Chapter 24 Referred pain from internal organs

Pain from Internal Organs and Headache: The Challenge of Comorbidity

Headache and visceral pain are common clinical painful conditions, which often co-exist in the same patients. Numbers relative to their co-occurrence suggest possible common pathophysiological mechanisms. The aim of the present narrative review is to describe the most frequent headache and visceral pain associations and to discuss the possible underlying mechanisms of the associations and their diagnostic and therapeutic implications based on the most recent evidence from the international literature. The conditions addressed are as follows: visceral pain from the cardiovascular, gastrointestinal, and urogenital areas and primary headache conditions such as migraine and tension-type headache. The most frequent comorbidities involve the following: cardiac ischemic pain and migraine (possible shared mechanism of endothelial dysfunction, oxidative stress, and genetic and hormonal factors), functional gastrointestinal disorders, particularly IBS and both migraine and tension-type headache, primary or secondary dysmenorrhea and migraine, and painful bladder syndrome and headache (possible shared mechanisms of peripheral and central sensitization processes). The data also show that the various visceral pain-headache associations are characterized by more than a simple sum of symptoms from each condition but often involve complex interactions with the frequent enhancement of symptoms from both, which is crucial for diagnostic and treatment purposes.

Tramadol for chronic pain in adults: protocol for a systematic review with meta-analysis and trial sequential analysis of randomised clinical trials

BACKGROUND

Chronic pain in adults is a frequent clinical symptom with a significant impact on patient well-being. Therefore, sufficient pain management is of utmost importance. While tramadol is a commonly used pain medication, the quality of evidence supporting its use has been questioned considering the observed adverse events. Our objective will be to assess the benefits and harms of tramadol compared with placebo or no intervention for chronic pain.

METHODS/DESIGN

We will conduct a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis to assess the beneficial and harmful effects of tramadol in any dose, formulation, or duration. We will accept placebo or no intervention as control interventions. We will include adult participants with any type of chronic pain, including cancer-related pain. We will systematically search the Cochrane Library, MEDLINE, EMBASE, Science Citation Index, and BIOSIS for relevant literature. We will follow the recommendations by Cochrane and the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement. The risk of systematic errors ('bias') and random errors ('play of chance') will be assessed. The certainty of evidence will be evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

DISCUSSION

Although tramadol is often being used to manage chronic pain conditions, the beneficial and harmful effects of this intervention are unknown. The present review will systematically assess the current evidence on the benefits and harms of tramadol versus placebo or no intervention to inform clinical practice and future research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42019140334.

Somatovisceral Convergence in Sleep-Wake Cycle: Transmitting Different Types of Information via the Same Pathway

Convergence of somatic and visceral inputs occurs at the levels of nervous system ranging from spinal cord to cerebral cortex. This anatomical organization gave explanation to a referred pain phenomenon. However, it also presents a problem: How does the brain know what information is coming for processing-somatic or visceral - if both are transferred by the same spinal cord fibers by means of the standard neuronal spikes? Recent studies provided evidence for cortical processing of interoceptive information largely occurring in sleep, when somatosensation is suppressed, and for the corresponding functional brain networks rearrangement. We suggest that convergent units of the spinal cord would be able to collectively provide mainly somatosensory information in wakefulness and mainly visceral in sleep, solving the puzzle of somatovisceral convergence. We recorded spiking activity from the spinal cord lemniscus pathway during multiple sleep-wake cycles in freely behaving rabbits. In wakefulness high increased spiking corresponded to movements. When animals stopped moving this activity ceased, the fibers remained silent during passive wakefulness. However, upon transition to sleep fibers began firing again. Analysis of spiking patterns of individual fibers revealed that in the majority of them spiking rates recovered in slow wave sleep. Thus, despite cessation of motion and a corresponding decrease of somatic component of the convergent signal, considerable ascending signaling occurs during sleep, that is likely to be visceral. We also recorded evoked responses of the lemniscus pathway to innocuous electrostimulation of the abdominal viscera, and uncovered the existence of two groups of responses depending upon the state of vigilance. Response from an individual fiber could be detected either during wakefulness or in sleep, but not in both states. Wakefulness-responsive group had lower spiking rates in wakefulness and almost stopped spiking in sleep. Sleep-responsive retained substantial spiking during sleep. These groups also differed in spike amplitudes, indicative of fiber diameter differences; however, both had somatic responses during wakefulness. We suggest a mechanism that utilizes differences in somatic and visceral activities to extract both types of information by varying transmission thresholds, and discuss the implications of this mechanism on functional networks under normal and pathological conditions.

