Neuropathic pain symptoms on the modified painDETECT correlate with signs of central sensitization in knee osteoarthritis.

OBJECTIVE: Clinical tools are needed to identify and target a neuropathic-like phenotype, which may be associated with central sensitization (CS), in osteoarthritis (OA). The modified painDETECT questionnaire (mPD-Q) has face and content validity for identifying neuropathic-like symptoms in knee OA. To further validate the mPD-Q, this study assessed the unknown relationship between mPD-Q scores and signs of CS on quantitative sensory testing (QST) in knee OA. DESIGN: 36 Individuals were recruited with chronic, symptomatic, knee OA without other pain/neurological conditions. Reference QST data were obtained from 18 controls/32 eligible knees, enabling identification of sensory abnormalities/CS among case knees. A standardized questionnaire assessed psychological factors (depressive symptoms and pain catastrophizing), and for individual knees, mPD-Q and pain intensity scores. A standardized/comprehensive QST protocol was conducted for each knee. QST signs of CS were defined as: mechanical hyperalgesia and/or enhanced temporal summation and/or allodynia. The relationship between the presence of CS (yes/no) and a pre-selected mPD-Q score (≤12 or >12), by knees, was assessed using generalized estimating equations. RESULTS: Among 57 eligible case knees, 45.6% had ≥1 sign of CS. Controlling for age, knees with higher mPD-Q scores (>12.0) had higher odds of having QST signs of CS (adjusted odds ratio (OR) = 5.6; 95% confidence interval (CI), 1.3-22.9). This relationship was unaffected by controlling for depression and pain intensity, but was attenuated by pain catastrophizing. CONCLUSIONS: Among painful OA knees, higher mPD-Q scores were associated with greater odds of having signs of CS. Thus, the mPD-Q may aid the identification of CS in people with chronic knee OA.

Neuropathic pain symptoms in a community knee OA cohort.

OBJECTIVE: A neuropathic pain (NP) questionnaire may facilitate the identification of a neuropathic component to osteoarthritis (OA) pain. An existing questionnaire, the painDETECT, was modified for use in knee OA and administered to measure the prevalence and correlates of NP symptoms among adults with this condition. METHOD: Sensibility of the modified painDETECT (mPD-Q) was assessed in 20 OA subjects followed by mail administration in an established knee OA cohort. NP symptoms were defined using a previously established, painDETECT cut-point. Correlates of NP symptoms, including OA severity (Western Ontario and McMaster Universities Osteoarthritis Index, Von Korff Chronic Pain Grade pain subscale score), psychological factors (Centre for Epidemiological Studies Depression Scale, Pain Catastrophizing Scale), and concomitant medical conditions, were evaluated using logistic regression. Construct validity of the mPD-Q was evaluated through co-administration with another NP questionnaire (S-LANSS). RESULTS: The mPD-Q had face and content validity. Of 259 eligible cohort members, 171 (66%) completed the questionnaire; 28% had NP symptoms on the mPD-Q (19% among those without neurological conditions). Independent correlates of NP symptoms were: pain intensity (adjusted odds ratio [OR]=2.1 per 10 unit increase, P<0.0001), the presence of referred back/hip pain (adjusted OR=2.9, P=0.024), number of painful joints (OR=1.2, P=0.20) and one or more self-reported neurological condition (OR=3.0, P=0.026). CONCLUSIONS: Among older adults with chronic symptomatic knee OA, over one-quarter had NP symptoms localized to their knees using the mPD-Q. The mPD-Q may facilitate the identification of a neuropathic component to pain in adults with knee OA who may benefit from further evaluation and/or treatment for NP.

Age differences in nociception and pain behaviours in the rat.

Much remains to be learned about the effects of ageing on pain. Studies of life-span changes in nociception and pain behaviours in the rat are equivocal making it difficult to draw firm conclusions. This paper reviews the available data and finds that age differences in nociception may be dependent on the pain test employed. Specifically, reflexive responses to nociceptive stimuli do not change with age while there may be no change or a linear decrease with age on more highly organized tests of nociception. Interestingly, age differences in pain behaviours on models of tissue injury and inflammation may not be linear. It is shown that important changes that begin at mid-life in neuroanatomy, neurochemistry and endogenous pain inhibition may be associated with alterations in pain sensitivity. Several testable hypotheses which might encourage future research in this domain are developed throughout this paper.

