Myogenic failure in posterior urethral valve disease: real or imagined?

It has been suggested that hypocontractility or myogenic failure develops in older boys with a history of 9 posterior urethral valved as the hyperactive, poorly compliant bladders decompensate with age. Also a much higher prevalence of myogenic failure has been reported than we have observed. We determine the prevalence of myogenic failure in boys with a posterior urethral valve and whether myogenic failure was a consequence of earlier detrusor instability or diminished compliance.

We retrospectively reviewed the urodynamic findings of 51 boys after transurethral ablation of a posterior urethral valve. Group 1 (longitudinal group) consisted of 11 boys 12 to 19 years old who had undergone at least 1 serial urodynamic study before and 1 after age 10 years. Group 2 (younger group) included 33 boys whose urodynamic testing was performed before age 10 years. Group 3 (older group) comprised 7 previously treated boys whose initial urodynamic study was done after age 12 years.

Overall, myogenic failure was noted in 3 (all group 1) of 51 (5.9%) patients. Each of the 3 boys initially had a hypocompliant bladder, and myogenic failure developed only after institution of anticholinergic therapy and resolved once anticholinergics were discontinued. An additional 34 boys treated with anticholinergics did not have myogenic failure. No tendency towards myogenic failure or marked increase in bladder capacity for age was noted in the older boys.

In our experience myogenic failure is uncommon and more likely secondary to anticholinergic therapy than a preordained consequence of valve disease. We postulate that our proactive, early aggressive use of urodynamic studies and pharmacotherapy to identify and manage the secondary effects of valve disease reduces the incidence of myogenic failure.