Suprasacral spinal cord injury (SCI) frequently leads to neurogenic detrusor overactivity (NDO), resulting in elevated bladder storage pressures, urinary incontinence, and an increased risk of upper urinary tract damage. Early regulation of bladder function is a key objective of SCI rehabilitation, particularly during the subacute phase when pathological spinal reflex pathways are still developing. Pharmacological treatments are considered first-line therapy for NDO; however, adequate control may not be achieved in all patients, and treatment tolerance may be limited. Non-invasive neuromodulation techniques have emerged as alternative or adjunctive approaches for managing lower urinary tract dysfunction, but evidence regarding their effectiveness in SCI-related NDO-especially when applied during the subacute period-remains limited. This prospective randomized comparative study aims to evaluate and compare the effectiveness of transcutaneous sacral neurostimulation (TSNS) and transcutaneous tibial neurostimulation (TTNS) applied during the subacute phase of suprasacral SCI in preventing the development of neurogenic detrusor overactivity. A secondary objective is to assess the effects of these interventions on the severity of neurogenic bowel dysfunction. Eligible adult patients with subacute suprasacral SCI will be randomized into three groups: TTNS, TSNS, or a control group receiving standard care without neuromodulation prior to urodynamic assessment. Urodynamic parameters including detrusor pressure, bladder compliance, and maximal cystometric capacity, will be compared between groups. Functional outcomes and symptom severity related to neurogenic bladder and bowel dysfunction will also be evaluated. By investigating non-invasive neuromodulation strategies applied early after SCI, this study aims to contribute evidence regarding the prevention of NDO development and to support the optimization of neuromodulation use in clinical practice for individuals with suprasacral SCI.