Chemotherapy-induced peripheral neuropathy (CIPN): current therapies and topical treatment option with high-concentration capsaicin.

Cancer diagnosis and treatment are drastic events for patients and their families. Besides psychological aspects of the disease, patients are often affected by severe side effects related to the cancer itself or as a result of therapeutic interventions. Particularly, chemotherapy-induced peripheral neuropathy (CIPN) is the most prevalent neurological complication of oral or intravenous chemotherapy. The disorder may require dose reduction of chemotherapy and is accompanied by multiple symptoms with long-term functional impairment affecting quality of life (QoL), e.g., sensory and functional deteriorations as well as severe pain. Although CIPN may reverse or improve after termination of the causative chemotherapy, approximately 30-40% of patients are faced with chronicity of the symptoms. Due to the advantages in cancer diagnosis and treatments, survival rates of cancer patients rise and CIPN may occur even more frequently in the future. In this review, we summarize current recommendations of leading national and international societies regarding prevention and treatment options in CIPN. A special focus will be placed on current evidence for topical treatment of CIPN with high-dose capsaicin. Finally, an algorithm for CIPN treatment in clinical practice is provided, including both pharmacologic and non-pharmacologic modalities based on the clinical presentation.

Quantitative sensory phenotyping in chronic neuropathic pain patients treated with unilateral L4-dorsal root ganglion stimulation.

BACKGROUND: In a previous study, we reported that selective dorsal root ganglion stimulation (DRGSTIM) at DRG level L4 promoted a favorable outcome for complex regional pain syndrome (CRPS) patients along with DRGSTIM-related changes of inflammatory biomarkers in blood and saliva. The impact on somatosensation is largely unknown. Herein, we assessed the quantitative sensory profile to quantify L4-DRGSTIM effects in CRPS patients. METHODS: Twelve refractory CRPS patients (4 female; 8 male; mean age 69 ± 9 years) received standardized quantitative sensory testing (QST) protocol at baseline and after 3 months of unilateral L4-DRGSTIM assessing nociceptive and non-nociceptive thermal and mechanical sensitivity of the knee affected by CRPS and the contralateral non-painful knee area. RESULTS: At baseline, CRPS subjects showed significantly increased thresholds for warmth, tactile and vibration detection (WDT, MDT and VDT) and exaggerated pain summation (WUR). After 3 months of unilateral L4-DRGSTIM all pain parameters exhibited trends towards normalization of sensitivity accumulating to a significant overall normalization for pain sensitivity (effect size: 0.91, p < 0.01), while with the one exception of WDT all non-nociceptive QST parameters remained unchanged. Overall change of non-nociceptive detection was negligible (effect size: 0.25, p > 0.40). Notably, reduction of pain summation (WUR) correlated significantly with pain reduction after 3 months of L4-DRGSTIM. CONCLUSIONS: Selective L4-DRGSTIM lowered ongoing pain in CRPS patients and evoked significant normalization in the pain domain of the somatosensory profile. Thermoreception and mechanoreception remained unchanged. However, larger randomized, sham-controlled trials are highly warranted to shed more light on effects and mechanisms of dorsal root ganglion stimulation on quantitative sensory characteristics. The study protocol was registered at the 15.11.2016 on German Register for Clinical Trials (DRKS ID 00011267). https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00011267.

Update on structured pain assessment for the documentation of diagnosis-independent symptoms and signs associated with pain.

Concerning the diagnosis and therapy of pain syndromes, standardized descriptions similar to those used in the examination of psychopathological findings via the system produced by the AMDP ("Arbeitsgemeinschaft für Methodik und Dokumentation in der Psychiatrie", i. e., the working group establishing standardized methodology and documentation within psychiatry) are still lacking. Therefore, the authors of this article have founded a working group to establish standardized methodology and documentation for symptoms and signs associated with pain, although not at a diagnosis-specific level, in order to promote standardization in the documentation of pain and rating of the symptoms associated with a given set of medical results. This article presents a system for documenting the symptoms and signs associated with pain globally and independently of the diagnosis (Structured Pain Assessment System) with nomenclature that is inspired by the AMDP system. The objective of this working group is to develop documentation for a uniform multidimensional pain assessment (with defined terminology) that serves as a comparable and unified standard in the field.