Acute headache management in emergency department. A narrative review

Headache is a significant reason for access to Emergency Departments (ED) worldwide. Though primary forms represent the vast majority, the life-threatening potential of secondary forms, such as subarachnoid hemorrage or meningitis, makes it imperative for the ED physician to rule out secondary headaches as first step, based on clinical history, careful physical (especially neurological) examination and, if appropriate, hematochemical analyses, neuroimaging or lumbar puncture. Once secondary forms are excluded, distinction among primary forms should be performed, based on the international headache classification criteria. Most frequent primary forms motivating ED observation are acute migraine attacks, particularly status migrainous, and cluster headache. Though universally accepted guidelines do not exist for headache management in an emergency setting, pharmacological parenteral treatment remains the principal approach worldwide, with NSAIDs, neuroleptic antinauseants, triptans and corticosteroids, tailored to the specific headache type. Opioids should be avoided, for their scarce effectiveness in the acute phase, while IV hydration should be limited in cases of ascertained dehydration. Referral of the patient to a Headache Center should subsequently be an integral part of the ED approach to the headache patients, being ascertained that lack of this referral involves a high rate of relapse and new accesses to the ED. More controlled studies are needed to establish specific protocols of management for the headache patient in the ED.

Hartmann’s Procedure for Complicated Diverticulitis: A Critical Reappraisal

Background:

Complicated diverticulitis in advanced stages (Hinchey III, IV) is an important surgical emergency for which Hartmann’s Procedure (HP) has traditionally represented the gold standard treatment. HP, however, has high mortality and morbidity and a low percentage of reanastomosis rate. Increasing efforts have therefore been made in recent years to propose alternatives.

Objective:

To critically review studies on the outcome of HPvs.alternative procedures for complicated diverticulitis Resection-Anastomosis without [RA] or with [RAS] protective stomia, Laparoscopic Lavage [LL].

Methods:

Literature search in PubMed for original and review papers in the past 20 years (up to July 2019) with keywords: Hartmann’s procedure, complicated diverticulitis.

Results:

Comparative studies on HPvs. RA/RAS overall reveal better outcomes of RA/RAS,i.e., reduced mortality, morbidity and healthcare costs. However, most studies have limitations due to lack of randomization, limited number of patients and significant impact of surgeons’ specialization and hospital setting/organization in the decision of the type of surgery to perform. These factors might induce preferential allocation of the most critical patients (advanced age, hemodynamic instability, numerous comorbidities) to HP rather than RA/RAS. LL shows promising results but has been tested in a too small number of trialsvs. HP to draw definite conclusions.

Conclusion:

Though valid alternatives to HP are being increasingly employed, consensus on the best approach to complicated diverticulitis has not yet been reached. HP is still far from representing an obsolete intervention, rather it appears to be the preferred choice in the most critical patients.

Cannabinoids versus placebo or no intervention for pain: protocol for a systematic review with meta-analysis and trial sequential analysis

INTRODUCTION

Pain is a frequent clinical symptom with significant impact on the patient's well-being. Therefore, adequate pain management is of utmost importance. While cannabinoids have become a more popular alternative to traditional types of pain medication among patients, the quality of evidence supporting the use of cannabinoids has been questioned. The beneficial and harmful effects of cannabinoids in patients with pain is unknown. Accordingly, we aim to assess the efficacy, tolerability and safety of cannabinoids (herbal, plant-derived extracts and synthetic) compared with placebo or no intervention for any type of pain.

