The analgesic placebo effect is well documented by numerous studies. Many important influencing factors, however, are yet to be discovered. In the arena of placebo effects and clinical implications, expectancies play a central role. Expectancies are shaped by processes of classical and social learning as well as verbal instructions and are strongly related to emotional factors. Expectancies trigger a cascade of endogenous opioids and nonopioids, which alter the experience of pain. For clinical application it is important to know, that placebo research yields ethical possibilities to use placebo effects without deception and without using placebos. Since placebo effects contribute to responses to active anal-gesics, it is feasible to enhance patients’ benefits from pain treatments by increasing the additional placebo effect. There are several possibilities to use the placebo effects via shaping and adapting information about analgesic medication and via associating medication intake with a positive context. A positive patient–clinician communication atmosphere is very important to generate clinically meaningful placebo effects in pain medicine.

Supplemental Digital Content is Available in the Text. Social observational learning can augment the effect of pain medication in patients with chronic low back pain leading to a reduction in perceived pain-related disability.

We describe a 16-year-old boy with intestinal lymphangiectasia, lymphedema of the limbs and genitalia, mild mental retardation, and facial anomalies (Hennekam syndrome) and cutaneous lesions. Severe edema in the genital area created a gigantic mass that included the scrotum and penis. Numerous grouped red-violaceous pseudo-vesicular lesions and plaques, as well as verrucous brown papules, were present on the penis and scrotum. The prepuce was hypertrophic, with severe phimosis. Histologic analysis revealed dilated lymphatic vessels lined by a discontinuous layer of flat endothelial cells in the papillary dermis and extending down to the reticular dermis. Dilated blood vessels were also present but no cellular abnormalities were identified. A diagnosis of superficial cutaneous lymphatic malformations was made. To the best of our knowledge, this is the first detailed cutaneous histologic investigation in a patient with Hennekam syndrome. We assume that the onset of cutaneous lesions in our patient was likely triggered by a generalized worsening of his lymphedema.

IntroductionChronic lower back pain (CLBP) is a frequent cause of medical consultations worldwide, and it results in decreased quality of life and disability. Current treatments for CLBP are often not effective, and alternatives are urgently needed. Three promising possibilities have emerged: (1) open-label placebo treatment reduces chronic pain, (2) placebo treatment is as efficacious as opioid treatment with a high correlation between patient expectation and treatment outcome, and (3) observing positive effects in another patient can improve functional capacity. We hypothesise that treatment expectations can be positively influenced through social observation and improve treatment outcome.Methods and analysisIn our clinical trial, we will randomise patients with CLBP into five groups. Two groups receive either a 3 week course of treatment with an analgesic (ANA) (metamizole/dipyrone) or with open-label placebos (OLP). For one of each group, we will build treatment expectations through observational learning and assess its impact on the treatment. For this purpose, one group each will watch either a positive or a neutral video. The intervention groups will be compared with a control group that will not be given any medication or observational learning. Participants will be recruited via all institutions in the Hamburg metropolitan area that treat patients with CLBP. Patients are eligible for inclusion if they are at least 18 years or older, have CLBP (of at least 3 months duration), and agree to potentially receive an active ANA or an OLP. Patients with pain-related “red flags” will be excluded. The study requires 150 participants (30 participants per group) to assess the differences in the primary outcome, pain intensity. Secondary outcomes include changes in treatment expectations, anxiety, comorbid depression, stress-related neuroendocrine measures, functional and structural connectivity, functional capacity, and ANA consumption. All outcomes and treatment expectations will be measured before and after the intervention and 3 months post-intervention.Ethics and disseminationEthical approval was obtained in January 2020 from the Hamburg Medical Ethics Council (ref number PV7067). Outcomes will be disseminated through publications in peer-reviewed journals and presentations at national and international conference meetings.Trial registration numberThe approved trial protocol was registered at the German Clinical Trials Register (DRKS) and can be found at drks.de (Identifier: DRKS00024418).