Subgrouping of facilitatory or inhibitory conditioned pain modulation responses in patients with chronic knee pain. Explorative analysis from a multicentre trial.

BACKGROUND: Facilitatory and inhibitory conditioned pain modulation (CPM) responses are observed in healthy volunteers and chronic pain patients, but the clinical implications for phenotyping are unknown. This study aimed to subgroup and compare chronic knee pain patients according to their CPM responses. METHODS: This explorative, cross-sectional study included 127 patients with chronic knee pain (osteoarthritis or following total knee arthroplasty). Individual CPM responses were categorized as facilitatory (test stimuli pain intensity increased when conditioning stimuli were applied), as inhibitory (test stimuli pain intensity decreased) or as no change (defined as less than 5.3% change in pain intensity). Outcomes were clinical pain intensities, temporal summation, widespread pain, self-reported physical function, PainDETECT questionnaire and Pain Quality Assessment Scale. Data were analysed as comparisons between the inhibitory and the facilitatory groups and using multivariate linear regression models. RESULTS: Fifty-four patients had facilitatory CPM responses, 49 had inhibitory CPM responses, and 24 showed no change in CPM response. A between-group difference was observed for self-reported physical function, with the facilitatory CPM group reporting better function (54.4 vs. 46.0, p = 0.028) and the facilitatory CPM group reported more deep pain sensations (3.2 vs. 2.0, p = 0.021). The remaining outcomes showed no between-group differences. Higher clinical pain intensity and facilitated temporal summation were associated in the facilitated CPM group but not in the inhibitory CPM group. CONCLUSION: These explorative findings indicated that quantitative clinical and experimental differences exist between facilitatory or inhibitory CPM responses in a chronic knee pain patient population. Differences in patients' CPM responses should be further investigated to unravel possible clinical importance. SIGNIFICANCE: Our findings confirm that conditioned pain modulation consist of inhibitory and facilitatory responders among a patient population with chronic knee pain. This explorative study indicates that patients with either facilitatory or inhibitory conditioned pain modulation could exhibit differences in pain outcomes. Subgrouping of chronic pain patients depending on individual conditioned pain modulation responses could be considered in phenotyping patients prior to inclusion in clinical trials or used for personalizing the management regime.

Citizen involvement in COVID-19 contact tracing with digital tools: a qualitative study to explore citizens' perspectives and needs.

BACKGROUND: Contact tracing (CT) is a key strategy when dealing with outbreaks of infectious diseases such as COVID-19. The scale of the COVID-19 pandemic has often left public health professionals (PHPs), who are responsible for the execution of CT, unable to keep up with the rapid and largescale spread of the virus. To enhance or support its execution, and potentially lower the workload for PHPs, citizens may be more actively involved in CT-tasks that are commonly executed by PHPs (referred to as 'self-led CT'). There is limited insight into citizens' perspectives on and needs for self-led CT for COVID-19. This study aims to explore the perspectives and needs of Dutch citizens on taking more responsibilities in the execution of CT for COVID-19, potentially through the use of digital tools. METHODS: An exploratory qualitative study was performed, in which online semi-structured interviews were conducted. Questions were based on the Reasoned Action Approach and Health Belief Model. Interviews were audio-recorded and transcribed verbatim. A thematic analysis was conducted to identify citizens' perspectives and needs to participate in self-led CT. RESULTS: We conducted 27 interviews with Dutch citizens. Seven main themes were identified from the interviews: 1) 'Citizens' perspectives on self-led CT are influenced by prior experiences with regular CT', 2) 'Citizens' felt responsibilities and the perceived responsibilities of the PHS in CT shape their perspectives on self-led CT', 3) 'Anticipated impacts of self-led CT on the CT-process', 4) 'Citizens' attitude towards the application of self-led CT depends on their own perceived skills and the willingness and skills of others', 5) 'Shame and social stigma may hamper participation in self-led CT', 6) 'Concerns about privacy and data security: a barrier for self-led CT', and 7) 'Citizens' perspectives and anticipated needs for the implementation and application of self-led CT in practice'. CONCLUSIONS: Most interviewees hold a positive attitude towards self-led CT and using digital tools for this purpose. However, their intention for self-led CT may depend on various factors, such as prior experiences with regular CT, and their perceived self-efficacy to participate. Perspectives and needs of citizens should be considered for the future implementation of self-led CT in practice.

Healthcare worker protection against mpox contamination: position paper of the French Society for Hospital Hygiene.

