In this study, TTNS will be used to help neurogenic bladder in SCI. First, acute SCI subjects which respond to TTNS will be identified as seen on urodynamic studies (USD). Then, responders will be invited to participate in a randomized control trial of a 2-week protocol of TTNS to test for safety and efficacy during inpatient rehabilitation to evaluate bladder changes based upon pre- and post- urodynamic testing, as well as 2-month follow-up.