Bladder Anatomy and Dysfunction

					Bladder Anatomy and
    Dysfunction

 Suzanne L. Groah, MD,
        MSPH
Neuroanatomy of Micturition
   From the Top Down
      Micturition - Anatomy
Micturition center is located where in the
brain?
– Frontal lobe
Function of micturition center (excitatory or
inhibitory?)
– Send tonically inhibitory signals to the
  detrusor muscle to prevent the bladder from
  emptying (contracting) until a socially
  acceptable time and place to urinate is
  available.
       Next stop is the…..
Pons
                      Pons
The major relay center between the brain and
the bladder
What is the function of the pons?
– Coordinating the activities of the urinary sphincters
  and the bladder so that they work in synergy
What is the specific anatomic location?
– Pontine micturition center
– The PMC coordinates the urethral sphincter
  relaxation and detrusor contraction to facilitate
  urination
  Pontine Micturition Center
Bladder filling  detrusor muscle stretch
receptors  signal to the pons  brain
– Perception of this signal (bladder fullness) as a
  sudden desire to go to the bathroom
– Normally, the brain sends an inhibitory signal to the
  pons to inhibit the bladder from contracting until a
  bathroom is found.
Brain  deactivating signal to PMC
– Urge to urinate disappears
– When urination appropriate, brain sends excitatory
  signals to the pons, allowing voiding
   Pontine Micturition Center
Excitatory or inhibitory?
– Excitatory
Stimulation of the PMC causes what actions of the…
– Urethral sphincter?
      Open
– Detrusor?
      Contract
The PMC is affected by emotions
– Hence, some urinate when they are excited or scared
– The brain’s control of the PMC is part of the social training that
  children experience during growth and development
– Brain takes over the control of the pons at age…
      2 - 4 years
 Next Stop After the PMC….
Spinal cord
 Normal Micturition – Spinal
           Cord
Function
– Long communication pathway between the brainstem
  and the sacral spinal cord
– Sensory information from bladder  Sacral cord 
  Pons  Brain  Pons  Spinal cord  Sacral cord
   Bladder
Normal bladder filling/emptying
– Spinal cord acts as an important intermediary
  between the pons and the sacral cord
– Intact spinal cord is critical for normal micturition
 Normal Micturition – Spinal
           Cord
Sacral spinal cord – what is the
significance?
– Sacral reflex center
    Responsible for bladder contractions
    Primitive voiding center
      – In infants, the brain is not mature enough to command
        the bladder
      – SRC controls urination in infants and young children
      – When urine fills the infant bladder, an excitatory signal 
        sacral cord  spinal reflex center  detrusor contraction
         involuntary detrusor contractions with coordinated
        voiding
Bladder – Normal
 Neuroanatomy
Bladder - Anatomy
 Neuroanatomy - Peripheral
     Nervous System
3 components

