OBJECTIVES: The aim of this study was to investigate whether acute electrical stimulation of the posterior tibial nerve could suppress detrusor contractions in multiple sclerosis (MS) patients with neurogenic detrusor overactivity. METHODS: Two successive slow-fill cystometries (16 ml/min) were carried out in eight MS patients with neurogenic detrusor overactivity. The first filling served as control without stimulation. In the second filling, electrical stimulation using needle electrodes was applied automatically to the posterior tibial nerve when the detrusor pressure exceeded 10 cm H(2)O. An additional filling in which the needle electrodes were replaced by surface electrodes was carried out in three patients. RESULTS: The control filling showed detrusor overactivity in eight patients, but electrical stimulation of the posterior tibial nerve failed to suppress detrusor contractions in all tested patients. CONCLUSIONS: Although neuromodulative effects may be obtained with therapeutic electrical stimulation of the posterior tibial nerve, no acute effects were demonstrated. For this reason, electrical stimulation of pudendal afferents remains the only option if acute suppression of a detrusor contraction is required.