To investigate the influence of chronic nociceptive pain on endogenous pain modulation, the effect of heterotopic noxious conditioning stimulation (HNCS) on perception of various somatosensory modalities was assessed in 15 patients with painful osteoarthritis of the hip. Thirteen patients were re-assessed when pain-free 6-14 months following surgery. Sex- and age matched healthy subjects assessed at similar time intervals served as controls. The effects of HNCS were tested using the upper extremity submaximal effort tourniquet test. Subjects rated tourniquet-induced pain intensity on a visual analogue scale (VAS). Quantitative sensory testing (QST) was performed contralaterally to the maximally painful area in 13 patients and contralaterally to the second most painful area in two patients (i.e. lateral thigh n = 12, frontal thigh n = 1, lateral calf n = 2). Sensibility was assessed before, during and 45 min following the tourniquet test. Perception thresholds to light touch were assessed using von Frey filaments and pressure pain thresholds by pressure algometry. Perception thresholds to non-painful and painful warmth and cold were determined using a Thermotest. In both sessions, patients rated the tourniquet-induced pain higher than controls at the start (P < 0.003 and P < 0.006, respectively), but not at the end of the tourniquet test. Decreased sensitivity to light touch (P < 0.001) and innocuous cold (P < 0.002) was seen during the tourniquet in patients and controls alike, on both occasions, while perception thresholds to innocuous warmth and heat pain remained unaffected. In the first session, pressure pain thresholds increased during the tourniquet test in controls (P < 0.002), but not in patients. In the second session, pressure pain thresholds increased during the tourniquet test in controls (P < 0.001) and in patients (P < 0.02). In conclusion, no pressure pain modulation was induced by HNCS in patients before surgery, as opposed to controls, suggesting a dysfunction in systems subserving 'diffuse noxious inhibitory controls' (DNIC). Normal pressure pain modulation induced by HNCS was seen when patients were re-assessed in a pain-free state following surgery, indicating that the dysfunction of DNIC had been maintained by chronic nociceptive pain.

To investigate the effect of chronic nociceptive pain on somatosensory perception, quantitative sensibility testing was performed in the most painful area and the homologous contralateral side in 14 patients with painful osteoarthritis of the hip. Twelve patients were reassessed in a painfree state 6-14 months following surgery. Von Frey filaments were used to test low-threshold mechanoreceptive function. Pressure pain sensitivity was assessed with a pressure algometer and thermal sensitivity with a Thermotest. Sex- and age-matched controls were examined in the corresponding areas at similar time intervals. There was no statistically significant difference between groups in the sensitivity to light touch and innocuous cold in either session. Compared to controls, patients had increased sensitivity to pressure pain in the most painful area (p < 0.002), bilaterally increased sensitivity to innocuous warmth (p < 0.03), cold pain (p< 0.05) and a tendency toward bilaterally increased sensitivity to heat pain (p = 0.054) before surgery. In the painful area, patients' sensitivity to pressure pain decreased (p < 0.04) and, remaining within normal limits, sensitivity to light touch increased (p < 0.006) compared to values prior to surgery. No statistically significant differences between the groups were seen following surgery, indicating that the sensibility changes had been maintained by chronic nociceptive pain.

The frequency of slipping and osteoarthritis of the contralateral hip was recorded in 260 patients with slipped upper femoral epiphysis between 1910 and 1960. Twenty-three of these patients (9%) had primary bilateral slipping, 32 (12%) had a contralateral slip diagnosed later during adolescence and a further 104 (40%) had signs of contralateral slipping at follow-up 16 to 66 years later, giving a total of 159 cases (61%) with bilateral slips. Of the 104 slippings diagnosed at follow-up, 25% showed osteoarthritis. It is concluded that, with a slipped epiphysis, prophylactic contralateral pinning should be performed to avoid slipping and to reduce the risk of osteoarthritis.

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In this prospective study, 56 women (2.3%) of 2,358 (47% nulliparous and 53% multiparous) delivered during a 12-month period at the Department of Obstetrics and Gynecology, Malmö General Hospital, had symptoms of carpal tunnel syndrome during pregnancy. All (33 nulliparous and 23 multiparous women) were examined, at the outpatient's maternity care unit and within 4-5 weeks from the time of debut of symptoms, by a specialist in hand surgery. At that time the most common symptoms were paresthesia and nocturnal pain. Twenty-nine had signs of reduced sensibility and 14 of them had a positive two-point discrimination test. All had generalized edema. Conservative treatment with splinting of the wrist at night made 46 out of 56 symptom-free. Of the remaining 10 women, 3 had to be operated on, whereas 7 received only conservative treatment, as the expected time for parturition was very close. One of them had to be operated on after delivery. In conclusion, carpal tunnel syndrome during pregnancy is most common in primiparas with generalized edema. Conservative treatment is sufficient for symptom relief in most women (80%) but a few cases need operative intervention to abolish the severe pain and to avoid disturbances of hand function.

Cerebrospinal fluid (CSF) levels of substance P like immunoreactivity (SPLI) were determined in 11 patients with painful osteoarthritis in hip or knee, 9 patients with rhizopatic pain from a herniated lumbar disc, and in 9 healthy volunteers without pain. The patients with osteoarthritis had increased levels of SPLI in CSF (p < 0.001) compared to the controls. A positive correlation was also seen between the CSF SPLI and the degree of pain. At a second lumbar puncture 5 months after operation, SPLI had decreased, but was still significantly higher than in the controls. No difference in CSF SPLI was seen in the patients with herniated lumbar disc compared to the controls, neither before treatment, nor at follow up CSF postoperatively. The results suggest that nociceptive joint pain is consistent with increased SPLI in CSF. Differences in SPLI in CSF may be useful to differentiate pain from various origin, and may also increase our understanding of different pain mechanisms.

No abstract

Characterization and di¡erentiation of joint pain is di⁄cult. Though degenerative changes in joints are frequent causes of pain in hip and knee, these changes are not always painful, and other possible causes of pain must also be considered. In degenerative changes in the spine, the problem is even more complex, as peripheral neuropathic pain, caused by mechanical compression and/or leakage of cytokines irritating nerve roots may be di⁄cult to di¡erentiate from nociceptive pain from intervertebral joints, discs or muscles. We know now that nociceptive pain has often referred to areas of pain with numbness and parestesthethic sensations, previously regarded as characteristic for neurogenic pain. Furthermore, in patients with painful coxarthrosis quantitative sensory testing (QST) has shown disturbed sensory thresholds not only in regions adjacent to the a¡ected hip but also contralaterally. These sensory disturbances, previously noted in neuropathic pain, normalized after successful surgery with relief of pain, thus con¢rming the relation to the hip joint. Patients with painful coxarthrosis also have moderately increased substance P activity in cerebrospinal £uid. Thus the ¢ndings show some similarities with ¢bromyalgic patients with highly increased substance P in cerebrospinal £uid and sensory disturbances. In conclusion, joint pain has a profound impact on the sensory system and need a multimodal approach.