Neurogenic bladder refers to lower urinary tract dysfunction caused by neurological disorders.
Etiology
Any condition that affects the neural regulation of urine storage and/or voiding may lead to bladder and/or urethral dysfunction, resulting in neurogenic bladder.
Central Nervous System Factors
Almost all central nervous system disorders, such as cerebrovascular accidents, Parkinson’s disease, Alzheimer’s disease, cranial tumors, cerebral palsy, spinal cord diseases, lumbar disc herniation, or spinal canal stenosis causing nerve compression, may disrupt the normal micturition process, leading to neurogenic bladder. These conditions manifest as various types of voiding dysfunction.
Peripheral Nervous System Factors
These primarily affect the conduction of peripheral nerves, resulting in reduced bladder sensation and diminished detrusor contractility. For example, 25–85% of diabetic patients may develop a diabetic bladder, with the prevalence significantly increasing in those with a diabetes duration of more than 10 years. Substance abuse, such as ketamine misuse, may also damage the functional nerves supplying the bladder and urethra, causing lower urinary tract dysfunction.
Infectious Diseases
Infectious conditions such as acquired immunodeficiency syndrome (AIDS), herpesvirus infection, and Guillain-Barré syndrome may involve the peripheral or central nerve fibers that innervate the bladder and urethral sphincters, leading to corresponding voiding abnormalities.
Iatrogenic Factors
Pelvic nerve plexus injury caused by spinal surgeries or radical pelvic operations, such as rectal cancer resections or radical hysterectomies, may result in bladder voiding dysfunction.
Clinical Manifestations
Neurogenic bladder is not a single disease but a group of disorders with diverse clinical presentations depending on the location, extent, and severity of neurological damage. Bladder compliance may range from high to low, bladder wall tension may range from high to low, and detrusor contractility may vary from absent contraction to hyperreflexia. Coordination between the detrusor and the internal and external urethral sphincters may range from coordinated to varying degrees of incoordination.
Lower urinary tract symptoms can be divided into storage phase symptoms, voiding phase symptoms, and post-voiding phase symptoms based on the micturition cycle:
- Storage phase symptoms include urgency, frequent urination, nighttime urination, urinary incontinence, lack of urinary sensation, and bladder pain or discomfort.
- Voiding phase symptoms include hesitancy, a weak urinary stream, straining during urination, intermittent urination, and voiding with abdominal pressure.
- Post-voiding phase symptoms often involve post-void dribbling and may lead to acute or chronic urinary retention.
Symptoms are often recorded in a voiding diary. Increased intravesical pressure may compress or cause reflux at the ureteral orifices, resulting in upper urinary tract dilation and impaired renal function. Due to neural injury, affected individuals may also experience sexual dysfunction, changes in bowel habits or fecal incontinence, sensory or motor impairments of the limbs, or psychological symptoms.
Diagnosis and Differential Diagnosis
The diagnosis of neurogenic bladder involves three main aspects: identifying the primary neurological lesion, diagnosing lower and upper urinary tract dysfunction and related urological complications, and identifying dysfunctions of other related organs and systems.
A detailed medical history is the cornerstone of diagnosing neurogenic bladder. Key aspects include the presence of congenital disorders, diabetes, trauma, Parkinson’s disease, cerebrovascular accidents, prior surgeries, and other neurological conditions. Comprehensive neurological physical examinations are essential. Additionally, the evaluation should also assess the presence of sexual and bowel dysfunction associated with neurological conditions, including erectile dysfunction and constipation.
Laboratory tests may include urinalysis, urine culture for pathogens, and evaluation of renal function. Imaging techniques such as urinary system ultrasound, plain X-rays, CT scans, MRI of the nervous or urinary system, and renography can assess the structural and functional status of the urinary system and determine the location and extent of neurological damage.
