All types of bladder dysfunction caused by an interruption of normal bladder innervation by the nervous system are referred to as neurogenic bladder. (Other names for this disorder include neuromuscular dysfunction of the lower urinary tract, neurologic bladder dysfunction, and neuropathic bladder.) Neurogenic bladder can be hyperreflexia (hypertonic, spastic, or automatic) or flaccid (hypotonic, atonic, or autonomous).
An upper motor neuron lesion (at or above T12) causes spastic neurogenic bladder, with spontaneous contractions of detrusor muscles, increased intravesical voiding pressure, bladder wall hypertrophy with trabeculation, and urinary sphincter spasms. A lower motor neuron lesion (at or below S2 to S4) causes flaccid neurogenic bladder with decreased intravesical pressure, increased bladder capacity and residual urine retention, and poor detrusor contraction.
The following are possible causes of neurogenic bladder:
Signs and Symptoms
Patients with hypotonic neurogenic bladders have flaccid and distended bladders and constantly leaking small amounts of urine (overflow dribbling). In patients with chronic hypotonic neurogenic bladder, urinary tract infections are common.
Patients with spastic neurogenic bladders from upper spinal cord lesions usually suffer from incontinence.
Several diagnostic tests are used to assess bladder function. For example, voiding cystourethrography is used to evaluate bladder neck function, vesicoureteral reflux, and continence.
Urodynamic studies allow the evaluation of how urine is stored in the bladder, how well the bladder empties urine, and the rate of movement of urine out of the bladder during voiding. These studies consist of four components:
- Urine flow study (uroflow) shows diminished or impaired urine flow.
- Cystometry is used to evaluate bladder nerve supply, detrusor muscle tone, and intravesical pressures during bladder filling and contraction.
- Urethral pressure profile is used to determine urethral function with respect to length of the urethra and outlet pressure resistance.
- Sphincter electromyography correlates the neuromuscular function of the external sphincter with bladder muscle function during bladder filling and contraction. This indicates how well the bladder and urinary sphincter muscles work together.
Videourodynamic studies are used to correlate visual documentation of bladder function with pressure studies.
Retrograde urethrography reveals strictures and diverticula. This test isn't done routinely.
The goals of treatment are to maintain the integrity of the upper urinary tract, control infection, and prevent urinary incontinence through evacuation of the bladder, drug therapy, surgery or, less often, nerve blocks and electrical stimulation.
Techniques for bladder evacuation include Valsalva's maneuver and intermittent self-catheterization. Tapping over the bladder can also initiate voiding but, even when performed properly, this practice isn't always successful and doesn't always eliminate the need for catheterization.
The patient can perform Valsalva's maneuver himself by sitting on the toilet and forcefully exhaling (while keeping his mouth closed). This helps the bladder release urine and promotes complete emptying.
Intermittent self-catheterization is more effective than either tapping or Valsalva's maneuver. It's a major advance in treatment because it completely empties the bladder without the risks of an indwelling catheter. A male can perform this procedure more easily, but a female can learn self-catheterization with the help of a mirror. Intermittent self-catheterization, along with a bladder retraining program, is especially useful in patients with flaccid neurogenic bladder. Anticholinergics and alpha-adrenergic stimulators can help the patient with hyperreflexic neurogenic bladder until intermittent self-catheterization is performed.
Drug therapy for neurogenic bladder may include terazosin and phenoxybenzamine to facilitate bladder emptying and propantheline, methantheline, flavoxate, dicyclomine, imipramine, and pseudoephedrine to aid urine storage.
When conservative treatment fails, surgery may be used to correct the structural impairment through transurethral resection of the bladder neck, urethral dilation, external sphincterotomy, or urinary diversion procedures. Implantation of an artificial urinary sphincter may be necessary if permanent incontinence follows surgery.
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