Topical Ambroxol 20% for the Treatment of Classical Trigeminal Neuralgia - A New Option? Initial Clinical Case Observations.

BACKGROUND: Trigeminal neuralgia is difficult to treat and shows upregulation of sodium channels. The expectorant ambroxol acts as a strong local anesthetic, about 40 times stronger than lidocaine. It preferentially inhibits the channel subtype Nav 1.8, expressed especially in nociceptive C-fibers. It seemed reasonable to try ambroxol for the treatment with neuropathic facial pain unresponsive to other standard options. MATERIAL AND METHODS: Medical records of patients suffering from classical trigeminal neuralgia (n = 5) and successful pain reduction following topical ambroxol 20% cream in addition to standard treatment are reported. RESULTS: All patients reported pain attacks with pain intensity between 4 and 10 NRS (numeric pain scale). In all cases they could be triggered, 3 patients reported additional spontaneous pain. Attacks were reduced in all 5 patients. Pain reduction achieved following ambroxol 20% cream was 2-8 points (NRS) earliest within 15-30 minutes and lasted for 4-6 hours mostly. This was reproducible in all cases; in one case pain was eliminated after 1 week. No patient reported side effects or skin changes; oral medication was reduced in 2 patients. CONCLUSION: For the first time, a clinically significant pain relief following topical ambroxol 20% cream in patients with trigeminal neuralgia is reported. In view of the positive side effect profile, topical ambroxol for patients with such a highly impaired quality of life should be investigated further as a matter of urgency.

Does participation in art classes influence performance on two different cognitive tasks?

OBJECTIVES: Effects of two mentally stimulating art interventions on processing speed and visuo-spatial cognition were compared in three samples. METHOD: In a randomized 10-week art intervention study with a pre-post follow-up design, 113 adults (27 healthy older adults with subjective memory complaints, 50 healthy older adults and 36 healthy younger adults) were randomly assigned to one of two groups: visual art production or cognitive art evaluation, where the participants either produced or evaluated art. ANOVAs with repeated measures were computed to observe effects on the Symbol-Digit Test, and the Stick Test. RESULTS: Significant Time effects were found with regard to processing speed and visuo-spatial cognition. Additionally, there was found a significant Time × Sample interaction for processing speed. The effects proved robust after testing for education and adding sex as additional factor. CONCLUSION: Mental stimulation by participation in art classes leads to an improvement of processing speed and visuo-spatial cognition. Further investigation is required to improve understanding of the potential impact of art intervention on cognitive abilities across adulthood.

[The AMDS system for the documentation of symptoms and signs associated with pain]. / Das AMDS-System zur Dokumentation von Schmerzbefunden.

The authors present a system for nomenclature and documentation of symptoms and signs associated with pain. The system was compiled in a staged process by the study group for methods and documentation of pain-associated symptoms and signs (Arbeitsgemeinschaft für Methodik und Dokumentation von Schmerzbefunden [AMDS]). The suggested items were elaborated from terms used in current national and international guidelines and classifications and in part integrated into superordinate terms. The items that were built up by this approach aim to reflect the broad spectrum of pain diseases. The items for the description of pain-associated symptoms and signs are divided into the areas of algesiomotor, psychoalgesiological and somatoalgesiological findings. The aim is the documentation of a multidimensional algesiological description of findings with defined terminology, which can serve as a comparable and unified standard, particularly in the field of pain assessment. The AMDS system should enable a systematic description of pain, which is a reliable foundation for diagnostics, therapy planning and expert case evaluation.

Neuromodulation of Electrically Induced Hyperalgesia in the Trigeminocervical System.

