Human Studies

Despite the clinical effectiveness of Spinal Cord Stimulation (SCS), potential structural brain modifications have not been explored. Our aim was to identify structural volumetric changes during subsensory SCS, in patients with Failed Back Surgery Syndrome (FBSS).

The STarT Back approach comprises subgrouping low back pain (LBP) patients according to risk of persistent LBP-related disability, with appropriate matched treatments. In a twelve-month clinical trial and implementation study, this stratified care approach was clinically and cost-effective compared to usual, non-stratified care. Despite the chronic nature of LBP and associated economic burden, model-based economic evaluations in LBP are rare and have shortcomings. This study therefore produces a de-novo decision model of this stratified care approach for LBP management to estimate the long-term cost-effectiveness and address methodological concerns in LBP modelling.A cost-utility analysis from the NHS perspective compared stratified care with usual care in patients consulting in primary care with non-specific LBP. A Markov state-transition model was constructed where patient prognosis over ten years was dependent upon physical function achieved at twelve months. Data from the clinical trial and implementation study provided short term model parameters, with extrapolation using two cohort studies of usual care in LBP.Base-case results indicate this model of stratified care is cost-effective, delivering 0.14 additional quality-adjusted life years (QALYs) at a cost-saving of £135.19 per patient over a time horizon of ten-years. Sensitivity analyses indicate the approach is likely to be cost-effective in all scenarios, and cost-saving in most.It is likely this stratified care model will help reduce unnecessary healthcare usage whilst improving patient quality of life. Whilst decision analytic modelling is employed in many conditions, its use has been underexplored in LBP and this paper also addresses associated methodological challenges.

Objectives The cardinal symptom of burning mouth syndrome (BMS) is long-lasting pain and comprehensive health-related quality of life (HRQL) assessments may estimate how well patients with BMS live in relation to their health issues. The aims of the study were to explore general and BMS-specific HRQL based on an HRQL model and to compare HRQL in patients with BMS and age-matched controls. Methods For this case-control study 56 female patients with BMS and 56 female controls completed the following: A general questionnaire with Global items for life satisfaction, general health and oral health; General Population-Clinical Outcomes in Routine Evaluation (GP-CORE); Hospital Anxiety and Depression Scale (HADS); and Oral Health Impact Profile-14 (OHIP-14). Patients with BMS completed additional questionnaires which included BMS-problem severity, a global item for ratings of overall severity perceptions measured by visual analog scale (VAS); and BMS-modified Multidimensional Pain Inventory-Swedish version (MPI-S). BMS-modified MPI-S includes the three subscales Pain severity, Interference and Social support. Results Patients with BMS scored worse on all global items, GP-CORE, HADS and OHIP-14 compared to controls and the differences were large. Patients with severe BMS problems, as defined by a median split on BMS-problem severity, scored worse on the BMS-modified MPI-S subscale Pain severity and the difference was large. Conclusions We found clearly impaired general HRQL in patients with BMS compared to controls. For specific HRQL, the severity of pain was worse among patients with higher overall BMS-problem severity. The HRQL model with global ratings together with physical, psychological and social concepts has capacity to increase comparability and validity of studies, however further evaluations of the measures are needed. The HRQL model may be used over time to increase the understanding of different HRQL aspects and their internal relationships. In clinical settings, with an increased knowledge of one´s own distinctive quality of life abilities and restrictions, the patients with BMS can be guided and supported to manage their long-lasting pain. The HRQL model may be an aid toward bridging distinctions between general and oral health to further encourage collaboration between medicine and odontology.

The pathophysiology of pain in neuropathy is complex and may be linked to sensory phenotypes. Quantitative sensory testing, a standardized method to evaluate sensory profiles in response to defined stimuli, assesses functional integrity of small and large nerve fiber afferents and central somatosensory pathways. It has revealed detailed insights into mechanisms of neuropathy, yet, it remains unclear if pain directly affects sensory profiles. The main objective of this study was to investigate sensory profiles in patients with various neuropathic conditions, including polyneuropathy, mononeuropathy, and lesions to the central nervous system, in relation to self-reported presence or absence of pain and pain sensitivity using the Pain Sensitivity Questionnaire.A total of 443 patients (332 painful and 111 painless) and 112 healthy participants were investigated. Overall, loss of sensation was equally prevalent in patients with and without spontaneous pain. Pain thresholds were equally lowered in both patient groups, demonstrating that hyperalgesia and allodynia is just as present in patients not reporting any pain. Remarkably, this was similar for dynamic mechanical allodynia. Hypoalgesia was more pronounced in painful polyneuropathy whereas hyperalgesia was more frequent in painful mononeuropathy (compared to painless conditions). Self-reported pain sensitivity was significantly higher in painful than in painless neuropathic conditions.Our results reveal the presence of hyperalgesia and allodynia in patients with central and peripheral lesions of the somatosensory system not reporting spontaneous pain. This shows that symptoms and signs of hypersensitivity may not necessarily coincide, and that painful and painless neuropathic conditions may mechanistically blend into one another.

Preclinical data implicate large conductance calcium-activated potassium (BK) channels in the pathogenesis of headache and migraine, but the exact role of these channels is still unknown. Here, we investigated whether opening of BK channels would cause headache and vascular effects in healthy volunteers.

Chronic pain studies investigating the ability to detect sensory processing differences related to thalamic gating using electroencephalographic (EEG) alpha have yielded conflicting results. Alpha's basic psychometric properties in pain populations requires further study. The present study reports on the test-retest reliability and internal consistency of EEG alpha power in older adults with chronic knee pain.