Summation

About: Summation is a research topic. Over the lifetime, 954 publications have been published within this topic receiving 45593 citations. The topic is also known as: summation & sum of a sequence.

The Effects of High-frequency, Non-noxious TENS on RIII Nociceptive Flexion Reflex and Temporal Summation in Human Subjects

Abstract: Background: Transcutaneous electrical nerve stimulation (TENS) has been used widely, but its effects are controversial. This is probably due to the varying intensity and type of pain. We designed a study to assess the effects of the TENS on the RIII nociceptive flexion reflex as the resting pain level and the temporal summation as a repeated, movement related pain in 7 normal volunteer subjects. Methods: High frequency (80 Hz), non-noxious TENS was applied over the left popliteal fossa for 20 minutes. Ipsilateral RIII reflexes induced by single electrical stimulus and temporal summation of pain responses to repeated stimuli (five stimuli at 2 Hz) were recorded before, during (just before stopping), and subsequently at 20 minutes after TENS. Results: R (III) nociceptive flexion reflex activity during and after TENS was more significantly decreased than before treatment. However, the temporal summation threshold was not changed. Conclusions: We conclude that high frequency, non-noxious TENS could be effective on resting pain relief in the same segment but not on the movement related pain.

Central sensitization in CRPS patients with widespread pain: A cross-sectional study.

Abstract: OBJECTIVE Widespread pain hypersensitivity and enhanced temporal summation of pain (TSP) are commonly reported in patients with complex regional pain syndrome (CRPS) and discussed as proxies for central sensitization. This study aimed to directly relate such signs of neuronal hyperexcitability to the pain phenotype of CRPS patients. METHODS Twenty-one CRPS patients and 20 healthy controls (HC) were recruited. The pain phenotype including spatial pain extent (assessed in % body surface) and intensity were assessed and related to widespread pain hypersensitivity, TSP, and psychological factors. Quantitative sensory testing (QST) was performed in the affected, the contralateral and a remote (control) area. RESULTS CRPS patients showed decreased pressure pain thresholds in all tested areas (affected: t(34)=4.98, p < 0.001, contralateral: t(35)=3.19, p = 0.005, control: t(31)=2.65, p = 0.012). Additionally, patients showed increased TSP in the affected area (F(3,111)=4.57, p = 0.009) compared to HC. TSP was even more enhanced in patients with a high compared to a low spatial pain extent (F(3,51)=5.67, p = 0.008), suggesting pronounced spinal sensitization in patients with extended pain patterns. Furthermore, the spatial pain extent positively correlated with the Bath Body Perception Disturbance Scale (ρ = 0.491; p = 0.048). CONCLUSION Overall, we provide evidence that the pain phenotype in CRPS, i.e., spatial pain extent, might be related to sensitization mechanism within the central nociceptive system. This study points towards central neuronal excitability as a potential therapeutic target in patients with more widespread CRPS.

Effect of Spatial Summation on Action of Nociceptive Stimuli on the Cerebral Cortex

Abstract: Hardy, Wolff, and Goodell 1 found in extensive studies that the threshold of pain in man was independent of the size of the cutaneous area that was stimulated. Whereas temporal and spatial summation processes have a profound influence on the sensory threshold of touch and temperature sensations, the investigations of Hardy and others showed that the pain threshold was lowered by temporal but not by spatial summation. On the contrary, it is well known that both forms of summation influence the intensity and duration of the reflex reactions resulting from nociceptive stimulation. Since this statement is based largely on spinal reflexes, it appeared desirable to investigate the effect of spatial and temporal summations on cerebral reactions induced by nociceptive stimulation. Method Experiments were performed on lightly anesthetized cats prepared under thiopental (Pentothal) and local anesthesia, later supplemented by chondodendron tomentosum extract, purified (Intocostrin). Artificial respiration was used routinely. The