In the context of the recent re-emergence of mpox worldwide, the French Society for Hospital Hygiene (SF2H) performed a literature review of the transmission paths and proposed specific recommendations for healthcare workers (HCWs) caring for patients with suspected or confirmed MPXV. In developed countries, the risk of contamination among HCWs in healthcare facilities seemed to be very low, limited to contamination through needle stick injuries. Two additional contamination cases were reported and not fully explained. Beyond healthcare settings, the analysis of the literature highlighted (i) a main contamination route during sexual intercourse, mainly among men who have sex with men, and (ii) a very low secondary attack rate in other contexts, such as schools or jails. Numerous studies have reported molecular or virus identification on surfaces or in the air surrounding patients, without any association with the low secondary case incidence; moreover, the minimum infectious dose through air or mucosal exposure is still unknown. Owing to the lack of evidence of MPXV respiratory transmission in the healthcare setting, the SF2H recommends the implementation of standard and contact precautions combined with medical/surgical mask use. Owing to the lack of evidence of transcutaneous contamination, the SF2H recommends the use of gloves only if contact with cutaneous lesions or mucous membranes occurs. Regarding the risk of contamination from the environment in healthcare facilities, additional studies must be conducted to investigate this.

Reflections from the OARSI 2022 clinical trials symposium: The pain of OA-Deconstruction of pain and patient-reported outcome measures for the benefit of patients and clinical trial design.

OBJECTIVE: Osteoarthritis (OA) drug development is hampered by a number of challenges. One of the main challenges is the apparent discordance between pain and structure, which has had a significant impact on drug development programs and has led to hesitance among stakeholders. Since 2017, the Clinical Trials Symposium (CTS) has been hosted under the Osteoarthritis Research Society International (OARSI) leadership. OARSI and the CTS steering committee yearly invite and encourage discussions on selected special subject matter between regulators, drug developers, clinicians, clinical researchers, biomarker specialists, and basic scientists to progress drug development in the OA field. METHOD: The main topic for the 2022 OARSI CTS was to elucidate the many facets of pain in OA and to enable a discussion between regulators (Food and Drug Administration (FDA) and the European Medicines Agency (EMA)) and drug developers to clarify outcomes and study designs for OA drug development. RESULTS: Signs or symptoms indicative of nociceptive pain occur in 50-70% of OA patients, neuropathic-like pain in 15-30% of patients, and nociplastic pain in 15-50% of patients. Weight-bearing knee pain is associated with bone marrow lesions and effusions. There are currently no simple objective functional tests whose improvements correlate with patient perceptions. CONCLUSIONS: The CTS participants, in collaboration with the FDA and EMA, raised several suggestions that they consider key to future clinical trials in OA including the need for more precise differentiation of pain symptoms and mechanisms, and methods to reduce placebo responses in OA trials.

Dutch public health professionals' perspectives and needs regarding citizen involvement in COVID-19 contact tracing through digital support tools: an exploratory qualitative study.

BACKGROUND: Contact tracing (CT) is an important, but resource-intensive tool to control outbreaks of communicable diseases. Under pandemic circumstances, public health services may not have sufficient resources at their disposal to effectively facilitate CT. This may be addressed by giving cases and their contact persons more autonomy and responsibility in the execution of CT by public health professionals, through digital contact tracing support tools (DCTS-tools). However, the application of this approach has not yet been systematically investigated from the perspective of public health practice. Therefore, we investigated public health professionals' perspectives and needs regarding involving cases and contact persons in CT for COVID-19 through DCTS-tools. METHODS: Between October 2020 and February 2021, we conducted online semi-structured interviews (N = 17) with Dutch public health professionals to explore their perspectives and needs regarding the involvement of cases and contact persons in CT for COVID-19 through DCTS-tools, in the contact identification, notification, and monitoring stages of the CT-process. Interviews were audio recorded and transcribed verbatim. A thematic analysis was performed. RESULTS: Four main themes related to Dutch public health professionals' perspectives and needs regarding involving cases and contact persons in CT for COVID-19 through DCTS-tools emerged from the data: 'Distinct characteristics of CT with DCTS-tools'; 'Anticipated benefits and challenges of CT for COVID-19 with DCTS- tools'; 'Circumstances in CT for COVID-19 that permit or constrain the application of DCTS-tools'; and 'Public health professionals' needs regarding the development and application of DCTS-tools for CT'. Public health professionals seem to have a positive attitude towards involving cases and contact persons through DCTS-tools. Public health professionals' (positive) attitudes seem conditional on the circumstances under which CT is performed, and the fulfilment of their needs in the development and application of DCTS-tools. CONCLUSIONS: Dutch public health professionals seem positive towards involving cases and contact persons in CT for COVID-19 through DCTS-tools. Through adequate implementation of DCTS-tools in the CT-process, anticipated challenges can be overcome. Future research should investigate the perspectives and needs of cases and contact persons regarding DCTS-tools, and the application of DCTS-tools in practice.