Age is not an impediment to effective use of patient-controlled analgesia by surgical patients.

BACKGROUND: Obstacles to the use of patient-controlled analgesia (PCA) by elderly surgical patients have not been well-documented. Age differences in preoperative psychological factors, postoperative pain and analgesic consumption, treatment satisfaction, and concerns regarding PCA were measured to identify factors important to effective PCA use. METHODS: Preoperatively, young (mean age +/- SD, 39 +/- 9 yr; n = 45) and older (mean age +/- SD, 67 +/- 8 yr; n = 44) general surgery patients completed measures of attitudes toward and expectations of postoperative pain and PCA, psychological distress, health opinions, self-efficacy, and optimism. On the first 2 postoperative days, pain at rest and with movement and satisfaction with pain control were assessed using visual analog scales. Daily opioid intake was recorded. When PCA was discontinued, satisfaction and concerns about it were assessed. RESULTS: The older patients expected less intense pain (P

Age differences in the response to the formalin test in rats.

We report the results of a study designed to assess age differences in the response to the formalin test, a model of tissue injury and inflammation, while controlling for differences in weight and motoric abilities in three groups of adult male Long-Evans rats: young (3 months old), middle-aged (18 months old), and old (24 months old). The first part of the study assessed initial differences in responsivity and found that the middle-aged group showed the greatest response, whereas the young and old groups did not differ from each other. In the second part of the study, the young and middle-aged animals were followed for a 4-month period. The formalin test was repeated at 2-month intervals. These results indicate that there may be an age-associated change in the sensitivity to tonic pain and that this sensitivity may peak at mid-life.

Chronic pain in elderly people.

Chronic pain in elderly people has only recently begun to receive serious empirical consideration. There is compelling evidence that a significant majority of the elderly experience pain which may interfere with normal functioning. Nonetheless, a significant proportion of these individuals do not receive adequate pain management. Three significant factors which may contribute to this are (1) lack of proper pain assessment; (2) potential risks of pharmacotherapy in the elderly; and (3) misconceptions regarding both the efficacy of nonpharmacological pain management strategies and the attitudes of the elderly towards such treatments. In this review the most commonly used assessment instruments and patterns of age differences in the experience of chronic pain are described and evidence for the efficacy of psychological pain management strategies for this group is reviewed.

Differential consequences of left- and right-sided chronic pain.

OBJECTIVE: To test the neuropsychological hypothesis that left-sided pain will have more adverse consequences than right-sided pain by virtue of activation of the "depressogenic" right hemisphere. DESIGN: A retrospective analysis comparing data of chronic pain patients with left-sided pain to patients with right-sided pain. PATIENTS: All of the right-handed patients (n = 85) presenting with unilateral shoulder, arm, and hand pain and suspected of having Thoracic Outlet syndrome (TOS) were assessed as potential candidates for surgery at the Toronto Western Hospital Pain Investigation Unit over a 5-year period. OUTCOME MEASURES: Minnesota Multiphasic Personality Inventory (MMPI), SIP (Sickness Impact Profile). RESULTS: Contrary to the intuitive expectation that right-sided pain would be more disruptive in right-handed subjects, patients with left-sided pain had higher MMPI scores for hysteria and hypochondriasis and also had higher scores on the physical dimension of the SIP. CONCLUSION: Differences between the groups could not be accounted for by different etiologies because the proportions and causes of left- and right-sided pain were comparable. The results are consistent with the hypothesis that unilateral stimulation activates the contralateral cerebral hemisphere and arouses the emotions associated with that hemisphere.

The consequences of experimentally induced and chronic unilateral pain: reflections of hemispheric lateralization of emotion.

In a series of three studies with right handed subjects, left side pain is tolerated less well than right side pain with a cold pressor, and results in greater emotional disturbance, both with a cold pressor and in chronic pain patients. In the second study where comparisons are made with non-stimulated controls, acute left side pain results in higher state anxiety scores than controls; right side pain and control groups are comparable. The differences between the reactions to left and right side pain are consistent with activation of the emotional properties of the hemisphere contralateral to the painful stimulation.