Search results for "Pain Threshold"

The effects of diazepam on the behavioral structure of the rat's response to pain in the hot-plate test: Anxiolysis vs. pain modulation

2011

The aim of the present study was to evaluate, by means of quantitative and multivariate analyses, the effects of diazepam on the behavioral structure of the rat's response to pain in the hot-plate test as well as whether such changes are associated with drug-induced effects on anxiety and/or nociception. To this purpose, ten groups of male Wistar rats were intraperitoneally injected with saline, diazepam (0.25, 0.5 and 2 mg/kg), FG-7142 (1, 4 and 8 mg/kg) or morphine (3, 6 and 12 mg/kg). The mean number and mean latency to first appearance were calculated for each behavioral component. In addition, multivariate cluster and adjusted residual analyses based on the elaboration of transition ma…

Explicit episodic memory for sensory-discriminative components of capsaicin-induced pain: Immediate and delayed ratings

2008

Pain memory is thought to affect future pain sensitivity and thus contribute to clinical pain conditions. Systematic investigations of the human capacity to remember sensory features of experimental pain are sparse. In order to address long-term pain memory, nine healthy male volunteers received intrader- mal injections of three doses of capsaicin (0.05, 1 and 20 lg, separated by 15 min breaks), each given three times in a balanced design across three sessions at one week intervals. Pain rating was performed using a computerized visual analogue scale (0-100) digitized at 1/s, either immediately online or one hour or one day after injection. Subjects also recalled their pains one week later.…

Inflammatory Pain Promotes Increased Opioid Self-Administration: Role of Dysregulated Ventral Tegmental Area μ Opioid Receptors

2015

Pain management in opioid abusers engenders ethical and practical difficulties for clinicians, often resulting in pain mismanagement. Although chronic opioid administration may alter pain states, the presence of pain itself may alter the propensity to self-administer opioids, and previous history of drug abuse comorbid with chronic pain promotes higher rates of opioid misuse. Here, we tested the hypothesis that inflammatory pain leads to increased heroin self-administration resulting from altered mu opioid receptor (MOR) regulation of mesolimbic dopamine (DA) transmission. To this end, the complete Freund's adjuvant (CFA) model of inflammation was used to assess the neurochemical and functi…

Bone Trauma Causes Massive but Reversible Changes in Spinal Circuitry.

2016

Abstract Bone fracture with subsequent immobilization of the injured limb can cause complex regional pain syndrome (CRPS) in humans. Mechanisms of CRPS are still not completely understood but bone fracture with casting in mice leads to a similar post-traumatic inflammation as seen in humans and might therefore be an analog to human CRPS. In this article we report behavioral and spinal electrophysiological changes in mice that developed swelling of the paw, warming of the skin, and pain in the injured limb after bone fracture. The receptive field sizes of spinal neurons representing areas of the hind paws increased after trauma and recovered over time—as did the behavioral signs of inflammat…

Response to letter by Werner et al.

2012

Thermal Thresholds Predict Painfulness of Diabetic Neuropathies

2004

OBJECTIVE—Pathophysiology explaining pain in diabetic neuropathy (DN) is still unknown. RESEARCH DESIGN AND METHODS—Thirty patients with peripheral DN (17 men and 13 women; mean age 52.4 ± 2.5 years) were investigated. Fifteen patients had neuropathic pain, and 15 patients were free of pain. Patients were followed over 2 years and examined at the beginning and thereafter every 6 months. Clinical severity and painfulness of the DN were assessed by the neuropathy impairment score and visual analog scales (VASs). Cold and warm perception thresholds as well as heat pain thresholds were obtained for evaluation of Aδ- and C-fibers. Nerve conduction velocities (NCVs) and vibratory thresholds were …

Learning influence on the behavioral structure of rat response to pain in hot-plate

2011

Aim of the research was to study, by means of descriptive and multivariate analyses, whether, and how, learning influences the behavioral structure of rat response to pain. To this purpose, a hot-plate test daily repetition procedure was carried out on male Wistar rats for five days. A 6-day interval without stimulation elapsed before last test was carried out on day 12. After composition of an ethogram, descriptive (number, latency, per cent distribution) and multivariate analyses (cluster, stochastic) were carried out for each scheduled test day. One-way ANOVA and Newman-Keuls post-hoc test for multiple comparisons revealed significant changes for climbing, jumping, front-paw licking and …

Thermal hypoaesthesia differentiates secondary restless legs syndrome associated with small fibre neuropathy from primary restless legs syndrome.

2010

This study aimed to assess thermal and mechanical perception and pain thresholds in primary idiopathic restless legs syndrome and secondary restless legs syndrome associated with small fibre neuropathy. Twenty-one patients (age: 53.4 + or - 8.4, n = 3, male) with primary restless legs syndrome and 13 patients (age: 63.0 + or - 8.2, n = 1, male) with secondary restless legs syndrome associated with small fibre neuropathy were compared with 20 healthy subjects (age: 58.0 + or - 7.0; n = 2, male). Differential diagnosis of secondary restless legs syndrome associated with small fibre neuropathy was based on clinical symptoms and confirmed with skin biopsies in all patients. A comprehensive quan…

Dysynchiria is not a common feature of neuropathic pain

2006

Patients with chronic neuropathic pain (non-CRPS) and brush-evoked allodynia watched a reflected image of their corresponding but opposite skin region being brushed in a mirror. Unlike complex regional pain syndrome Type 1, this process did not evoke any sensation at the affected area ('dysynchiria'). We conclude that central nociceptive sensitisation alone is not sufficient to cause dysynchiria in neuropathic pain. The results imply a difference in cortical pain processing between complex regional pain syndrome and other chronic neuropathic pain.

Immediate effects of active versus passive scapular correction on pain and pressure pain threshold in patients with chronic neck pain.

2012

OBJECTIVE: The purpose of this study was to investigate the effect of active vs passive scapular correction on pain and pressure pain threshold at the most symptomatic cervical segment in patients with chronic neck pain. METHODS: Twenty-three volunteers with chronic, idiopathic neck pain were recruited (age, 38.9 ± 14.4 years; sex [man/woman], 3/20; Neck Disability Index, 28.1% ± 9.9%). Subjects were randomly allocated to 2 groups: active scapular correction or passive scapular correction. Pressure pain threshold and pain intensity rated on a numerical rating scale during a posteroanterior glide over the most symptomatic cervical segment were measured before and immediately after the active…