Bed bug infestation in a French university hospital: control strategy, financial impact and perspectives.

BACKGROUND: With the increase in international travel and development of insecticide resistance, a re-emergence of the bed bug has been observed since the 2000s and it is becoming a worldwide public health problem. Hospitals and other medical settings have not been spared, while the cases reported remain limited. However, there are no specific recommendations for the healthcare settings in the literature. AIM: To report our experience of a bed bug infestation in a medical unit, in the French University Hospital Centre of Brest, caused by the admission of a patient carrier in October 2020. We described the practical methods used to control bed bugs infestation, evaluated the cost of this episode and created a specific procedure to take care of at-risk patients or known carriers of bed bugs. FINDINGS: The decision to close the unit for global treatment was taken after the investigations using a sniffer dog revealed that four rooms were infested. The closure lasted 24 days. We estimated the total cost of the infestation to be approximately US$400,000. No other wave of infestation occurred. We created a specific protocol of care for patients who were known carriers or at risk of carriage of bed bugs to graduate a strategy of control. CONCLUSION: Bed bug infestations in health facilities have a major impact on the care of patients and relevant economic consequences. Prevention and education policies are an essential starting point to respond to the scale of the phenomenon.

The descending pain modulation system predicts short term efficacy of multimodal pain therapy: an observational prospective cohort study.

OBJECTIVES: Treating chronic pain patients with multimodal pain therapy (MMPT) alters perception, awareness, and processing of pain at multiple therapeutic levels. Several clinical observations suggest that the effects of therapy may go beyond the possible sum of each level of therapy and may be due to a central descending inhibitory effect measurable by conditioned pain modulation (CPM). Thus, we investigated whether CPM is able to identify a group of patients that benefit particularly from MMPT. METHODS: This was an observational prospective cohort study. Patients were hospitalized on a special pain medicine ward with specially trained staff for 10 days. The patients were questioned and had investigations before and shortly after MMPT and were followed-up on 3 months post discharge. Before and after treatment, subjects were investigated via CPM and quantitative sensory testing (QST) as well as completing questionnaires. The study was registered in the German Clinical Trials Register (DRKS00006850). RESULTS: During the study period of 24 months, 224 chronic pain patients were recruited. 51 percent of patients completed the study period. There was an improvement in overall groups regarding all domains assessed, lasting beyond the end of the intervention. Patients with a sufficient CPM effect, defined as a reduction in pain during the conditioning stimulus, at baseline did show a more pronounced reduction in mean pain ratings than those without. This was not the case 3 months after therapy. Furthermore, sufficient CPM was identified as a predictor for pain reduction using a linear regression model. CONCLUSION: In conclusion, this study shows that while a heterogeneous group of patients with chronic pain disorders does sustainably benefit from MMPT in general, patients with a sufficient CPM effect do show a more pronounced decrease in pain ratings directly after therapy in comparison to those without.

Pain at one body site can be reduced, when another painful stimulus occurs at the same time. This mechanism is referred to as conditioned pain modulation (CPM).Some patients with chronic pain are treated using different methods such as medication, physiotherapy, and patient education in an in-patient setting, referred to as multimodal pain therapy (MMST). To improve pain therapy, it is vital to identify whether patients who respond especially well to a certain treatment show specific characteristics (i.e. mechanism-based therapy). We investigated whether the prospect of success of MMST is related to how well CPM works in patients. We assessed the CPM effect and sensory function of 224 patients with chronic pain before and after therapy to answer this question. Additionally, patients completed questionnaires about their pain, mood, quality of life, and sleep directly after therapy and three months later. All patients showed improvement after therapy, but in those in which CPM worked well, pain was reduced stronger than in those in which CPM did not. Three months after treatment, the difference disappeared.

Quantitative sensory testing (QST). English version.