1. Somatic nervous system via
   _________nerve
   Autonomic nervous system
  2. Sympathetics via ________________ nerve
  3. Parasympathetics via _____________ nerve
 Bladder Neuroanatomy
Sympathetic receptors & their locations
1. _____________________
2. _____________________
    Bladder NeuroAnatomy
Sympathetic receptors
– Adrenergic
    _ 1
     – Trigone, bladder neck, urethra
     – Maintain continence by contraction of bladder neck
       smooth muscle
    2-Adrenergics
     – Bladder neck and body of bladder
     – Inhibitory when active to
           Relax bladder neck on void
           Relax bladder body for storage (minor)
    Bladder Neuroanatomy –
    Parasympathetic receptor
Parasympathetic receptors
– Muscarinic
    Type
     – Cholinergic
    Anatomic location
     – Bladder, trigone, bladder neck, urethra
   Normal Micturition - ANS
Normally, bladder and the internal urethral
sphincter primarily are under sympathetic vs.
parasympathetic nervous system control?
– Sympathetic
SNS activity
– Bladder can increase capacity without increasing
  detrusor resting pressure
– Stimulates the internal urinary sphincter to remain
  tightly closed
– Inhibits parasympathetic stimulation
– Micturition reflex is inhibited
Normal Micturition – Autonomic
      Nervous System
Parasympathetic nervous system
 – Stimulates detrusor to _______________
 – Immediately preceding parasympathetic
   stimulation, sympathetic influence on the
   internal urethral sphincter becomes
   suppressed so that the internal sphincter
   relaxes and opens
 – Pudendal nerve is inhibited  external
   sphincter opens  facilitation of voluntary
   urination
Normal Micturition – Somatics
Regulates the actions of voluntary muscles
– External urinary sphincter
– Pelvic diaphragm
Innervation is via the….
– ______________________________
     Originates from the nucleus of Onuf
     Activation of the pudendal nerve causes  contraction
     of the external sphincter and the pelvic floor muscles
     Neuropraxia of pudendal may occur with….
      – Difficult or prolonged vaginal delivery, causing stress urinary
        incontinence
Normal Micturition - Physiology
2 phases
 – Filling and emptying
Normal micturition cycle requires that the urinary
bladder and the urethral sphincter work together
as a coordinated unit to store and empty urine
 – Storage
      Bladder is a low-pressure receptacle
      Urinary sphincter – closed with high resistance to urinary flow
 – Emptying
      Bladder contracts to expel urine
      Urinary sphincter – opens to allow urinary flow
Normal Micturition - Physiology
Filling phase
 – Bladder
      Accumulates increasing volumes of urine
      Pressure inside the bladder remains low
      Pressure within the bladder must be __________ than
      the urethral pressure during the filling phase
 – Bladder filling dependent on
      Intrinsic viscoelastic properties of the bladder
      Inhibition of the parasympathetic nerves
 – Bladder filling primarily is a passive or active event?
Normal Micturition - Physiology
Bladder filling
 – Sympathetic nerves also facilitate urine
   storage
     Inhibition of the parasympathetic nerves from
     triggering bladder contractions
     Directly cause relaxation and expansion of the
     detrusor muscle.
     Close the bladder neck by constricting the internal
     urethral sphincter
 – Thus, sympathetic input to the lower urinary
   tract is constantly active during bladder filling.
          Normal Micturition
During bladder filling - pudendal nerve becomes
excited.
– Pudendal nerve stimulation  contraction of the
  external urethral sphincter
– Urethral pressure maintained by the continence
  mechanism, which is composed of ??
     Contraction of the external sphincter
     Contraction of the internal sphincter
Pressure gradients
– Continence = urethral pressure > or < bladder
  pressure
– Incontinence = urethral pressure < or > intravesical
  pressure is abnormally high
