To our knowledge, direct measurement of active closure of the bladder neck during bladder contraction resulting in bladder neck dyssynergia and outflow obstruction has not yet been demonstrated. A total of 34 spinal cord injury patients underwent urodynamic investigation with 2 micro-transducer catheters in the urethrovesical and anorectal regions, respectively. Proper localization of the transducers was done with an image intensifier. The respective role of the striated and smooth muscles on bladder neck activity was evaluated after pudendal nerve blocks and phentolamine injections. Of the patients 25 had active bladder neck dyssynergia with concomitant detrusor-sphincter dyssynergia. Pressures were higher in the bladder neck than in the bladder. Pudendal blocks abolished detrusor-sphincter but not bladder neck dyssynergia, which was decreased by additional phentolamine but only in patients in whom bladder neck dyssynergia was associated with autonomic hyperreflexia. Evidence is presented that active bladder neck dyssynergia may exist in patients with a neurogenic bladder and that it is seemingly dependent on alpha 1-postsynaptic and alpha 2-presynaptic adrenoreceptors.