bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pain sensitivity changes in chronic pain patients with and without spinal cord stimulation assessed by nociceptive withdrawal reflex thresholds and electrical pain thresholds
Authors: Biurrun Manresa J.A. , Sörensen J. , Sandell A.-C. , Andersen O.K. , Arendt-Nielsen L. , Gerdle B. 
Published: July 2012

Abstract

Background and aim
Previous studies have shown that patients with chronic pain had significantly lower nociceptive withdrawal reflex thresholds (NWR-T) and electrical pain thresholds (EP-T) than healthy controls. Patients with chronic pain and implanted spinal cord stimulator (SCS) system presents an opportunity to study dynamic pain sensitivity changes in a situation where patients just have been stimulated (i.e., pain-free or greatly reduced pain) and compare with the situation where patients are not stimulated (i.e., experiencing severe pain).

Methods
Seventeen volunteers with chronic neuropathic pain and a SCS implanted for pain relief participated in the experiment. Volunteers were asked to turn off the SCS and refrain from medication at least 8 h before the experiment. Electrical stimulation (train-of-five 1-ms pulses delivered at 200 Hz) was applied to the arc of the foot in order to elicit the NWR and electromyographic responses were recorded from tibialis anterior muscle. A staircase procedure was used to assess the NWR-T and a Visual-Analog-Scale (VAS) scale (range 0–10) was used to assess the EP-T. After the initial testing, the SCS was turned on, and thresholds were reassessed after 1 h. Paired t-tests were used to compare the thresholds before and after the SCS was turned on. All values are presented as mean ± SD.

Results
The NWR-T were significantly higher after the SCS was turned on (before: 16.3 ±8.1 mA; after: 19.0 ± 10.9 mA; p = 0.028). EP-T did not show any significant differences (before: 3.2 ± 1.5 mA; after: 2.9 ± 2.0 mA; p = 0.324).

Conclusion
Results showed a higher NWR-T after the SCS was turned on, which indicates a depression of spinal nociception. Moreover, the NWR-T was able to detect ongoing and relatively quick changes in pain sensitivity.
Pain prevalence in a university hospital in Iceland
Authors: Zoëga S. , Ward S. , Aspelund T. , Sveinsdóttir H. , Sigurdsson G. , Gunnarsdóttir S. 
Published: July 2012

Abstract

Background/aims
Despite multiple efforts to improve practice, pain is prevalent in many hospital settings causing unnecessary complications and suffering. The aim of the study was to explore the epidemiology of pain in a university hospital in Iceland.

Methods
A point prevalence study was conducted in 23 departments in medical and surgical services in a 650 bed university hospital in January 2011. Data was collected from medical charts and with a questionnaire (APS-POQ-R) assessing pain severity and quality of pain management. Participants had to be 18 years or older, hospitalized for at least 24 h, speak Icelandic, alert, and able to participate.

Results
Of the 369 participants the mean (SD) age was 67.9 (17.6) years (range 18–100) and gender proportions were equal. Response rate was 80%. Of patients in pain (scoring ≥1 on a 0–10 scale) the mean (SD) worst pain severity was 5.6 (2.5). Total pain prevalence was 80.4%, but of patients in pain 36.5% had mild (1–4) pain, 22.6% moderate (5–6) and 40.9% had severe (7–10) pain. The mean (SD) proportion of time spent in severe pain was 25.9% (27.0%). Pain was both more prevalent, [χ2(1, N= 367) = 7.05, p = 0.008] and severe [t(365) =−4.16, p = 0.000] in women compared to men. Similarly, pain was more prevalent [χ2(1, N= 368) = 9.71, p = 0.002] and severe [t(216,2) =−3.18, p = 0.002] in surgical services compared to medical. Worst pain severity was weakly negatively associated with age [r(369) =−0.23, p = 0.000]. Worst pain severity was higher in patients receiving pain medications [t(357) =−9.84, p = 0.000] and in patients using non-pharmacological methods to treat their pain [t(311.7) =−5.76, p = 0.000].

