Human Studies

In this issue you will find a paper by Vibe Fersum et al., entitled "Cognitive Functional Therapy in Patients with Non Specific Chronic Low Back Pain: A Randomized Controlled Trial 3-year Follow Up" (Vibe Fersum 2019). This article is protected by copyright. All rights reserved.

To measure and compare the total and normalised tibial nerve movements during forward bending in patients with and without failed back surgery syndrome (FBSS) and persistent leg pain following anatomically successful lumbar decompression surgery and demonstrated no psychological stress. Nerve pathomechanics may contribute to FBSS with persistent leg pain following anatomically successful lumbar decompression surgery.

To evaluate the diagnostic value of symptoms of chronic polyneuropathy and to construct and validate a simple questionnaire that can help diagnose chronic polyneuropathy.

Medically unexplained pain in children and adolescents is a common and increasing health care problem. Primary care is usually the first point of contact for these patients. It is the overall objective of this study to investigate treatment outcome of medically unexplained pain in pediatric primary care and to identify predictors of treatment failure.

Sexual assault (SA) is associated with increased risk for chronic pain, but the mechanisms for this relationship are poorly understood. To explore whether disrupted descending inhibition is involved, this study used a conditioned pain modulation (CPM) task to study inhibition of pain and the nociceptive flexion reflex (NFR; a correlate of spinal nociception) in 32 pain-free SA survivors. This group was compared to 32 pain-free, trauma-exposed persons without SA (no-SA group) and a group of 40 pain-free persons who reported no trauma exposure (no-TE). CPM was assessed from painful electric stimulations (test stimulus) delivered to the ankle before, during, and after participants submerged their hand in painful 10°C water (conditioning stimulus). Pain ratings and NFR were assessed in response to test stimuli. All groups demonstrated significant inhibition of pain during CPM. However, only the no-TE group demonstrated significant inhibition of NFR. The no-SA group showed no inhibition of NFR, whereas the SA group showed significant facilitation of NFR. These findings suggest that trauma exposure may impair inhibitory cerebrospinal circuits, but that SA may specifically promote facilitation of spinal nociception. Perspective: This study suggests trauma exposure disrupts cerebrospinal inhibition of spinal nociception but that exposure to sexual assault further promotes chronic pain risk by facilitating spinal nociception. This help may help elucidate the pain risk mechanisms in trauma survivors.

Hyperalgesia and allodynia are frequent in neuropathic pain. Some pain questionnaires like the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) and the Neuropathic Pain Scale (NPS) include self-assessment or bedside-testing of hyperalgesia/allodynia. The aim of this study was to determine to what extent LANSS and NPS data are congruent with findings upon quantitative Sensory Testing (QST).Self-reported presence of dynamic mechanical allodynia (DMA) and descriptors of hot, cold or deep ongoing pain (NPS, LANSS) as well as bedside findings of mechanical allodynia (LANSS) were compared to signs of DMA and thermal hyperalgesia upon QST in 617 neuropathic pain patients.Self-reported abnormal skin sensitivity (LANSS) showed a moderate concordance with DMA during bedside test (67.9%, k=0.391) or QST (52.8%, k=0.165). Receiver operating curve analysis for self-reported DMA yielded similar area-under-the-curve values for LANSS (0.65, CI: 0.59-0.97%) and NPS (0.71, CI: 0.66-0.75%) with high sensitivity but low specificity. Self-reported deep pain intensity was higher in patients with blunt pressure hyperalgesia, but not in patients with DMA or thermal hyperalgesia. No correlations were observed between self-reported hot or cold pain quality and thermal hyperalgesia upon QST.Self-reported abnormal skin sensitivity has a high sensitivity to identify patients with DMA, but its low specificity indicates that many patients mean something other than DMA when reporting this symptom. Self-reported deep pain is related to deep-tissue hypersensitivity, but thermal qualities of ongoing pain are not related to thermal hyperalgesia. Questionnaires mostly evaluate the ongoing pain experience while QST mirrors sensory functions. Therefore, both methods are complementary for pain assessment.