The Clinical journal of pain
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Randomized Controlled Trial
Plasma vitamin C is lower in postherpetic neuralgia patients and administration of vitamin C reduces spontaneous pain but not brush-evoked pain.
Plasma vitamin C concentrations have been suggested to be related to pain modulation in postherpetic neuralgia (PHN), an intractable neuropathic pain syndrome. In this study, we first compared plasma concentrations of vitamin C between healthy volunteers and PHN patients and then designed a symptom-based and mechanism-based approach to assess the analgesic effect of intravenous vitamin C on spontaneous and brush-evoked pain. ⋯ Plasma vitamin C status plays a role in PHN, and intravenous ascorbate helps relieve spontaneous pain in PHN.
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Neuropathic pain disorders are usually characterized by spontaneous ongoing or intermittent symptoms, stimulus-evoked positive sensory phenomena, and negative sensory phenomena. Spontaneous individual subject specific phenomena are identified in the neurologic history and are quantifiable by means of self-reported neuropathic pain symptoms tools such as scales, inventories, and questionnaires. Negative and positive sensory phenomena are assessed by the neurologic bedside examination and quantitative sensory testing (QST), which refers to psychophysical tests of sensory perception during the administration of stimuli with predetermined physical properties and following specific protocols. ⋯ To yield useful results, QST requires a cooperative subject and carefully standardized methods, including standardization of the stimulus parameters as well as the testing environment, instructions, and evaluation methods. This manuscript provides a concise review of fundamental concepts necessary for understanding the role of QST in the process of eliciting information about sensory abnormalities associated with neuropathic pain and the place of that information in analysis of pain mechanisms. Together with the companion manuscript, this review provides definitions that should help further the use of QST as a diagnostic tool as well.
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The aim of this study was to investigate whether generalized deep tissue hyperalgesia exists in patients with chronic unilateral lateral epicondylalgia (LE). ⋯ This revealed a widespread mechanical hypersensitivity in patients with LE, which suggest that central sensitization mechanisms are involved in patients with unilateral LE. The generalized decrease in PPT levels was associated with elbow pain intensity, supporting a role of peripheral sensitization mechanisms in the initiation or maintenance of central sensitization mechanisms. In addition, females may be more prone to the development of generalized mechanical hypersensitivity.
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The Internet is an increasingly popular information resource for patients. Patients with chronic pain are a subsection of the community who are likely to seek information about their condition, but previously little was known about the quality of information they may encounter during an Internet search. ⋯ Although we cannot determine whether patients accurately interpret the quality of websites, our study confirms that good quality information about chronic pain is unlikely to be retrieved by our patients on the Internet.
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The outcome of complex regional pain syndrome (CRPS) is relatively unknown. High disease resolution rates have been reported, but also long-lasting impairments in many patients. This study aims to assess CRPS outcome in a population-based cohort of CRPS patients. ⋯ Severe CRPS outcome is rare, but a majority of patients has persistent impairments at 2 or more years since onset.