BrainstemThe brainstem is located at the base of the skull. Within the brainstem is a specialized area known as the pons, a major relay center between the brain and the bladder. The pons is responsible for coordinating the activities of the urinary sphincters and the bladder so that they work in synergy. The mechanical process of urination is coordinated by the pons in the area known as the pontine micturition center (PMC). The PMC coordinates the urethral sphincter relaxation and detrusor contraction to facilitate urination.
The pons is a major relay center between the brain and the bladder. The mechanical process of urination is coordinated by the pons in the area known as the pontine micturition center (PMC)
Complications of a Neurogenic Bladder:
The following problems are often associated with a neurogenic bladder:
* Urine leakage
Urine leakage often occurs when the muscles holding urine in do not get the right message.
* urine retention
Urine retention often happens if the muscles holding urine in do not get the message that it is time to let go.
* damage to the tiny blood vessels in the kidney
Damage to the tiny blood vessels in the kidney often happens if the bladder becomes too full and urine backs up into the kidneys, causing extra pressure.
* infection of the bladder or ureters
Infection of the bladder or ureters often results from urine that is held too long before being eliminated.
Neurogenic bladder is bladder dysfunction (flaccid or spastic) caused by neurologic damage. The primary symptom is overflow incontinence. Risk of serious complications (eg, recurrent infection, vesicoureteral reflux, autonomic dysreflexia) is high. Diagnosis involves imaging and cystoscopy or urodynamic testing. Treatment involves catheterization or measures to trigger urination.
Any condition that impairs bladder and bladder outlet afferent and efferent signaling can cause neurogenic bladder. Causes may involve the CNS (eg, stroke, spinal injury, meningomyelocele, amyotrophic lateral sclerosis), peripheral nerves (eg, diabetic, alcoholic, or vitamin B12 deficiency neuropathies; herniated disks; damage due to pelvic surgery), or both (eg, Parkinson's disease, multiple sclerosis, syphilis). Bladder outlet obstruction often coexists and may exacerbate symptoms.
In flaccid (hypotonic) neurogenic bladder, volume is large, pressure is low, and contractions are absent. It may result from peripheral nerve damage or spinal cord damage at the S2 to S4 level. After acute cord damage, initial flaccidity may be followed by long-term flaccidity or spasticity, or bladder function may improve after days, weeks, or months.
In spastic bladder, volume is normal or small, and involuntary contractions occur. It usually results from brain damage or spinal cord damage above T12. Precise symptoms vary by site and severity of the lesion. Bladder contraction and external urinary sphincter relaxation are typically uncoordinated (detrusor-sphincter dyssynergia).
Mixed patterns (flaccid and spastic bladder) may be caused by many disorders, including syphilis, diabetes mellitus, brain or spinal cord tumors, stroke, ruptured intervertebral disk, and demyelinating or degenerative disorders (eg, multiple sclerosis, amyotrophic lateral sclerosis).
Symptoms and Signs
Overflow incontinence is the primary symptom in patients with a flaccid or spastic bladder. Patients retain urine and have constant overflow dribbling. Men typically also have erectile dysfunction. Patients with spastic bladder may have frequency, nocturia, and urgency or spastic paralysis with sensory deficits.
Common complications include recurrent UTIs and urinary calculi. Hydronephrosis with vesicoureteral reflux may occur because the large urine volume puts pressure on the vesicoureteral junction, causing dysfunction with reflux and, in severe cases, nephropathy. Patients with high thoracic or cervical spinal cord lesions are at risk of autonomic dysreflexia (a life-threatening syndrome of malignant hypertension, bradycardia or tachycardia, headache, piloerection, and sweating due to unregulated sympathetic hyperactivity). This disorder may be triggered by acute bladder distention (due to urinary retention) or bowel distention (due to constipation or fecal impaction).
- Postvoid residual volume
- Renal ultrasonography
- Serum creatinine
- Usually cystography, cystoscopy, and cystometrography with urodynamic testing
Diagnosis is suspected clinically. Usually, postvoid residual volume is measured, renal ultrasonography is done to detect hydronephrosis, and serum creatinine is measured to assess renal function. Further studies are often not obtained in patients who are not able to self-catheterize or ask to go to the bathroom (eg, severely debilitated elderly or post-stroke patients). In patients with hydronephrosis or nephropathy who are not severely debilitated, cystography, cystoscopy, and cystometrography with urodynamic testing are usually recommended and may guide further therapy. Cystography is used to evaluate bladder capacity and detect reflux. Cystoscopy is used to evaluate duration and severity of retention (by detecting bladder trabeculations) and to check for bladder outlet obstruction. Cystometrography can determine whether bladder volume and pressure are high or low; if done during the recovery phase of flaccid bladder after spinal cord injury, it can help evaluate detrusor functional capacity and predict rehabilitation prospects (see Voiding Disorders: Testing). Urodynamic testing of voiding flow rates with sphincter electromyography can show whether bladder contraction and sphincter relaxation are coordinated (see Voiding Disorders: Testing).
- Increased fluid intake
- Surgery as last resort
Prognosis is good if the disorder is diagnosed and treated before kidneys are damaged.
Specific treatment involves catheterization or measures to trigger urination. General treatment includes renal function monitoring, control of UTIs, high fluid intake to decrease risk of UTIs and urinary calculi (although this measure may exacerbate incontinence), early ambulation, frequent changes of position, and dietary Ca restriction to inhibit calculus formation.
