Neurourology Flashcards
What composes the upper and lower urinary tracts? What are functions of lower tract?
Upper: kidney, ureter
Lower: bladder, urethra for storage and periodic expulsion
What kind of reflex does micturition depend on?
Spinal-pontine-spinal reflex pathway, aka supraspinal reflex
What brain areas are involved in voluntary control of the bladder? What areas receive sensory input?
Motor: medial PFC and cingulate gyrus
Sensory: PAG, VPL (thal), insular cortex
What will a lesion to medial PFC cause?
Urinary incontinence
Describe the conscious viscerosensation of bladder pathway.
Bladder -> a-delta thinly myelinated fiber to DRG -> interneuron in S2,3,4 -> PAG, VPL -> insular cortex
What causes stress incontinence?
Pressure from coughing, laughing, sneezing, lifting; due to bladder support issues
What is urge incontinence? What are causes?
Sudden onset of intense urge, overactive bladder; bladder irritation/tumors, diabetes, bening prostatic hypertrophy
What is overflow incontinence? Causes?
Cannot empty bladder, leading to overflow; benign prostatic hypertrophy
What is functional incontinence? Causes?
Physical or mental impairment; paralysis or dementia
What is reflex incontinence? Causes?
Urine loss without sensation/warning; SCI
Describe innervation of the bladder.
ANS PSNS and SNS in inferior hypogastric plexus, and somatomotor pudendal n to external sphincter
Where is the pontine micturition center? What does it do? What neurotransmitter does it use?
Dorsal part of rostral pons; part of voiding reflex to empty bladder when distention detected; glutamate
How do SCI affect bladder control?
Renal failure due to lack of voiding reflex, requires catheterization
Where are beta adrenergic sympathetic receptors on the bladder, and what do they do?
Detrusor muscle, for relaxation and storage of urine
Where are alpha adrenergic sympathetic receptors on the bladder, and what do they do?
Internal urethral sphincter, to contract for continence
What class of medicine can help urinary incontinence?
Cholinergic blocking drugs, although contraindicated in geriatrics for worsening cognitive impairment
What are the three targets of sympathetics reflexes to maintain continence?
Inhibit ganglionic PSNS in bladder, inhibit detrusor (beta receptors), stimulate internal sphincter (alpha receptors)
What is the external urethral sphincter reflex?
DRG detection of distention -> interneuron -> pudendal somatomotor to contract external urethral sphincter
What is the guarding reflex?
After intense abd/perineal stimulation DRG -> interneuron -> pudendal to contract external urethral sphincter
How does guarding reflex change after SCI?
Interneuron inhibits pudendal nerve instead of exciting, leading to relaxation of external urethral sphincter
What is the pathway for voluntary inhibition of micturition?
DRG distention -> inter -> PAG/VPL -> insula, PFC, cingulate -> mPFC -> inhibit PMC & activate pudendal n -> external sphincter
What happens when bladder long tracts aren’t myelinated? In whom is this common?
Loss of bladder control; infants and MS
What happens when there are lesions to medial prefrontal urinary area? What may cause this?
Frontal-type incontinence; falx cerebri meningioma, anterior cerebral a infarct, frontal medial TBI, etc.
What is lesioned to cause areflexic/flaccid bladder?
Loss of detrusor contraction (lesion PSNS S2,3,4, pelvic splanchnic n, or DRG viscerosensory in diabetic neuropathy) and loss of external sphincter control if cord lesion S2,3,4 (pudendal)
What are consequences of areflexic bladder?
Urinary retention and overflow, atrophy of detrusor
What causes hyperreflexic bladder?
SCI above sacral cord or brain lesion (mPFC, post limb internal capsule). Flaccid, then over time C-fiber replaces A-delta fiber, projecting to different interneurons, to sacral PSNS pregang -> chronic firing of detrusor
Which types of neurogenic bladder are considered LMN and UMN bladder lesions?
LMN: areflexic/flaccid
UMN: hyperreflexic/spastic
What is detrusor-external sphincter dyssynergia?
After spastic bladder forms, ext sphincter contracts and does not relax; hypertrophy of detrusor and urge incontinence
What are the consequences of acute SCI/neurogenic shock?
Hypotension, bradycardia, priapism, loss of bulbo-anal reflex, temporary reflex loss below lesion (until shock over)
What is autonomic dysreflexia?
After SCI above T6, SNS below lesion not regulated. Simple stimuli like full bladder cause vasoconstriction sub-diaphragmatic aa
What are the 3 classic signs of autonomic dysreflexia?
Sudden onset of hypertension, sweating above level of lesion, cutaneous vasodilation above level of lesion
Why is a headache in an SCI patient potentially lethal?
Sign of potentially fatal hypertension stroke due to norepi from postgang SNS
Why does SCI cause cutaneous sweating above the lesion?
Heat stress to hypthal via ALQ -> T-L pregang SNS above lesion -> postgang with ACh -> sweating above level of lesion b/c no input below lesion
