<p style="text-align: justify;">Aldo Liguori; Jacob Juel; Stefano Liguori; MassimilianoValeriani, Carina Graversen, MSc;Søren S. Olesen; Asbjørn M. Drewes</p><p style="text-align: center;">（1 Istituto Paracelso, Rome, Italy; 2 Department of Anatomic, Histologic, Forensic Medicine and Locomotor System Sciences, Faculty of Pharmacy and Medicine, Sapienza University; 3 MechSense, Department of Gastroenterology and Hepatology, Aalborg University Hospital, Aalborg, Denmark; 4Department of Neurology, Paediatric Hospital Bambino Gesù, Rome, Italy;&nbsp; 4 Center for Sensory-Motor Interaction, Department of Health Science and Technology, Faculty of&nbsp;</p><p style="text-align: center;">Medicine, Aalborg University, Aalborg, Denmark）</p><p style="text-align: justify;"><strong>Abstract</strong>：<strong>Objective</strong>. Acupuncture is increasingly used as an alternative to medical therapy for various painconditions. To studythe effect of acupuncture in experimental and clinicalstudies, a control&nbsp; condition&nbsp; with&nbsp; sham&nbsp; acupuncture&nbsp; isneeded.&nbsp; However,&nbsp; as&nbsp; such&nbsp; models&nbsp; have&nbsp; not&nbsp; been establishedin assessment of acupuncture effect against visceral pain,this study aimed to validate a new method for blinded shamacupuncture in experimental rectal pain.Materials and methods.Fifteen subjects underwent a sequence of eithersham or real acupuncture in randomized order. In the shamarm, a hollow inner tube with a sharp tip was fitted into anouter tube and subjects were blinded to the stimulations.Before and after the intervention, pain was induced by rectalstimulation with&nbsp; an&nbsp; inflatable&nbsp; balloon distended until&nbsp; thesubjects’ pain&nbsp; threshold&nbsp; was&nbsp; reached. The&nbsp; resting electroencephalogram&nbsp; (EEG)&nbsp; was&nbsp; quantified&nbsp; by&nbsp; spectral&nbsp; power&nbsp; analysisto&nbsp; explore&nbsp; the&nbsp; central nervous system effects objectively.Additionally, after the second study day, the subject wasasked to indicate the sequence of interventions.Results. A significant increase in rectal balloon volume was observed after sham 12±21 mL (P=0.049) and real acupuncture17±30 mL (P=0.046). However, the change in volume wasnot different between groups (P&nbsp; = 0.6). No differences in EEGspectral power distributions&nbsp; between&nbsp; sham&nbsp; and&nbsp; real&nbsp; acupuncturewere&nbsp; seen&nbsp; (all&nbsp; P&gt;0.6).&nbsp; The&nbsp; correct sequence of sham andacupuncture was indicated by 36% of the subjects (P=0.4).Conclusions.&nbsp; The presented sham procedure provides avalid method for blinding of “sham acupuncture” and maybe used in future blinded controlled trials of acupuncture forvisceral pain.&nbsp;</p><p><strong>Key&nbsp; words</strong>:&nbsp; acupuncture,&nbsp; sham-controlled,&nbsp; sham&nbsp; acupuncture,&nbsp; experimental&nbsp; visceral&nbsp; pain, abdominal pain, EEG ,spectral power analysis.</p><p><br/></p>