Urology Flashcards
Core concepts of the lower urinary tract
- dependent on the CNS
- element of voluntary
- function dependent upon learned behaviour
- neural activity : tonic / phasic
Micturition: a goal oriented behaviour example
Stages
- Initiation and imagination
(Initial sensation of needing to urinate) - Exploring and foraging
(Thinking of fete where you can go to if the urge arises) - Attainment and satiation
(Urge to urinate)
Explain the phasic activity and functions of the LUT
Storage phase
(low pressure collection of urine in the bladder)
- detrusor = relaxed
- sphincter = active (contacts to stop urination)
Voiding phase
(Periodic expulsion through urethra)
- detrusor = Active
- sphincter = relaxed
Peripheral innervation and the LUT
Sympathetic
(T11-L1 spinal cord segments)
- sphincter and detrusor innervation
Parasympathetic
(S2-4 spinal cord segments)
- detrusor innervation
Somatic
- external urethral sphincter
How the spine controls the phases of LUT
Storage
- bladder to urethra procontinence guarding reflex
- sympathetic mediated detrusor relaxation
Full bladder
- bladder to urethra inhibitory reflex
- bladder to urethra e excitatory reflex
- these form part of the spinobulospinal reflex which allows higher centres to exert control over voiding
What are the four conditions, to allow for voiding
- Is there enough urine in the bladder ?
- Is it socially appropriate?
(Must take place at the right time and place) - Is voluntary voiding emotionally appropriate?
(Consider secondary emotions eg embarrassment) - Is it safe to void?
(Any threats to environmental)
Investigating LUT functions
Imaging studies evaluating grey matter activity:
Changes to metabolism
- SPECT
- PET
Changes in blood flow oxygen levels
- PET
- fMRI
- Near Infrared spectroscopy (NIRS)
Changes in electrical and magnetic signal:
- EEG
- MEG
- evoked potentials
Bladder filling:
(Healthy control)
-good bladder control
-small volume infused
-mild sensation
-large bladder volume
-strong desire to void ^
(Poor bladder control)
- urinary urgency and proven DO
- small volume infused
- mild sensations
- large volumes
- strong desire to void but no DO
What are the key forebrain regions involved?
- dorsal anterior cingulate cortex
- insula (important role in introception)
- medial prefrontal cortex (mPFC)
- parahippocampal cortex
Explain the working model of LUT control;
- forebrain neuronal circuits
The forebrain and brainstem circuits modulate this spinalbulbospinal reflex
Brain stem and spinal cord connections form the spinobulbospinal voiding reflex
(Reflex is inhibited so voiding is maintained)
Circuits:
1 . Is voiding app
- insula medial prefrontal cortex (social aspect involvement)
- direct pathway to PAG
- Is it emotionally appropriate
- generate the desire to void and urgency
- dorsal anterior cingulate cortex (dACC), supplementary motor area SMA
- anterior insula (processing degree of bladder filling) - Is it safe
- parahippocampal complex, PAG (involved in subconscious monitoring of bladder events
Spinobulbar limb of the voiding reflex
Is there enough urine in the bladder?
- afferent signals from the lower spinal cord ascend to the PAG (periaqueductal grey) provide information about bladder fullness
What neuronal circuits are involved in degrees of storage in the storage phase ?
Small bladder volume filling
= unconscious suppression (circuit 3, parahippocampal complex and PAG
Greater bladder volume
= more insular activity, greater perception of bladder fullness
With urgency
= additional continence mechanisms
Activation (circuit 2, dACC/SMA)
Deactivation (circuit 1, mPFC)
Voiding reflex inhibited through the PAG
- as bladder volume and wall tension increase, afferent signals from urothelium and bladder wall receptors become stronger
- stage phase promote urinary storage and suppresses voiding
What are the 2 brain networks that maintain continence and how do they work?
1.Default mode network- resting state
- involves mPFC, parahippocampus gyrus, mid temporal cortex
- most of circuits 1 & 3 overlap (not insula and lateral PFC)
- Co-deactivation occurs when attention is needed
- suppression of voiding through the PAG
2.Salience network
- network involved in detecting stimuli that draw attention
- involves bilateral insula and dorsal anterior cingulate cortex (dACC)*
- circuit 2 overlap
- SMA co-activation ( tightening of pelvic muscles and suppression of detrusor contractions)
- associated with perception of strong desire and urgency (introceptive sensations)
Insula- limbic sensory cortex
ACC- limbic motor cortex
Both frequently co-activated
What is the PAG, ands what does it do
The PAG is the periaqueductal grey
Midbrain PAG
-receives ascending signals from the lower spinal cord
- receives descending signals from forebrain networks
- decision to void based upon input from different neural pathways, decide whether voiding reflex should be triggered or not.
