Low back pain: critical assessment of various scales.

PURPOSE: To study the various pain assessment tools based on their psychometric properties and ease of use. METHODS: Published articles on psychometric properties of pain tools were accessed and data collected for low back pain (LBP)-specific tools, generic tools, neuropathic LBP tools, tools for cognitively impaired patients, and tools for acute LBP. RESULTS: Among the LBP-specific tools, Roland Morris Disability Questionnaire (RMDQ) and Oswestry Disability Index (ODI) have good construct validity and reliability, and responsiveness over short intervals. Quebec Back Pain Disability Scale (QBPDS) gauges only disability and sleep. Among the generic tools, McGill Pain Questionnaire (MPQ), West Haven-Yale Multidimensional Pain Inventory (MPI), and Brief Pain Inventory (BPI) show good responsiveness, but BPI is the only tool validated for LBP. Neuropathic Pain Scale (NPS) and Short Form-MPQ-2 (SF-MPQ-2) are both reliable tools for neuropathic LBP. For cognitively impaired patients, Pain Assessment in Advanced Dementia (PAINAD), Abbey Pain Scale (APS), and Doloplus-2 are all reliable tools, but PAINAD has good construct validity. For acute pain, Clinically Aligned Pain Assessment (CAPA) is reliable and responsive, but presently, unidimensional tools and SF-MPQ-2 are the tools most preferred. CONCLUSION: Based on psychometric properties and ease of use, the best tools for LBP seem to be RMDQ/ODI (among LBP-specific tools), BPI (among generic tools), SF-MPQ-2/NPS (for neuropathic LBP), PAINAD (for cognitively impaired patients), and unidimensional tools and SF-MPQ-2 (for acute pain). Overall, BPI seems to be a tool that can be relied upon the most. These slides can be retrieved under Electronic Supplementary Material.

Central Neuropathic Pain and Profiles of Quantitative Electroencephalography in Multiple Sclerosis Patients.

Pain has a significant impact on the quality of life of patients with multiple sclerosis (MS). However, the neurophysiological mechanisms of central neuropathic pain in a MS course are not known. We hypothesized that changes in power spectral density (PSD) that take place in the electroencephalography (EEG) of MS patients with and without the central neuropathic pain (CNP) would differ. The study aimed to assess the features of quantitative EEG using the PSD indicator along with peak frequencies in the standard frequency bands in MS patients with and without CNP. We have analyzed the quantitative spectral content of the EEG at a resting state in 12 MS patients with CNP, 12 MS patients without CNP, and 12 gender- and age-matched healthy controls using fast Fourier transformation. Based on the ANOVA, at the group level, the theta band absolute and relative PSD showed an increase, whereas alpha band relative PSD showed a decrease in MS patients both with and without CNP. However, only in MS with CNP group, the absolute and relative PSD in the beta1 and beta2 bands increased and exceeded that in patients without pain. Only MS patients with CNP demonstrated the significantly increased absolute PSD for the theta, beta1, and beta2 frequency bands in most regions of interest. In the theta band, MS patients with CNP displayed the increase in absolute spectral power for the mid-temporal derivation of the right hemisphere and the increase in relative spectral power for the prefrontal derivation of this hemisphere. In the beta1 band, the increase in absolute spectral power was observed for the three temporal derivations of the right hemisphere, whereas in the beta2 band, for the occipital, parietal, and temporal lobes of both hemispheres. In the alpha band, only a relative spectral power decrease was revealed for the occipital lobes of both hemispheres and parietal lobe of the right hemisphere. In MS patients with CNP, the frequencies of the dominant spectral power (peak frequencies) in the high-frequency beta band were higher than in the healthy control in posterior areas of the left hemisphere. Data could represent central nervous system alterations related to central neuropathic pain in MS patients that lead to the disturbances in cortical communication.

The effect of heterotopic noxious conditioning stimulation on Aδ-, C- and Aß-fibre brain responses in humans.

Human studies have shown that heterotopic nociceptive conditioning stimulation (HNCS) applied to a given body location reduces the percept and brain responses elicited by noxious test stimuli delivered at a remote body location. It remains unclear to what extent this effect of HNCS relies on the spinal-bulbar-spinal loop mediating the effect of diffuse noxious inhibitory controls (DNICs) described in animals, and/or on top-down cortical mechanisms modulating nociception. Importantly, some studies have examined the effects of HNCS on the brain responses to nociceptive input conveyed by Aδ-fibres. In contrast, no studies have explored the effects of HNCS on the responses to selective nociceptive C-fibre input and non-nociceptive Aß-fibre input. In this study, we measured the intensity of perception and event-related potentials (ERPs) to stimuli activating Aδ-, C- and Aß-fibres, before, during and after HNCS, obtained by immersing one foot in painful cold water. We observed that (i) the perceived intensity of nociceptive Aδ- and C-stimuli was reduced during HNCS, and (ii) the ERPs elicited by Aδ- and Aß- and C-stimuli were also reduced during HNCS. Importantly, because Aß-ERPs are related to primary afferents that ascend directly through the dorsal columns without being relayed at spinal level, the modulation of these responses may not be explained by an influence of descending projections modulating the transmission of nociceptive input at spinal level. Therefore, our results indicate that, in humans, HNCS should be used with caution as a direct measure of DNIC-related mechanisms.