Normal Micturition - Physiology
Pressure Gradients
 – During bladder filling –
      Small  in intravesical pressure
      When the urethral sphincter is closed, the intraurethral
      pressure > the intravesical pressure
 – With  intraabdominal pressure (cough, sneeze,
   laugh, physical activity), some pressure transmitted to
   both the bladder and urethra
      If the pressure is evenly transmitted to both the bladder
      and urethra, Ø incontinence
      If pressure transmitted to the bladder is > urethra,
      stress incontinence results
Normal Micturition - Emptying
Involuntary (reflex) or voluntary
– Infants involuntarily reflex void when the volume of
  urine exceeds the voiding threshold
     Bladder wall stretch receptors  sacral cord 
     pudendal nerve 
      – relaxation of the levator ani relaxation of pelvic floor muscle
      – Opens external sphincter
     Also, sympathetic nerves  relaxation of internal
     sphincter
     Parasympathetic nerves  detrusor contraction
     Bladder pressure > urethral pressure  urinary flow
Normal Micturition - Emptying
A repetitious cycle of bladder filling and
emptying occurs in newborn infants
As the infant brain develops, the PMC also
matures and gradually assumes voiding control
– During childhood, primitive voiding reflex becomes
  suppressed and the brain dominates bladder function
    Toilet training usually is successful at age 2-4 years
    Primitive voiding reflex may reappear in people with
    SCI
  Delayed/Voluntary Voiding
Healthy adults are aware of bladder filling and
can willfully initiate or delay voiding
Normally, the PMC functions as an on-off switch
that is activated by stretch receptors in the
bladder wall and is modulated by inhibitory and
excitatory neurologic influences from the brain.
When voiding must be delayed
– Brain bombards the PMC with inhibitory signals to
  prevent detrusor contractions
– Individual actively contracts the levator muscles to
  keep the external sphincter closed
Normal Micturition – Delayed
        Emptying
Voiding = coordination of both the ANS
and somatic nervous system, which are in
turn controlled by the PMC located in the
brainstem and regulated by the brain
                Work-Up
U/a and c & s
BUN & Cr
– if compromised renal function is suspected
Postvoid residual urine
– If high, the bladder may be contractile or the
  bladder outlet may be obstructed
                  Work-Up
Filling cystogram
– Bladder capacity
– Bladder compliance
– Presence of phasic
  contractions (detrusor
  instability)
       Work-Up - Cystogram
Static Cystogram              Voiding cystogram
– Confirm the presence of     – Bladder neck and
  stress incontinence
                                urethral function
– Degree of urethral motion
                                (internal and external
– Presence of a cystocele
                                sphincter) during filling
– Intrinsic sphincter
  deficiency                    and voiding phases
– Vesicovaginal fistula       – Urethral diverticulum
– Bladder diverticulum        – Urethral obstruction
                              – Vesicoureteral reflux
 Work-Up - Cystometrogram
Volume vs pressure graph
Evaluates
– Detrusor compliance
– Stability of detrusor
                  Pressures
Rectal pressure = abdominal pressure
True detrusor pressure = intravesical pressure –
rectal (abdominal) pressure
Normal bladder resting pressure =
– 8 – 40 cm H20
Nl compliance is <= 15 cm H20 increase in
pressure during filling
Avg urethral closure pressure is
– 60 cm H20
– 80 cm H20
     Work-Up - Urodynamics
Filling cystometry
Flow/pressure study
– Detrusor pressure at maximum flow
– Obstruction to passage of urine (high pressure, low flow) can be
  distinguished from a lack of tone in the detrusor muscle (low
  pressure, low flow)
Electromyography
– Coordinated or uncoordinated voiding
– Detrusor sphincter dyssynergia
Videocystourethography
– Combined x-ray or ultrasound
                 Normal Cystometry