METHODS AND ANALYSES

We will conduct a systematic review of randomised clinical trials with meta-analysis and Trial Sequential Analysis to assess the beneficial and harmful effects of cannabinoids in any dose, formulation and duration. We will accept placebo or no treatment as control interventions. We will include participants with any type of pain (acute and chronic pain, cancer-related pain, headache, neuropathic pain or any other types of pain). We will systematically search The Cochrane Library, MEDLINE, Embase, Science Citation Index and BIOSIS for relevant literature. We will follow the recommendations by Cochrane and the Preferred Reporting Items for Systematic Review and Meta-Analysis statement. The risk of systematic errors (bias) and random errors (play of chance) will be assessed. The overall certainty of evidence will be evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

Ethical approval is not a requirement since no primary data will be collected. The findings of this systematic review will be submitted for peer-reviewed publication and disseminated in national and international conferences.

DISCUSSION

Although cannabinoids are now being used to manage different pain conditions, the evidence for the clinical effects are unclear. The present review will systematically assess the current evidence for the benefits and harms of cannabinoids to inform practice and future research.

Effects of topical vs injection treatment of cervical myofascial trigger points on headache symptoms in migraine patients: a retrospective analysis

Background

In migraine patients with cervical myofascial trigger points whose target areas coincide with migraine sites (M + cTrPs), TrP anesthetic injection reduces migraine symptoms, but the procedure often causes discomfort. This study evaluated if a topical TrP treatment with 3% nimesulide gel has similar efficacy as the injection but produces lesser discomfort with higher acceptability by the patients.

Methods

Retrospective analysis of medical charts of M + cTrPs patients in the period January 2012–December 2016 at a single Headache Center. Three groups of 25 patients each were included, all receiving migraine prophylaxis (flunarizine 5 mg/day) for 3 months and symptomatic treatment on demand. Group 1 received no TrP treatment, group 2 received TrP injections (bupivacaine 5 mg/ml at basis, 3rd, 10th, 30th and 60th day), group 3 received daily TrP topical treatment with 1.5 g of 3% nimesulide gel for 15 consecutive days, 15 days interruption and again 15 consecutive days. The following were evaluated: monthly number of migraine attacks and rescue medications, migraine intensity; pain thresholds to skin electrical stimulation (EPTs) and muscle pressure stimulation (PPTs) in TrP and target (basis, 30th, 60th and 180th days); discomfort from, acceptability of and willingness to repeat treatment (end of study). ANOVA for repeated measures and 1-way ANOVA were used to assess temporal trends in each group and comparisons among groups, respectively. Significance level was set at p < 0.05.

Results

Migraine improved over time in all groups, but significantly more and earlier in those receiving TrP treatment vs no TrP treatment (0.02 < p < 0.0001, 30–180 days for intensity and rescue medication, 60–180 days for number). All thresholds in the non-TrP-treated group did not change over time, while significantly improving in both the injection and nimesulide gel groups (0.01 < p < 0.0001, 30–180 days). Improvement of migraine and thresholds did not differ in the two TrP-treated groups. Discomfort was significantly lower, acceptability and willingness to repeat treatment significantly higher (0.05 < p < 0.0001) with gel than injection.

Conclusion

In migraine patients, topical treatment of cervical TrPs with 5% nimesulide gel proves equally effective as TrP injection with local anesthetics but more acceptable by the patients. This treatment could be effectively associated to standard migraine prophylaxis to improve therapeutic outcomes.

Calcitonin gene-related peptide receptor as a novel target for the management of people with episodic migraine: current evidence and safety profile of erenumab

Migraine is a highly disabling neurological condition, and preventative treatment still remains problematic, due to aspecificity of the majority of the currently available prophylactic drugs. Calcitonin-gene-related peptide (CGRP) plays a crucial role in migraine pathophysiology; agents aimed at blocking its activity have, therefore, been developed in recent years, among which are monoclonal antibodies (mAbs) against CGRP, to prevent migraine. Erenumab is the only mAb that targets the CGRP receptor instead of the ligand, with high specificity and affinity of binding. This review will report on the most recent data on erenumab characteristics and on the results of clinical trials on its employment in the prevention of episodic migraine (4–14 monthly migraine days): one Phase II and two Phase III trials (completed) and one Phase III trial (ongoing). Monthly subcutaneous administration (70 mg or 140 mg) of erenumab vs placebo for 3–6 months showed significantly higher efficacy in reducing the mean monthly number of migraine days and the use of migraine-specific medication, and in decreasing physical impairment and impact of migraine on everyday activities (P<0.001). A favorable safety profile was demonstrated by the lack of significant differences in the occurrence of adverse events in erenumab-treated vs placebo-treated patients. Global results so far obtained point to erenumab as a new promising candidate for the preventative treatment of episodic migraine. Licence applications for erenumab were recently submitted to the Food and Drug Administration in the USA and European Medicines Agency in Europe (May/June 2017).

