Due to its high prevalence and the substantial individual and socio-economic burden chronic pain is a huge challenge for patients, physicians and the society. Using neuroimaging structural and functional alterations have been described in the brain of patients suffering from chronic pain (Apkarian, Hashmi et al. 2011, Baliki and Apkarian 2015). However, reproducibility and functional significance of these changes are only incompletely understood. For example it remains unclear, if these changes covariate with clinical parameters and if they can be influenced or reversed by appropriate therapy. Some of the structural and functional brain changes in chronic pain patients have been shown to be reversible using magnetic resonance imaging after successful interventional pain treatment (Seminowicz, Wideman et al. 2011) or cognitive-behavioral therapy (Seminowicz, Shpaner et al. 2013, Shpaner, Kelly et al. 2014). Interdisciplinary multimodal pain therapy (IMPT) as a biopsychosocial treatment approach comprising physiotherapy and psychotherapy in structured programs has been shown to be effective in alleviating chronic pain of different entities including those where interventional therapy options are lacking or have been unsuccessful (Kaiser, Treede et al. 2017). The present study aims to investigate the influence of a structured IMPT approach provided in a day-clinic program of 20 treatment days on the functional brain network structure in chronic pain patients. To this end, a graph-theory based analysis (Bullmore and Sporns 2009) will be applied to electroencephalography (EEG) resting-state data from 30 chronic pain patients before and after IMPT and results will be correlated with behavioral and clinical data. In this observational study chronic pain patients that have been screened for participation in IMPT as part of routine medical care are invited to participate in a baseline visit prior to participation and a follow-up visit 6 months after completion of the program.

This will add to a better understanding of the complex functional brain alterations in chronic pain and might contribute to identify neuronal markers or even predictors for therapeutic responses in multimodal pain treatments. Moreover, the broad availability and easy applicability of EEG-measurements might enable a wide therapeutic application of potential findings in the near future.

Inclusion Criteria:

• Chronic pain (duration >6 months, not primary headache disease)
• Willing and able to comply with physical (e.g. able to get up from the floor without help) and psychological (e.g. motivation for behavioural change) requirements of the IMPT-day-clinic setting as assessed by a physician, psychologist and physiotherapist on a screening visit as part of routine medical care prior to participation
• Willing and able to sign informed consent for study participation

Exclusion Criteria:

• Recent change in chronic pain condition (e.g. surgery or injury within the last 3 months)
• Concomitant neurological or psychiatric disease apart from Depression (especially severe mental disorder or psychopathology)
• Regular (daily) intake of benzodiazepines
• Addiction problems

All chronic pain patients eligible according to the inclusion and exclusion criteria (see eligibility criteria) participating in the IMPT-day-clinic programme of the Center for Interdisciplinary Pain Medicine at the Klinikum rechts der Isar of the Technische Universität München in the year 2018 are invited to voluntarily participate in the study.