Neurogenic Bladder

• Neurogenic (neuropathic) bladder involves disturbance in the bladder and sphincter function due to neuromuscular lesion.
• The urinary bladder is the only visceral smooth-muscle organ under voluntary control from the cerebral cortex (somatic and autonomic).
• Regulation of voiding function involves many levels of the nervous system.

Bladder Innervations

• Parasympathetic innervation from S2,3,4 (n. erigentes) is cholinergic and excitatory for the detrusor muscle.
• Sympathetic innervation from T10-12 and L1-2 via the hypogastric plexus innervates the trigone, blood vessels of the bladder, smooth muscle of prostate and bladder neck, and inhibits bladder smooth muscle contraction.
• The external sphincter is innervated by the pudendal nerve (spinal segments S2,3,4) somatic nerve fiber.
• Sensory nerve fibers transmit signals through all nerves.

Physiology of Urine Storage and Micturition

• During the storage phase (filling or resting), bladder pressure remains low despite substantial volume increase due to the elasticity of connective tissue and muscle fibers, making the bladder highly compliant.
• Storage phase involves sphincter contraction and bladder relaxation.
• The first desire to void is typically felt at a volume of 150-200cc.
• The average bladder capacity is 350-400cc.
• Micturition results from a spino-bulbar reflex that causes simultaneous detrusor contraction and urethral relaxation.
• Micturition is initiated by relaxation of the external urethral sphincter and pelvic floor, allowing urine to enter the posterior urethra and activate detrusor contraction.
• Micturition involves bladder contraction and urethral relaxation.

Causes of Neurogenic Bladder

• Brain-related causes include CVA, tumors, dementia, or infection.
• Spinal cord injuries such as trauma, prolapsed disc, meningomyelocele, or myelitis can cause neurogenic bladder.
• Peripheral nerve damage such as neuropathy, diabetes mellitus (DM), pelvic surgery, or fracture can cause neurogenic bladder.
• Myogenic causes can also lead to neurogenic bladder.

Classifications of Neurogenic Bladder

• Hyperactive bladder or sphincter conditions exist.
• Hypoactive bladder or sphincter conditions exist.
• Upper motor neuron lesions (UMNL) result in a spastic bladder.
• Lower motor neuron lesions (LMNL) result in a flaccid bladder.
• Uncoordinated function (dyssynergia) may occur.

Overactive Bladder

• Repeated involuntary detrusor muscle contraction during the filling phase, leading to increased intravesical pressure (IVP) and frequent urination.

Pathophysiology of UMNL

• UMNL leads to high-pressure or spastic bladder.
• Increased IVP causes hypertrophy and vesical wall thickening, resulting in a small bladder capacity and compression on the lower ureteric orifice, potentially leading to hydronephrosis.
• Chronic IVP may lead to bladder sacculation and diverticulae formation.

Pathophysiology of LMNL

• LMNL results in low-pressure, flaccid, hyporeflexic or atonic bladder.
• Bladder atony is characterized by a lax, large-capacity, and thin-walled bladder.
• Poor contractility leads to variable amounts of residual urine, resulting in overflow incontinence.
• Sphincteric hyperactivity results in detrusor-sphincteric dyssynergia.
• Sphincteric hypoactivity results in incontinence.

CVA and Neurogenic Bladder

• Following a CVA, spinal shock can result in a flaccid neurogenic bladder, which may change into a spastic type.

Symptoms of Neurogenic Bladder

• Symptoms include frequency, poor stream, urgency, urge incontinence, overflow incontinence, and retention of urine.
• Urinary tract infections (UTIs) and stone formation and nocturnal enuresis are symptoms of neurogenic bladder
• Renal failure.

Signs of Neurogenic Bladder

• General signs include coma, hemiplegia or paraplegia, and other neurological deficits.
• Uremic facies is a general sign of Neurogenic Bladder, also include distended bladder, palpable hydronephrotic kidneys and signs of incontinence (wet clothes and excoriation marks).
• The anal sphincter could be either lax or tight.
• Neurological deficits.

Imaging Studies for Neurogenic Bladder

• Ultrasound (US) assesses bladder capacity and wall thickness, residual urine, diverticulae, hydronephrosis, and stones.
• Intravenous Urography (IVU) provides the same information as US, plus renal function.
• Cystogram reveals a Christmas tree appearance in spastic types and a large bladder in flaccid types, as well as sacculae and diverticulae.
• Stones in vesical diverticulae are suggestive of neurogenic bladder.
• High-grade reflux and large bladder size suggest flaccid neuropathic bladder.

Urodynamic Study

• Cystometry assesses bladder capacity, intravesical pressure (IVP), compliance, and sensation.
• Urethroprofilometry measures intraurethral pressure during filling and urination.
• Electromyography (EMG) monitors the pelvic floor (external sphincter).
• Flowmetry measures the flow rate of urine during urination against time.

Treatment of Neurogenic Bladder

• Treatment should be directed toward the causative pathology such as disc prolapse or DM.
• For medical management, anticholinergics are used in hyperreflexic bladder, detrusor stimulants in hyporeflexic bladder, and skeletal muscle relaxants in hyperactive sphincters.
• Anticholinergics include oxybutynin, tolterodine, and darifenacine.
• Tricyclic antidepressants (TCAD) such as imipramine are used.
• Botulinum toxin A can be administered to paralyze muscle.
• Desmopressin can be administered intranasally to reduce urine production.
• If retention is present, utilize clean intermittent catheterization (CIC)
• Indwelling catheters, condoms, and penile clamps may be needed for incontinence.

Endoscopic Treatments

• Collagen injection at the bladder neck to improve continence or VU reflux.
• Sphincterotomy.
• Botulinum toxin injection in the bladder or external sphincter.

Surgical Options

• Augmentation cystoplasty is a surgical option.
• Vesicostomy.
• Dorsal rhizotomy can be performed to convert a hyperactive bladder to a hypoactive one by cutting the dorsal root.
• Sacral anterior root stimulator implantation.
• Artificial urethral sphincter implantation.
• TVT ant TOT.