Urodynamic studies provide objective and quantitative assessments of lower urinary tract function, evaluate the potential impact of lower urinary tract lesions on upper urinary tract function, and serve as an important basis for classifying neurogenic bladder. Key parameters include free urinary flow rate, residual urine volume, bladder pressure-volume measurements during filling phases, and pressure-flow studies during voiding phases. Lower urinary tract and pelvic floor neuro-electrophysiological tests assess the integrity of nerve innervation and conduction in the lower urinary tract and pelvic floor.
Treatment
The treatment goals for neurogenic bladder include the protection of upper urinary tract function, restoration (or partial restoration) of lower urinary tract function, improvement of urinary incontinence, and enhancement of the patient's quality of life, with a primary focus on protecting upper urinary tract function. The treatment principles involve managing the underlying disease and preventing or addressing complications. Treatment approaches are selected in a stepwise manner, following the progression from conservative to surgical methods, prioritizing non-invasive and minimally invasive techniques before invasive procedures. Personalized treatment plans are formulated based on urodynamic assessments and the individual patient's condition. Lifelong regular follow-up is recommended, with modifications to the treatment plan based on disease progression.
Conservative Treatment
Conservative measures include assisted voiding, lower urinary tract rehabilitation, intermittent catheterization, electrical stimulation therapy, and acupuncture. Assisted voiding methods may involve techniques such as tapping over the bladder in the suprapubic region, compressing the penis to induce sacral reflex voiding, applying manual pressure over the bladder from the suprapubic area downwards, or increasing abdominal pressure using the Valsalva maneuver (straining, breath-holding, etc.). Lower urinary tract rehabilitation methods include timed voiding, pelvic floor muscle training, and pelvic floor biofeedback.
Pharmacological treatments include the use of muscarinic receptor antagonists to suppress reflex detrusor contractions, beta-3 adrenergic receptor agonists to relax the detrusor muscle and improve bladder compliance, and alpha-receptor antagonists to reduce bladder outlet resistance. Electrical stimulation therapies, such as intravesical bladder stimulation and pelvic floor muscle stimulation, may improve bladder compliance, encourage voiding, or enhance urinary continence.
Surgical Treatment
Surgical options include procedures aimed at reconstructing storage and/or voiding functions, combined procedures for simultaneous storage and voiding restoration, and urinary diversion surgeries.
Procedures to restore storage function include:
- Botulinum toxin A (BTX-A) bladder wall injection: By inhibiting acetylcholine release at the presynaptic membrane of motor nerve terminals, the detrusor muscle becomes relaxed due to loss of innervation, reducing pressure during the storage phase and increasing bladder capacity.
- Autologous bladder augmentation: This involves removing the hypertrophic detrusor layer while preserving the integrity of the bladder mucosa to create an "artificial diverticulum," thereby improving bladder compliance, reducing intravesical pressure during the storage phase, and protecting the upper urinary tract.
- Enterocystoplasty (intestinal bladder augmentation): This procedure uses ileum or sigmoid colon segments to construct low-pressure, large-capacity reservoirs for urine storage.
For patients with partial urethral sphincter deficiency, artificial urinary sphincter implantation may be considered.
Procedures to restore voiding function include:
- Bladder muscle reconstruction surgery to enhance detrusor contractility.
- Techniques to reduce urethral resistance, such as BTX-A injection into the urethral sphincter, urethral sphincterotomy, or urethral stent implantation. Postoperative urinary incontinence may necessitate the use of external collecting devices.
Surgical procedures to reconstruct both storage and voiding functions include:
- Sacral dorsal root rhizotomy combined with sacral anterior root electrical stimulation, or sacral neuromodulation techniques.
- Sacral neuromodulation is particularly effective in treating refractory voiding disorders, enhancing urinary flow rates, reducing residual urine volume, alleviating lower urinary tract symptoms and constipation, and improving quality of life.
If the above surgical treatments prove ineffective, urinary diversion should be considered to protect upper urinary tract function and enhance the patient's quality of life.
Neurogenic bladder is a highly heterogeneous condition, and no single treatment is typically sufficient to achieve optimal results. Treatment strategies should be tailored and combined based on the type and cause of neurogenic lower urinary tract dysfunction.