Quantitative sensory testing (QST) is a standardized and formalized clinical sensitivity test. Testing describes a subjective (psychophysical) method that entails a cooperation of the person to be examined. Within its framework, calibrated stimuli are applied to capture perception and pain thresholds, thus providing information on the presence of sensory plus or minus signs. The presented QST battery imitates natural thermal or mechanical stimuli. The aim is to acquire symptom patterns of sensory loss (for the functioning of the thick and thin nerve fibers) as well as a gain of function (hyperalgesia, allodynia, hyperpathia) with a simultaneous detection of cutaneous and deep tissue sensibility. Most of the tested QST parameters are normally distributed only after a logarithmic transformation (secondary normal distribution)-except the number of paradoxical heat sensations, of cold and heat pain thresholds, and vibration detection thresholds. A complete QST profile can be measured within 1 h. QST is suitable not only for clinical trials but also in practice as a diagnostic method to characterize the function of the somatosensory system-from the peripheral nerve fiber receptor to the projection pathways to the brain.

[Rheumatic diseases and neuropathic pain : Diagnosis and treatment]. / Rheumatische Erkrankungen und neuropathischer Schmerz : Diagnose und Therapie.

Pain is a leading symptom in inflammatory rheumatic diseases. For a long time it has been assumed that this pain is of nociceptive origin; however, in about one fifth of all patients the pain remains despite successful anti-inflammatory treatment and is not typically described as nociceptive by those affected. Recent studies indicate that some patients with rheumatoid arthritis (RA) experience pain with a neuropathic pain component. The treatment of neuropathic pain with damage to the somatosensory system differs markedly from the treatment of nociceptive pain in which the pain processing system is intact. Thus, the recognition and, above all, the more precise differentiation of the pain symptoms of affected patients make a decisive contribution to a successful treatment. With the help of a few points in the history and a physical examination, the assumption of the diagnosis neuropathic pain can often be rejected or substantiated. Pain with a neuropathic component does not adequately respond to typical analgesics. Instead, the high efficacy of co-analgesics, such as anticonvulsants and antidepressants, has been repeatedly proven.

Wearing of face masks by healthcare workers during COVID-19 lockdown: what did the public observe through the French media?

Wearing a face mask is a major issue in the fight against the spread of the COVID-19 pandemic. The French general population widely started to wear this personal protective equipment usually dedicated to healthcare workers, without being educated to its correct use. People base their behaviour on what they see in the media. However, we observed that mask wearing of healthcare workers published in the media during the pandemic only conformed to good practice guidelines in 70.8% of the photographs collected on some of the main French information websites. Health authorities should communicate widely regarding the good practices for mask wearing in the general population.

[Treatment of polyneuropathy: autonomic symptoms and pain]. / Therapie der Polyneuropathie ­ autonome Symptome und Schmerzen.

BACKGROUND: The treatment of polyneuropathy includes symptomatic therapy of sensory, motor and autonomic dysfunctions. AIM: This article provides an overview of the current treatment recommendations for polyneuropathy, focusing on pain. METHODS: Current treatment guidelines will be discussed based on a literature research. RESULTS: Calcium-channel anticonvulsants gabapentin/pregabalin as well as antidepressants duloxetine and amitriptyline are recommended as first line therapeutics. Alternatively, topical therapeutics can be used in the case of localized disorders. In individual cases, opioids or other antidepressants/anticonvulsants may be effective. Pharmacological treatment is often limited due to adverse events, which affect the central nervous system in particular. DISCUSSION: In general, treatment for polyneuropathy should follow a multimodal concept and include the treatment of other symptoms. When choosing pain medication, comorbidities, patient's age and adverse events need to be taken into consideration. Phenotype-based stratification may support specialized pain therapy and achieve the best medical treatment.

International consensus guidelines for surgery and the timing of intervention in chronic pancreatitis.

BACKGROUND/OBJECTIVES: Chronic pancreatitis (CP) is a complex inflammatory disease with pain as the predominant symptom. Pain relief can be achieved using invasive interventions such as endoscopy and surgery. This paper is part of the international consensus guidelines on CP and presents the consensus guideline for surgery and timing of intervention in CP. METHODS: An international working group with 15 experts on CP surgery from the major pancreas societies (IAP, APA, JPS, and EPC) evaluated 20 statements generated from evidence on 5 questions deemed to be the most clinically relevant in CP. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the level of evidence available for each statement. To determine the level of agreement, the working group voted on the 20 statements for strength of agreement, using a nine-point Likert scale in order to calculate Cronbach's alpha reliability coefficient. RESULTS: Strong consensus was obtained for the following statements: Surgery in CP is indicated as treatment of intractable pain and local complications of adjacent organs, and in case of suspicion of malignant (cystic) lesion; Early surgery is favored over surgery in a more advanced stage of disease to achieve optimal long-term pain relief; In patients with an enlarged pancreatic head, a combined drainage and resection procedure, such as the Frey, Beger, and Berne procedure, may be the treatment of choice; Pancreaticoduodenectomy is the most suitable surgical option for patients with groove pancreatitis; The risk of pancreatic carcinoma in patients with CP is too low (2% in 10 year) to recommend active screening or prophylactic surgery; Patients with hereditary CP have such a high risk of pancreatic cancer that prophylactic resection can be considered (lifetime risk of 40-55%). Weak agreement for procedure choice in patients with dilated duct and normal size pancreatic head: both the extended lateral pancreaticojejunostomy and Frey procedure seems to provide equivalent pain control in patients. CONCLUSIONS: This international expert consensus guideline provides evidenced-based statements concerning key aspects in surgery and timing of intervention in CP. It is meant to guide clinical practitioners and surgeons in the treatment of patients with CP.