OBJECTIVE: Trigeminal and cervical afferents converge on neurons of the trigeminocervical complex and may significantly alter the function of these neurons. This interaction may have implications for the pathophysiology and treatment of primary headache disorders. Therefore, the aim of this work was to study pain modulatory mechanisms within the trigeminocervical complex. SUBJECTS: We used an electrical pain model challenging pro- and antinociceptive systems in 19 healthy volunteers. METHODS: Transcutaneous supraorbital noxious electrical low-frequency stimulation (0.5 Hz), known to induce both hyperalgesia due to central sensitization (as a marker of pain facilitation) and habituation (as a marker of pain inhibition), was combined with different noxious stimulation paradigms applied to the innervation territory of upper cervical afferents. We investigated the effects of concurrent stimulation in the cervical/extratrigeminal system on habituation profiles, hyperalgesic area, pain, and detection thresholds in the trigeminal system. RESULTS: It was previously shown that conditioning 20-Hz noxious electrical stimuli may provoke centrally mediated sensory decline that possesses heterotopic antihyperalgesic properties. Occipital and forearm costimulation at a frequency of 20 Hz had no significant modulating effect on supraorbital pain adaptation, hyperalgesic area, or pain perception. Effects for trigeminal stimulation were independent of occipital stimulus intensity. Furthermore, for single occipital stimulation at 0.5 and 20 Hz, no somatosensory changes could be demonstrated within the trigeminal system. CONCLUSION: Trigeminal nociception stayed unchanged despite of occipital costimulation.

Effects of Different Anesthetics on Pain Processing in an Experimental Human Pain Model.

OBJECTIVE: After surgical procedures, anesthesia itself may affect pain perception. Particularly, there is increasing evidence that opioids not only have analgesic effects but also provoke pronociceptive changes, that is, opioid-induced hyperalgesia. We investigated the effect of different anesthetic regimens on pain processing in volunteers using a transdermal electrical pain model. In this model, stimulation of epidermal nerve fibers representing mainly peptidergic C-nociceptors leads to secondary hyperalgesia and habituation to the stimulus. METHODS: Forty-eight healthy volunteers underwent conditioning noxious stimulation (CS) over 5 days. On day 2, the volunteers were randomized into 4 groups: control group (no anesthesia) and 3 groups receiving anesthesia before CS in anesthetic doses: propofol (P), propofol/remifentanil (PR), and propofol/remifentanil/S-ketamine (PRK). Quantitative sensory testing was performed on days 1 through 5 and on day 22. RESULTS: In every group, CS was associated with short- and long-term habituation to the electrical stimulus. Repetitive CS resulted in unmodified short-term sensitization with stable areas of hyperalgesia. Although the PR group showed a trend toward increased areas of hyperalgesia on day 2, no significant differences were detectable between the groups. In contrast, anesthesia resulted in decreased intensity of the electrically evoked pain on day 2. Finally, the mechanical pain threshold before CS on day 5 was increased in all groups and remained elevated 3 weeks after the first CS, consistent with a long-term antinociceptive effect after CS. CONCLUSIONS: The results suggest a short-term analgesic effect of general anesthesia. Furthermore, the conditioning stimulation over several days induced differential modulation of pro- and antinociceptive systems.

Reliability and validity of the range of motion scale (ROMS) in patients with abnormal postures.

OBJECTIVE: Sustained abnormal postures (i.e., fixed dystonia) are the most frequently reported motor abnormalities in complex regional pain syndrome (CRPS), but these symptoms may also develop after peripheral trauma without CRPS. Currently, there is no valid and reliable measurement instrument available to measure the severity and distribution of these postures. The range of motion scale (ROMS) was therefore developed to assess the severity based on the possible active range of motion of all joints (arms, legs, trunk, and neck), and the present study evaluates its reliability and validity. METHODS: Inter- and intra-rater reliability of the ROMS was determined in 16 patients with abnormal sustained postures, who were videotaped following a standard video protocol in a university hospital. The recordings were rated by a panel of international experts. In addition, 30 patients were clinically tested with both the Burke-Fahn-Marsden (BFM) scale as well as the ROMS to assess construct validity. RESULTS: Inter-rater reliability for total ROMS scores showed an intra-class correlation coefficient (ICC) of 0.85. The majority of the scores for the separate joints (13 out of 18) demonstrated an almost perfect agreement with ICCs ranging from 0.81 to 0.94; of the other items, one showed fair, one moderate, and three substantial agreement. The ICCs for the intra-rater reliability ranged from moderate to almost perfect (0.68-0.98). Spearman's correlation coefficients between corresponding body areas as measured with the ROMS or BFM were all above 0.82. CONCLUSION: The ROMS is a reliable and valid instrument to evaluate the severity and distribution of sustained abnormal postures.

