Micturition

Question 1

LMN bladder dysfunction

Answer 1

Lesion in S1-S3 –> pelvic n and pudendal n

1. Dec tone to detrusor m (pelvic n)
2. Dec tone to external urethral sphincter (pudendal n)

Question 2

LMN bladder - clinical picture

Answer 2

Clinical picture:

• urine dribbling from poor sphincter tone
• flaccid bladder, poor detrusor tone
• bladder easily expressed
• bladder volume may be small due to dribbling, but often is very large and distended due to lack of detrusor tone

Question 3

UMN bladder dysfunction

Answer 3

Lesion cranial to L7 (cranial to pelvic and pudendal nn)

• disrupts afferent information from reaching pontine micturition center
• Pelvic n remains intact, so detrusor m retains palpable tone/shape
• pudendal n remains intact, so external urethral sphincter mm retains tone

Question 4

UMN bladder dysfunction - clinical picture

Answer 4

Clinical picture:

• large, full bladder with palpable shape/tone
• difficult to express
• bladder voiding may occur as reflex/overflow urination

Question 5

Autonomic dysfunction (e.g Dysautonomia)

Answer 5

• Common dz in midwest
• dysuria
• attempts to urinate, postures, senses that bladder is full
• but despite normal signals to void, only able to dribble sm amts of urine
• residual volume remains large
• Clinically, other autonomic signs present (e.g. non-responsive PLR, ileus, megaesophagus,m dec anal tone, etc)

Question 6

Bladder atony

Answer 6

• stretch injury of detrusor mm, in which tight junctions are disrupted and bladder contraction cannot occur at the level of the mm fibers
• occurs when bladder remains maximally distended for too long
• poor prognosis for return to fxn, depending on duration
• treat by placing indwelling catheter to keep bladder empty for a few days, combine with pharmacologic therapy

Question 7

Drug for hyperactive urethral sphincter

Answer 7

phenoxybenzamine or prazosin

Question 8

Drug used to relax striated mm

Answer 8

valium

Question 9

Drug for detrusor atony

Answer 9

Cisapride or bethanechol

*Tx with meds to relax urethral sphincter should ALWAYS be instituted first

Question 10

Drug for urethral atony

Answer 10

PPA, estrogen

*remember, this is neuro class –> determine cause (neurological) before we just put patients on drugs