Effects of tapentadol on chronic pain and parameters of central sensitization.

INTERVENTION: ‐ Tapentadol: Dose: start dose of 50mg 2x/day, increase by 50mg 2x/day every 3 days until sufficient analgesia is reached with tolerable adverse effects. Max 500 mg/day. Route: Oral administration Duration: 8 weeks ‐ Pregabalin: Dose: start dose of 75mg 2x/day, increase by 75mg 2x/day every 3 days until sufficient analgesia is reached with tolerable adverse effects. Max 600 mg/day. Route: Oral administration Duration: 8 weeks CONDITION: Chronic pain, Central sensitisation ; ; PRIMARY OUTCOME: Central Sensitzation parameters; ; ‐ pressure pain threshold (PPT); ; ‐ pressure pain tolerance threshold (PTT); ; ‐ conditioned pain modulation (CPM); ; ‐ size of allodynia; ; ‐ Wind‐up ratio (WUR); ; ‐ Central Sensitization Inventory (CSI) SECONDARY OUTCOME: ‐ Visual Analog Scale (VAS) ; ; ‐ Pain Disability Index (PDI) ; ; ‐ Pain Catastrophizing Scale (PCS) ; ; ‐ Pain Vigilance and Awareness Questionnaire (PVAQ) ; ; ‐ Adverse effects of the medications ; ; ‐ Dosages of the medication during the treatment period INCLUSION CRITERIA: ‐ Gender: female ‐ Age of patients (18‐65 years old) ‐ Presence of proven endometriosis or CLBPr ‐ Signs of central sensitization ‐ No contraindications for opioids or pregabalin. ‐ Signed informed consent.