Human Studies

Fibromyalgia syndrome (FMS) is a chronic pain syndrome characterized by widespread pain and a variety of non-pain symptoms. Central sensitivity phenomena are found consistently in FMS. Additionally, several researchers proclaimed that a subgroup of FMS patients may present with unrecognized peripheral small fiber neuropathy (SFN). Laser-evoked brain potentials (LEP) are considered as a reliable method for the functional assessment of the thermo-nociceptive system, including the evaluation of SFN.

Two recent studies suggest that experimental pain sensitivity is associated with low-grade systemic inflammation. However, only two biomarkers have been identified and the studies were conducted in adult individuals where confounding effects of comorbid diseases cannot be excluded. We therefore tested associations between pain sensitivity and 119 inflammation-related serum biomarkers in 827 healthy adolescents (15-19 years) in the population-based Tromsø Study: Fit Futures. The main outcome measure was cold-pressor pain tolerance (CPT), tested by placing the dominant hand in circulating cold (3°C) water for a maximum of 105s. Secondary outcomes were heat and pressure pain threshold and tolerance. Twelve proteins and six fatty acids were significantly associated with CPT after adjustment for possible confounding factors and correction for multiple comparisons. Of these, all fatty acids and 10 proteins were protective, i.e. higher biomarkers levels were associated with increased CPT, whereas two biomarkers were associated with lower tolerance. Taken together these biomarkers predicted completion of the tolerance test with a C-statistic of 0.65. Results for heat and pressure pain tolerance were remarkably similar, strengthening the generalizability of our findings. In this cohort of young healthy individuals, we found a relationship between inflammation-related biomarkers and pain tolerance and thresholds. Biomarkers with anti-inflammatory and analgesic effects predominated, suggesting that the development of prophylactic dietary or pharmaceutical treatments may be possible.

Spinal cord stimulation has been an established treatment for chronic back and leg pain for more than 50 years; however, outcomes are variable and unpredictable, and objective evidence of the mechanism of action is needed. A novel spinal cord stimulation system provides the first in vivo, real-time, continuous objective measure of spinal cord activation in response to therapy via recorded evoked compound action potentials (ECAPs) in patients during daily use. These ECAPs are also used to optimise programming and deliver closed-loop spinal cord stimulation by adjusting the stimulation current to maintain activation within patients' therapeutic window. We aimed to examine pain relief and the extent of spinal cord activation with ECAP-controlled closed-loop versus fixed-output, open-loop spinal cord stimulation for the treatment of chronic back and leg pain.

Disruptions of lumbar intervertebral discs may lead to severe discogenic low back pain (LBP). Severe pain has a deleterious effect on physical function and quality of life. Spinal cord stimulation (SCS) is a robust treatment for many neuropathic pain conditions. New innovations may be well-suited to treat neuropathic chronic LBP, including discogenic pain. The aim of this prospective study was to determine the effect of dorsal root ganglion (DRG) stimulation for a well-selected group of patients with discogenic LBP with no history of previous back surgeries.

Patients with radicular low back pain (radicular LBP, sciatica) frequently describe their pain as "shooting" or "radiating". The dictionary meaning of these words implies rapid movement, and indeed, many sufferers report feeling pain moving rapidly from the lower back or buttock into the leg. But others do not. Moreover, the sensation of movement is paradoxical; it is neither predicted nor accounted for by current ideas about the pathophysiology of radicular LBP. We have employed a structured questionnaire to evaluate the sensory qualities associated with "shooting" and "radiating" in 155 patients, 98 with radicular LBP and 57 with trigeminal neuralgia (TN), a second chronic pain condition in which shooting/radiating are experienced. Results indicated a spectrum of different sensations in different people. While many sciatica patients reported rapid downward movement of their pain, even more reported downward expansion of the area of pain, some reported upward movement and for some there was no spatial dynamic at all. The velocity of movement or expansion was also variable. By cross-referencing sensations experienced in the sciatica and TN cohorts with known signal processing modes in the somatosensory system, we propose testable hypotheses concerning the pathophysiology of the various vectorial sensations reported, their direction and velocity, and the structures in which they are generated. Systematic evaluation of qualitative features of "shooting" and "radiating" pain at the time of diagnosis can shed light on the pain mechanism in the individual patient and perhaps contribute to a better therapeutic outcomes.

To present the clinical picture, the associated complications and the genetic findings of Jordanian patients diagnosed with Congenital insensitivity to pain with anhidrosis (CIPA).