Glisson's capsule cauterisation is associated with increased postoperative pain after laparoscopic cholecystectomy: a prospective case-control study

INTRODUCTION Postoperative pain after laparoscopic cholecystectomy has three components: parietal, visceral and referred pain felt at the shoulder. Visceral peritoneal injury on the liver (Glisson's capsule) during cauterisation sometimes occurs as an unavoidable complication of the operation. Its effect on postoperative pain has not been quantified. In this study, we aimed to evaluate the association between Glisson's capsule injury and postoperative pain following laparoscopic cholecystectomy. METHODS The study was a prospective case-control of planned standard laparoscopic cholecystectomy with standardized anaesthesia protocol in patients with benign gallbladder disease. Visual analogue scale (VAS) abdominal pain scores were noted at 2 and 24 hours after the operation. One surgical team performed the operations. Operative videos were recorded and examined later by another team to detect presence of Glisson's capsule cauterisation. Eighty-one patients were enrolled into the study. After examination of the operative videos, 46 patients with visceral peritoneal injury were included in the study group, and the remaining 35 formed the control group. RESULTS VAS pain score at postoperative 2 and 24 hours was significantly higher in the study group than control (P = 0.027 and 0.017, respectively). CONCLUSIONS Glisson's capsule cauterisation in laparoscopic cholecystectomy is associated with increased postoperative pain. Additional efforts are recommended to prevent unintentional cauterisation.

Anti-CGRP monoclonal antibodies in migraine: current perspectives

Migraine is a highly disabling neurological pain disorder in which management is frequently problematic. Most abortive and preventative treatments employed are classically non-specific, and their efficacy and safety and tolerability are often unsatisfactory. Mechanism-based therapies are, therefore, needed. Calcitonin gene-related peptide (CGRP) is recognized as crucial in the pathophysiology of migraine, and new compounds that target the peptide have been increasingly explored in recent years. First tested were CGRP receptor antagonists; they proved effective in acute migraine treatment in several trials, but were discontinued due to liver toxicity in long-term administration. Monoclonal antibodies against CGRP (LY2951742, ALD-403, and LBR-101/TEV-48125) or its receptor (AMG334) were subsequently developed. As reviewed in this study, numerous phase 1 and 2 trials and preliminary results of phase 3 trials have shown a good safety/tolerability profile and efficacy in migraine prevention, especially in high frequent episodic and chronic forms. Being macromolecules, these mAbs are not suitable for oral administration; however, their intravenous or subcutaneous delivery can be performed at relatively low frequency-every month or even quarterly-which enhances patients' compliance. Although not all migraineurs respond to this treatment, and longer administration periods will be needed to assess long-term effects, the results so far obtained are extraordinarily promising. The future introduction of mAbs on the market will probably represent a turning point for prevention similar to that represented by triptans for abortive treatment in migraine.

Laparoscopic Cholecystectomy for Gallbladder Calculosis in Fibromyalgia Patients: Impact on Musculoskeletal Pain, Somatic Hyperalgesia and Central Sensitization