The Liverpool duodenum-and spleen-preserving near-total pancreatectomy can provide long-term pain relief in patients with end-stage chronic pancreatitis.

PURPOSE: Total pancreatectomy may improve symptoms in patients with severe end-stage chronic pancreatitis. This might be achieved whilst preserving both the duodenum- and spleen-(DPSPTP). Mature clinical outcomes of this approach are presented. METHODS: Single-centre prospective cohort study performed between September 1996 and May 2016. Demographic, clinical details, pain scores and employment status were prospectively recorded during clinic attendance. RESULTS: Fifty-one patients (33 men, 18 women) with a median (interquartile range) age of 40.8 (35.3-49.4) years, a median weight of 69.8 (61.0-81.5) Kg and a median body mass index of 23.8 (21.5-27.8), underwent intended duodenum-and spleen-preserving near-total pancreatectomy for end-stage chronic pancreatitis. Aetiology was excess alcohol in 25, idiopathic (no mutation) in 15, idiopathic (SPINK-1/CFTR mutations) in two, hereditary (PRSS1 mutation) in seven and one each post-necrotising pancreatitis and obstructive pancreatic duct divisum in 1. The main indication for surgery was severe pain. Findings included parenchymal calcification in 79% and ductal calculi in 24%, a dilated main pancreatic duct in 57% and a dilated main bile duct in 17%, major vascular involvement in 27% and pancreato-peritoneal fistula in 2%. Postoperative complications occurred in 20 patients with two deaths. Median pain scores were 8 (7-8) preoperatively and 3 (0.25-5.75) at 5 years (p = 0.013). Opiate analgesic use was significantly reduced postoperatively (p = 0.048). Following surgery, 22 (63%) of 38 patients of working age re-entered employment compared with 12 (33%) working preoperatively (p = 0.016). CONCLUSION: Duodenum-and spleen-preserving near-total pancreatectomy provided long-term relief in adult patients with intractable chronic pancreatitis pain, with improved employment prospects.

[Pharmacotherapy of chronic neuropathic pain]. / Pharmakologische Therapie chronischer neuropathischer Schmerzen.

Chronic neuropathic pain has a prevalence of 6.9-10% in the general population. The current recommendations for treatment are presented based on a literature search. Neuropathic pain requires the use of co-analgesic, antidepressant, anticonvulsant drugs and topical agents because non-opioid analgesic drugs are usually ineffective. The use of meta-analyses tricyclic antidepressants, selective serotonin-norephinephrine reuptake inhibitors, and calcium channel anticonvulsants are recommended as the drugs of first choice. Under certain conditions chronic neuropathic pain can be treated with opioids. Topical therapeutics are only used to treat peripheral neuropathic pain. At present the use of drugs is independent of the etiology of the pain. Comorbidities, concomitant medication, potential side effects and patients' age have to be considered in treatment planning.

Differentiation of Autoimmune Pancreatitis from Pancreatic Cancer Remains Challenging.

