Physiology of Micturition

Physiology of Micturition

1. Dept of Urology
Govt Royapettah Hospital and Kilpauk Medical College
Chennai

2. Moderators:
Professors:
Prof. Dr. G. Sivasankar, M.S., M.Ch.,
Prof. Dr. A. Senthilvel, M.S., M.Ch.,
Asst Professors:
Dr. J. Sivabalan, M.S., M.Ch.,
Dr. R. Bhargavi, M.S., M.Ch.,
Dr. S. Raju, M.S., M.Ch.,
Dr. K. Muthurathinam, M.S., M.Ch.,
Dr. D. Tamilselvan, M.S., M.Ch.,
Dr. K. Senthilkumar, M.S., M.Ch.
Dept of Urology, GRH and KMC, Chennai. 2

3. Neurogenic Control -Overview
1. FrontalMicturition
Centre
2. Pontine Micturition
Centre
3. Spinal Cord
4. Sacral Reflex Centre
5. Pelvic nerve
6. Pudendalnerve
7. Urethra
8. Sphincter
9. Pelvic floor
10. Bladder
11. Hypogastricnerve
3Dept of Urology, GRH and KMC, Chennai.

4. Neuroanatomy of Micturition
Storage–Stability and good compliance of Bladder
Empty –Contraction of detrusor and opening of
Urethra
Parasympathetic -Pelvic nerve
Sympathetic -Hypogastric nerve
Somatic nerves-Pudendal nerve
4Dept of Urology, GRH and KMC, Chennai.

5. Neuroanatomy of
Lower Urinary Tract
5Dept of Urology, GRH and KMC, Chennai.

6. Neurogenic control
Brain:
-Master control
-Conscious social control
-Frontal lobe
-Tonically inhibitory signals to detrusor.
-[Stroke,dementia,cancer, CP, parkinson, shy drager
syndrome…. ]
6Dept of Urology, GRH and KMC, Chennai.

7. Brain stem:
-Pons-PMC –Barington’snucleus-Dorsal
pontinetegmentum
-inborn excitatory nature.
-a relay switch in the voiding pathway.
-coordinates the urethral sphincter relaxation and
detrusor contraction to facilitate urination.
-affected by emotions.
-brain takes over the control of the pons at age 3-4
years.
-the stretch receptors of the detrusor muscle send
a signal to the pons, which in turn notifies the
brain.
7Dept of Urology, GRH and KMC, Chennai.

8. Sacral spinal cord:
-Primitive voiding center –sacral reflex center –
bladder contractions.
-Important intermediary between the pons and
the sacral cord.
-Spinal injury: urinary frequency, urgency and
urge incontinence and are unable to empty
bladder. [detrusor sphincter dyssynergia with
detrusorhyperreflexia (DSD-DH)]. (multiple
sclerosis).
-Or detrusorareflexia. (herniated disc/ tumor)
8Dept of Urology, GRH and KMC, Chennai.

9. Urinary tract innervation
9Dept of Urology, GRH and KMC, Chennai.

10. Peripheral nerves:
-Sympathetic: constantly active. [T10-L2].
1. Bladder to increase its capacity without
increasing detrusor resting pressure
(accommodation) and stimulates the internal
urinary sphincter to remain tightly closed.
2.Sympathetic activity also inhibits para
sympathetic stimulation [S2-4]
(opposite action).
10Dept of Urology, GRH and KMC, Chennai.

11. Somatic nervous system:
-External urinary sphincter and the pelvic
diaphragm.
-Pudendal nerve [S2-3] originates from the
nucleus of Onuf and regulates the voluntary
actions of the external urinary sphincter and the
pelvic diaphragm.
-Shy-dragersynd : lesion in Onuf nucleus.
-Neuropraxia : after delivery-stress incontinence.
-Suprasacral-infrapontine spinal cord trauma can
cause overstimulation of the pudendal nerve -
urinary retention.
11Dept of Urology, GRH and KMC, Chennai.

12. Innervation of
Lower Urinary Tract
Bladder-cholinergic parasympathetic-contraction;
beta-adrenergic & NO–relaxation
Bladder neck –alpha-adrenergic-contration
Urethral muscles-cholinergic parasympathetic, NO,
cholinergic somatic nerves
12Dept of Urology, GRH and KMC, Chennai.

13. Storage of Urine
Stable bladder
Good compliance
Competent urethra-mucosa, submucosa, smooth
muscles, striated skeletal muscles (external sphincter)
Good pressure transmission and hammock effect
during stress
13Dept of Urology, GRH and KMC, Chennai.

14. 14Dept of Urology, GRH and KMC, Chennai.

15. Empty of Urine
Sustained detrusor contraction-cholinergic
parasympathetic fibers
Relaxation of bladder neck –alpha-adrenergic
sympathetic nerves
Relaxation of external sphincter-cholinergic pudendal
nerves
Patent non-obstructive urethra
15Dept of Urology, GRH and KMC, Chennai.

16. 16Dept of Urology, GRH and KMC, Chennai.

17. Efficient Bladder Empty
Hypersensitive bladder-low detrusor contractility
Inadequate contractility in elderly
Bladder outlet obstruction-Bladder neck dysfunction,
Prostatic enlargement, Urethral stricture,
Cystocele, External sphincter dyssynergia
17Dept of Urology, GRH and KMC, Chennai.