Conclusions
Pain was prevalent in the hospital and an unsatisfactory proportion of patients experienced moderate to severe pain. The quality of pain management in the hospital needs to be improved. Further studies are needed to test and evaluate the efficacy and effectiveness of interventions aimed at advancing pain practice in the hospital setting.
The effect of tail-docking neonate piglets on ATF-3 and NR2B immunoreactivity in coccygeal dorsal root ganglia and spinal cord dorsal horn neurons: Preliminary data
Authors: Sandercock D.A. , Monteiro A. , Scott E.M. , Nolan A.M. 
Published: July 2012

Abstract

Background/aims
Tail docking neonatal piglets remains a controversial animal welfare issue. Although banned in the UK, it is widely practiced in many countries as a safeguard against tail biting among pigs reared in intensive systems. Concerns exist whether tail docking can induce chronic pain in later life. This preliminary study examined the effects of partial tail amputation on activating transcription factor 3 (ATF3), a marker of peripheral nerve injury and regeneration and NMDA-glutamate receptor NR2B subunit which participates in the mediation of chronic pain.

Methods
Procedures were performed according to the ethical guidelines for the study of experimental pain in animals. Six piglets (2–3 days old) were tail-docked (a portion of the tail amputated with sterile surgical cutters), six piglets (2–3 days old) were sham-docked. Three animals from each treatment were euthanised 7 and 56 days post-amputation. Coccygeal dorsal root ganglia (DRG) and spinal cord were collected post-mortem for immunohistochemistry.

Results
ATF3 immunoreactivity (IR) was significantly increased (p <0.05) in the DRG neurons from tail-docked piglets 7 days after tail amputation, compared with sham-docked piglets. ATF3-IR was not different in sham and tail-docked piglets 56 days post amputation. NR2B-IR was significantly increased (p < 0.05) in dorsal horn neurons in tail-docked piglets compared with intact piglets 7 days after docking. There was no difference in NR2B-IR in neurons 56 days post amputation, compared with intact piglets.

Conclusions
Increased ATF3 and NR2B-IR 7 days after tail-docking suggests that injury to the peripheral nerves in the tail was sufficient to trigger neuronal regeneration and altered dorsal horn signaling respectively, however the effects of tail-docking on neuronal regeneration and nociceptive signaling were relatively short lasting. Tail-docking neonatal piglets does not cause sustained changes in ATF3, which might suggest ongoing nerve fibre damage and NR2B which might be implicated in chronic pain.
Acute behavioural responses to tail docking in piglets – Effects of increasing docking length?
Authors: Herskin Mette S. , Giminiani Pierpaolo Di , Damgaard Birthe M. , Thodberg Karen 
Published: July 2012

Abstract

Background and aim
Tail docking has been suggested as an animal model of neuropathy and pain based on findings of relations between the degree of neuroma formation and the docking length. We examined effects of docking length on behaviour of piglets during and 6 h after tail docking.

Methods
Piglets were tail docked 2–4 d post-partum. We used 53 piglets and four treatments: intact (I), removal of either 25 (Q), 50 (H) or 75% (T) of the tail. The piglets were kept with sow and littermates under production conditions, and docked using a gas-heated instrument. Behaviour was observed during docking and for the following 6 h.

Results
Tail docking led to behavioural changes, the magnitude of which to some extend depended on docking length. Increased docking length led to increased intra-procedural vocalization score (0, 0.6 ± 0.2, 1.4 ± 0.2 and 1.4 ± 0.2 for I, Q, H and T, respectively, P<0.001). In the initial 6h, increased docking length led to increased time spent in the heated creep area (2 ± 1%, 15 ± 6%, 18±8% and 30±6% for I, Q, H and T, respectively; P<0.05). Piglet posture was affected as well, showing that increased docking length led to decreased lying (71 ± 2%, 68 ± 2%, 61 ± 2% and 61 ± 2% for I, Q, H and T, respectively, P<0.01) and increased time spent active (24 ± 2%, 23 ± 2%, 32 ± 2% and 30 ± 3% for I, Q, H and T, respectively, P< 0.05). Pain specific behaviours such as trembling or tail flicking were registered and occurred in 5 ± 1% and 9 ± 1% of observations. However, no effects of docking length could be shown.

Conclusions
Piglets responded behaviourally to tail docking. Increasing docking length led to increased pain responses such as intra-procedural vocalizations, hiding behaviour and reduced rest, indicative of increased pain. These results confirm earlier reports suggesting that tail docking might be suitable as an animal model for neuropathy and pain.
Neuroplastic alterations in brain responses to painful visceral stimulations reflects individual neuropathic symptoms in diabetes mellitus patients
Authors: Brock Christina , Graversen Carina , Frøkjær Jens B. , Søfteland Eirik , Valeriani Massimiliano , Drewes Asbjørn M. 
Published: July 2012

Abstract

Background/aims
Abnormal visceral sensory function in diabetes mellitus (DM) leads to neuronal changes in the enteric, peripheral and/or central nervous system (CNS). To explore the role of diabetic autonomic neuropathy (DAN) in patients with long-standing DM, we investigated psychophysical responses and neuronal activity recorded as evoked brain potentials (EPs) and dipolar source modelling.

