Transcutaneous Neuromodulation at ST36 (Zusanli) is More Effective than Transcutaneous Tibial Nerve Stimulation in Treating Constipation

Background and Goals:Combined transcutaneous neuromodulation (TN) at acupoint ST36 (Zusanli) and TN at the posterior tibial nerve (PTN) has been reported effective in treating functional constipation. This study was designed to compare the effectiveness of TN between these 2 points.Materials and Methods:Eighteen functional constipation patients (M/F: 9/9) were recruited to participate in a cross-over study with a 2-week TN at ST36 and a 2-week TN at PTN. A bowel movement diary, and the questionnaires of Patient Assessment of Constipation Symptom (PAC-SYM) and Constipation Quality of Life (PAC-QoL) were completed; anorectal manometry and spectral analysis of heart rate variability for assessing the autonomic function were performed.Results:(1) Both TN at ST36 and TN at PTN improved constipation-related symptoms (PAC-SYM scores on pre-TN vs. post-TN: 1.4±0.1 vs. 0.6±0.1 for ST36, 1.4±0.1 vs. 0.9±0.1 for PTN, both P≤0.001). (2) TN at ST36, but not TN at PTN, increased the number of weekly spontaneous bowel movements (0.9±0.2 pre-TN vs. 3.5±0.7 post-TN, P<0.001) and decreased the total PAC-QoL score. TN at ST36 was more potent than TN at PTN in improving the PAC-SYM score (decrement 0.8±0.1 vs. 0.5±0.1, P<0.05). (3) TN at ST36 rather than TN at PTN resulted in a reduction in sensation thresholds, including rectal distention for urge (134.1±14.3 mL pre-TN vs. 85.6±6.5 mL post-TN, P<0.01) and maximum tolerance (P<0.05). (4) Both TN at ST36 and TN at PTN significantly increased vagal activity and decreased sympathetic activity (P<0.05).Conclusions:TN at ST36 is more potent than TN at PTN in treating constipation and improving constipation-related symptoms and rectal sensation.