What is the voiding reflex and what does it do?
- activation beyond a set level triggers switch to activate voiding reflex
- when switch in PAG is made, *PMC is activated
*(Pontine micturition centre) - sets of events that initiates micturition
- efferent signals descend through the SC and active parasympathetic regions
- stimulates smooth muscle of bladder- detrusor contraction
- relaxation of urethral sphincter
What is the hierarchy of LUT functions
Cerebral cortex
- sensation/timing of micturition
Brain stem
- coordination of reflexes
Spinal cord
- amplification
Afferent - from SC
Efferent - from PMC
peripheral nerves
- relay
What is the role of each system in the storage phase
- Sympathetic system = Activated
- Parasympathetic system = Inhibited
- Pudendal nerve = Activated
(Pelvic floor, sphincter)
What is the role of each system in the voiding phase
- Sympathetic system = Inhibited
- Parasympathetic system = Activated
- Pudendal nerve = Inhibited
(Pelvic floor, sphincter)
Suprapontine urology
What might you see
Detrusor overactivity
Intact neural programs
(Synergic contraction of the detrusor and sphincter muscles)
PD and urology
PD
- nocturia, urinary urgency, constipation most common non motor symptoms)
- overactive bladder in PD more disabling ( due to worse dopaminergic mechanisms)
Dopamine modulates micturition reflex
Nocturia:
Reduced functional bladder capacity
- detrusor overactive
- reduced bladder compliance
- circadian rhythm disturbances
- incomplete bladder emptying
Nocturnal Polyuria
- medical comorbidities
- circadian rhythm disturbances
- cardiovascular dysautonomia
- nocturnal sleep disturbances - convenience voids.
^ Melotonin improved nocturia
Spinal cord lesion
Types and symptoms
Spinal cord damage, disconnects brain stem centres from spinal efferents regarding information to the LUT
Spinal reflex
- small capacity bladder
- detrusor overactivity
- reduced bladder compliance
- small volume voids
- variable off of bladder sensation
Detrusor sphincter dyssynergia
- during attempted voiding, sphincter contracts concurrently with with detrusor muscles, due to disrupted neural programme
Typical spinal symptoms
- storage/ voiding symptoms
- PVR : usually elevated
- detrusor overactivity, detrusor sphincter dyssynergia
Sacral/ infrasacral lesion
Sacral cord
- voiding difficulties
- chronic retention
- variable loss of bladder sensations
- PVR: elevated
- often acontractile detrusor
What are the management options for urological dysfunction?
Botulinum toxin
Neuromodulation (nerve stimulation)
Oral agents
- antimuscarinic agents
- beta 3 receptor agonists (activate b3)
- Alpha receptor blockers
Incontinence, what are the potential causes?
Overactivity
Overflow
Stress incontinence
Functional
- mobility
- toilet access
Cognitive impairment
- visuospatial disorientation
- memory
- aphasia
- compulsive
- behaviour
- social inhibition
- apraxia
What are the next steps following incontinence ?
- Start tolterodine and review after 3 months
- Check post void residual
- Request a urodynamics test
What is the protocol following reported bladder symptoms in a neurological clinic
Urgency + frequency
Test for UTI
Measure PVR
<100mls —> (YES)
- treat with antimuscarinics
<100mls —> (NO)
- teach CISC, if it doesn’t work then treat with antimuscarinics
Follow up to assess effectivity
If better - continent
No better, test PVR
Measuring PVR:
Incomplete bladder emptying associated with:
- worsening storage symptoms
- recurrent UTIs
What are the types of support and treatment for bladder problems
Oral agents
- fesoterodine (tovias, once daily)
- darifenacin (emselex, once daily)
Botulinum toxin
Neuromodulation
Pelvic flow training
Changes to fluid intake
Bladder training example;
Home based self help
UCLH protocol
Pelvic floor, bladder and bowel exercises.
What are some alternative treatments to bladder problems
Mirabegron
Sympathetic (adrenergic control)
- beta3 adrenoreceptor agonist
- increases relaxation
- increases storage capacity
- decreased voiding frequency
^ follow up showed:
- improved overactive bladder symptoms
Side effects :
- tolerable, but dry mouth
- severe constipation (started using laxatives)
Percutaneous tibial nerve stimulation, PTNS
10-12 week course
- 30 minute weekly sessions
- 34 gauge needle
- 20Hz, 200sec
- current strength changed (0-10 mA)
^ 4 month follow up showed:
- satisfied with symptoms; no longer intrusive
- attend top up as and when required
