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Physiology of Lower Urinary Tract Function (including
Neurogenic Bladder)
Eric S. Rovner, M.D.Professor of UrologyMedical University of South Carolina
Outline
Physiology of Micturition Micturition cycle Neurologic factors Pharmacology
Neurogenic Bladder Lesions above pons Lesions below pons above sacral SC Lesions of sacral SC and peripheral NS
Ideal Plumbing Requirements for a Terrestrial
Store a reasonable amount of urine at a pressure < kidney filtration pressure (25 to 40 cm H2O)
Rapid on-demand emptying
The micturition cycle:Filling/StorageEmptying
Micturition Cycle: Simplified*
*Wein
Bladder Filling and Urine Storage Requirements:
Reservoir: Accommodation of increasing volumes of urine
At a low intravesical pressure (compliance) With appropriate sensation
Absence of involuntary bladder contractions Overactivity
Outlet: A bladder outlet that is closed at rest and remains so
during increases in intra-abdominal pressure
Urine Emptying Requirements:
Reservoir: Coordinated bladder contraction of adequate magnitude (or
other increase in pressure)
Outlet: Absence of anatomic obstruction Concomitant lowering of resistance at the level of:
Smooth muscle of bladder neck and proximal urethra Striated muscle that surrounds urethra
Voiding Dysfunction*
Pathophysiology simplified All voiding dysfxn is sub-classified as abnormality of:
Filling/storage:• Bladder• Urethra• Both
Emptying:• Bladder• Urethra• Both
Key factors:BladderSmooth sphincterStriated sphincterSensation
*Wein
Voiding dysfunction
Because of urethra Too weak:
SUI (sphincteric) Too strong
BOO/retention/DESD
Because of the bladder Too weak
Detrusor underactivity (retention) Too strong
Detrusor overactivity (OAB/UUI)
Because of both (MIXED)
“I am not certain why humans or
animals are continent of urine and
feces and I am not convinced that
anyone really knows.”
J. Berry, 1961
(Berry Prosthesis)
Physiology of Urinary Continence
Continence = urethral closure forces > bladder expulsive forces
Bladder
Urethra
>>1. Sphincters2. Connective tissue3. Urethral mucosa
1. Intravesical (IBC’s, compliance)2. Extravesical (abdominal, etc.)
=Continence
Micturition reflex at sacral SC:Coordination/influenced by higher centers
What defines neurogenic voiding dysfunction?
Abnormality in storage or voiding function of the bladder as a result of a neurologic disturbance
Must be confirmed by objective evidence of a nervous system disorder
Patterns of Neurogenic dysfunction
Often predicted by level of injury/disease
However, limited by Complete/Incomplete Description of sx’s is often poor (sensory loss)
“….the bladder is an unreliable witness”
Other co-morbidities (diabetes, CHF, etc.) Other pelvic disease (POP, SUI, BPH, etc.)
Incidence of Bladder Dysfunction
Spinal cord injury (8k new/yr) 70%–80%
Multiple sclerosis (400k) 50%–80%
Lumbo-sacral DDD 27%-92% (60-90% overall prevalence with 5% sciatica)
Radical pelvic surgery 16%-20%
Parkinson’s disease 15%–35%
Diabetes (17,000,000) 10%–30%
CVA (540k new/yr) 10%–15%
Central Nervous SystemCortex, Basal Ganglia, Cerebellum
-Frontal lobes and cingulate gyrus
-Voluntary initiation of voiding
-Inhibition of reflex voiding activity
-Supra-pontine structures are generally inhibitory on the LUT
-Injuries (CVA, etc.) release this inhibition
-detrusor overactivity, and clinical sxs of urgency, frequency, incontinence
Central Nervous System: Pons
Coordination of sphincter and bladder
- Afferent input (ascending and descending)
-bladder wall and supra-pontine centers
• - Efferent outflow (descending)
-sacral spine
- somatic
- parasympathetic centers for voiding
-T-L spine
-sympathetic nerves for accomodation
Injuries separating Pons from LUT(SCI, MS) : reflex voiding patterns and uncoordinated voiding
Supra-sacral spinal injury/disease
Functional Abnormality Depends on
chronology, type of lesion completeness
Neurogenic Detrusor Overactivity Striated sphincter dysynergia
If above T6 (Sympathetic Outflow Tract)
• Smooth sphincter dysynergia
• Autonomic dysreflexia
Infrasacral Injury/Disease
Clinical Presentation Urge/frequency or urinary retention +/- straining to void Usually continent
Most common urodynamic abnormality Detrusor areflexia Normal innervation of the striated sphincter Normal smooth sphincter function Irritative lesions- detrusor overactivity
Goals of NGB Evaluation
Accurate diagnosis characterization of voiding dysfunction (NGB)
Reassess as needed
recognition of concomitant non-neurogenic VD BPH, SUI, etc.
