Consider complete transection of the spinal cord to interrupt
upper motor neuron (UMN) input
to the bladder. Like UMN input to the the biceps (for example),
interruption is followed immediately by spinal shock and flaccidity.
Thus the bladder would be atonic and fill and retain the urine immediately
following the injury. Later, spasticty follows the spinal shock.
Now when the bladder fills a little and is stretched, it immediately spills.
So the key to the answer being wrong is never
results in urinary retention. In spinal cord lesions above the sacral
cord, there is both an atonic (acute) or flaccid bladder and a spastic