruption of the gate control could cause pain or itch evoked by innocuous mechanical stimuli, a hallmark symptom for many chronic pain or itch patients.

The implementation of the Neuroid in the Gate Control System leads to new ideas about pain processing

INTRODUCTION: Several theories have been proposed to elucidate the mechanisms related with pain perception, among which, the Gate Control Theory (GCT) provides one of the most explicit explanations. This theory, as elegantly conceived, is unable to explain how the Frequency-Intensity (F-I) curves exhibited by Aβ- and C-fibres influence pain processing. In this paper, a novel neuron-model known as the Neuroid, which emphasizes the functional rather the physiological character of nerve cells, was used as the main building block to replicate the Gate Control System (GCS). METHODS: Two Aβ-fibre models were built: one model that preserved the paradoxical relation between the activation threshold and the F-I curve slope, and one model based on the hypothetical average response across the receptive field. RESULTS: The results suggest that the average response of the Aβ-fibres does not increase monotonically but reaches a plateau for high intensity stimuli. In addition, it was seen that activation of C-fibres does not necessarily imply the activation of projection neurons and, therefore, the onset of pain sensation. Also, we observed that the activation of Aβ-fibres may both, decrease and increase the activity of the projections neurons, an aspect which has not been directly described in previous works. CONCLUSION: Hypothetical implications arise as a consequence of the implementation of the Neuroid, specifically, about the correlation between the intensity of stimulation and the physiological pain threshold.

Effects of Seifu on Blood Pressure, Pain and Edema / 日本温泉気候物理医学会雑誌

<B>Introduction</B><BR>  Seifu, devised in 1992 by Xu, is a method of treatment through “pulling the skin”, unlike the approaches of treatment adopted in Shiatsu, massage, or acupuncture. This paper reports our recent evaluations of the effects of Seifu on the blood pressure, pain, and edema.<BR><B>Materials and Methods</B><BR>  The blood pressure was measured before and after Seifu in 36 individuals (mean age : 78.6±6.6 years) who underwent Seifu for 5 sessions or more. The effects on edema were evaluated in 14 individuals aged 45-90. Changes in the severity of edema following Seifu were analyzed. The effects on pain were evaluated in two ways.<BR>1) Effects on acute pain<BR>  The effects on pain arising from injection into the knee were evaluated in three groups of patients with osteoarthritis of the knee: Group A (injection after the application of Seifu to the acupuncture point Gohkoku (LI4); n=7, mean age: 72.8±2.8 years), Group B (injection after the application of Seifu to the area around the knee; n=198, mean age: 75.3±9.1 years) and Group C (injection after the application of Seifu to the acupuncture point Saninkoh (SP6) ; n=62, mean age: 75.0±7.5 years).<BR>2) Effects on subcuate and chronic pain<BR>  Pain was evaluated before and after Seifu using a visual analog scale (VAS) in 103 patients with some subacute or chronic pain(n=594, mean age: 73.4±12.4 years).<BR><B>Results</B><BR>1. Blood pressure<BR>  The blood pressure decreased significantly in 5 and increased significantly in the normal range in 1 of the 36 subjects. No significant change in the blood pressure was noted in the other 30 subjects.<BR>2. Edema<BR>  Seifu was effective against pitting edema. However, in pateints followed for long periods of time after the surgical treatment of breast cancer, the skin hardness decreased but edema showed no marked reduction. Seifu exerted no effect on Quincke edema.<BR>3. Pain<BR>1) Acute pain<BR>  Pain at the time of injection was not alleviated in Group A. Pain at the time of injection was alleviated in 73.3% of the subjects from Group B and 69.4% from Group C. This percenatge did not differ significantly between Groups B and C.<BR>2) Subacute and chronic pain<BR>  Mean VAS±SD decreased significantly from 6.6±2.0 before to 3.4±1.8 after Seifu (p<0.001).<BR><B>Discussion</B><BR>  Seifu was shown to be effective against pitting edema. In cases where lymph ducts and vascular walls are intact, edema is expected to be alleviatedl by the Seifu-induced activation of lymph system autotransportation and its milking action on veins.<BR>Seifu seems to alleviate pain via the mechanism proposed in the gate control theory.<BR><B>Conclusion</B><BR>  Seifu is simple to apply and effective against pitting edema and pain, without exhibiting adverse effects on the blood pressure.