Characterization of somatosensory profiles in patients with Crohn's disease.

BACKGROUND: Crohn's disease (CD) is a painful chronic inflammatory bowel disease. It primarily affects terminal ileum, but the involvement of large and small intestines or extraintestinal manifestations is very common. CD may go along with neurogenic inflammation, mediated by substance P and CGRP, which are also key players in pain transmission. This may in turn contribute to hyperalgesia and altered somatosensory function in CD. METHODS: One hundred and three (103) patients with CD and 80 healthy volunteers were enrolled. Patient characteristics and disease history were documented. We used quantitative sensory testing (QST) to investigate the somatosensory profile in patients and volunteers. We also calculated z-scores for the QST results of the patients with CD based on the data of our control group. A 2-step cluster analysis, using all QST data, was performed to find subgroups within patients and volunteers. RESULTS: Thresholds of warm detection, mechanical pain, and vibration detection did significantly differ between patients with CD and volunteers. Z-scores indicated a general trend of sensory loss in CD patients with a significant relationship between patients with a sensory loss for cold and warm detection. In the hyposensitive cluster of the CD cohort, patients were more frequently male, had a higher incidence of extraintestinal manifestations, and suffered longer from CD. CONCLUSIONS: Our findings are consistent with the presence of a subclinical small fiber neuropathy. The group of CD patients with pronounced neuropathy findings were predominantly males, had a higher incidence of extraintestinal manifestations, and tended to have a longer history of disease duration.

Serial repetitive transcranial magnetic stimulation (rTMS) decreases BDNF serum levels in healthy male volunteers.

Although repetitive transcranial magnetic stimulation (rTMS) is established in the treatment of depression, there is little knowledge about the underlying molecular mechanisms. In the last decade, the neurotrophic hypothesis of depression entailed a plethora of studies on the role of neurogenesis-associated factors in affective disorders and rTMS treatment. In the present study, we hypothesised a sham-controlled increase of peripheral brain-derived neurotrophic factor (BDNF) levels following serial rTMS stimulations in healthy individuals. We investigated the influence of a cycle of nine daily high-frequency (HF)-rTMS (25 Hz) stimulations over the left dorsolateral prefrontal cortex (DLPFC) on serum levels of BDNF in 44 young healthy male volunteers. BDNF serum concentrations were measured at baseline, on day 5 and on day 10. Overall, the statistical analyses showed that the active and sham group differed significantly regarding their responses of BDNF serum levels. Contrary to our expectations, there was a significant decrease of BDNF only during active treatment. Following the treatment period, significantly lower BDNF serum levels were quantified in the active group on day 10, when compared to the sham group. The participants' smoking status affected this effect. Our results suggest that serial HF-rTMS stimulations over the left DLPFC decrease serum BDNF levels in healthy male volunteers. This provides further evidence for an involvement of BDNF in clinical rTMS effects.

Comprehensive visualization of paresthesia in breast cancer survivors.

PURPOSE: As breast cancer survivors are benefiting increasingly from advanced forms of therapy, the side effects of locoregional treatment in the adjuvant setting are becoming more and more important. This article presents a new method of assessing the spatial distribution of paresthesia in breast cancer survivors after different locoregional treatments. METHODS: A structured questionnaire assessing paresthesia, with body pictograms for marking paresthesia areas, was completed by 343 breast cancer survivors. The image information was digitized, generating gray-scale summation images with numbers from 0, indicating black (100 % of the patients had paresthesia), to 255, indicating white (none had paresthesia). The resulting map visualization showed the locations of paresthesia on body pictograms. The group included patients who had undergone breast-conserving surgery (BCS) and mastectomy, and also patients who had received percutaneous and interstitial radiation. RESULTS: A total of 56.5 % of the patients stated that they had paresthesia. The paresthesia areas were distributed within the range suggested by clinical experience. Most patients stated that they had paresthesia in the upper outer quadrant and axilla. Patients who had undergone mastectomy or percutaneous radiotherapy appeared to have more paresthesia on some areas of the body surface. Patients who had undergone mastectomy indicated larger areas of paresthesia than those with BCS-4,066 pixels (px) vs. 2,275 px. Radiotherapy did not appear to influence the spatial distribution of paresthesia. CONCLUSIONS: Paresthesia is a common symptom after breast cancer treatment. This paper describes a new method of assessing this side effect to improve and individualize treatment for it in the future.

