Breakthrough PainAdministration, BuccalFentanylLabor PainAnalgesics, OpioidPainAnalgesia, EpiduralPain MeasurementDouble-Blind MethodNeoplasmsChronic DiseaseChronic PainPain ManagementPain ThresholdPain, PostoperativeRadionuclide GeneratorsLow Back PainBack PainPain, IntractableAbdominal PainNeck PainPelvic PainPain PerceptionFacial Pain