Fibromyalgia, a chronic syndrome of diffuse musculoskeletal pain and somatic hyperalgesia from central sensitization, is very often comorbid with visceral pain conditions. In fibromyalgia patients with gallbladder calculosis, this study assessed the short and long-term impact of laparoscopic cholecystectomy on fibromyalgia pain symptoms. Fibromyalgia pain (VAS scale) and pain thresholds in tender points and control areas (skin, subcutis and muscle) were evaluated 1week before (basis) and 1week, 1,3,6 and 12months after laparoscopic cholecystectomy in fibromyalgia patients with symptomatic calculosis (n = 31) vs calculosis patients without fibromyalgia (n. 26) and at comparable time points in fibromyalgia patients not undergoing cholecystectomy, with symptomatic (n = 27) and asymptomatic (n = 28) calculosis, and no calculosis (n = 30). At basis, fibromyalgia+symptomatic calculosis patients presented a significant linear correlation between the number of previously experienced biliary colics and fibromyalgia pain (direct) and muscle thresholds (inverse)(p<0.0001). After cholecystectomy, fibromyalgia pain significantly increased and all thresholds significantly decreased at 1week and 1month (1-way ANOVA, p<0.01-p<0.001), the decrease in muscle thresholds correlating linearly with the peak postoperative pain at surgery site (p<0.003-p<0.0001). Fibromyalgia pain and thresholds returned to preoperative values at 3months, then pain significantly decreased and thresholds significantly increased at 6 and 12months (p<0.05-p<0.0001). Over the same 12-month period: in non-fibromyalgia patients undergoing cholecystectomy thresholds did not change; in all other fibromyalgia groups not undergoing cholecystectomy fibromyalgia pain and thresholds remained stable, except in fibromyalgia+symptomatic calculosis at 12months when pain significantly increased and muscle thresholds significantly decreased (p<0.05-p<0.0001). The results of the study show that biliary colics from gallbladder calculosis represent an exacerbating factor for fibromyalgia symptoms and that laparoscopic cholecystectomy produces only a transitory worsening of these symptoms, largely compensated by the long-term improvement/desensitization due to gallbladder removal. This study provides new insights into the role of visceral pain comorbidities and the effects of their treatment on fibromyalgia pain/hypersensitivity.

Impact of migraine on fibromyalgia symptoms

BACKGROUND

Fibromyalgia (FMS) and high frequency episodic/chronic migraine (M) very frequently co-occur, suggesting common pathophysiological mechanisms; both conditions display generalized somatic hyperalgesia. In FMS-M comorbidity we assessed if: a different level of hyperalgesia is present compared to one condition only; hyperalgesia is a function of migraine frequency; migraine attacks trigger FMS symptoms.

METHODS

Female patients with fibromyalgia (FMS)(n.40), high frequency episodic migraine (M1)(n.41), chronic migraine (M2)(n.40), FMS + M1 (n.42) and FMS + M2 (n.40) underwent recording of: -electrical pain thresholds in skin, subcutis and muscle and pressure pain thresholds in control sites, -pressure pain thresholds in tender points (TePs), -number of monthly migraine attacks and fibromyalgia flares (3-month diary). Migraine and FMS parameters were evaluated before and after migraine prophylaxis, or no prophylaxis, for 3 months with calcium-channel blockers, in two further FMS + H1 groups (n.49, n.39). 1-way ANOVA was applied to test trends among groups, Student's t-test for paired samples was used to compare pre and post-treatment values.

RESULTS

The lowest electrical and pressure thresholds at all sites and tissues were found in FMS + M2, followed by FMS + H1, FMS, M2 and M1 (trend: p < 0.0001). FMS monthly flares were progressively higher in FMS, FMS + M1 and FMS + M2 (p < 0.0001); most flares (86-87 %) occurred within 12 h from a migraine attack in co-morbid patients (p < 0.0001). Effective migraine prophylaxis vs no prophylaxis also produced a significant improvement of FMS symptoms (decreased monthly flares, increased pain thresholds)(0.0001 < p < 0.003).

CONCLUSIONS

Co-morbidity between fibromyalgia and migraine involves heightened somatic hyperalgesia compared to one condition only. Increased migraine frequency - with shift towards chronicity - enhances both hyperalgesia and spontaneous FMS pain, which is reversed by effective migraine prophylaxis. These results suggest different levels of central sensitization in patients with migraine, fibromyalgia or both conditions and a role for migraine as a triggering factor for FMS.