Brain activity during sympathetic response in anticipation and experience of pain.

Pain is a multidimensional phenomenon with sensory, affective, and autonomic components. Here, we used parametric functional magnetic resonance imaging (fMRI) to correlate regional brain activity with autonomic responses to (i) painful stimuli and to (ii) anticipation of pain. The autonomic parameters used for correlation were (i) skin blood flow (SBF) and (ii) skin conductance response (SCR). During (i) experience of pain and (ii) anticipation of pain, activity in the insular cortex, anterior cingulate cortex (ACC), prefrontal cortex (PFC), posterior parietal cortex (PPC), secondary somatosensory cortex (S2), thalamus, and midbrain correlated with sympathetic outflow. A conjunction analysis revealed a common central sympathetic network for (i) pain experience and (ii) pain anticipation with similar correlations between brain activity and sympathetic parameters in the anterior insula, prefrontal cortex, thalamus, midbrain, and temporoparietal junction. Therefore, we here describe shared central neural networks involved in the central autonomic processing of the experience and anticipation of pain.

Patients' experience and utilization patterns of diclofenac gel in Germany: a real-world study with a prospective longitudinal survey and a retrospective analysis of pharmacy data.

OBJECTIVE: Describe and characterize treatment patterns, satisfaction, improvement in pain and functional impairment (health-related quality of life [HRQoL]) in users of over the counter (OTC) Voltaren gel diclofenac (VGD) 2.32% and 1.16% in a real-world setting. METHODS: This observational real-world German study had prospective and retrospective components. The prospective data were collected from electronic surveys completed by adults who purchased VGD to treat their musculoskeletal pain at baseline and 4 and 12 weeks after baseline. Retrospective data were from a 12-month (March 2019 to February 2020) abstraction from dispensing software platforms used in select German pharmacies. RESULTS: Surveys from 467 participants (mean age 60.8 years) were analyzed. Average pain severity at baseline was 6.0 on an 11-point Numeric Rating Scale (0 = no pain, 10 = worst possible pain), improving by 0.8 and 1.2 points at Weeks 4 and 12, respectively. Performance of functional activities (daily/physical/social activities and errands/chores) improved and the proportion of participants with at least moderate interference decreased at both follow-up timepoints. Retrospective analyses indicated that majority of patients receiving VGD (n = 95,085) were ≥65 years old (67.9%), had one dispensed tube (70.8%) and did not switch to another topical treatment (including other NSAIDs) (77.3%), and were co-prescribed at least one cardiovascular medication (74.3%). CONCLUSIONS: This study provides the first real-world insights into OTC VGD use in Germany. The participants using VGD reported a decrease in pain severity and an improvement of HRQoL while under treatment, as well as resulting satisfaction with treatment. Patients infrequently switched to alternate topical therapies/NSAIDs.

Varicella Zoster Virus-Specific Hyperimmunoglobulin in the Adjuvant Treatment of Immunocompromised Herpes Zoster Patients: A Case Series.

