NBME 4 B1 Q3 ----Interesting question - stranger016

[ArchivalUser]

17. A 72-year-old man is brought to the physician by his wife because of a 6-month history of difficulty walking, cognitive decline, and urinary incontinence. He has not had dysuria or nocturia. His wife says that his short-term memory is decreased and he has had intermittent confusion. On examination, he has a broad-based, short-stepped gait with some reduction of step height. He is oriented to person and place but not to time. He learns four words with some difficulty and recalls zero after 3 minutes. Which of the following is the most likely explanation for the patient's urinary incontinence?

A
) Bladder neck dyssynergia

B
) Chronic bladder inflammation

C
) Detrusor-sphincter dyssynergia

D
) Failure of bladder neck closure

E
) Failure to inhibit the voiding reflex

[ArchivalUser]

This patient clearly has NPH(Normal Pressure Hydrocephalus):triad of symptoms:dementia,incontinence,and gait disturbance ataxia all frontal lobe syndromes.
But the incontinence is due to Detrusor instability according to Urodynamic studies.
Pl. see the article in link:Mechanism of bladder dysfunction in idiopathic normal pressure hydrocephalus†‡by googling.

So, the And.is probably C

[ArchivalUser]

i think the answer for this one is ee
clearly as u said this patient has NPH...
in NPH due to dilation of the ventricles,there will be distortion of cortical fibres and ehnce there will be damage to the fibers going to the pontine micturation center,this would lead to failure to inhibit the voiding reflex

as u said incontinence is due to detrusor instability but the mechanism is due to loss of inhibition of voiding reflex

i think c would have been right if the lesion would have been below the pon and above the sacrum(UMN lesion)

what do u say?

[ArchivalUser]

Agreed you are right, that's the mechanism.