Methods
Fifteen healthy volunteers and 14 type-1 DM patients with DAN were assessed with a symptom score index characterizing upper GI abnormalities. Multi-channel (62) electroencephalography was recorded during painful electrical stimulation of the lower oesophagus. Brain activity to painful stimulations was modelled by use of Brain Electrical Source Analysis (BESA).

Results
Diabetic patients had higher stimulus intensities to evoke painful sensation (P<0.001), longer latencies of N2 and P2 components (both P<0.001), lower amplitudes of P1–N2 and N2–P2 complexes (P<0.001; P = 0.02). Inverse modelling of brain sources showed deeper bilateral insular dipolar source localization (P = 0.002). Symptom score index was negatively correlated to the depth of insular activity (P = 0.004) and positively correlated to insular dipole strength (P = 0.03).

Conclusion
DM patients show neuroplastic changes in the central nervous system. The role of abnormal insular processing may explain the development and persistence of upper GI-symptoms related to DAN. This enhanced understanding of DAN may have clinical and therapeutical implications.
Hyperalgesia in human skin and deep-tissues inside and outside of a UVB irradiated area
Authors: Vecchio Silvia Lo , Petersen Lars J. , Graven-Nielsen Thomas , Finocchietti Sara , Gazerani Parisa , Arendt-Nielsen Lars 
Published: July 2012

Abstract

Background/aims
The ultraviolet B (UVB) inflammatory pain model is often used to induce a steady hyperalgesic area in human skin. UVB causes a well-described erythema, developing maximal response within about 24 h. The aim of the present study was to investigate if cutaneous UVB irradiation can influence both superficial and deep-tissue mechanical pain thresholds in the site of irradiation and in the surrounding area.

Methods
An area of 3 cm × 4 cm, located on the low back of 16 healthy volunteers, was irradiated by UVB (Medlight, Germany; 3xMED: Minimal Erythema Dose). The degree of inflammation was detected by measuring superficial blood flow before and after irradiation, inside and outside the stimulated area. Applying quantitative sensory assessments, mechanical pain threshold changes were detected one day after irradiation, within and outside of the irradiated area. Sensitivity to cutaneous mechanical stimuli was assessed using pin prick and deep-tissue pressure pain thresholds were evaluated on 12 spots (4 within and 8 outside, 1.5 cm distant from the irradiated area) by a computer-controlled pressure algometer (Aalborg University, Denmark; 1.0 cm2 flat probe, 0.5 cm2 flat probe and a V-shaped probe with a contact surface of 0.03 cm2).

Results
24 h after exposure, the irradiated skin showed clear erythema with a boundary matching the irradiated area and a statistically significant increase in cutaneous blood flow (P < 0.001) compared with baseline assessment. Cutaneous pin prick pain thresholds and deep-tissue pressure pain thresholds (all probes) were significantly decreased inside and outside the irradiated area (P < 0.05).

Conclusions
Cutaneous UVB irradiation reduces mechanical pain thresholds to pin-prick and pressure stimulation which may indicate allodynic responses in both the skin and in deep-tissues. Expansion of the responses to areas outside the irradiated zone confirmed the presence of secondary hyperalgesia to mechanical stimuli.
Effect of experimental jaw muscle pain on bite force during mastication
Authors: Shimada A. , Baad-Hansen L. , Svensson P. 
Published: July 2012

Abstract

Background/aims
Muscular pain often impairs masticatory function in Temporomandibular disorder patients. The specific aim of this study was to investigate how the bite force during mastication is influenced by experimental muscle pain caused by infusion of glutamate into the masseter muscle.

