A total of 13 patients with proved lesions of the cauda equina underwent neurological evaluation. All patients had video urodynamic testing, while 9 underwent a varying combination of pelvic floor electromyography, lumbosacral evoked potentials to tibial nerve stimulation and the sympathetic skin response from the perineum. All patients had detrusor areflexia with varying degrees of bladder neck incompetence. Reports of clinical and experimental studies are discussed in relation to the pathophysiology of bladder neck function following lesions of the pudendal and preganglionic pelvic nerve to explain why there have been conflicting reports in the literature regarding bladder neck function with lesions of the cauda equina. The adaptive changes observed in the experimental animal, consisting of random regeneration of the cholinergic neuroeffective junctions, adrenergic hyperinnervation and an increased sensitivity of the prejunctional inhibitory muscarinic receptors on the adrenergic nerve, may explain the degree of variability of bladder neck incompetence observed clinically.