Effects of PDE5 Inhibitors and sGC Stimulators in a Rat Model of Artificial Ureteral Calculosis

Urinary colics from calculosis are frequent and intense forms of pain whose current pharmacological treatment remains unsatisfactory. New and more effective drugs are needed to control symptoms and improve stone expulsion. Recent evidence suggested that the Nitric Oxide (NO) / cyclic guanosine monophosphate (cGMP) / phosphodiesterase type 5 (PDE5) system may contribute to ureteral motility influencing stone expulsion. We investigated if PDE5 inhibitors and sGC stimulators influence ureteral contractility, pain behaviour and stone expulsion in a rat model of ureteral calculosis. We investigated: a)the sex-specific PDE5 distribution in the rat ureter; b)the functional in vitro effects of vardenafil and sildenafil (PDE5 inhibitors) and BAY41-2272 (sGC stimulator) on induced ureteral contractility in rats and c)the in vivo effectiveness of vardenafil and BAY41-2272, alone and combined with ketoprofen, vs hyoscine-N-butylbromide alone or combined with ketoprofen, on behavioural pain indicators and stone expulsion in rats with artificial calculosis in one ureter. PDE5 was abundantly expressed in male and female rats’ ureter. In vitro, both vardenafil and BAY41-2272 significantly relaxed pre-contracted ureteral strips. In vivo, all compounds significantly reduced number and global duration of “ureteral crises” and post-stone lumbar muscle hyperalgesia in calculosis rats. The highest level of reduction of the pain behaviour was observed with BAY41-2272 among all spasmolytics administered alone, and with the combination of ketoprofen with BAY41-2272. The percentage of stone expulsion was maximal in the ketoprofen+BAY41-2272 group. The NO/cGMP/PDE5 pathway is involved in the regulation of ureteral contractility and pain behaviour in urinary calculosis. PDE5 inhibitors and sGC stimulators could become a potent new option for treatment of urinary colic pain.

Visceral pain: the ins and outs, the ups and downs

PURPOSE OF REVIEW

Visceral pain represents a major clinical problem, yet far less is known about its mechanisms compared with somatic pains, for example, from cutaneous and muscular structures.

RECENT FINDINGS

In this review, we describe the neuroanatomical bases of visceral pain signalling in the peripheral and central nervous system, comparing to somatic pains and also the channels and receptors involved in these events. We include an overview of potential new targets in the context of mechanisms of visceral pain and hypersensitivity.

SUMMARY

This review should inform on the recognition of what occurs in patients with visceral pain, why comorbidities are common and how analgesic treatments work.

Cystitis increases colorectal afferent sensitivity in the mouse

Studies in humans and rodents suggest that colon inflammation promotes urinary bladder hypersensitivity and, conversely, that cystitis contributes to colon hypersensitivity, events referred to as cross-organ sensitization. To investigate a potential peripheral mechanism, we examined whether cystitis alters the sensitivity of pelvic nerve colorectal afferents. Male C57BL/6 mice were treated with cyclophosphamide (CYP) or saline, and the mechanosensitive properties of single afferent fibers innervating the colorectum were studied with an in vitro preparation. In addition, mechanosensitive receptive endings were exposed to an inflammatory soup (IS) to study sensitization. Urinary bladder mechanosensitive afferents were also tested. We found that baseline responses of stretch-sensitive colorectal afferents did not differ between treatment groups. Whereas IS excited a proportion of colorectal afferents CYP treatment did not alter the magnitude of this response. However, the number of stretch-sensitive fibers excited by IS was increased relative to saline-treated mice. Responses to IS were not altered by CYP treatment, but the proportion of IS-responsive fibers was increased relative to saline-treated mice. In bladder, IS application increased responses of muscular afferents to stretch, although no differences were detected between saline- and CYP-treated mice. In contrast, their chemosensitivity to IS was decreased in the CYP-treated group. Histological examination revealed no changes in colorectum and modest edema and infiltration in the urinary bladder of CYP-treated mice. In conclusion, CYP treatment increased mechanical sensitivity of colorectal muscular afferents and increased the proportion of chemosensitive colorectal afferents. These data support a peripheral contribution to cross-organ sensitization of pelvic organs.