Where is my pain?

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Whole-body mapping of spatial acuity for pain and touch.

Tactile spatial acuity is routinely tested in neurology to assess the state of the dorsal column system. In contrast, spatial acuity for pain is not assessed, having never been systematically characterized. More than a century after the initial description of tactile acuity across the body, we provide the first systematic whole-body mapping of spatial acuity for pain

Valve hemodynamic performance and myocardial strain after implantation of a third-generation, balloon-expandable, transcatheter aortic valve

Background: Left ventricular (LV) mechanics are impaired in patients with severe aortic stenosis (AS); however, transcatheter aortic valve implantation (TAVI) may positively affect LV mechanics. Assessed herein is the performance of the SAPIEN 3 transcatheter heart valve (THV) and the effect of TAVI on LV function recovery, as assessed by global longitudinal strain (GLS). Methods: A subset of patients from the SOURCE 3 registry (n = 276) from 16 European centers received SAPIEN 3 balloon-expandable THV. Echocardiography was performed at baseline, postprocedure, and at 1 year, including assessment of GLS using standard two-dimensional images, and was analyzed in a core laboratory. Paired analyses between baseline and discharge, baseline and at 1 year were conducted. Results: Hemodynamic parameters were improved after TAVI and sustained to 1 year. At 1 year, the rate of moderate to severe paravalvular leaks (PVL), and moderate to severe mitral and tricuspid regurgitations were 1.8%, 1.7%, and 8.0%, respectively. The discharge GLS (–15.6 ± 5.1; p = 0.004; n = 149) improved significantly from baseline (–15.1 ± 4.8) following TAVI. This improvement was sustained at 1 year compared with baseline (–17.0 ± 4.6, p < 0.001; n = 100). Conversely, LV ejection fraction (LVEF) did not significantly change following TAVI (p = 0.47). Conclusions: Following TAVI with a third-generation THV, valve performances were good at 1 year with low PVL rate. The LV mechanics improved immediately after the procedure and were maintained at 1 year. These findings demonstrate the benefit of TAVI on LV mechanics, and suggests that GLS may be superior to LVEF in assessing this benefit. Clinicaltrial.gov number: NCT0269895

Use of spinal cord stimulation in managing neuropathic foot pain: an observational pilot case series study

Objective: In cases of complex regional pain syndrome where conservative treatment is unsuccessful in controlling neuropathic foot pain spinal cord stimulation may be considered. To our knowledge there have been no such cases reported in the foot & ankle literature. The aim of the study was to establish useful information that may supplement our understanding of this complex multifactorial problem and help toinform future management of similar cases. Methods: A pilot observational case series study was undertaken to investigate the use of spinal cord stimulation in the management of neuropathic foot pain using five cases with complex regional pain syndrome (type I). Results: Reduced pain following spinal cord stimulation was reported. The interval between diagnosis and commencement of spinal cord stimulation was variable between cases and maybe responsible for differing levels and timing of pain relief experienced. Conclusion: Careful preoperative diagnosis, robust patient selection and close postoperative monitoring are vital for a successful outcome. The small sample size and potential for bias, limit the generalizability to a larger population. A larger study is therefore indicated to expand upon preliminary findings

Valve in Valve: Three-Dimensional Transoesophageal Echocardiogram and Multi-Slice CT Images of Bio-Prosthetic Aortic Valve Replaced by Medtronic CoreValve.

Valve-in-valve trans-cutaneous aortic valve implantation (TAVI) is now feasible and in a recent multi-centre study showed performed with high technical success rates, acceptable post-procedural valvular function, and excellent functional improvement.1) Multi-modality cardiac imaging in such patient's is slowly becoming routine and it is becoming pivotal for physicians to recognize structural and anatomical changes present in such patients. A 70-year-old gentleman was admitted to our unit with pyrexia and suspected infective endocarditis. He had previously undergone bio-prosthetic aortic valve implantation in 2004 for aortic stenosis. When he re-presented with heart failure in 2012 due to re-stenosis of the aortic valve bio-prosthesis, he was deemed not suitable for re-do surgery because of high-risk involved. Thus, he had TAVI using Medtronic CoreValve. Three-dimensional transoesophageal echocardiogram (3D TEE) and multi-slice contrast enhanced computed tomography (CT) scan were performed to look for the source of infection. 3D TEE clearly showed the grove of CoreValve in aortic sinus and that it was well seated (Fig. 1). Position and location of the CoreValve was also confirmed on CT thorax with 3D vascular multi-slice reconstruction (Fig. 2). Two-dimensional short-axis colour Doppler views confirmed patent left main stem and location of the strut in relation to it (Fig. 3). The highlight of this peculiar case is that the CoreValve can be recognised by 3D TEE and also CT. However, it is not possible to distinguish the remnant leaflets of the previous bio-prosthesis. This is important to bear in mind when performing and reporting TEE and CT in patients with aortic valve in valve systems. To best of our knowledge, this state-of-the-art 3D-volume rendered multi-modality imaging assessment of valve in valve TAVI has not been reported previously in literature