INTRODUCTION: Immunocompromised patients are at increased risk for herpes zoster (HZ)-associated complications. Despite standard therapy with systemic antiviral drugs and analgesics, complications are frequently encountered, including generalization of lesions or persistent neuropathic pain, so-called post-herpetic neuralgia (PHN). Given the scarcity of literature and awareness of therapeutic options to improve patient outcomes, especially for vulnerable patient groups, here we describe a strategy based on early intensification of treatment with a varicella zoster virus-specific hyperimmunoglobulin (VZV-IgG), which is approved in the adjuvant treatment of HZ. METHODS: For this case series, we selected four cases of HZ in patients with impaired immunity due to hemato-oncologic disease or immunosuppressive treatment who presented with either existing generalized lesions and/or severe pain or with other risk factors for a complicated HZ course such as PHN. They were considered to be representative examples of different patient profiles eligible for intensification of treatment by the addition of VZV-IgG to virostatic therapy. CASE REPORT: All patients showed a rapid response to combined treatment with VZV-IgG and a virostatic agent. In two patients who had generalized lesions, the formation of new lesions ceased 1 day after VZV-IgG infusion. One patient, with mantle cell lymphoma, achieved complete healing of the lesions 9 days after diagnosis of HZ, a rare occurrence compared to similar cases or cohorts. A patient with HZ in the cervical region showed a good response after a single dose of VZV-IgG. None of the patients developed post-zoster-related complications. Combination therapy of a virostatic agent and VZV-IgG was well tolerated in these four cases. CONCLUSION: This case series demonstrates highly satisfactory treatment effectiveness and tolerability for VZV-IgG in the adjuvant treatment of immunocompromised HZ patients and supports early intensification of HZ therapy in patients at high risk of severe disease progression.

Detection of low level cryoglobulins by flow cytometry.

Several patients with cryoglobulin (CG) associated symptoms are seronegative for CG and other potentially causative biomarkers. We analyzed whether it is possible to detect cryoprecipitates by flow cytometry and whether the sensitivity of their demonstration can be increased as compared to visual inspection. Sera from 91 patients with suspected CG associated symptoms and 33 healthy controls were examined for the presence of CG by conventional visual testing and by flow cytometry for small diffracting particles. For calibration purposes we tested lipid micelle dilutions (positive controls) by both methods. The minimum concentrations of lipid micelles to be detected by visual inspection and flow cytometry were 128.5 and 2.0 pg ml(-1), respectively. Among the 91 patients and 33 controls, only 1 patient serum was positive for CG by conventional testing. This sample was also positive on flow cytometry. In the serum of a patient known to be positive for CG, laser diffracting particles were quantified by flow cytometry after keeping serum at 4°C for 3 days. Of the 91 patients, 14 additional samples displayed cold precipitates which redissolved after rewarming during flow cytometry. All 15 (1 + 14) patients positive for CG on flow cytometry suffered from symptoms usually associated with CG. Some precipitates were labeled with anti IgG and IgM antibodies confirming that the particles detected by flow cytometry contained immunoglobulins. No small diffracting particles were detected in the sera of the 33 healthy controls. Flow cytometry is equally specific but much more sensitive in the detection of CG than visual inspection.

Visual pain mapping in endometriosis.

PURPOSE: To construct pain maps in order to describe the distribution of pelvic pain in a group of endometriosis patients and endometriosis-free patients, to assess the feasibility of this method. METHODS: A total of 159 patients with pelvic pain who were scheduled for diagnostic laparoscopy. RESULTS: A total of 117 patients with and 42 patients without endometriosis were included. The pain distribution between these two patient groups appeared to differ in some peripheral anatomical structures. In the endometriosis patients, the pain was most frequently located in the rectouterine pouch. CONCLUSIONS: In endometriosis patients, pain mapping to assess preoperative pain sensations relative to the anatomic location of endometriotic lesions is feasible. The pain provoked by vaginal examination is frequently perceived as median relative to the actual anatomic location of the endometriotic lesions. Several anatomic and neurophysiological factors may explain this phenomenon.

Modulation of somatosensory profiles by spinal cord stimulation in primary Raynaud's syndrome.