  Rectal P


Intravesical P



  Detrusor P



Infused volume
Stable Bladder with Rectal
       Cancellation
Stable Bladder
            Detrusor Hyperactivity




The normal detrusor if filled slowly accepts 300 - 600 ml without rise in
pressure. If the bladder undergoes phasic contraction while the patient
is trying to inhibit voiding this is called Detrusor overactivity. Note the
low bladder capacity
Low Compliance Bladder
Neurogenic Detrusor Hyperactivity




Cystometry Neurogenic detrusor overactivity is overactivity in the
presence of confirmed neuropathy in this case Multiple Sclerosis.
Often the detrusor is unstable without sensation and the pressure
involved tend to be higher than idiopathic instability
     Work-Up - Cystoscopy
Cystoscopy
– Bladder cancer
– Bladder stone
– Indicated in persistent irritative voiding symptoms or
  hematuria
   Problems and Treatment
Classification
– Failure to store because of the bladder
– Failure to store because of the outlet
– Failure to empty because of the bladder
– Failure to empty because of the outlet
             Medications
Alpha-adrenergic drugs
– Location - Bladder neck receptors
– Function - Increase bladder outlet resistance
  by contracting the bladder neck
– Example - pseudoephedrine
            Medications
Estrogen derivatives
– Mechanism - Increases the tone of urethral
  muscle by up-regulating the alpha-adrenergic
  receptors in the surrounding area
– Mechanism - Enhances alpha-adrenergic
  contractile response to strengthen pelvic
  muscles
– Use in…Stress incontinence
                Medications
Anticholinergic drugs
– Function - Inhibit involuntary bladder contractions
– Adverse effects
     Blurred vision
     Dry mouth
     Heart palpitations
     Drowsiness
     Facial flushing
– Ex. Pro-banthine, Levsin
               Medications
Antispasmodic drugs
– Function - Relax the smooth muscles of the urinary
  bladder
– Function - Direct spasmolytic action on the smooth
  muscle of the bladder
– Adverse effects similar to anticholinergic agent
     Impaired mental alertness and physical coordination
– Ex. Ditropan, Detrol
             Medications
Tricyclic antidepressant drugs
– Mechanism - Increase norepinephrine and
  serotonin levels
– Mechanism - Anticholinergic and direct
  muscle relaxant effects on the urinary bladder
– Ex. elavil
            Pathophysiology
Brain Lesions – stroke, tumor, CP, Parkinsons
disease, hydrocephalus
– Above the pons
    Destroys the master control center, causing a complete
    loss of voiding control
    Primitive voiding reflex remains intact
    S/Sx
      – Urge incontinence or spastic bladder
            Bladder empties too often with relatively low quantities
            Storing urine in the bladder is difficult
         Pathophysiology
SCI (after resolution of spinal shock)
– Urge incontinence
– External sphincter may have paradoxical
  contractions
    Detrusor-sphincter dyssynergia
          Pathophysiology
Peripheral nerve injury - Diabetes mellitus,
severe genitoanal herpes, pernicious
anemia, neurosyphilis, and AIDS
– Result in silent/painless urinary retention
– DM - lose the sensation of bladder filling first,
  then difficulty urinating
                      CVA
Brain may enter into a temporary acute cerebral
shock phase
– Bladder retention with detrusor areflexia
Then detrusor hyperreflexia with coordinated
urethral sphincter activity
– PMC released from the cerebral inhibitory center
– S/Sx
     Urinary frequency, urgency, and urge incontinence
Treatment
– Early – indwelling catheter or CIC
– Hyperreflexia – Timed void ± anticholinergics
             Brain Tumor
Detrusor hyperreflexia with coordinated
urethral sphincter
S/Sx
– Urinary frequency
– Urgency
– Urge incontinence
Treatment
– Anticholinergics
         Parkinsons Disease
Characterized by detrusor hyperreflexia and
urethral sphincter bradykinesia
S/Sx
–   Urinary frequency
–   Urgency
–   Nocturia
–   Urge incontinence
Treatment
– Anticholinergic agents
         Multiple Sclerosis
Focal demyelinating lesions of the CNS often
involve the posterior and lateral columns of the
C spinal cord
Poor correlation between the clinical symptoms
and urodynamic findings
UD
– Detrusor hyperflexia (50-90% with MS)
– Approx 50% demonstrate DSD-DH
– 20-30% have detrusor areflexia
Treatment individualized
          Diabetic cystopathy
Usually, 10+ years after the onset of DM
Autonomic and peripheral neuropathy
– Segmental demyelination
– Impaired nerve conduction
S/Sx
– Loss of sensation of bladder filling
– Loss of motor function
Urodynamics
–   Elevated residual urine
–   Decreased bladder sensation
–   Impaired detrusor contractility
–   Detrusor areflexia.
           Herniated Disc
Lumbar disc herniation  irritation of the
sacral nerves  detrusor hyperreflexia
Acute compression of sacral roots
(trauma)  detrusor areflexia.
Urodynamics
– Sacral nerve injury
    Detrusor areflexia with intact bladder sensation
     internal sphincter denervation may occur
    Striated sphincter is preserved