Pain
-
Clinical use of quantitative sensory testing (QST) requires standardization. The German research network on neuropathic pain (DFNS) solves this problem by defining reference data stratified for test site, gender and age for a standardized QST protocol. In this report we have targeted two further problems: how to adjust for age-related sensory changes, and how to compare groups of patients with the reference database. ⋯ Simulations for various sample sizes and variances showed that method B was more conservative than method A. We present a simple way of calculating method B for data that have been z-normalized. This technique makes the DFNS reference data bank applicable for researchers beyond the DFNS community without a need for subsampling of subjects from the database.
-
Pain behaviors provide meaningful information about adolescents in chronic pain, enhancing their verbal report of pain intensity with information about the global pain experience. Caregivers likely consider these expressions when making judgments about their adolescents' medical or emotional needs. Current validated measures of pain behavior target acute or procedural pain and young or non-verbal children, while observation systems may be too cumbersome for clinical practice. ⋯ However, significant correlations were found between parent-reported pain behaviors and parent- and adolescent-reported functional disability, pain catastrophizing, depressive symptoms, and poorer quality of life. The assessment of pain behaviors provides qualitatively different information than solely recording pain intensity and disability. It has clinical utility for use in behavioral treatments seeking to reduce disability, poor coping, and distress.
-
Widespread central hypersensitivity is present in chronic pain and contributes to pain and disability. According to animal studies, expansion of receptive fields of spinal cord neurons is involved in central hypersensitivity. We recently developed a method to quantify nociceptive receptive fields in humans using spinal withdrawal reflexes. ⋯ This study provides for the first time evidence for widespread expansion of reflex receptive fields in chronic pain patients. It thereby identifies a mechanism involved in central hypersensitivity in human chronic pain. Reverting the expansion of nociceptive receptive fields and exploring the prognostic meaning of this phenomenon may become future targets of clinical research.
-
Hypnosis modulates pain perception but the associated brain mechanisms in chronic pain conditions are poorly understood. Brain activity evoked by painful repetitive pin-prick stimulation of the left mental nerve region was investigated with use of fMRI in 19 patients with painful temporomandibular disorders (TMD) during hypnotic hypoalgesia and hyperalgesia and a control condition. Pain intensity and unpleasantness of the painful stimulation was scored on a 0-10 Numerical Rating Scale (NRS). ⋯ Unexpectedly, direct contrasts between control and hypnotic hyperalgesia conditions revealed significant decreases in S1 during hyperalgesia. Direct contrasts between control and hypnotic hypoalgesia conditions demonstrated significant decreases in right posterior insula and BA21, as well as left BA40 during hypoalgesia. These findings are the first to describe hypnotic modulation of brain activity associated with nociceptive processing in chronic TMD pain patients and demonstrate that hypnotic hypoalgesia is associated with a pronounced suppression of cortical activity and a disconnection between patient-based scores and cortical activity in S1 during hypnotic hyperalgesia.
-
Understanding deep muscle pain is of increasing importance for evaluating clinical pathologic pain states. Previously, a central role of deep muscle tissue in the development of ongoing pain behavior after incision was demonstrated. The underlying mechanisms, however, remain unclear. ⋯ Sensitization of afferents to heat and mechanical stimulation was prominent in group IV afferents after incision; both heat (38.0 vs. 40.5°C in control) and mechanical response threshold (median: 5.0 vs. 22.0 mN in control) were decreased. The finding hat incision increased ongoing activity of muscle afferents is consistent with our previous in vivo studies and supports the idea that deep muscle tissue has a prominent role in the genesis of ongoing pain after incision. The enhanced chemosensitivity of muscle afferents to lactic acid after incision suggests an increased response to an ischemic mediator that may contribute to pain and hyperalgesia caused by surgery in deep tissues.