In addition to its action on motor nerves, onaBoNT-A also affects sensory nerve pathways. Recent studies show that IDO is caused by both motor and sensory nerve dysfunction, therefore injecting the "trigone", a part of the bladder where sensory nerves are particularly dense, may be of clinical benefit. Three studies comparing trigone versus trigone-sparing injection of botulinum toxin in the treatment of IDO have been carried out. One of these indicated a significant benefit in targeting the trigone and the other two did not show any difference.