What happens to micturition in spinal cord injury?
Following bilateral lesions to the spinal cord, the bladder initially becomes flaccid (acute) and eventually becomes spastic (chronic).
This dysfunction occurs because with bilateral cord damage the detrusor muscle of the bladder loses its cortical inputs.
Like the deep tendon reflexes, it initially becomes flaccid, resulting in urinary retention.
As the bladder fills, overflow incontinence may develop because the bladder cannot hold any more urine.
As time passes, the detrusor muscle becomes spastic (just as the deep tendon muscles become hyperactive).
Small stretches in the detrusor muscle result in voiding.
This spastic bladder results in urinary frequency and urgency.