18. Storage & voiding reflexes
18Dept of Urology, GRH and KMC, Chennai.

19. Sensory Afferents
A-delta fibers –Micturition reflex, stretch and fullness
sensation
C-fibers –Noxious sensation, capsaicin sensitive
primary afferents (CSPA)
Dual sensory afferents in mammalian urinary bladder
19Dept of Urology, GRH and KMC, Chennai.

20. Dual Sensory Innervation of Urinary
Bladder
20Dept of Urology, GRH and KMC, Chennai.

21. Sustained Detrusor Contraction-
Urethrovesical Reflex
Stretch receptors in urethral wall
Detrusor overactivity in urgency-frequency syndrome
and SUI
Role of incompetent bladder neck
Low detrusor contractility in incompetent urethral
sphincter after prostatectomy
21Dept of Urology, GRH and KMC, Chennai.

22. Micturition detrusor pressure-
depends on urethral resistance
High voiding pressure indicates a greater urethral
resistance
Low voiding pressure indicates a lower urethral
resistance or a low detrusor contractility
Efficient bladder empty depends on a sustained
detrusor contraction
22Dept of Urology, GRH and KMC, Chennai.

23. Pharmacology of Micturition-
Increase storage efficiency
Reduce detrusor overactivity
Anticholinergic agents-oxybutynine, flavoxate,
imipramine
Ganglion blocker-bentyl
Beta-adrenergic agents
Botulinum toxin
Vanilloid receptor blockers-capsaicin, resiniferatoxin
23Dept of Urology, GRH and KMC, Chennai.

24. Pharmacology of Micturition-
Increase empty efficiency
Parasympathomimetic agent-Urecholine
Adrenergic blockers-inhibition of detrusor relaxation
(?)
24Dept of Urology, GRH and KMC, Chennai.

25. Pharmacology of Micturition-
Increase outlet resistance
Increase smooth muscle tone
Imipramine, methylephedrine
Increase striated muscle tone
Nitric oxide synthase inhibitor
Pelvic floor muscle training
25Dept of Urology, GRH and KMC, Chennai.

26. Pharmacology of Micturition-
Decrease outlet resistance
Decrease bladder neck & urethral resistance
Alpha-adrenergic blockers-dibenyline, terazosin,
tamsulosin, doxazosin
Nitric oxide donors
Botulinum toxin
Polysynaptic blocker –baclofen, diazepam
26Dept of Urology, GRH and KMC, Chennai.

27. Combination of Medication-Improve
Voiding Efficiency
Increased bladder sensation-intravesical capsaicin,
RTX
Detrusor overactivity-anticholinergic, intravesical
RTX, botulinum toxin
Detrusor underactivity –parasympathomimetics,
alpha-blocker, NO donors, striated muscle relaxant,
periurethral botulinum toxin injection
27Dept of Urology, GRH and KMC, Chennai.

28. Combined Medication –Improved
Voiding Efficiency
Urethral sphincter hypertonicity-alpha-blocker, NO
donors, striated skeletal muscle relaxant
Urethral sphincter overactivity-alpha-blocker, striated
muscle relaxant, NO donors, botulinum toxin
Bladder neck dysfunction-alpha-adrenergic blocker
28Dept of Urology, GRH and KMC, Chennai.

29. Combined Medication-Improved
Storage Efficiency
Detrusor Overactivity-anticholinergics,
sympathomimetics, imipramine
Intrinsic sphincter deficiency-imipramine,
sympathomimetics
DHIC-depends on voiding efficiency and grades of
incontinence
29Dept of Urology, GRH and KMC, Chennai.

30. 30Dept of Urology, GRH and KMC, Chennai.

31. CHANGES IN BLADDER FUNCTION
FREQUENCY-
AT BIRTH -30 TIMES.
6-12MONTHS -10-15
2YRS -8-10
12YRS -4-6
BLADDER CAPACITY-( ML)
KOFF’S FORMULA-(AGE(YRS)+2)*30
-INCREASES WITH AGE.
DETRUSSOR PRESSURE
-HIGH IN 1-2 YRS-LATER DECREASE WITH SPHICTER
COORDINATION
31Dept of Urology, GRH and KMC, Chennai.

32. PATHOPHYSIOLOGY
BRAIN LESION-lesion above pons control of voiding is
lost.primitive reflex persist.pt show urge incontinence or spastic
bladder.detrusor hyperreflexia with sphincter synergia.
Eg-stroke ,brain tumour.
SPINAL CORD INJURY-lesion bet pons and sacral cord-spinal
shock-urinary retention
After6-12 weeks nerves reactivates-urge incontinence.
-capsicain sensitive c fibres mediate these reflexes.
-neurotrophic growth factors produced in hypertrophied bladder muscle
contributes to c-fibre stimulation.
-detrusor sphincter dyssynergia with detrusor hyperreflexia.
SACRAL CORD INJURY –detrusor areflexia
PERIPHERAL NERVE INJURY-DM,AIDS-painless retention
of urine,hypocontractile bladder.
32Dept of Urology, GRH and KMC, Chennai.

33. THANK YOU
33Dept of Urology, GRH and KMC, Chennai.