Search results for "Algesia"
showing 10 items of 158 documents
Effects of Botulinum Toxin A on Allodynia in Chronic Migraine: An Observational Open-Label Two-Year Study.
2019
<b><i>Background:</i></b> Onabotulinumtoxin A (OBT-A) is a treatment option for chronic migraine (CM), though the possible effect on central sensitization and allodynia is still unknown. <b><i>Aims:</i></b> The present study aimed to evaluate (1) the long-term outcome of allodynia in a group of CM treated with OBT-A (2) if the presence and severity of allodynia could predict the long-term effect of OBT-A (3) if the improvement of allodynia, could contribute to the clinical efficacy of OBT-A. <b><i>Methods:</i></b> This was an observational, open-label, cohort study conducted on 99 CM patients treated for 1 year and 44 p…
Differential effect of Incobotulinumtoxin A on pain, neurogenic flare and hyperalgesia in human surrogate models of neurogenic pain
2017
Background: The effectiveness of Botulinum-neurotoxin A (BoNT/A) to treat pain in human pain models is very divergent. This study was conducted to clarify if the pain models or the route of BoNT/A application might be responsible for these divergent findings. Methods: Sixteen healthy subjects (8 males, mean age 27 ± 5 years) were included in a first set of experiments consisting of three visits: (1) Visit: Quantitative sensory testing (QST) was performed before and after intradermal capsaicin injection (CAPS, 15 μg) on one thigh and electrical current stimulation (ES, 1 Hz) on the contralateral thigh. During stimulation pain and the neurogenic flare response (laser-Doppler imaging) were ass…
Secondary hyperalgesia and perceptual wind-up following intradermal injection of capsaicin in humans.
1998
Wind-up and secondary hyperalgesia both are related to central sensitization, but whereas the former is explained by homosynaptic facilitation, the latter is due to heterosynaptic facilitation. To investigate possible interactions between both types of facilitation, we tested for alterations of perceptual wind-up in the secondary hyperalgesic skin zone adjacent to a capsaicin injection with light touch (by a cotton wisp) and punctate stimuli (calibrated von Frey hairs and pin pricks). Temporal summation of pain sensation (perceptual wind-up) was only observed with a clearly noxious stimulus (pin prick) presented at a repetition frequency of 0.6 s(-1), but not 0.2 s(-1). Pain ratings to trai…
Quantitative sensory testing in the German Research Network on Neuropathic Pain (DFNS): Somatosensory abnormalities in 1236 patients with different n…
2009
Neuropathic pain is accompanied by both positive and negative sensory signs. To explore the spectrum of sensory abnormalities, 1236 patients with a clinical diagnosis of neuropathic pain were assessed by quantitative sensory testing (QST) following the protocol of DFNS (German Research Network on Neuropathic Pain), using both thermal and mechanical nociceptive as well as non-nociceptive stimuli. Data distributions showed a systematic shift to hyperalgesia for nociceptive, and to hypoesthesia for non-nociceptive parameters. Across all parameters, 92% of the patients presented at least one abnormality. Thermosensory or mechanical hypoesthesia (up to 41%) was more frequent than hypoalgesia (up…
Generalized hyperalgesia in patients with chronic tension-type headache.
2006
Increased pain sensitivity in the central nervous system may play an important role in the pathophysiology of chronic tension-type headache (CTTH). Previous studies using pain thresholds as a measure of central pain sensitivity have yielded inconsistent results and only a few studies have examined perception of muscle pain without involvement of adjacent tissues. It has been suggested that suprathreshold testing might be more sensitive than threshold measurements in evaluation of central hyperexcitability in CTTH. The aim of the study was to compare pain ratings to suprathreshold single and repetitive (2 Hz) electrical stimulation of muscle and skin in cephalic (temporal and trapezius) and…
Neurogenic hyperalgesia versus painful hypoalgesia: two distinct mechanisms of neuropathic pain
2002
Patients with sensory disturbances of painful and non-painful character show distinct changes in touch and/or pain sensitivity. The patterns of sensory changes were compared to those of human surrogate models of neuropathic pain to assess the underlying mechanisms. We investigated 30 consecutive in-patients with dysaesthesia of various origins (peripheral, spinal, and brainstem lesions) and 15 healthy subjects. Tactile thresholds were determined with calibrated von Frey hairs (1.1mm). Thresholds and stimulus-response functions for pricking pain were determined with a series of calibrated punctate mechanical stimulators (0.2mm). Allodynia was tested by light stroking with a brush, Q-tip, and…
The role of heterosynaptic facilitation in long-term potentiation (LTP) of human pain sensation
2008
Long-term potentiation (LTP) of nociceptive synaptic transmission induced by high-frequency electrical stimulation (HFS) predominantly modulates natural somatosensory perceptions mediated by Adelta- and Abeta-fibers in humans at the site of conditioning stimulation. The relative contribution of homo- and heterosynaptic mechanisms underlying those perceptual changes remained unclear. We therefore compared changes of the somatosensory profile between a conditioned skin site (homotopic zone) and an area adjacent to conditioning HFS (heterotopic zone). HFS of the ventral forearm in 24 healthy subjects (mean pain 41/100) led to an abrupt increase of pain to single electrical test stimuli (pain a…
Perceptual correlates of nociceptive long-term potentiation and long-term depression in humans.
2004
Long-term potentiation (LTP) and long-term depression (LTD) of synaptic strength are ubiquitous mechanisms of synaptic plasticity, but their functional relevance in humans remains obscure. Here we report that a long-term increase in perceived pain to electrical test stimuli was induced by high-frequency electrical stimulation (HFS) (5 × 1 sec at 100 Hz) of peptidergic cutaneous afferents (27% above baseline, undiminished for >3 hr). In contrast, a long-term decrease in perceived pain (27% below baseline, undiminished for 1 hr) was induced by low-frequency stimulation (LFS) (17 min at 1 Hz). Pain testing with punctate mechanical probes (200 μm diameter) in skin adjacent to the HFS–LFS con…
Modality-specific sensory changes in humans after the induction of long-term potentiation (LTP) in cutaneous nociceptive pathways.
2007
The impact of long-term potentiation (LTP) in nociceptive pathways on somatosensory perception was examined by means of quantitative sensory testing (QST) in the ventral forearm of 12 healthy human subjects. Electrical high-frequency stimulation of the forearm skin (HFS; 5 x 1 s at 100 Hz and 10 x detection threshold) led to an abrupt increase of pain to single electrical test stimuli, which were applied through the same electrode (perceptual LTP +72%, p0.01). Perceptual LTP outlasted the 1-h observation period. The effects of HFS on somatosensory perception of natural test stimuli in the conditioned skin area were restricted to mechanical submodalities. Subjects exhibited a significant dec…
Effects of the NMDA-receptor antagonist ketamine on perceptual correlates of long-term potentiation within the nociceptive system
2007
We recently reported perceptual correlates of long-term potentiation (LTP) of synaptic strength within the nociceptive system demonstrating the functional relevance of LTP for human pain sensation. LTP is generally classified as NMDA-receptor dependent or independent. Here we show that low doses of the NMDA-receptor antagonist ketamine (0.25 mg/kg) prevented the long-term increase in perceived pain to electrical test stimuli, which was induced by high-frequency electrical stimulation (HFS) of nociceptive afferents. Whereas in a control experiment HFS led to a stable increase in perceived pain by 51% for the entire observation period of 1 h HFS given 4 min after i.v. ketamine was ineffective…