Detrusor sphincter dyssynergia (DSD) is a condition where the bladder muscle and the external urethral sphincter fail to coordinate during urination. This lack of synchronized action prevents the smooth passage of urine, impacting urinary control and overall health.
Understanding Detrusor Sphincter Dyssynergia
The process of urination involves a coordinated effort between the detrusor muscle, which forms the wall of the bladder, and the external urethral sphincter. When the bladder fills, nerve signals indicate the need to urinate. During normal voiding, the detrusor muscle contracts to push urine out, while simultaneously, the external urethral sphincter relaxes to open the pathway. This allows for a complete and unobstructed flow of urine.
In detrusor sphincter dyssynergia, this synchronized mechanism fails. As the detrusor muscle of the bladder attempts to contract and expel urine, the external urethral sphincter paradoxically contracts or remains closed instead of relaxing. This creates an obstruction, preventing urine from flowing freely out of the bladder. The bladder works against a closed outlet, leading to increased pressure within the bladder.
This uncoordinated action results in a functional blockage of urine flow, even though there might not be any physical obstruction. The bladder’s inability to empty properly can lead to urine retention and elevated bladder pressures. Over time, these sustained high pressures can have detrimental effects on the bladder wall and potentially impact the upper urinary tract, including the kidneys. The nervous system plays a central role in coordinating these actions, and a disruption in nerve signals underlies DSD.
Causes of Detrusor Sphincter Dyssynergia
Detrusor sphincter dyssynergia arises from damage or disruption to the neurological pathways that control bladder and sphincter function. These pathways involve complex signals between the brain, spinal cord, and the muscles of the lower urinary tract. When these nerve signals are interrupted, the bladder and sphincter can no longer communicate effectively to coordinate urination.
A common cause of DSD is a spinal cord injury, where the damage prevents proper nerve impulses from reaching the bladder and sphincter. Other neurological conditions that can lead to this discoordination include multiple sclerosis, a progressive disease affecting the brain and spinal cord, and Parkinson’s disease, which impacts movement and coordination. Conditions like transverse myelitis or tumors affecting the spinal cord can also disrupt the neural control necessary for coordinated voiding.
These neurological impairments interfere with the inhibitory signals that normally tell the external urethral sphincter to relax when the detrusor muscle contracts. Without these precise signals, the sphincter remains inappropriately tight, creating resistance to urine flow. The specific location and extent of neurological damage determine the severity and presentation of DSD.
Recognizing Detrusor Sphincter Dyssynergia
Individuals with detrusor sphincter dyssynergia often experience a range of noticeable urinary symptoms due to the obstructed urine flow. A common sign is difficulty initiating urination, requiring significant straining to start a stream. Despite effort, the bladder may not empty completely, leading to a persistent feeling of fullness even after voiding. This incomplete emptying creates a reservoir for bacteria, increasing the frequency of urinary tract infections (UTIs).
The uncoordinated action can also lead to urinary urgency, where there is a sudden, strong need to urinate, often followed by involuntary leakage or incontinence. Because the bladder is working against a closed sphincter, bladder pressure can rise, potentially causing urine to back up into the kidneys, which can damage kidney function over time.
Diagnosing Detrusor Sphincter Dyssynergia
Diagnosing detrusor sphincter dyssynergia involves a thorough medical history, physical examination, and specialized tests. The medical history focuses on urinary symptoms, infection frequency, and neurological conditions. The physical exam assesses neurological function and includes a pelvic examination.
Urodynamic studies are the primary diagnostic tools used to confirm DSD. These tests measure various aspects of bladder and sphincter function during filling and emptying. A cystometrogram, for example, evaluates bladder pressure changes as it fills and empties, while electromyography (EMG) of the external urethral sphincter measures the electrical activity of the sphincter muscle during urination.
These tests reveal the characteristic pattern of DSD: an increase in detrusor pressure coinciding with increased electrical activity or lack of relaxation in the external urethral sphincter. This simultaneous contraction of both the bladder and its outlet provides definitive evidence of the discoordination. Other tests, such as urine flow studies and post-void residual measurements, also help assess the extent of incomplete bladder emptying.
Managing Detrusor Sphincter Dyssynergia
Managing detrusor sphincter dyssynergia focuses on improving bladder emptying, reducing bladder pressure, and preventing complications like urinary tract infections and kidney damage. Treatment varies, with conservative strategies including timed voiding schedules or techniques to encourage bladder emptying.
Medications are used to relax the sphincter or manage bladder overactivity. Alpha-blockers, for instance, help relax the smooth muscle in the bladder neck, prostate, and external urethral sphincter, facilitating urine flow. Anticholinergic medications may be prescribed for excessive bladder contractions, though used cautiously to avoid further retention.
Botulinum toxin (Botox) injections directly into the external urethral sphincter can temporarily relax the muscle, allowing for easier urine passage, with effects lasting several months. Surgical procedures, such as a sphincterotomy (a small incision in the sphincter), may permanently reduce outflow resistance. Intermittent catheterization, where a thin tube is regularly inserted to drain the bladder, is a common and effective method to ensure complete bladder emptying and minimize complications.