BACKGROUND AND GOAL: Spinal cord stimulation (SCS) is an effective antinociceptive treatment for various neuropathic pain syndromes. Apart from antinociceptive action, it may modulate overall somatosensory perception. This case report targets the question of whether SCS may alter quantitative sensory testing (QST) in a patient with primary Raynaud's syndrome. MATERIALS AND METHODS: We report on a 44-year-old female patient with primary Raynaud's syndrome who had SCS via cervical and lumbar electrodes. QST was performed in a standardized manner assessing cold detection threshold (CDT) and warm detection threshold (WDT), cold pain threshold (CPT) and heat pain threshold (HPT), mechanical detection threshold (MDT) and mechanical pain threshold (MPT) thresholds, and vibration detection threshold (VDT) and pressure pain thresholds (PPT). We tested at the dorsum of the right/left hand of the patient with engaged and disengaged SCS. Test results were compared with a control group of 80 subjects. RESULTS: Without SCS, the patient showed a sensory decrease in CDT, MDT, MPT, and VDT. SCS influenced the perception of cold, warm, and tactile detection thresholds, whereby CDT, WDT, and VDT were impaired and MDT was improved. CONCLUSION: SCS significantly modulated the somatosensory profile in a patient with primary Raynaud's syndrome. These effects were pronounced in qualities involving Aß, C, and A∂ nerve fibers. Further investigations may help to understand the mechanisms of action of SCS.

Activation of central sympathetic networks during innocuous and noxious somatosensory stimulation.

Although pain is accompanied by autonomic nervous system responses, the cerebral circuits involved in the autonomic pain dimension remain elusive. Therefore, we used functional magnetic resonance imaging (fMRI) and investigated brain processing associated with cutaneous sympathetic vasoconstrictor reflexes during noxious stimulation. When a classical fMRI analysis based on the applied block design was performed, we were able to detect activations well known to be engaged in the central processing of touch and pain. A parametric fMRI analysis in which cutaneous vasoconstrictor activity was correlated with MRI signals revealed two distinct patterns of brain activity. During (i) noxious stimulation itself, brain activity correlated with sympathetic activity in the anterior insula, ventrolateral prefrontal cortex (VLPFC), anterior cingulate cortex (ACC), and secondary somatosensory cortex (S2). During (ii) baseline, brain activity correlated with sympathetic activity in the VMPFC, dorsolateral prefrontal cortex (DLPFC), OFC, PCC, cuneus, precuneus, occipital areas, and hypothalamus. Conjunction analysis revealed significant similar responses during periods of noxious stimulation and periods of sympathetic activation in the anterior insula, ACC and VLPFC (activation) and VMPFC, OFC, PCC, cuneus and precuneus (deactivation). Therefore, we here describe a cerebral network which may be engaged in the processing of the autonomic subdimension of the human pain experience.

Functional connectivity of the human insular cortex during noxious and innocuous thermal stimulation.

The insula plays a key role in brain processing of noxious and innocuous thermal stimuli. The anterior and the posterior portions of the insular cortex are involved in different ways in nociceptive and thermoceptive processing. Therefore, their stimulus-specific functional connectivity may also differ. Here we used functional magnetic resonance imaging (fMRI) to investigate the activity and functional connectivity of insular cortex subregions during noxious and innocuous thermal stimulation. In 11 healthy subjects, psychophysically controlled noxious and innocuous warm and cold stimuli were applied to the left forearm. To differentiate between the subregions of the insular cortex involved in pain processing and those involved in temperature processing, a 2×2 factorial fMRI analysis was performed. Pain processing insular areas (main effect of pain) were detected in bilateral aINS and contralateral pINS. Temperature processing insular areas (main effect of temperature) were also found in bilateral aINS and contralateral pINS. The individual signal time courses from the pain- and temperature processing insular activation clusters were used for calculation and comparison of stimulus-specific functional connectivity of aINS and pINS by means of a correlation analysis. As expected, both aINS and pINS were functionally connected to a large brain network - which predominantly includes areas involved in nociception and thermoception: primary (S1) and secondary (S2) somatosensory cortices, cingulate gyrus, prefrontal cortex (PFC) and parietal association cortices (PA). When statistically compared, during both noxious and innocuous stimulation, aINS was more strongly connected to PFC and to ACC than was pINS; pINS meanwhile was more strongly connected to S1 and to the primary motor cortex (M1). Interestingly, S2 was more strongly connected to aINS than to pINS during painful stimulation but not during innocuous thermal stimulation. We conclude that aINS is more strongly functionally connected to areas known for affective and cognitive processing, whereas pINS is more strongly connected with areas known for sensory-discriminative processing of noxious and somatosensory stimuli.