Methods
12 healthy adults participated, after providing informed consent. Customized metal frames of the intraoral bite force sensor were manufactured for all subjects, and placed on their preferred chewing side. To induce experimental pain, a sterile solution of glutamate (0.5 M) was infused into the posterior part of the masseter muscle. Isotonic saline (0.9%) was infused as a control (randomized, cross-over design). During chewing three different kinds of test food (two different size carrots and gummy), bite force, electromyographic (EMG) activity of bilateral masseter muscle and anterior temporalis muscle were recorded. The first and last five masticatory cycles were used for analyses. The outcome parameters were as follows; Visual Analog Scale (VAS) for pain, impulse and duration from the bite force signal, duration and amplitude of EMG. Three-way ANOVAs with food (3 levels), sessions (5 levels: baseline, during glutamate, baseline 2, during isotonic saline, follow-up), cycles (2 × 5 levels) were carried out.

Results
Glutamate caused moderate levels of pain (mean VAS: 2.4 ± 0.9) whereas isotonic saline only caused low levels of pain (Mean VAS: 0.7 ± 0.5). The ANOVA of impulse data, as well as most EMG data, demonstrated a significant effect of session. Post hoc tests showed significantly higher impulse values of both the first and last five cycles in the glutamate session compared to baseline whereas the EMG activity was significantly decreased (P < 0.05).

Conclusion
Surprisingly, experimental pain induced by glutamate increased the bite force during mastication coupled with a decrease in EMG activity. This indicates a major reorganization of the motor control during painful mastication.
Cognitive modulation of experimental pain at spinal and cortical levels
Authors: Simonsen Mie Hviid , Jensen Jakob Bredal , Andersen Ole Kæseler , Petrini Laura , Egsgaard Line Lindhardt , Mørch Carsten Dahl 
Published: July 2012

Abstract

Background/aims
Descending modulation of the nociceptive system has proven to be pronounced in healthy humans. The descending modulation can be activated by rather distinct methods such as strong tonic painful stimulation or changes in the cognitive state. The extent of descending modulation on spinal pain processing remains unclear. Therefore, we assessed simultaneous cognitive modulation of spinal and cortical processing of experimental pain.

Methods
Painful (1.7 × pain threshold (PT)) and non-painful (0.5 × PT) electrical stimulation was applied to the sole of the foot of 9 healthy subjects. Cortical activity was recorded by EEG from the vertex and the nociceptive withdrawal reflex (NWR) was recorded from the tibialis anterior muscle. Stimulations were applied during the Spatial Attention Task, where the subject was asked to indicate the direction of arrows presented in a computer screen, and when the subjects were relaxed. The subject was asked to rate the average pain intensity after 30 stimuli. A total of 240 stimuli were applied.

Results
The amplitude of the EEG P100 (p < 0.001), P300 (p = 0.019) peaks, the pain intensity (p < 0.001) and the NWR (p < 0.05) were all significantly higher when noxious stimulation was applied than when non-noxious stimuli were applied. The spatial attention task did not significantly modulate the amplitude of the P100 (p = 0.083), the P300 (p = 0.804) peaks, and the pain intensity (p = 0.139), but the NWR were significantly lower during the Spatial Attention Task (p = 0.042).

Conclusion
The results indicated that attracting the attention of the subjects to a task of spatial discrimination evoked a descending modulation affecting nociceptive processing at the spinal level. Still pain perception and late components of the vertex EEG were not significantly altered by the spatial attention task.
Multivariate pattern analysis of evoked brain potentials by temporal matching pursuit and support vector machine
Authors: Graversen Carina , Brock Christina , Frøkjær Jens Brøndum , Dimcevski Georg , Farina Dario , Drewes Asbjørn Mohr 
Published: July 2012

Abstract

Background/aims
Electroencephalography (EEG) recorded as evoked brain potentials (EPs) reflects the cortical processing to an external event. This approach is often used to study the altered response to acute pain in chronic pain patients compared to healthy volunteers. However, discrimination of the responses from the study populations is a non-trivial task, which calls for improved objective methods.

Methods
To develop and validate a new methodology, we analyzed data from 16 type-1 diabetes mellitus patients and 15 age and gender matched volunteers, by means of brain activity recorded from 62 EEG channels. The EEG signals were recorded as EPs elicited by painful electrical stimulations in the oesophagus with an intensity corresponding to the individual pain detection threshold. The EPs from all channels and subjects were decomposed simultaneously by a temporal matching pursuit (TMP) algorithm with Gabor atoms.

