Afferent pathways arising from the lower urinary tract after complete spinal cord injury or cauda equina lesion: clinical observations with neurophysiological implications.

Background: Afferents from the urinary tract transmit bladder sensations to the central nervous system. Spinal cord injury (SCI) may affect both efferent motor and afferent sensory pathways. Presence/absence of bladder sensations in patients with complete spinal cord, conus or cauda equina lesions was compared with neurologically unimpaired patients.

Methods: During urodynamics, bladder sensations were studied and compared in 59 patients: 21 patients with complete SCI below T6 and above Th12, 7 patients with a complete lesion of the conus medullaris, 11 patients with a complete lesion of the cauda equina, and 20 patients without neurological deficit.

Results: Two of 7 patients with complete conus lesion had a preserved filling sensation. Ten of 11 patients with complete lesion of the cauda equina reported a bladder filling sensation. Sensations are perceived at a similar pressure threshold but at a higher volume threshold.

Conclusions: In patients with a complete cauda or a lower conus lesion, a sensory input from the bladder is preserved. These findings imply that the preserved bladder filling sensation in complete cauda or lower conus lesions is possibly transferred through the intact hypogastric plexus to the thoracolumbar segments of the spinal cord.