Assess prognosis Urological
Neurological
Direct management
Neurourologic Evaluation
History Physical examination
neurologic examination PVR Creatinine U/A, C&S +/- Upper tract study +/- Urodynamic study +/- Cystoscopy
Urodynamics:Utility in prognosis and treatment in NGB
LUTS and PE do not correlate well with of type, extent or level of injury/disease…..or UDS findings
LUTS and PE do not correlate well with prognosis or “danger” to upper tracts (but UDS does!!!!)
In SCI/MS, level of injury not always predictive of UDS* Correlation of neuro imaging and UDS not exact
Therefore management often dictated by UDS
*Weld and Dmochowski, 2000
Detrusor overactivity with UI
Valsalva induced DO with UI
MS with sx’s of SUI with urge +/- UUI
SUI
Q
Vol
pVes
pAbd
pdet
EMG
47 y.o. with Sx’s of SUI after Rad Hyst. PVR=175cc
Treatment Issues in NGB
Assessing Safety 1st Upper tracts Risk factors: compliance, UTI’s, VUR, etc Other
Relieving Symptoms 2nd Incontinence Frequency, urgency Other
Goals of Management
Upper Tract Preservation (or improvement)
Absence or control of infection
Continence
Reduce or eliminate impact on QOL
Make an acceptable solution for the patient Physically Economically Socially Culturally
How to achieve goals
Adequate urine storage at low pressure
Adequate emptying in absence of obstruction
Adequate urethral closure forces (competence)
Selecting least invasive/expensive Rx option.
Individual management.
Rx of NGB
Bladder
Urethra
All Rx either All Rx either ΔΔ urethral or urethral or ΔΔ bladder pressure or both bladder pressure or both
Lesions above the ponsCVA, brain tumor, etc.
Usually:
Clinical presentation:1. frequency/urgency2. incontinence3. usually normal upper tracts
Urodynamics:1. detrusor overactivity2. synergic sphincters3. normal sensation4. normal emptying
Treatment: Lesions above pons
Strategy: Reduce detrusor overactivity Sphincters are OK usually
Management: Behavioral modification Antimuscarinics Sacral neuromodulation Botulinum toxin A Augmentation cystoplasty
Lesions between pons and sacral spinal cordMS, SCI, transverse myelitis, etc.
Clinical presentation:1. frequency/urgency (if sensation)
-overactivity vs. retention
2. incontinence (+/- awareness)3. beware upper tracts
Urodynamics:1. detrusor overactivity
-sometimes underactivity
2. dyssynergic sphincters3. +/- sensation4. abnormal emptying
Lesions between pons and sacral spinal cordMS, SCI, transverse myelitis, etc.
Strategy: 1. reduce detrusor overactivity (if present) 2. improve emptying (when problematic) 3. reduce storage pressure 4. protect upper tracts
Management: 1. Rx detrusor overactivity (drugs, Botox, etc.) 2. +/- CIC 3. +/- urinary diversion
Autonomic Hyperreflexia (Dysreflexia)
Autonomic Hyperreflexia (Dysreflexia)
THIS IS AN EMERGENCY
Lesions above T6-T8 Occurs after resolution of spinal shock
Often years later Must have viable distal SC
Assoc. with DSD
Autonomic Hyperreflexia(Dysreflexia)
Precipitating factors: Any distention of rectum or LUT LUT instrumentation (UDS) Urinary catheter issue
Tube change Obstructed catheter
• clot retention, etc. Long bone fracture Decubiti GI pathology Sexual activity Other
AH: Treatment
Find and reverse precipitating stimulus
Acute: Parenteral ganglionic blockers α blockers Others
Prophylaxis: Do procedures under spinal or general with careful
monitoring ?????? Nifedipine 10–20 mg orally 30 minutes prior; SL during Chronic α blockade (i.e. terazosin)
Lesions distal to the spinal cordDisc disease, radical pelvic surgery, diabetes etc.
Usually:
Presentation:1. frequency, urgency +/- incontinence2. +/- urinary retention, straining3. upper tracts at risk
Urodynamics:1. detrusor overactivity or underactivity2. impaired compliance, +/- contractility3. normal sensation4. no dyssynergia
Lesions distal to the spinal cordDisc disease, radical pelvic surgery, etc.
Strategy: 1. improve emptying (when problematic)2. reduce storage pressure3. protect upper tracts
Management:1. Rx poor emptying
+/- CIC2. improve compliance
Infrapontine lesions: Chronic Risk Factor
High intravesical storage pressure