Spinal cord injury (SCI) frequently results in the loss of voluntary control over bladder and bowel function, leading to incontinence. Paraplegia, defined as paralysis affecting the lower half of the body, arises from damage to the spinal cord, typically in the thoracic, lumbar, or sacral regions. This neurological damage disrupts the communication pathways between the brain and the organs responsible for elimination, resulting in neurogenic bladder and neurogenic bowel. While not every individual with paraplegia experiences incontinence, the underlying dysfunction is common and requires a dedicated, lifelong management plan.
The Connection Between Spinal Cord Injury and Autonomic Function
The body’s elimination processes are governed by the Autonomic Nervous System (ANS), which controls involuntary functions like the contraction of smooth muscles in the bladder and bowel walls. A spinal cord injury severs the communication between the brain and the lower spinal cord reflex centers for these organs.
This interruption means the brain can no longer receive sensory signals indicating a full bladder or rectum, nor can it send conscious commands to initiate or inhibit emptying. The sympathetic and parasympathetic branches of the ANS, which normally maintain continence, become disorganized. The nerves promoting storage and those triggering emptying (from sacral segments S2-S4) are no longer coordinated by the brain.
The smooth muscles and sphincters of the urinary and digestive tracts lose synchronized control, resulting in autonomic dysfunction. This disruption leads to both a failure to store urine or stool (incontinence) and a failure to empty completely (retention). The specific level of the SCI determines the exact pattern of this dysfunction and which reflexes remain intact below the injury site.
Understanding Neurogenic Bladder and Bowel
The loss of nervous system input creates two primary types of dysfunction, depending on the injury location relative to the sacral reflex center (S2-S4). Injuries above this center, typically in the thoracic or high lumbar spine, lead to a reflexic or spastic condition. Here, the reflex arc remains intact, causing the bladder or bowel muscle to contract involuntarily and unpredictably without brain coordination.
This reflexic pattern often results in an overactive bladder or bowel, leading to unexpected emptying and incontinence. For the bladder, this can cause detrusor-sphincter dyssynergia (DSD), where the bladder contracts while the sphincter remains closed, creating high pressure that can damage the kidneys.
Conversely, injuries that directly damage the sacral segments (S2-S4) result in a flaccid or areflexic condition. In the flaccid form, the muscles and sphincters lose tone and become overly relaxed. The bladder overfills because the muscle cannot contract forcefully, leading to overflow incontinence where urine leaks out due to excessive pressure. For the bowel, this results in slow stool movement and a lack of reflex emptying, making complete evacuation difficult.
Daily Management Strategies
The goal of managing neurogenic dysfunction is to achieve social continence and protect the upper urinary tract, preventing complications like Autonomic Dysreflexia (AD). Management is based on the specific type of neurogenic bladder and bowel present.
Bladder Management
Clean intermittent catheterization (CIC) is the standard of care for bladder management. This involves the periodic insertion of a tube to completely empty the bladder, typically four to six times daily. CIC mimics normal filling and emptying cycles, maintaining bladder health and reducing the risk of urinary tract infections compared to long-term indwelling catheters. If CIC is not feasible, an indwelling catheter, often a suprapubic one placed surgically, may be used. Medications are also used to manage bladder tone, either relaxing the muscle to increase storage capacity or tightening the sphincter to improve continence.
Bowel Management
Bowel management centers on establishing a structured Bowel Program (BP) to ensure regular, predictable, and complete evacuation. The program integrates techniques including dietary modifications to maintain soft, formed stool consistency. Timing is crucial, often utilizing the gastrocolic reflex—the natural urge to defecate that occurs after eating.
The BP uses mechanical stimulation, such as a suppository or mini-enema, to initiate a bowel movement in individuals with a reflexic bowel. This is often followed by digital stimulation to trigger the reflex and relax the internal sphincter. For a flaccid bowel, suppositories are often ineffective, and the program relies more on manual removal of stool to prevent impaction and leakage.