BACKGROUND: Autoimmune pancreatitis (AIP) is an uncommon form of chronic pancreatitis. Whilst being corticosteroid responsive, AIP often masquerades radiologically as pancreatic neoplasia. Our aim is to appraise demographic, radiological and histological features in our cohort in order to differentiate AIP from pancreatic malignancy. METHODS: Clinical, biochemical, histological and radiological details of all AIP patients 1997-2016 were analysed. The initial imaging was re-reviewed according to international guidelines by three blinded independent radiologists to evaluate features associated with autoimmune pancreatitis and pancreatic cancer. RESULTS: There were a total of 45 patients: 25 in type 1 (55.5%), 14 type 2 (31.1%) and 6 AIP otherwise not specified (13.3%). The median (IQR) age was 57 (51-70) years. Thirty patients (66.6%) were male. Twenty-six patients (57.8%) had resection for suspected malignancy and one for symptomatic chronic pancreatitis. Three had histologically proven malignancy with concurrent AIP. Two patients died from recurrent pancreatic cancer following resection. Multidisciplinary team review based on radiology and clinical history dictated management. Resected patients (vs. non-resected group) were older (64 vs. 53, p = 0.003) and more frequently had co-existing autoimmune pathologies (22.2 vs. 55.6%, p = 0.022). Resected patients also presented with less classical radiological features of AIP, which are halo sign (0/25 vs. 3/17, p = 0.029) and loss of pancreatic clefts (18/25 vs. 17/17, p = 0.017). There were no differences in demographic features other than age. CONCLUSION: Despite international guidelines for diagnosing AIP, differentiation from pancreatic cancer remains challenging. Resection remains an important treatment option in suspected cancer or where conservative treatment fails.

painPREDICT: first interim data from the development of a new patient-reported pain questionnaire to predict treatment response using sensory symptom profiles.

Objective: Sensory symptom patterns may be useful for predicting treatment response, and, thus, improve individual therapy in patients suffering from neuropathic pain (NeP). Existing screening questionnaires focus predominately on neuropathic mechanisms without consideration of nociceptive mechanisms or mixed pain states. This study aimed to develop a new questionnaire, painPREDICT, using a wide set of patient-reported descriptors potentially associated with neuropathic and nociceptive pain mechanisms, and to explore sensory symptom patterns. Methods: PainPREDICT was constructed based on exploratory (n = 27 patients) and cognitive debriefing interviews (n = 49 patients and nine physicians), across five NeP conditions. The pilot questionnaire was then administered in a non-interventional, cross-sectional, multi-center study to 840 pain patients across the US and Germany. The identification of a sensory symptom pattern was based on hybrid clustering resulting from items standardization followed by principal component analysis. Results: The final questionnaire included 20 items covering: pain intensity, location of pain, course of pain, and sensory symptoms. Most patients participating in the cross-sectional study suffered either from painful diabetic polyneuropathy (n = 330) or radiculopathy (n = 349), fewer from central pain (n = 61) or other types of NeP (n = 100). The hybrid clustering of the new questionnaire data identified three different characteristic sensory symptom profiles in patients with NeP: "Irritable nociceptors", "deafferentation pain", and "pain attacks with nociceptive component". Although some differences in the distribution of the sensory profiles were found, all profiles were represented in all NeP etiology groups. Conclusions: This study set the ground of painPREDICT and showed promising results for its use to categorize patients according to sensory symptom patterns.

Impact of suggestion on the human experimental model of cold hyperalgesia after topical application of high-concentration menthol [40%].

BACKGROUND: Human experimental pain models in healthy subjects offer unique possibilities to study mechanisms of pain within a defined setting of expected pain symptoms, signs and mechanisms. Previous trials in healthy subjects demonstrated that topical application of 40% menthol is suitable to induce cold hyperalgesia. The objective of this study was to evaluate the impact of suggestion on this experimental human pain model. METHODS: The study was performed within a single-centre, randomized, placebo-controlled, double-blind, two-period crossover trial in a cohort of 16 healthy subjects. Subjects were tested twice after topical menthol application (40% dissolved in ethanol) and twice after ethanol (as placebo) application. In the style of a balanced placebo trial design, the subjects received during half of the testing the correct information about the applied substance (topical menthol or ethanol) and during half of the testing the incorrect information, leading to four tested conditions (treatment conditions: menthol-told-menthol and menthol-told-ethanol; placebo conditions: ethanol-told-menthol and ethanol-told-ethanol). RESULTS: Cold but not mechanical hyperalgesia was reliably induced by the model. The cold pain threshold decreased in both treatment conditions regardless whether true or false information was given. Minor suggestion effects were found in subjects with prior ethanol application. CONCLUSIONS: The menthol model is a reliable, nonsuggestible model to induce cold hyperalgesia. Mechanical hyperalgesia is not as reliable to induce. SIGNIFICANCE: Cold hyperalgesia may be investigated under unbiased and suggestion-free conditions using the menthol model of pain.

In whom does horizontal canal BPPV recur?

PURPOSE: The objective of this study is to examine the rate of horizontal canal BPPV recurrence of the same type and search for predisposing factors.