Pain
-
We have examined the effect of an intradermal injection of phenylephrine (1mg/0.1 ml), an alpha-1-adrenoceptor agonist in normal subjects, and patients with sympathetically-independent (SIP) and sympathetically-maintained pain (SMP). Normal subjects and SIP patients experienced only brief stinging pain, while subsets of both sympathectomized and non-sympathectomized SMP patients (6/9 and 4/8, respectively) experienced an additional abnormal pain response accompanied by mechano-allodynia around the injection site. ⋯ Abnormal pain response evoked by norepinephrine or phenylephrine injection in the ipsilateral symptomatic limb of SMP patients may be due to injury-evoked nociceptor responsiveness to catecholamines. However, such a response in contralateral asymptomatic limbs suggests an additional factor that more likely than not is of central origin and may or may not be related to sympathectomy and its success or failure to treat pain.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Controlled trial of Internet-based treatment with telephone support for chronic back pain.
The purpose of this study was to investigate the effects of an Internet-based cognitive-behavioral intervention with telephone support for chronic back pain. Participants who met the criteria for chronic back pain (N=56) were randomly assigned to either an Internet-based cognitive behavioral self-help treatment or to a waiting-list control condition. The study period lasted 8 weeks and consisted of 1 week of self-monitoring prior to the intervention, 6 weeks of intervention, and 1 week of post-intervention assessment. ⋯ A follow-up of 3 months after treatment termination was completed in 92% (N=47) of the participants who completed the treatment intervention. Follow-up results showed that some improvement was maintained. Findings indicate that Internet-based self-help with telephone support, based on established psychological treatment methods, holds promise as an effective approach for treating disability in association with pain.
-
Comparative Study
Catastrophizing as a mediator of sex differences in pain: differential effects for daily pain versus laboratory-induced pain.
Sex differences in the experience of pain have been widely reported, with females generally reporting more frequent clinical pain and demonstrating greater pain sensitivity. However, the mechanisms underpinning such differences, while subject to intense speculation, are not well-characterized. Catastrophizing is a cognitive and affective process that relates strongly to enhanced reports of pain and that varies as a function of sex. ⋯ Women reported greater levels of catastrophizing, more recent painful symptoms, and demonstrated lower pain thresholds and tolerances for noxious heat and cold relative to men. Mediational analyses suggested that after controlling for negative mood, catastrophizing mediated the sex difference in recent daily pain but did not mediate the much larger sex differences in pain threshold and tolerance. These findings highlight the role of catastrophizing in shaping pain responses, as well as illuminating potentially important differences between experimental pain assessment and the clinical experience of pain.
-
Comparative Study
Can one predict the likely specific orofacial pain syndrome from a self-completed questionnaire?
To estimate the prevalence of orofacial pain (OFP) by specific diagnostic subgroups in the general population. Cross-sectional population study. General medical practice in South East Cheshire, UK. ⋯ The estimated prevalence in the general population of musculoligamentous/soft tissue type of OFP was 7%, dentoalveolar 7% and neurological/vascular 6%. This study has derived a statistical model to classify participants with OFP into three broad groups (musculoligamentous/soft tissue, dentoalveolar and neurological/vascular) based on questionnaire information about OFP (OFP chronicity, location and verbal descriptors of pain). It is potentially useful in large population studies of OFP, where a clinical examination is not possible, however, further validation of its performance in large populations are necessary.
-
Comparative Study
Spatial summation of heat pain within and across dermatomes in fibromyalgia patients and pain-free subjects.
The mechanisms of spatial summation of pain (SSP) include pain coding dependent on impulse frequency and the number of recruited central neurons. However, SSP may also be influenced by pain inhibitory mechanisms, such as diffuse noxious inhibitory controls. Abnormal interactions between pain inhibitory mechanisms and SSP may be relevant for chronic pain conditions such as fibromyalgia (FM) and may help explain why widespread pain is characteristic for this chronic pain syndrome. ⋯ Furthermore, SSP was more pronounced within one dermatome such as that of the index finger than across several dermatomes of the hand. These results were similar for both FM and NC subjects. Thus, mechanisms of SSP, including possible inhibitory factors that limit this relevant pain mechanism, appear to be similar for both FM and NC subjects.