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Alf Nachemson

Publications and source records attributed to Alf Nachemson.

7 recordsLinked to original sources
PubMed2004

Evidence of augmented central pain processing in idiopathic chronic low back pain.

OBJECTIVE: For many individuals with chronic low back pain (CLBP), there is no identifiable cause. In other idiopathic chronic pain conditions, sensory testing and functional magnetic resonance imaging (fMRI) have identified the occurrence of generalized increased pain sensitivity, hyperalgesia, and altered brain processing, suggesting central augmentation of pain processing in such conditions. We compared the results of both of these methods as applied to patients with idiopathic CLBP (n = 11), patients with widespread pain (fibromyalgia; n = 16), and healthy control subjects (n = 11). METHODS: Patients with CLBP had low back pain persisting for at least 12 months that was unexplained by MRI/radiographic changes. Experimental pain testing was performed at a neutral site (thumbnail) to assess the pressure-pain threshold in all subjects. For fMRI studies, stimuli of equal pressure (2 kg) and of equal subjective pain intensity (slightly intense pain) were applied to this same site. RESULTS: Despite low numbers of tender points in the CLBP group, experimental pain testing revealed hyperalgesia in this group as well as in the fibromyalgia group; the pressure required to produce slightly intense pain was significantly higher in the controls (5.6 kg) than in the patients with CLBP (3.9 kg) (P = 0.03) or the patients with fibromyalgia (3.5 kg) (P = 0.006). When equal amounts of pressure were applied to the 3 groups, fMRI detected 5 common regions of neuronal activation in pain-related cortical areas in the CLBP and fibromyalgia groups (in the contralateral primary and secondary [S2] somatosensory cortices, inferior parietal lobule, cerebellum, and ipsilateral S2). This same stimulus resulted in only a single activation in controls (in the contralateral S2 somatosensory cortex). When subjects in the 3 groups received stimuli that evoked subjectively equal pain, fMRI revealed common neuronal activations in all 3 groups. CONCLUSION: At equal levels of pressure, patients with CLBP or fibromyalgia experienced significantly more pain and showed more extensive, common patterns of neuronal activation in pain-related cortical areas. When stimuli that elicited equally painful responses were applied (requiring significantly lower pressure in both patient groups as compared with the control group), neuronal activations were similar among the 3 groups. These findings are consistent with the occurrence of augmented central pain processing in patients with idiopathic CLBP.

Adult↗
PubMed1994

Pain behavior in industrial subacute low back pain. Part I. Reliability: concurrent and predictive validity of pain behavior assessments.

The reproducibility of overt pain behavior ratings was shown to be reliable between independent observers. In the clinical evaluation of 103 blue collar workers with subacute low back pain (LBP), concurrent validity was high between Behavioural Signs (Waddell et al. 1980) and UAB Pain Behavior Rating scale (Richards et al. 1982). Correlations with pain rated on visual analogue scales (Scott and Huskisson 1976) were generally lower. Behavioural Signs correlated separately with covert pain behavior (general convictions concerning back strength and general health). It seems that subacute LBP patients do not behave as a homogenous group since pain behaviors predicted occupational handicap (absenteeism) in a non-linear fashion. Return to work was best predicted by UAB and covert pain behavior, absenteeism up to 2 years by covert pain behavior. The findings emphasize the potential social implications of overt pain behaviors and the importance of covert pain behavior in maintaining the sick role. The conclusion is that, in secondary prevention, where the main targets are to interfere with somatic deconditioning and sick-role development, a more diversified primary approach may be possible, based on supplementary use of relatively easy observational tests and quick self-reports.

Absenteeism↗