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Also known as
Detrusor-Sphincter Dyssynergia (DSD), Bladder Sphincter Dyssynergia, Detrusor External Sphincter Dyssynergia (DESD), Neurogenic Detrusor Overactivity (NDO), Bladder-Sphincter Dyscoordination, Detrusor-Striated Sphincter Dyssynergia
Definition
Detrusor sphincter dyssynergia (DSD) is a urological condition characterized by the lack of coordination between the detrusor muscle in the bladder and the external urethral sphincter during urination.1 This dysfunction occurs when the detrusor muscle contracts against a closed bladder outlet due to involuntary contraction of the urinary sphincter.2 From a physiologic standpoint, DSD likely represents disruption of the spinobulbospinal tract between the pontine micturition center (PMC) and Onuf’s nucleus, which results in high urethral closure pressures during a detrusor contraction.1
During normal micturition, the detrusor muscle contracts while the external urethral sphincter relaxes, allowing urine to flow freely. However, in DSD, this coordination is lost, leading to difficulty in emptying the bladder, increased bladder pressure, and urinary retention.3 Sustained elevated detrusor pressures exceeding 40 cm of water have been linked to hydronephrosis and renal deterioration.2 This signifies an increased detrusor leak point pressure, a characteristic frequently observed in DSD, especially the continuous type.2
Clinical Context
Detrusor sphincter dyssynergia is most commonly associated with neurologic conditions such as spinal cord injuries, multiple sclerosis, and spina bifida.2 These neurological pathologies disrupt the central nervous system pathways controlling urine storage and emptying, leading to loss of coordination between the detrusor muscle and urinary sphincters.1
DSD is classified into three types based on the pattern of sphincter activity during detrusor contraction:2
- Type 1: Crescendo increase in sphincter activity that peaks at the peak of detrusor contraction, followed by relaxation of the sphincter as the detrusor pressure decreases.
- Type 2: Sporadic contractions of the external sphincter throughout the detrusor contraction.
- Type 3: Complete occlusion of the sphincter for the entire duration of the detrusor contraction.
The diagnosis of DSD is made through urodynamic studies with or without fluoroscopy via electromyography, voiding cystourethrogram, or urethral profile pressures.1 It has been the author’s experience to follow up significant findings of DSD on urodynamics with cystoscopy to rule out the possibility of an underlying urethral stricture which can confound urodynamic findings.1
Patients with DSD may be at risk for autonomic dysreflexia, recurrent urinary tract infections, or upper tract compromise if the condition is not followed and treated appropriately.1 An association between DSD and autonomic dysreflexia has been suggested, although documenting this link has proven challenging because standardized diagnostic criteria for both conditions are lacking.2
Treatment options for DSD include:
- Conservative management: Clean intermittent self-catheterization (CISC) combined with antimuscarinics is the most effective and frequently used treatment for DSD.2 This modality allows for the drainage and emptying of the bladder, even in the presence of a dyssynergic sphincter, while antimuscarinic therapy reduces detrusor pressure and minimizes contractions.2
- Pharmacotherapy: Alpha-blockers such as tamsulosin have effectively reduced post-void residual volumes and increased voided volumes.2 Other medications include baclofen (particularly when administered intrathecally), benzodiazepines, and dantrolene sodium, although none of these are currently recommended as standard treatments.2
- Botulinum toxin injections: Botulinum toxin administered directly into the sphincter muscle through cystoscopy or transperineal ultrasonography has shown efficacy when other treatments prove ineffective, with reported durations ranging from 2 to 13 months.2 The technique involves injecting 100 units of botulinum toxin A into the dorsal portion of the sphincter muscle at specific positions.2
- Surgical interventions: External sphincterotomy, which involves the therapeutic destruction of the external sphincter, has historically been the standard treatment.2 Urethral stents have also been used as an alternative to sphincterotomy, with the advantage of being potentially reversible.1
- Sacral neuromodulation: This approach can potentially be highly beneficial in the treatment of DSD, although randomized and long-term studies to confirm its efficacy are lacking.2 Sacral neuromodulation seems to enhance bladder function by reducing average detrusor voiding pressures and preventing the development of DSD in specific experimental SCI animal models.2
In cases where patients cannot perform self-catheterization, indwelling catheters, particularly suprapubic tubes, are advisable.2