For flaccid bladder, especially if the cause is an acute spinal cord injury, immediate continuous or intermittent catheterization is needed. Intermittent self-catheterization is preferable to indwelling urethral catheterization, which has a high risk of recurrent UTIs and, in men, a high risk of urethritis, periurethritis, prostatic abscesses, and urethral fistulas. Suprapubic catheterization may be used if patients cannot self-catheterize.
For spastic bladder, treatment depends on the patient's ability to retain urine. Patients who can retain normal volumes can use techniques to trigger voiding (eg, applying suprapubic pressure, scratching the thighs); anticholinergics may be effective. For patients who cannot retain normal volumes, treatment is the same as that of urge incontinence (see Voiding Disorders: Treatment), including drugs (see Table 3: Voiding Disorders: Drugs Used to Treat Incontinence ) and sacral nerve stimulation.
Surgery is a last resort. It is usually indicated if patients have had or are at risk of severe acute or chronic sequelae or if social circumstances, spasticity, or quadriplegia prevents use of continuous or intermittent bladder drainage. Sphincterotomy (for men) converts the bladder into an open draining conduit. Sacral (S3 and S4) rhizotomy converts a spastic into a flaccid bladder. Urinary diversion may involve an ileal conduit or ureterostomy.
An artificial, mechanically controlled urinary sphincter, surgically inserted, is an option for patients who have adequate bladder capacity, good bladder emptying, and upper extremity motor skills and who can comply with instructions for use of the device; if patients do not comply, life-threatening situations (eg, renal failure, urosepsis) can result.
The Urinary System is made up of five major parts:
The two kidneys filter waste and excess water from the blood and produce urine. Urine is being produced every minute of the day.
Each kidney has a thin, hollow tube that connects to the bladder. Urine flows down the ureters from the kidneys and empties into the bladder. The ureters have one-way valves in them, so even if you were to stand on your head, urine could not flow back to the kidneys from the bladder.
The bladder is a collapsible sac lying in the pelvis. It is able to stretch to hold urine until you are ready to urinate. The bladder walls are made up of muscles known collectively as the detrusor muscles. When you are ready to urinate, the detrusor muscles contract (squeeze) to help push the urine from the bladder. The lower portion of the bladder, which funnels urine into the urethra, is called the bladder neck or bladder outlet.
The urethra is a small tube that allows urine to flow from the bladder to outside the body. The male urethra is 8-10 inches long and the female urethra is 1-2 inches long. The external urethral opening from the body is called the meatus for both men and women.
The Sphincter Muscles
The internal and external sphincter muscles form a ring around the urethra to keep urine in the bladder. When you are ready to urinate, these muscles relax to allow urine to flow out of the bladder.
Normally, when the bladder become full (about 1-2 cups for most people), nerve endings in the bladder wall send a message to the brain via the spinal cord. The brain sends a message back to the bladder to contract the detrusor muscles and relax the sphincter muscles so you can void. If you can't get to a toilet, the brain delays the messages until you are ready to void.
The bladder, along with the rest of the body, undergoes dramatic changes. Since messages between the bladder and the brain cannot travel up and down the spinal cord, the voiding pattern described above is not possible. Depending on your type of spinal cord injury, your bladder may become either "floppy" (flaccid) or "hyperactive" (spastic or reflex).
The Flaccid Bladder
A floppy bladder loses detrusor muscle tone (strength) and does not contract for emptying. This type of bladder can be easily overstretched with too much urine, which can damage the bladder wall and increase the risk of infection. Emptying the flaccid bladder can be done with techniques such as Crede, Valsalva, or intermittent catheterization. It is very important that you do not let your bladder get overfull, even if it means waking up at night to catheterize yourself more frequently.
The Reflex Bladder
The detrusor muscles in a hyperactive bladder may have increased tone, and may contract automatically, causing incontinence (accidental voiding). Sometimes the bladder sphincters do not coordinate properly with the detrusor muscles, and medication or surgery may be helpful.
Foley or Suprapubic Catheter
A tube is inserted through the urethra or abdomen and into the bladder, where a balloon on the end holds it in place. It remains in the bladder and drains constantly, so the bladder is never full.
These collection devices are worn by men for incontinence problems. They are made of latex rubber or silicone that covers the penis and attaches to a tube that drains into a collection bag.
- External Continence Device (ECD)
An ECD is a method of continence management that attaches only to the tip of the penis using hydrocolloid, a hypoallergenic adhesive commonly used in wound and ostomy care. Urine is directed into a collection bag and does not come in contact with skin.
The bladder muscles contract to start the bladder-emptying process. This may be under your control (voluntary) or not (involuntary):
- Normal Voiding
This is done under your control. When the bladder gets full, messages are sent to the sacral level of the spinal cord and carried to the brain. The brain sends messages back to the bladder to contract, and to the sphincter muscle to open, so you can void.
This surgical process weakens the bladder neck and sphincter muscle to allow urine to flow out more easily. After this surgery, you will urinate involuntarily, and must wear a collection device.
- Condom Catheter
These collection devices are worn by men for incontinence problems or after sphincterotomy (see above). They are made of latex rubber or silicone that covers the penis and attaches to a tube that drains into a collection bag.
Voiding is encouraged in one of several ways, such as:
- Anal or Rectal Stretch
This method for relaxing the urinary sphincter is usually used along with an abdominal corset and valsalva (see below).
This method involves manually pressing down on the bladder.
The area over the bladder is tapped with the fingertips or the side of the hand, lightly and repeatedly, to stimulate detrusor muscle contractions and voiding.
This method involves increasing pressure inside the abdomen by bearing down as if you were going to have a bowel movement.
A passageway is constructed using the appendix so that catheterization can be done through the abdomen to the bladder.
- Bladder Augmentation
Surgical enlargement of the bladder.