Urodynamics in the spinal injury

The management of the lower urinary tract is of vital importance in spinal injury. Until fairly recently kidney failure was the biggest late killerof spinally injured patients. The reason for this is that in the absence of intact neurology the bladder can become hyperreflexic generating very high detrsuor pressures, reflux and thus hydronephrosis.

The type of bladder depends on the level and the complenessof the spinal lesion.

The principal micturition centre is in the sacral part of the cord. Hence complete destruction of the sacral nerve roots can result in a completely a contractile bladder. A partial lesion may leave weak reflex activity.
Since the pontine centre is also required for synnergic voiding a lesion between sacral and pontine levels can leave a bladder which does have reflex voiding but it is inefficient and uncoordinated.
Brain lesions mainly result in loss of voluntary control of voiding. With the advent of PET scanning more is being learnt about cerebaral control of voiding.
Immediately post spinal injury, the constant innervation of the external sphincter may be lost. This often returns and in fact the inability to realx the external sphincter can often result in the spinally injured patient requiring sphincterotomy.