A neurogenic bladder is a condition where a person lacks bladder control due to damage to the nerves that coordinate bladder function. A complex network of nerves and muscles typically work together to hold and release urine, but nerve damage disrupts this communication between the brain, spinal cord, and bladder.

The etiology of neurogenic bladder is damage to the nerves or central nervous system (brain and spinal cord) that control bladder function. This disruption prevents the bladder muscles and nerves from properly communicating, which can lead to either an overactive or underactive bladder.

The signs and symptoms of a neurogenic bladder depend on whether the bladder is overactive (spastic) or underactive (flaccid). This condition results from nerve damage that disrupts communication between the bladder and the brain.

Overactive (spastic) bladder

With a spastic bladder, the bladder muscles contract involuntarily or frequently, causing symptoms that resemble an overactive bladder.

• Urinary urgency: A sudden, compelling need to urinate immediately.
• Urinary frequency: Urinating more than eight times a day, often in small amounts.
• Urge incontinence: Leakage of urine following a sudden, strong urge to void.
• Nocturia: Waking up frequently during the night to urinate.
• Difficulty emptying: While the bladder contracts often, it may not empty completely

Underactive (flaccid) bladder

A flaccid bladder loses muscle tone and stretches, causing it to overfill without the person feeling the need to urinate. This leads to overflow incontinence.

• Urinary retention: Inability to empty the bladder completely, or at all.
• Overflow incontinence: Constant dribbling or leakage of urine from a bladder that is too full.
• Loss of sensation: Not being able to tell when the bladder is full.
• Weak or dribbling stream: The bladder muscles do not have enough force to produce a strong urine stream.
• Straining: Needing to strain to urinate.

Tests

The evaluation for a neurogenic bladder involves several types of tests, including urodynamics, imaging, and lab work, to assess both bladder function and the underlying nerve damage. A doctor will begin with a medical history and physical exam before recommending diagnostic tests.

Bladder function tests (Urodynamics)

Urodynamic studies are a series of tests that evaluate how the bladder and urethra store and release urine.

• Cystometrogram (CMG): This measures the pressure inside the bladder as it is being filled. A catheter fills the bladder with a fluid, and sensors measure the bladder pressure and volume, identifying whether the bladder is overactive or underactive.
• Electromyography (EMG): Sensors are placed near the urethra and rectum to measure the electrical activity of the nerves and muscles of the pelvic floor. It helps detect involuntary bladder contractions and sphincter function.
• Pressure flow study: This test measures the bladder pressure and urine flow rate at the same time to assess bladder and sphincter function during urination.
• Uroflowmetry: The patient urinates into a special device that measures the speed and volume of urine flow. It helps detect weak bladder muscles or blockages.
• Post-void residual (PVR) measurement: This measures the amount of urine left in the bladder after urination. It is typically done with an ultrasound scan of the bladder, or by inserting a catheter. A high PVR indicates that the bladder is not emptying completely.

Imaging tests

Imaging helps evaluate the structure of the kidneys, bladder, and central nervous system to identify the source of nerve damage and potential complications.

• Ultrasound (Sonography): This non-invasive test uses sound waves to create images of the kidneys and bladder. It is used to check for kidney swelling (hydronephrosis), bladder size, and to measure PVR.
• CT and MRI scans: These advanced imaging tests can provide detailed pictures of the brain, spinal cord, kidneys, and surrounding structures to identify the underlying cause of nerve damage.
• X-rays of the skull and spine: These are sometimes used to detect problems with the brain or spine that could be affecting bladder control.
• Cystoscopy: A doctor inserts a thin, flexible tube with a camera into the bladder through the urethra to look for blockages, stones, or other abnormalities. Laboratory tests

Laboratory tests

Blood and urine tests are performed to screen for infections, kidney function, and other related issues.

• Urinalysis and urine culture: A urine sample is checked for signs of infection, blood, or protein. A urine culture is done if an infection is suspected.
• Blood tests: Blood tests to measure blood urea nitrogen (BUN) and creatinine are used to evaluate kidney function, which can be affected by neurogenic bladder.

Treatment for neurogenic bladder depends on the underlying cause and can involve lifestyle changes, medications, catheterization, and surgery. The primary goals are to prevent kidney damage and improve the patient's quality of life by managing symptoms.

Lifestyle and behavioral strategies

• Bladder training: Involves following a timed voiding schedule to develop a more predictable urination pattern.
• Pelvic floor exercises: Strengthening the pelvic floor muscles with exercises like Kegels can help improve bladder control, especially for overactive bladder symptoms.
• Dietary management: Avoiding bladder irritants such as caffeine and alcohol can help manage symptoms.
• Double voiding: After urinating, standing up and sitting down to try again can help ensure the bladder is fully empty.
• Credé and Valsalva techniques: Applying manual pressure to the bladder may help with emptying. However, these are generally not recommended for most spinal cord injury patients due to the risk of high bladder pressure, which can damage the kidneys

Medications

• Anticholinergics and antimuscarinics: These are the standard medical treatment for an overactive neurogenic bladder. They relax the bladder muscles, reduce spasms, and increase bladder capacity. Examples include oxybutynin, tolterodine, and trospium.
• Beta-3 agonists: Newer agents, like mirabegron and vibegron, relax the bladder muscles and may have fewer side effects than anticholinergics. They are used to treat detrusor overactivity.
• Alpha-blockers: For patients who have trouble emptying their bladder, these medications relax the bladder neck and prostate to improve urine flow.
• Onabotulinumtoxin A (Botox): Injected into the bladder muscle, this can relax an overactive bladder, and its effects can last up to 9 months. It is used when other medications have failed.
• Desmopressin: May be used to treat nocturnal polyuria (excessive urination at night) in neurogenic bladder patients.

Catheterization and drainage

• Clean intermittent catheterization (CIC): Involves inserting a small, thin tube into the bladder several times a day to drain it. It is considered the gold standard for managing incomplete bladder emptying.
• Indwelling catheters: For long-term use, a catheter can be inserted through the urethra or abdomen (suprapubic catheter) to provide continuous drainage. A suprapubic catheter is often preferred for long-term use as it reduces the risk of urethral trauma and irritation.

Neuromodulation

• Sacral neuromodulation (SNM): An implantable device sends mild electrical signals to the sacral nerves, which influence bladder and bowel function. It is a treatment for overactive bladder and non-obstructive urinary retention in carefully selected patients who haven't responded to other treatments.
• Percutaneous tibial nerve stimulation (PTNS): Delivers electrical impulses to the tibial nerve near the ankle to stimulate the sacral nerves. It is often used for urgency and frequency.

Surgical procedures

• Artificial urinary sphincter: An inflatable cuff is implanted around the urethra to control severe stress incontinence.
• Bladder augmentation (cystoplasty): Enlarges the bladder using a section of the patient's intestine to increase capacity and lower pressure. This is an option for patients with small, non-compliant bladders.
• Urinary diversion: Redirects the flow of urine into an external pouch when other options have failed. It is considered for the most severe cases of neurogenic bladder.
• Sling procedures: A sling is used to support the bladder and urethra to treat stress incontinence

• Neurogenic bladder residual refers to the significant amount of urine left in the bladder after a person with a neurogenic bladder attempts to void. This condition is caused by nerve damage affecting the bladder's ability to contract and the sphincter's ability to relax properly, leading to incomplete emptying. High residual urine volumes are a key diagnostic indicator of voiding dysfunction in neurogenic bladder and can lead to complications such as urinary tract infections, kidney damage, and bladder stones. 

• Rate as voiding dysunction or urinary tract infection, whichever is predominant.