Results
Amplitude and phase features were classified by a support vector machine (SVM) to discriminate patients from healthy volunteers. A classification performance of 93.1% (P<0.001) was obtained when applying a majority voting scheme to the 3 best performing channels (FC4, C1, and C6) and including features from 2 atoms. The most discriminative features were determined by the slope coefficients from the SVM decision rule, which identified the biomarkers as delayed latency of the first atom (N2–P2 complex) and decreased amplitude of the second atom (NI–P1 complex).

Conclusion
The combination of TMP and SVM is a novel approach to classify two study populations, which may provide a new objective tool to identify biomarkers from various chronic pain populations.
Chronic pain after breast augmentation is associated with both signs of peripheral nerve injury and central nervous mechanisms
Authors: Kaasa T. , Romundstad L. , Stubhaug A. 
Published: July 2012

Abstract

Background/aims
The mechanisms behind chronic postsurgical pain remains unsettled. Quantitative sensory testing and questioning sensory function may help understand mechanisms behind the transition from acute to chronic pain. The aim of this study was to assess these aspects in postsurgical patients with and without chronic postsurgical pain.

Methods
116 women, who answered a questionnaire in a four years follow-up study of pain, sensory changes and quality of life after cosmetic breast augmentation surgery [1], were invited to participate in a psychophysical study. Twenty women answered the request and filled in a questionnaire, and 12 of these women finally met for examination.

Results
Six of the 12 women had pain in the area of surgery, three were pain-free, but reported sensory changes and three reported no pain or sensory disturbances. We performed a detailed quantitative sensory examination, with a protocol adapted from Rollke et al. [2] While only 3/6 patients in the pain-free group reported hypoesthesia, an area of hypoesthesia to tactile-, heat- and cold stimuli was identified in all subjects when examined (Table 1).

Table 1

Number in each group (subjects with pain vs. subjects without pain) showing presence of sensory characteristics.

Pain (N = 6)
No pain (N = 6)

Questionnaire

Hypoesthesia
5
3

Hyperesthesia
6
3

Examination

Hypoesthesia (tactile, heat, cold)
6
6

Hypersensitivity detected
4
1

Hyperpathia to heat
5
5

Paradoxical heat sensation during cold stimulation
4
0

Allodynia, cotton
0
0

Allodynia, brush
0
1

Cold allodynia
5
1

Abnormal temporal summation
5
1

Deep pain after algometry
4
0

The most striking difference between the group reporting pain and the one not reporting pain was the presence of paradoxical heat sensation, cold allodynia, abnormal temporal summation, and the presence of deep pain during/after pressure pain threshold testing with the algometer in the group with pain.

Conclusion
Self-reported sensory changes under-estimated sensory changes. Sensory testing revealed signs of peripheral nerve injury changes in all subjects, while signs of central nervous changes were found predominantly in patients with persistent pain.
Treatment with topical capsaicin: Experience from a pain clinic
Authors: Rørbæk Marianne , Ventzel Lise , Gottrup Hanne 
Published: July 2012

Abstract

Background
Neuropathic pain is usually treated with antidepressants and anticonvulsant. The use of systemic treatment is, however, limited due to poor tolerability and low efficacy. Qutenza, a topical capsaicin patch (8%), is a relatively new treatment for patients with peripheral neuropathic pain (PNP) conditions. The indication for using topical capsaicin treatment is peripheral neuropathic pain in patients without diabetes.

Aim
To describe the use of topical capsaicin treatment in a pain clinic in patients with PNP.

Methods
Case series of patients in a neuropathic pain clinic.

Results
Since October 2010, 40 patients with PNP with different aetiologies have been treated with topical capsaicin; 14 patients had nerve injuries in feet or lower leg or polyneuropathy, 13 patients had nerve lesions related to fingers, hands or arms, seven patients had pain after thoracotomy, four patients postherpetic neuralgia, and two patients had other lesions.
Almost half of the patients (47%) were responders and achieved a decrease in pain intensity as well as increased their quality of life (QoL). Responders received 1–6 treatments with capsaicin. Most responders were found in the post-thoracotomy group, of which 86% had a clinical significant reduction in pain. In the group with injuries to the hands, fingers and arms, 46% experienced a reduction in pain. Only 23% of patients with PNP in the feet and lower leg were responders; these patients had a clinical significant increase in QoL.

Conclusion
In 40 patients with PNP who were treated with topical capsaicin, we found an increase in QoL and a decrease in mean pain intensity of 3 measured on a VAS scale (0–10) in 47% of the treated patients.