Urinary retention due to sacral myeloradiculitis: a clinical and neurophysiological study. We report 5 cases of sacral myeloradiculitis presenting with transient urinary retention. Neurophysiological testing, including bulbocavernosus reflex, pudendal evoked response and external anal sphincter electromyography, was performed. Parasympathetic pelvic nerves, pudendal nerves as well as the spinal cord seem to be involved to various degrees in this infrequent disorder. 