Diseases or injuries of the spinal cord between the pons and the sacral spinal cord also result in spastic bladder or overactive bladder. People who are paraplegic or quadriplegic have lower extremity spasticity. Initially, after spinal cord trauma, the individual enters a spinal shock phase where the nervous system shuts down. After 6-12 weeks, the nervous system reactivates. When the nervous system becomes reactivated, it causes hyperstimulation of the affected organs. For example, the legs become spastic.
These people experience urge incontinence. The bladder empties too quickly and too frequently. The voiding disorder is similar to that of the brain lesion except that the external sphincter may have paradoxical contractions as well. If both the bladder and external sphincter become spastic at the same time, the affected individual will sense an overwhelming desire to urinate but only a small amount of urine may dribble out. The medical term for this is detrusor-sphincter dyssynergia because the bladder and the external sphincter are not in synergy. Even though the bladder is trying to force out urine, the external sphincter is tightening to prevent urine from leaving.
The causes of spinal cord injuries include motor vehicle and diving accidents. Multiple sclerosis (MS) is a common cause of spinal cord disease in young women. Those with MS also may exhibit visual disturbances, known as optic neuritis. Children born with myelomeningocele may have spastic bladders and/or an open urethra. Conversely, some children with myelomeningocele may have a hypocontractile bladder instead of a spastic bladder.