Factors affecting mechanical (nociceptive) thresholds in piglets

AbstractObjectiveTo evaluate the stability and repeatability of measures of mechanical (nociceptive) thresholds in piglets and to examine potentially confounding factors when using a hand held algometer.Study designDescriptive, prospective cohort.AnimalsForty-four piglets from four litters, weighing 4.6 ± 1.0 kg (mean ± SD) at 2 weeks of age.MethodsMechanical thresholds were measured twice on each of 2 days during the first and second week of life. Data were analyzed using a repeated measures design to test the effects of behavior prior to testing, sex, week, day within week, and repetition within day. The effect of body weight and the interaction between piglet weight and behaviour were also tested. Piglet was entered into the model as a random effect as an additional test of repeatability. The effect of repeated testing was used to test the stability of measures. Pearson correlations between repeated measures were used to test the repeatability of measures. Variance component analysis was used to describe the variability in the data.ResultsVariance component analysis indicated that piglet explained only 17% of the variance in the data. All variables in the model (behaviour prior to testing, sex, week, day within week, repetition within day, body weight, the interaction between body weight and behaviour, piglet identity) except sex had a significant effect (p < 0.04 for all). Correlations between repeated measures increased from the first to the second week.Conclusions and Clinical relevanceRepeatability was acceptable only during the second week of testing and measures changed with repeated testing and increased with increasing piglet weight, indicating that time (age) and animal body weight should be taken into account when measuring mechanical (nociceptive) thresholds in piglets. Mechanical (nociceptive) thresholds can be used both for testing the efficacy of anaesthetics and analgesics, and for assessing hyperalgesia in chronic pain states in research and clinical settings

Pain Management in Patients with Impaired Kidney Function

Huge numbers of patients referred to pain service have kidney function impairment to some extent. Pain physicians face puzzling cases and may find themselves struggling and divided between the decisions of providing adequate pain reliever, at the same time avoiding further damage to kidneys, and excessive accumulation of medications and their metabolites, also negative interactions with patient’s other medications. In this chapter, we will reason about the prevalence of pain in patients with renal impairment, pharmacodynamics and pharmacokinetics of pain medications in this group, optimization of pain control, preferred choice of drugs according to the level of kidney damage, and feasibility of alternative pain management techniques

Sensory profiles in women with neuropathic pain after breast cancer surgery

Purpose We performed a detailed analysis of sensory function in patients with chronic post-surgical neuropathic pain (NP) after breast cancer treatments by quantitative sensory testing (QST) with DFNS (German Research Network on Neuropathic Pain) protocol and bed side examination (BE). The nature of sensory changes in peripheral NP may reflect distinct pathophysiological backgrounds that can guide the treatment choices. NP with sensory gain (i.e., hyperesthesia, hyperalgesia, allodynia) has been shown to respond to Na+-channel blockers (e.g., oxcarbazepine). Methods 104 patients with at least "probable" NP in the surgical area were included. All patients had been treated for breast cancer 4-9 years ago and the handling of the intercostobrachial nerve (ICBN) was verified by the surgeon. QST was conducted at the site of NP in the surgical or nearby area and the corresponding contralateral area. BE covered the upper body and sensory abnormalities were marked on body maps and digitalized for area calculation. The outcomes of BE and QST were compared to assess the value of QST in the sensory examination of this patient group. Results Loss of function in both small and large fibers was a prominent feature in QST in the area of post-surgical NP. QST profiles did not differ between spared and resected ICBN. In BE, hypoesthesia on multiple modalities was highly prevalent. The presence of sensory gain in BE was associated with more intense pain. Conclusions Extensive sensory loss is characteristic for chronic post-surgical NP several years after treatment for breast cancer. These patients are unlikely to respond to Na+-channel blockers.Peer reviewe

Iatrogenic damage to the mandibular nerves as assessed by the masseter inhibitory reflex

Iatrogenic injury of the inferior alveolar or lingual nerves frequently leads to legal actions for damage and compensation for personal suffering. The masseter inhibitory reflex (MIR) is the most used neurophysiological tool for the functional assessment of the trigeminal mandibular division. Aiming at measuring the MIR sensitivity and specificity, we recorded this reflex after mental and tongue stimulations in a controlled, blinded study in 160 consecutive patients with sensory disturbances following dental procedures. The MIR latency was longer on the affected than the contralateral side (P < 0.0001). The overall specificity and sensitivity were 99 and 51%. Our findings indicate that MIR testing, showing an almost absolute specificity, reliably demonstrates nerve damage beyond doubt, whereas the relatively low sensitivity makes the finding of a normal MIR by no means sufficient to exclude nerve damage. Probably, the dysfunction of a small number of nerve fibres, insufficient to produce a MIR abnormality, may still engender important sensory disturbances. We propose that MIR testing, when used for legal purposes, be considered reliable in one direction only, i.e. abnormality does prove nerve damage, normality does not disprove it

Sensory Symptom Profiles and Co-Morbidities in Painful Radiculopathy

Painful radiculopathies (RAD) and classical neuropathic pain syndromes (painful diabetic polyneuropathy, postherpetic neuralgia) show differences how the patients express their sensory perceptions. Furthermore, several clinical trials with neuropathic pain medications failed in painful radiculopathy. Epidemiological and clinical data of 2094 patients with painful radiculopathy were collected within a cross sectional survey (painDETECT) to describe demographic data and co-morbidities and to detect characteristic sensory abnormalities in patients with RAD and compare them with other neuropathic pain syndromes. Common co-morbidities in neuropathic pain (depression, sleep disturbance, anxiety) do not differ considerably between the three conditions. Compared to other neuropathic pain syndromes touch-evoked allodynia and thermal hyperalgesia are relatively uncommon in RAD. One distinct sensory symptom pattern (sensory profile), i.e., severe painful attacks and pressure induced pain in combination with mild spontaneous pain, mild mechanical allodynia and thermal hyperalgesia, was found to be characteristic for RAD. Despite similarities in sensory symptoms there are two important differences between RAD and other neuropathic pain disorders: (1) The paucity of mechanical allodynia and thermal hyperalgesia might be explained by the fact that the site of the nerve lesion in RAD is often located proximal to the dorsal root ganglion. (2) The distinct sensory profile found in RAD might be explained by compression-induced ectopic discharges from a dorsal root and not necessarily by nerve damage. These differences in pathogenesis might explain why medications effective in DPN and PHN failed to demonstrate efficacy in RAD